La Niña will give us a wet summer. That’s great weather for mozzies

The return of the La Niña weather pattern will see a wetter spring and summer in many parts of Australia.

We know mosquitoes need water to complete their life cycle. So does this mean Australia can expect a bumper mozzie season? How about a rise in mosquito-borne disease?

While we’ve seen more mosquitoes during past La Niña events, and we may well see more mosquitoes this year, this doesn’t necessarily mean we’ll see more related disease.

This depends on a range of other factors, including local wildlife, essential to the life cycle of disease-transmitting mosquitoes.

What is La Niña?

La Niña is a phase of the El Niño-Southern Oscillation, a pattern of ocean and atmospheric circulations over the Pacific Ocean.

While El Niño is generally associated with hot and dry conditions, La Niña is the opposite. La Niña brings slightly cooler but wetter conditions to many parts of Australia. During this phase, northern and eastern Australia are particularly likely to have a wetter spring and summer.

Australia’s most recent significant La Niña events were in 2010-11 and 2011-12.

Why is wet weather important for mosquitoes?

Mosquitoes lay their eggs on or around stagnant or still water. This could be water in ponds, backyard plant containers, clogged gutters, floodplains or wetlands. Mosquito larvae (or “wrigglers”) hatch and spend the next week or so in the water before emerging as adults and buzzing off to look for blood.

If the water dries up, they die. But the more rain we get, the more opportunities for mosquitoes to multiply.

Mosquitoes are more than just a nuisance. When they bite, they can transmit viruses or bacteria into our blood to make us sick.

While Australia is free of major outbreaks of internationally significant diseases such as dengue or malaria, every year mosquitoes still cause debilitating diseases.

These include transmission of Ross River virus, Barmah Forest virus and the potentially fatal Murray Valley encephalitis virus.

What happens when we get more rain?

We’ve know for a long time floods provide plenty of water to boost the abundance of mosquitoes. With more mosquitoes about, there is a higher risk of mosquito-borne disease.

The amount of rainfall each summer is also a key predictor for seasonal outbreaks of mosquito-borne disease, especially Ross River virus.

Inland regions of Queensland, New South Wales and Victoria, especially within the Murray Darling Basin, are particularly prone to “boom and bust” cycles of mosquitoes and mosquito-borne disease.

In these regions, the El Niño-Southern Oscillation is thought to play an important role in driving the risks of mosquito-borne disease.

The hot and dry conditions of El Niño aren’t typically ideal for mosquitoes.

But historically, major outbreaks of mosquito-borne disease have been associated with extensive inland flooding. This flooding is typically associated with prevailing La Niña conditions.

For instance, outbreaks of Murray Valley encephalitis in the 1950s and 1970s had significant impacts on human health and occurred at a time of moderate-to-strong La Niña events.

Over the past decade, when La Niña has brought above average rainfall and flooding, there have also been outbreaks of mosquito-borne disease.

These have included: Victoria’s record breaking epidemic of Ross River virus in 2016-17 after extensive inland flooding; southeast Queensland’s outbreak of Ross River virus in 2014-15, partly attributed to an increase in mosquitoes associated with freshwater habitats after seasonal rainfall; and eastern Australia’s major outbreaks of mosquito-borne disease associated with extensive flooding during two record breaking La Niñas between 2010 and 2012. These included Murray Valley encaphalitis and mosquito-borne illness in horses caused by the closely related West Nile virus (Kunjin strain).

We can’t say for certain there will be more disease

History and our understanding of mosquito biology means that with the prospect of more rain, we should expect more mosquitoes. But even when there are floods, predicting outbreaks of mosquito-borne disease isn’t always simple.

This is because of the role wildlife plays in the transmission cycles of Ross River virus and Murray Valley encephalitis virus.

In these cases, mosquitoes don’t hatch out of the floodwaters carrying viruses, ready to bite humans. These mosquitoes first have to bite wildlife, which is where they pick up the virus. Then, they bite humans.

So how local animals, such as kangaroos, wallabies and water birds, respond to rainfall and flooding will play a role in determining the risk of mosquito-borne disease. In some cases, flooding of inland wetlands can see an explosion in local water bird populations.

How can we reduce the risks?

There isn’t much we can do to change the weather but we can take steps to reduce the impacts of mosquitoes.

Wearing insect repellent when outdoors will help reduce your chance of mosquito bites. But it’s also important to tip out, cover up, or throw away any water-holding containers in our backyard, at least once a week.

Local authorities in many parts of Australia also undertake surveillance of mosquitoes and mosquito-borne pathogens. This provides an early warning of the risk of mosquito-borne disease.

This article originally appeared at The Conversation on 5 October 2020.

Global Health Security 2019 – Mosquito threats and community engagement

While we can embrace technology to track pathogens and diseases, engaging the community to be more aware of the risk and the ways to avoid them will be critical in reducing the public health burden across the globe. This was a key message repeated again and again throughout the sessions at the inaugural Global Health Security conference in Sydney.

The event around 800 delegates representing academia, local, national and international governmental and non-governmental organizations, public and animal health and security professionals, and the private sector. There were representatives from over 65 countries.

I had the opportunity to contribute in a couple of sessions, firstly the ‘Emerging Infectious Diseases in a Changing Global Environment’ workshop at the university of Sydney. This was co-presented by the Marie Bashir Institute for Infectious Diseases and Biosecurity and CREID – NHMRC Centre of Research Excellence in Emerging Infectious Disease. It was described as an “event is an opportunity for policy makers, public health and clinical researchers, veterinarians, scientists, and WHO representatives to come together and define the health security issues related to emerging infectious diseases (EIDs) and antimicrobial resistance (AMR) in the Asia-Pacific region.”

I spoke about mosquitoes in Australian cities and the challenges facing the management of issues associated with urban planning, constructed and rehabilitated wetlands, endemic mosquito-borne disease risk, and exotic mosquito threats. A little nervous having the Chief Medical Officer of Australia (Prof Brendan Murphy) in the front row, along with representatives of WHO and CDC but a wonderful opportunity to share my research and perspectives on these local issues.

The following day, I spoke in the “Challenges with Zoonotic Diseases” session alongside Elpidius Rukambile and Berihun Afera Tadele. An interesting session (chaired by Siobhan Mor) that, through the panel discussion, highlighted the importance of community engagement, as well as communications between policy makers and those “on the ground” in improving public health outcomes in the “one health” space.

I spoke about the issues surrounding exotic mosquito threats in Australia with a focus on the results of recent work on the far north coast of NSW. The work we did there highlighted the need for cooperation between all levels of government but also the critical importance of engaging the local community. Notwithstanding the effort required to go from property to property searching for introduced mosquitoes, such as Aedes aegypti or Aedes albopictus, understanding the role of the community in this response provided essential. Successful local eradication of any introduced mosquito will require assistance from the local community.

The abstract of my presentation is below:

Building capacity to address the unexpected challenges associated with the emerging threat of exotic mosquitoes in Australia

Webb C (1,2),  Doggett S (2), Piazza K (3), McNicoll D (3), Sly A (4), Neilson J (4), Dean A (5), Bethmont A (6).

1 University Of Sydney, Westmead NSW, Australia; 2 NSW Health Pathology, Westmead NSW, Australia; 3 Tweed Shire Council, Tweed Heads NSW, Australia; 4 Department of Agriculture and Water Resources, Canberra ACT, Australia; 5 University of Queensland, Brisbane QLD, Australia; 6 NSW Health, North Sydney NSW, Australia

Introduction. Ongoing evolution of trade pathways increases the risk of exotic mosquitoes, especially Aedes albopictus and pesticide resistant Ae. aegypti, establishing or expanding their range in Australia. This highlights the need for health authorities to develop strategic response plans considering different risk scenarios. Context and Aim. Key challenges to exotic mosquito response in Australian include capacity at local government level and community acceptance of measures. Several strategic initiatives were used to study these challenges in the NSW Northern Rivers region. Method. Field exercises were undertaken with representatives of 11 local and state authority stakeholders, surveying approximately 300 residential properties for potential mosquito habitats. A survey of community attitudes to mosquito threats and responses was also conducted, with over 700 responses collected. Findings. Surveys found almost 4,000 actual and potential container breeding sites, demonstrating potential for exotic mosquito establishment and subsequent need to manage local transmission risks of pathogens including dengue, chikungunya and Zika viruses. Surveys of community attitudes found significant community resistance to required mosquito control activities, indicating responses would be challenging and need strategic planning. Innovative contribution to policy and practice. Strategic response plans must address mosquito biology but also not underestimate the need for active community engagement.

Overall, it was a wonderful meeting. It was, however, unfortunate that I couldn’t spend as much time in sessions as I would have liked. There were plenty of tweets so check in on the hashtag #GHS2019. There is also the very important “The Sydney Statement on Global Health Security” to come out of the meeting, please check it out.

Were you at the meeting? What did you think? Join the conversation on Twitter.

 

 

The long hot summer of mosquito and media wrangling

“Webb’s a mosquito researcher with NSW Health Pathology, and while it may sound like potentially the worst job in the world to the rest of us, it’s important work.” – Ten Daily, 14 Jan 2019.

Every summer I’m required to juggle those pesky mosquitoes and help out with requests from media. Over the past 6 months or so I’ve responded to about 70 media requests and here is a round up of some fun highlights and other bits and pieces.

There was a wide range of media requests this summer, from morning TV through to talkback radio, podcasts and live interviews via Skype. There was once a time when the only acceptable way to do a radio interview was via landline connected phone. This summer I did interviews via mobile, Skype, and various  smartphone apps! Times are a changing.

A fun segment on Channel 7’s ‘Sunrise’ breakfast show on why mosquitoes bite some people more than others; always a challenge taking in a cage a live mosquitoes to the studio, especially travelling in via public transport!

—

A hot and dry summer must mean less mosquitoes, right?

The outlook for the 2018-2019 “mosquito season” was for it to be fairly routine. The Bureau of Meteorology was predicting a hot and dry summer under the influence of El Nino. At the time I wrote a piece for The Conversation highlighting that just because it was dry, that didn’t mean we wouldn’t see plenty of mosquitoes.

In coastal regions of Australia, tidal flooding of local wetlands often offsets any impact due to lack of rainfall. Mosquitoes such as Aedes vigilax certainly respond well and there were some very high mosquito numbers recorded in early spring. Usually, the media interest in mosquitoes starts increasing once the politicians break for the summer, this year there was plenty of interest early on!

NSW Health also issued a media release to get the community thinking about the potential mosquito impacts ahead of the summer holiday period and asked me to be the spokesperson. These warnings often prompt a different range of media interest, usually news bulletins for radio. Unlike the traditional radio interviews in which you’re responding to the host’s questions, only “grabs” (short statements regarding the topic) are required. I’ve learned there is a fine art to being concise in these statements and it pays to give some thought to what you’ll say ahead of calling up the news desk!

Some of the media coverage in early summer was less about bites and more about why mosquitoes disturb your sleep! I spoke with Channel Ten about how you can beat these bedroom buzzers! Here are some tips on beating the buzz of mosquitoes in the bedroom.

These concerns about mosquitoes in the bedroom prompted questions about the suitability of mosquito coils as a person protection measures. I’d written about this issue before but there was also some media coverage at the Daily Telegraph and Sydney Morning Herald.

There was also a funny segment on The Project:

—

Warm weather, warm blood, and hungry mosquitoes

As summer kicked in, I did a bunch of “pre-season” interviews about the outlook for the mosquito activity ahead. One of them was with the Sydney Morning Herald. There was also a piece in Illawarra Murcury on the mosquitoes around Newcastle. I even chatted with ABC Illawarra about the mosquitoes bringing in the new year along the NSW coast. I also chatted with the team at the Daily Mail. Also the Daily Telegraph.

Once summer really hit (and the mosquitoes really started biting following heavy rains), everyone’s mind turned to one of the most commonly asked questions….why do mosquitoes bite me more than my friends? You can check out my contribution to a story by ABC Science below:

The usual coverage of mosquito impacts during the Australia Day holiday also popped up. Will my diet influence the likelihood of being bitten? I spoke with Channel Ten. The University of Sydney media team also put out a piece on why what you eat or drink makes not difference when it comes to stopping mosquito bites. A story picked up and republished by ABC News.

—

Combining fieldwork and media requests

“Ballina council is calling in an expert to hunt for some ladies – Medical Entomologist Dr Cameron Webb will visit the area next week in search of blood sucking girls.” – EchoNet Daily, Ballina

While undertaking some work for Ballina Shire Council on the NSW far north coast, I helped out managing a few media requests associated with local mosquito problems and the work of council. It was fun squeezing in some print, TV, radio, and social media activities between the work in the wetlands.

I also participated in a “Q and A” on the Ballina Shire Council Facebook page where residents could ask questions about how best to protect themselves from mosquitoes. See here.

Mosquito-borne disease in the city

The detection of Ross River virus in mosquitoes around Sydney sparked some additional interest from media (and anxiety from local community). Coverage in Sydney Morning Herald here.  It prompted me to write an article about what the actual health implications were of finding the pathogen in a heavily urbanised areas such as the Parramatta River compared to the more bushland dominated Georges River.

The issue of wildlife and their role in urban transmission cycles of Ross River virus is always a tricky one. How do you balance wildlife conservation and mitigation of health risks? Together will colleagues I wrote about this at The Conversation.

The media coverage of the Ross River virus detection provided an opportunity for NSW Health Pathology to share some insights into how we research local mosquitoes and the pathogens they’re carrying. See below for a short video from the mangroves along the Parramatta River.

Did you know we monitor mosquitoes around the state to provide public health advice to @NSWHealth? Here’s our mozzie guru @Mozziebites (Dr Cameron Webb) explaining how we do this important work! pic.twitter.com/zpCTs7p3DL

— NSW Health Pathology (@NSWHPathology) January 10, 2019

—

Declining insects, increasing mosquitoes, and the need to spray our backyards

One of the other stories bubbling along during the last year or so were the reports of declining global insect populations. I first spoke to the media about this issue back in early 2018. I was quoted in a couple of other stories too, clearly there was a lot of interest in this issue. This story gained plenty of attention and I spoke with various radio and print media about this challenge were facing with potential insect declines and how we can measure them. I even wrote an article about whether mosquitoes may be in decline too!

I spoke about this issue, and more generally about mosquitoes on an episode of the Science on Top podcast too.

There has been suggestions that insecticides may be contributing to declining insect populations. Earlier in the year, I was one of the coauthors of a paper that called for the need to better understand integrated pest control in our cities and become less reliant on insecticides. There was also an associated article at The Conversation. This was also republished at Domain.

—

Floods in the north, floods in the south

The incredible flooding around Townsville in far north QLD created some major concern. Despite some initial concerns about increased mosquito risk, there weren’t any substantial increases in mosquito-borne disease reported. I spoke to ABC News about the potential risks.

The flooding that did trigger a big boost in mosquito numbers occurred in SE QLD and northern NSW. Local wetlands were inundated by tides and rain, resulting in some phenomenal numbers of mosquitoes in early autumn. I spoke to ABC and Great Lakes Advocate about the climatic factors that triggered this unusual mosquito activity.

Everyone was on weather watch late in the season too. A few extra downpours prompted concerns about more increases in autumn mosquito populations. I spoke with Sydney Morning Herald after a particularly wet weekend in March.

Finally, I helped the Australian Academy of Science make a video exploring why mosquitoes bite and how to stop them!

—

Join the conversation on Twitter, did you catch me talking mosquitoes this summer? Did it help you protect your family from mosquito bites?

—

Mosquitoes feed on frogs, very small frogs…

I was excited to be asked back on the Science on Top podcast recently to record an episode about mosquitoes, currently declines in insect populations (are mosquitoes on the way out too?), and whether recent flooding in north QLD would result in increased mosquito populations and risk of mosquito-borne disease outbreak.

Please subscribe to the podcast, its a really fun and relaxed look at whats making headlines in the science world. The crew themselves describe the podcast as:

The Australian podcast about science, health and technology news. Join Ed Brown and his panel of co-hosts each week as we talk about the latest and coolest research and discoveries in the world of science. We’re joined by special guests from all over the science field: doctors, professors, nurses, teachers and more.

If you’re interested, you can chase up my previous guest spot with them talking “Everything Zika” back in 2016.

I still hold some aspirations of starting my own podcast. Problem is finding the time (there isn’t even enough time to catch up on my podcast “to do” list). Perhaps this is a project for the coming summer.

Would you listen to a podcast about mosquitoes and the people who study them?

You can catch up on a couple of other podcasts I’ve guested on over the past few years. Check out Flash Forward (The Ultimate Swatting) and Arthropod (Getting to Know Mosquitoes).

Oh, and mosquitoes do feed on frogs. Frog blood, not the whole thing. It would have to be a very small frog…

 

 

 

Ross River virus in Sydney, should we be worried?

Health authorities in NSW recently released warnings to avoid mosquito bites following the detection of Ross River virus in wetlands along two major river systems in metropolitan Sydney. Whats going on and should these findings be something to be worried about?

What is Ross River virus?

Ross River virus is the most commonly reported mosquito-borne disease in Australia. The virus is spread by the bite of a mosquito and about 40 different mosquito species have been implicated in its transmission.

The disease caused by Ross River virus is not fatal but it can be severely debilitating.

Thousands of Australian’s are infected each year. We have some idea of the quantity of infections as Ross River virus disease is classified as a notifiable disease. While the official statistics indicate there are around 5,000 cases of illness across the country (there are between 500 and 1,500 cases per year in NSW), there are likely to be many more people that experience a much milder illness and so never get blood tests to confirm infection. These people won’t appear in official statistics.

What makes Ross River virus a fascinating pathogen to study is also what makes it extremely difficult to predict outbreaks. Transmission cycles require more than just mosquitoes. Mosquitoes don’t emerge from local wetlands infected with the virus, they need to bite an animal first and become infected themselves before then being able to pass on the pathogen to people.

It is generally thought that kangaroos and wallabies are the most important animals driving outbreak risk. However, we’re starting to better understand how the diversity of local wildlife may enhance, or reduce, likely transmission risk.

How was the virus found in Sydney?

The recent warnings have been triggered by the results of mosquito trapping and testing around Sydney. NSW Health coordinates an arbovirus and mosquito monitoring program across the state and this includes surveillance locations within metropolitan Sydney.

Mosquitoes are collected using traps baited with carbon dioxide. They trick the mosquitoes into thinking the trap is an animal. By catching mosquitoes, we can better understand how the pest and public health risks vary across the city and the conditions that make mosquitoes increase (or decrease) in numbers.

It mostly occurs around the metropolitan region’s northern and southern river systems and generally associated with estuarine or brackish-water wetlands. In these areas, there are often abundant mosquitoes and wildlife. Along the Parramatta River, there are often abundant mosquito populations but given the heavily urbanised landscape, there aren’t many kangaroos and wallabies.

The nuisance impacts of mosquitoes, such as Aedes vigilax, dispersing from the estuarine wetlands of the Parramatta River can create challenges for local authorities. These challenges include targeted wetland conservation and rehabilitation strategies along with ecologically sustainable mosquito control programs.

Is the detection of the virus in Sydney unusual?

The detection of Ross River virus is not that unusual. Detection of Ross River virus (as well as other mosquito-borne viruses such as Stratford virus) along the Georges River in southern Sydney is an almost annual occurrence. The local health authorities routinely issue warnings and in recent years have successfully used social media to spread their messages.

Ross River virus has also previously been detected along the Parramatta River.

While there have been confirmed local clusters of locally acquired Ross River virus in the suburbs along the Georges River, there have been no confirmed cases of Ross River virus disease in the suburbs along the Parramatta River.

There are a few reasons why more disease isn’t reported. Health authorities are active in promoting personal protection measures, sharing recommendations on insect repellent use and providing regular reminders of the health risks associated with local mosquitoes. It isn’t unreasonable to think these actions raise awareness and encourage behaviour change that reduces mosquito bites and subsequent disease.

Along the Georges River, there is clearly a higher risk of infection given the more significant wildlife populations, especially the wallabies common throughout Georges River National Park. By comparison, along the Parramatta River there are fewer bushland areas and virtually no wallabies (except for the occasional one hopping across the Sydney Harbour Bridge). Even in the wetland areas around Sydney Olympic Park, there is abundant bird life, meaning mosquitoes are probably more likely to be biting the animals than people. A study looking at the blood feeding preferences of mosquitoes in the local area found that animals were more likely to be bitten, mosquitoes actually only fed on humans about 10% of the time.

It is important that if you’re spending a lot of time outdoors in these areas, especially close to wetlands and bush land areas at dawn and dusk when mosquitoes are most active, take measure to reduce the risk of being bitten. Cover up with long sleeved shirts and long pants and apply an insect repellent. Choose a repellent that contains either DEET (diethlytoluamide), picaridin, or oil of lemon eucalyptus. Apply it to all exposed skin to ensure there is a thin even coat – a dab “here and there” doesn’t provide adequate protection. More tips here.

Also, keep in mind that just because cooler weather has arrived, the health risks associated with mosquitoes remain. That means keeping in mind that mosquitoes will be out and about just as football and netball seasons start so take along some mosquito repellent to training nights.

++

Join the conversation on Twitter!

++

 

 

 

 

 

 

 

Can citizen science help stop mosquito-borne disease outbreaks?

Mosquito surveillance has been a critical component of how health authorities manage the risk of mosquito-borne disease. Data on the abundance and diversity of mosquitoes, together with activity of mosquito-borne pathogens, can guide decisions on when and how to apply mosquito control agents or issue public health warnings.

Almost every state and territory in Australia conducts seasonal mosquito surveillance. The exceptions are Tasmania and ACT, although both have had some limited investigations over the years. Even among those doing routine surveillance, the program structure varies but most include the collection of mosquitoes. This is how we can determine if it really is “the worst mosquito season ever”!

The programs are currently are working well in providing early warnings of outbreaks of mosquito-borne disease. These programs often include mosquito trapping undertaken by local governments and, occasionally, members of the public. For may years there has been a strong interest in citizen scientists undertaking mosquito sampling, particularly by some schools. The projects that I’ve been involved with have rarely got off the ground for various reasons. School holidays at the peak of mosquito season doesn’t help. Beyond that, the consumable costs of the traps we use, especially the dry-ice (carbon dioxide) used to bait the traps, can be a barrier to involvement. Dry-ice use in schools, and the associated health and safety issues, has been a cause for concern too. Finally, the fact that mosquitoes may be attracted to traps operated in school or community grounds and that these mosquitoes may be carrying disease-causing pathogens can often raise concerns.

As a result, there really haven’t been any major citizen science based mosquito surveillance programs until recently. Things are changing.

One reason local authorities are starting to turn their minds to a citizen science based approach is that the threat of exotic mosquitoes will require a shift in focus from the swamps to the suburbs. The mosquitoes that drive outbreaks of dengue, particularly Aedes aegypti and Aedes albopictus live in water-holding containers in backyards and populations are not as easily measured by traditional surveillance approaches. This is why there has been a much stronger engagement with the public in Far North QLD (a region where Aedes aegypti is present and causes occasional outbreaks of dengue) where health authorities are regularly visiting backyards looking for and controlling backyard mosquitoes

There are many reasons why citizen science is starting to come into play when it comes to mosquito surveillance more broadly. Technology is getting better (as highlighted by many smartphone apps) but also, some of the laboratory techniques are getting cheaper. This is a really critical issue.

A breakthrough in rapid testing of mosquitoes led to the development of an award winning initiative in Brisbane by Metro South Health and Queensland Health Forensic & Scientific Services. The Zika Mozzie Seeker project combines this new laboratory technique with DIY mosquito traps by the general public to help track exotic mosquitoes. In short, residents create their own mosquito trap out of a bucket or recycled plastic container, it is filled with water and placed in a yard with a small piece of paper hung inside. Mosquitoes then drop by to lay eggs on the paper. After a couple of weeks, the traps are collected and egg filled paper strips sent to the lab and tested to track the DNA of local and exotic mosquitoes. The project has been an amazing success with around 2,000 participants being involved in recent years (that adds up to about 150,000 mosquito eggs collected and tested). Luckily, no exotic mosquitoes have been detected.

But when it comes to citizen science based projects, perhaps it isn’t the mosquitoes collected (the backyard mosquito battles are fun to track though) but the awareness raised that is important. Awareness not only of the risks posed by mosquitoes, but what you can do about them through the safe and effective use of mosquito repellents and other personal protection measures. Engaging the public through citizen science may be the way to go. It doesn’t always work in reaching new audiences, as was discovered in a mosquito surveillance project in South Australia, but that doesn’t mean it won’t!

Perhaps the rise in new smartphone apps will help. There are a few out there, like the Globe Observer and Mosquito Alert. These, and other smartphone apps, deserve their own post (stay tuned). However, the significant initiative of recent years has been the Global Mosquito Alert project. Launched in May 2017, here is an extract from their media release:

The new initiative, launched under the name ‘Global Mosquito Alert’, brings together thousands of scientists and volunteers from around the world to track and control mosquito borne viruses, including Zika, yellow fever, chikungunya, dengue, malaria and the West Nile virus. It is the first global platform dedicated to citizen science techniques to tackle the monitoring of mosquito populations. The programme is expected to move forward as a collaboration involving the European, Australian and American Citizen Science Associations as well as the developing citizen science community in Southeast Asia.

With such momentum, it is an exciting time to consider the potential of citizen science in Australian mosquito surveillance programs. This is what i will be exploring in my presentation at the Australian Citizen Science Conference in Adelaide this week.

I’ll be presenting the paper on Wednesday 7 February 2018 in the “Empower with Data” session. The full abstract of our presentation is below:

The public as a partner in enhancing mosquito surveillance networks to protect public health

Craig Williams (1), Brian L. Montgomery (2), Phil Rocha (2), and Cameron Webb (3)

(1) University of South Australia, School of Pharmacy and Medical Sciences; (2) Metro South Public Health Unit, Queensland Health; (3) Medical Entomology, Marie Bashir Institute of Infectious Diseases and Biosecurity, University of Sydney

Mosquito-borne diseases are pervasive public health concerns on a global scale. Strategic management of risk requires well-designed surveillance programs, typically coordinated by local health authorities, for both endemic and exotic mosquitoes as well as the pathogens that they may transmit. There is great potential to utilise citizen science to expand the reach of current surveillance programs, particularly those centred on urban areas. There is increasing focus internationally on the role of citizen science in mosquito surveillance as evidenced by the establishment of the ‘Global Mosquito Alert’ project driven by multiple international stakeholders and citizen science associations. In Australia, new initiatives to engage the public in mosquito surveillance are emerging in multiple centres; utilizing a range of emerging field and laboratory technologies that remove previously existing barriers to community involvement. In South Australia, citizen science entomology programs have been trialed, and mosquito trapping and identification technology to expand existing trapping networks has been assessed. In suburban South-East Queensland, Zika Mozzie Seeker is linking citizen scientists into a network by using new laboratory techniques to rapidly screen for Ae. aegypti DNA in large numbers of eggs collected from DIY ovitraps,. In NSW, citizen science is being used to promote biodiversity and delineate pest and non-pest activity of mosquitoes associated with urban wetlands and surrounding suburbs. Citizen science holds great potential for public engagement activities as well as serving to enhance existing surveillance operations.

 

Join the conversation on Twitter by following Dr Cameron Webb, A/Prof Craig Williams and keep an eye on the meeting via the hashtag #CitSciOz18

Ross River virus in Melbourne, how did that happen?

Health authorities in Victoria have been warning of mosquito-borne Ross River virus for much of the summer. The state is experiencing one of its worst outbreaks of the disease but cases have mostly been across inland regions. Now it’s hit Melbourne. How has this happened?

Ross River virus is the most commonly reported mosquito-borne disease in Australia. There are usually about 5,000 cases across Australia. However, in 2015 there was a major spike in activity with around 9,000 cases reported. It is a common misconception that the disease is only found in northern regions of Australia. I’m often told “I heard the disease is moving south from QLD?” That’s not the case.

The virus is just as much a natural part of the Australian environment as the mosquitoes and the wildlife that maintain transmission cycles.

While there are generally more cases in northern Australia, nowhere is safe. Some of the largest outbreaks have occurred in southern regions of Western Australia, South Australia, Victoria and even Tasmania.

The virus is widespread but is generally associated with rural regions. A driving factor in determining the activity of Ross River virus is that more than just mosquitoes are involved in outbreaks. The virus is maintained in the environment in native wildlife, especially kangaroos and wallabies. Even when and where there are high numbers of mosquitoes, without wildlife, outbreak risk is low. This is the reason why any clusters of locally infected cases in metropolitan regions are typical in areas where there are wetlands, wildlife and mosquitoes occurring together. We’ve seen this on the urban fringe of Sydney and Perth in recent years.

The announcement of locally acquired cases in the suburbs of Frankston and Casey, in Melbourne’s south-east, has taken many by surprise. Should it have?

Victoria is no stranger to mosquitoes and outbreaks of mosquito-borne disease. There are mosquito surveillance and mosquito control programs in place in many regions and historically there have been major outbreaks of mosquito-borne disease. From freshwater flood plains of the inland to the tidally flooded estuarine wetlands of the coast, Victoria has diverse and often abundant mosquitoes. But cases in the metropolitan region are rare.

Victorian mosquitoes are not all bad but over a dozen different mosquito species can spread Ross River virus.

The region where these cases have been identified are in proximity to bushland and wetland areas. There is no doubt plenty of mosquitoes and suitable wildlife too. While this is the first time local transmission has been documented, that doesn’t mean the virus hasn’t circulated in the past, or even that cases may have occurred.

For individuals infected but only suffering mild symptoms, the illness can be easily discounted as nothing more than a mild case of the flu. Without appropriate blood tests, these cases never appear in official statistics. For this reason, many mosquito researchers believe that the number of notified cases across the country is just the tip of the iceberg with many milder infections going diagnosed.

But why in Melbourne now?

It is difficult to know for sure. The two most likely explanations are that either environmental conditions were ideal for mosquitoes and suitable populations of wildlife were present so that the virus was much more active in the local environment than previously. The second explanation is that the virus may have been introduced to the region by a traveller or movement of wildlife. In much the same way Zika virus made its way from SE Asia to South America in the last few years, mosquito-borne viruses move about in people and animals, much less so than mosquitoes themselves (but that isn’t impossible either).

Victoria (as well as inland NSW) is experiencing one of its largest outbreaks of Ross River virus on record following significant flooding of inland regions. With so much activity of the virus in the region, perhaps an infected bird or person travelling to the metropolitan region brought the virus with them. When bitten by local mosquitoes, the virus started circulated among local mosquitoes and wildlife.

Most people infected by Ross River virus are bitten by a mosquito that has previously fed on a kangaroo or wallaby.

Once it’s made its way to metropolitan regions, the virus can be spread from person to person by mosquitoes. Common backyard mosquitoes, especially Aedes notoscriptus, can transmit the virus but as these mosquitoes are not particularly abundant, don’t fly vary far and will just as likely bite animals as humans, they’re unlikely to drive major urban outbreaks of the disease. This mosquito doesn’t pack the same virus-spreading-punch as mosquitoes such as Aedes aegypti that spreads dengue, chikungunya and Zika viruses. Aedes aegypti isn’t in Victoria.

We’re unlikely to see significant spread of Ross River virus across Melbourne but that doesn’t mean Victorians should be complacent. As there is no cure for Ross River virus disease, the best approach is to avoid being infected in the first place. Preventing mosquito bites is the best approach. For my tips and tricks on avoiding mosquito bites see this recent paper in Public Health Research and Practice as well as my article for The Conversation.

Keep an eye on the website of Victoria Health for more information.

 

 

 

 

 

West Aussies versus the local mozzies

This is a special guest post from Dr Abbey Potter, Senior Scientific Officer, Environmental Health Hazards, WA Health. I’m currently mentoring Abbey as part of The Public Health Advocacy Institute of WA (PHAIWA) Mentoring Program. Its been a great experience as we navigate through some of the strategies to raise awareness of mosquito-borne disease and advocate for better approaches to addressing the public health risks associated with mosquitoes.

Living in WA, we’re all too familiar with the pesky mosquito. We know they bite but what we often don’t consider is that they can transmit serious and sometimes deadly diseases. In fact, a recent survey of locals indicated that knowledge of mosquito-borne disease is pretty limited, particularly among younger adults aged 18-34 years and those living in the Perth Metro. It’s pretty important we’re aware of the risks posed by these pint-sized blood suckers and how you can avoid them… and here’s why!

The Facts

On average, more than 1,000 people will be infected with a mosquito-borne disease in WA every year. Our mossies can transmit Ross River virus, Barmah Forest virus, West Nile virus (Kunjin substrain) and Murray Valley encephalitis virus. All four cause diseases that are debilitating at best, causing weeks to months of symptoms. Murray Valley encephalitis is limited to the north of the State but is so serious it can result in seizures, coma, brain damage and even death.

Forget the bush, most people bitten in their own backyard. West Aussies are all very prone to getting eaten alive while socialising outdoors but if you’re up in the north of the State, you’ve also got a much higher likelihood of being bitten while boating, camping or fishing or working outside, compared to the rest of the state.

And don’t think you’re off the hook when you head off on holidays. A further 500 WA residents return from overseas travel with an exotic mosquito-borne disease every year. Heading to Bali? Beware of dengue, especially young adult males who return home with the illness more than others. There is limited mosquito management in many overseas countries where disease-transmitting mozzies can bite aggressively both indoors and throughout the day. This catches West Aussies off guard, as we are accustomed to mozzies biting outdoors, around dusk and dawn. When you’re in holiday mode it’s likely that you’ll be relaxing, having a couple of drinks and not thinking about applying repellent. Oddly enough, mosquitoes may actually be more attracted to people whose body temperature is higher. This happens naturally when you consume alcohol, so best pull out the repellent before you crack your first beer.

Despite our attractiveness to mosquitoes, we aren’t really aware of the most effective ways to avoid bites or how we can do our bit to reduce breeding in our own backyards. If you live by the mantra Cover Up. Repel. Clean Up you’ll have no problems!

Western Australia has some amazingly beautiful wetlands but these saltmarshes around Mandurah can produce large populations of nuisance-biting mosquitoes!

Cover Up

If you know you are going to be outdoors when mosquitoes are active, wear loose, long-fitting clothing that is light in colour. Believe it or not, mosquitoes can bite through tight pants as tough as jeans – I’ve witnessed it!

If you’re staying in accommodation that isn’t mosquito-proof, consider bed netting.

Try to keep children indoors when mosquitoes are most active. If exposure can’t be avoided, dress them appropriately and cover their feet with socks and shoes. Pram netting can also be really useful.

Admittedly, it’s not always practical to wear long sleeves during our warm summer nights, so there are going to be times when you need to use repellent. Choose a product that actually works and apply it appropriately so it does the job. Despite our best intentions, this is where we often go wrong. There are a few basic things to cover here, so stick with it!

Ingredient: Science tells us that the best active ingredient for repelling mosquitoes is diethyltoluamide (DEET for short) or picaridin. You need to look for either one of these names on the repellent label under the ‘active constituents’ section.

Unfortunately, natural repellents and anything wearable (e.g. bands, bracelets or patches) have very limited efficacy. Experts don’t recommend you use them and I consider this very wise advice. It only takes a single mosquito bite to become infected and chances are you will receive at least one if you rely solely on a product of this nature. It just isn’t worth the risk.

Percentage: The next thing to consider is the percentage of the active ingredient. This can range anywhere from 7% to 80% which can make choosing a repellent confusing. Just remember, the higher the percentage, the LONGER the product will remain active for. It doesn’t mean it will repel mosquitoes better.

A repellent containing 16-20% DEET will provide around 4-6 hours of protection, and is a good place to start. Repellents labelled ‘tropical strength’ usually contain greater than 20% DEET – they are useful when you spend longer periods exposed to mosquitoes or if you are heading to a region where dengue, malaria or Zika is problematic. Kids repellents usually contain picaridin or <10% DEET.

Sometimes it can be tricky to work out the percentage of the active ingredient. You can see the Bushmans example below states this clearly, but the other bottles list the ingredient in grams per litre (g/L). No need for complex maths – just divide by 10 and you have the magic number! For example, the RID label below reports the product contains 160g/L of DEET. This would convert to 16% DEET – easy!

You can see a few examples here of effective repellents:

How to Apply: No doubt we would all prefer if repellents didn’t feel quite so gross on our skin or didn’t smell so bad. Even I have to admit that before I moved into this field, I was guilty of putting just a dab here and a dab there. Unfortunately, this is flawed logic that will only result in you being bitten!

Repellents must be applied correctly to be effective. That means reading the label and applying it evenly to all areas of exposed skin. Remember to reapply the product if you are exposed to mosquitoes for longer than the repellent protects you for. You’ll also have to reapply the repellent after sweaty activity or swimming.

For more information on repellent use in adults and children, click here.

Clean Up

Mosquitoes need water to breed, but only a very small amount. Water commonly collects in a range of things you may find in your backyard including pot plant drip trays, toys, old tyres, trailers and clogged up gutters. Mosquitoes also love breeding in pet water bowls, bird baths and pools if the water is not changed weekly or they are not well maintained. Rain water tanks can also be problematic so place some insect proof meshing over any outlets. When you’re holidaying, cover up or remove anything that may collect water.

**

If you need more official info from WA Health about mosquito-borne disease or simple ways to prevent being bitten click here. And if you want to read more about how much West Aussies know (or don’t know) about mossies, check out Abbey’s excellent paper here! Joint the conversation too on Twitter by following Abbey and Cameron.

Social media and blood suckers showcased at the International Congress of Entomology

Digital technology is changing a lot about how we undertake entomological research and communicate the results of that research to the community and policy makers.

This week in Orlando, Florida, is the International Congress of Entomology (ICE). A huge gathering of entomologists from around the world. While it was a great pleasure to be invited to participate, I couldn’t get over there this time.

I will, however, have a chance to present my work in the Symposium “Entomology in the Digital Age”  Friday, September 30, 2016 (01:30 PM – 04:45 PM), Convention Centre Room W222 A.

In the presentation I’ll share some of the reasoning behind my use of social media to engage the community with both entomological research and public health communication. Most importantly, it will focus on some of the metrics I’ve recorded alongside my use of social media, maintaining a blog of research and writing for outlets such as The Conversation.

I’ve written about my use of social media and how it can help extend the reach of public health messages and presented on the topic alongside a range of great speakers at the 2014 Entomological Society of America meeting in Portland.

This time around, technology is playing an even more direct role in my presentation! I’ve pre-recorded my presentation and it will be shown to the audience on the day among other presentations. I’ll also be checking into the session to answer questions. Despite the fact I’ll need to be up around 1:30am due to time differences, it should be fun.

See the abstract below…

Taking entomological research from the swamps to the suburbs with social media

Cameron E Webb

Connecting scientists and the community is critical. This is particularly the case for medical entomologists working in the field of mosquito-borne disease where the translation of entomological research into improved public health outcomes is a priority. While traditional media has been the mainstay of public health communications by local authorities, social media provides new avenues for disseminating information and engaging with the wider community. This presentation will share some insights into how the use of social media has connected new and old communications strategies to not only extend the reach of public health messages but also provide an opportunity to promote entomological research and wetland conservation. A range of social media platforms, including Twitter, Instagram, and WordPress, were employed to disseminate public health messages and engage the community and traditional media outlets. Engagement with the accounts of traditional media (e.g. radio, print, television, online) was found to be the main route to increased exposure and, subsequently, to increased access of public health information online. With the increasing accessibility of the community to online resources via smartphones, researchers and public health advocates must develop strategies to effectively use social media. Many people now turn to social media as a source of news and information and those in the field of public health, as well as entomological research more generally, must take advantage of these new opportunities. doi: 10.1603/ICE.2016.94611

---

If you’re at ICE, you can also catch up with my PhD student David Lilly who’ll be presenting our research into the development of insecticide resistance in bed bugs as part of the symposium “New Insights into Biology, Resistance Mechanisms, and the Management of the Modern Bed Bug” Friday, September 30, 2016, 01:30 PM – 04:45 PM, Convention Center, West Hall F4 (WF4).

Novel insecticide resistant mechanisms in the common bed bug, Cimex lectularius

David Lilly, Cameron E Webb and Stephen Doggett

Introduction: Research on field strains of Cimex lectularius from Australia has identified widespread resistance to pyrethroid insecticides, but variability in the magnitude expressed. To determine if differences in resistance mechanisms exist, collected strains were examined for the presence of metabolic detoxification and/or cuticle thickening. Methods: The presence and relative contribution of detoxifying esterases or cytochrome P450 monooxygenases were assessed. Bed bugs collected from Parramatta (NSW), Melbourne (VIC) – 2 strains, ‘N^o.2’ and ‘N^o.4’, and Alice Springs (NT) were exposed in topical bioassays employing deltamethrin and two pyrethroid synergists: piperonyl butoxide (PBO) and EN16/5-1. PBO inhibits both monooxygenases and esterases, whereas EN16/5-1 will inhibit esterases only. Thus in a comparative bioassay, the results can infer the dominant enzyme system. The Parramatta strain was then selected to study the potential presence of cuticle thickening. Nine-day-old male bed bugs were exposed to filter papers treated with the highest label rate of Demand Insecticide^®(200mL/10L of 25g/L lambda-cyhalothrin) and were grouped according to time-to-knockdown (< 2 hours, ≥ 4 hours, and survivors at 24 hours). Measurements of mean cuticle thickness at the transverse midpoint of the second leg tarsus were taken under electron microscope. Results/Conclusion: All strains possessed resistance that was inhibited by the synergists, with the Parramatta and Melbourne N^o.2 indicating esterase-dominance, and Alice Springs and Melbourne N^o.4 indicating cytochrome P450 monooxygenase-dominance. Cuticular measurements demonstrated that bed bugs surviving deltamethrin exposure had significantly thicker cuticles, denoting a novel form of resistance in these insects. doi: 10.1603/ICE.2016.92553

 

You can also see Stephen Doggett (co-author and photographer of A Guide to Mosquitoes of Australia) speaking on photographing mosquitoes to in the symposium “Insect Photography Symposium: Bringing the Small to the World.”

---

You can join the conversation on Twitter and keep an eye on all the fun in Orlando by keeping an eye on the tweet stream!

 

Taking Australian wetland research to China

My PhD student Jayne Hanford has been super busy this year. Not much more than a year into her candidature and she has already locked away a summer of research and has been presenting her findings at conferences here in Australia as well as overseas.

After recently sharing our research at the Society for Wetland Scientists Annual Conference held in Corpus Christi, Texas, USA and the Mosquito Control Association of Australia conference on the Gold Coast, Jayne is off to China for the 10th INTECOL International Wetlands Conference.

Her research is focused on understanding the links between wetland vegetation, aquatic biodiversity and mosquito populations. Better understanding of these links will assist management strategies that minimise actual and potential pest and public health risks associated with mosquitoes and urban wetlands.

Our abstract for the conference is below:

Is the Biodiversity Value of Constructed Wetlands Linked to their Potential Mosquito-Related Public Health Risks?

Jayne Hanford¹, Cameron Webb², Dieter Hochuli¹

¹School of Life and Environmental Sciences, The University of Sydney, Australia; ²Department of Medical Entomology, Westmead Hospital and The University of Sydney, Westmead, Australia

 Stormwater treatment wetlands constructed in cities can enhance the sustainability of urban biodiversity by providing wildlife refuge areas and habitat connectivity. However, the creation of wetlands for stormwater infrastructure can increase risks to public health and wellbeing by proliferating nuisance-biting and pathogen-transmitting mosquitoes. In severe cases, this proliferation can erode goodwill in the community for creating and protecting valuable wetland systems.  We compared mosquito assemblages at 24 natural and constructed urban wetlands in the greater Sydney region, Australia. Our aim was to determine if stormwater wetlands constructed with the goal to support high biodiversity value also had reduced associated mosquito risks. Wetlands were located across a gradient of urbanisation determined by surrounding human population density, and included sites with different aquatic and riparian habitat complexity and availability. Adult and larval mosquitoes and aquatic macroinvertebrates were sampled on two occasions through summer and autumn. Aquatic macroinvertebrates were used to derive health indices, as well as being a relative measure of aquatic diversity.  Diversity of adult mosquito species was high, and abundance varied greatly between wetlands. Macroinvertebrate assemblages were also highly variable between sites. Wetlands with greater habitat complexity had lower adult mosquito abundance and greater mosquito species diversity, compared to stormwater-specific wetlands with minimal available habitat. As expected, mosquito assemblages did not respond to urbanisation and aquatic macroinvertebrate assemblages per se, but appeared to respond to a complex suite of coarse and fine-scale features that may affect a wetland’s biodiversity value.  Effectively integrating wetlands into cities requires balancing their design for water infrastructure purposes, biodiversity resources and public health and wellbeing requirements. Understanding the risks as well as the benefits will enhance the value of constructed urban wetlands in sustainable cities while minimising public health risks posed by mosquitoes.

Jayne will be speaking in the “The next generation of wetland science: ecosystems, applications, and engineering” session in the Nanhu Room 1520-1530 on Wednesday 21 September.

You can keep an eye on whats happening in China by following Jayne on Twitter and checking the hashtag #IWC10

The Society for Wetland Scientists Annual Conference held in Corpus Christi, Texas, USA back in May included a paper by Jayne titled “Risky Wetlands? Conflicts between biodiversity value and public health” and prompted some great feedback and discussion among wetland scientists at the meeting. It was a successful trip and a timely reminder that I must get to one of the SWS meetings sometime soon, perhaps Puerto Rico?

Keep an eye out for Jayne’s research publications soon!