Do outbreaks of mosquito-borne disease always follow floods?

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Water, water everywhere…and mosquitoes soon to follow. It makes sense that with more water you’ll get more mosquitoes and with more mosquitoes you’ll get more mosquito-borne disease. Right? Well, not always.

With floods hitting parts of inland NSW, health authorities have issued warnings about mosquitoes and mosquito-borne disease.

Western NSW, has been substantially impacted by flooding this month and the region has been declared a natural disaster zone. The Lachlan River at Forbes has reached a level not seen for 25 years. There is a lot of water about. 35,000 mega litres of water has also been released from Wyangala dam resulting in further flooding. There could be more to come as “Superstorm 2016” continues to bring rain to south-east Australia. Evacuations continue.

The flooding has come at a time when the weather in warming up and there are already reports of mosquito numbers increasing. The biggest concern is that once the flood water recede, how long will pools of water remain, have mosquitoes got a “jump start”on the season?

On the other side of the world, Hurricane Matthew is threatening Florida. The Bahamas and Haiti have already been hit and more than 2 million people in the US have been told to evacuate their homes. Flooding is expected.

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Mosquitoes need water

There is no doubt that mosquito populations can increase rapidly following flood. There is even a group of mosquitoes commonly called “floodwater mosquitoes“. The desiccation resistant eggs of these mosquitoes are laying dormant in the cracks and crevices of flood plains, just waiting for the water to arrive. When it floods, the eggs hatch and in about a week or so, swarms of mosquitoes emerge.

For the most part, it isn’t immediately following the flooding, but in the weeks and even months following that can provide the most ideal conditions for mosquitoes. If temperatures aren’t high enough to drive rapid evaporation of ponding (or if additional rainfall keeps them topped up), mosquitoes can start building impressing population abundances. With more mosquitoes, the risk of mosquito-borne disease outbreak can increase.

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Rainfall records provided by the Bureau of Meteorology indicate that over the three months to September 2016, some regions of NT, QLD, NSW and Victoria received some of their highest rainfall on record for the period. (Bureau of Meterology)

A look back to floods and mosquito surveillance

In 2011-2012, QLD, NSW and Victoria saw incredible flooding. For those of us working in the field of mosquito-borne disease, we’re well aware of what that flooding can cause. Our attention was sparked when stories starting coming out from locals about this being the biggest flooding since the 1970s. Why was this important? Following flooding in the 1970s, we saw one of the biggest outbreaks of the potentially fatal Murray Valley encephalitis virus Australia has seen. This outbreak, and the response to the actual and potential health impacts, was essentially the genesis of many mosquito-borne disease surveillance programs across the country.

One of those programs was the NSW Arbovirus Surveillance and Mosquito Monitoring Program. Following the flooding in early 2012, there was a huge jump in mosquito populations in western NSW and one of the largest collections of mosquitoes in the history of the program was recorded with over 18,000 mosquitoes collected! Fortunately, we didn’t see any substantial activity of Muray Valley encephalitis virus but elsewhere in Australia, cases were reported.

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Mosquito-borne disease outbreaks need more than just mosquitoes

There is little doubt you need mosquitoes about for pathogen transmission. However, for many mosquito-borne diseases, the pathogens that cause the illness in people are naturally found in wildlife. Person to person transmission may occur but for pathogens such as West Nile virus, Ross River virus or Murray Valley encephalitis virus, the mosquitoes that inject their virus-filled saliva into people have bitten birds or mammals previously.

The role of wildlife is important to consider as the flooding may influence mosquito populations but they can also influence wildlife. While kangaroos and wallabies may be adversely impacted by floods, flood waters can provide a major boost for waterbirds.

In some instances, as is the case for Murray Valley encephalitis virus, floods provide ideal conditions for both mosquitoes and birds!

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Do floods really cause outbreaks of mosquito-borne disease?

There are few studies that have demonstrated that outbreaks of mosquito-borne disease always occur following floods.

Studies in North America had previously concluded that there wasn’t a direct link between hurricanes and flooding and mosquito-borne disease. But, that doesn’t mean there won’t potentially be a boost in nuisance-biting mosquitoes following flooding.There is often widespread spraying to control these pest mosquito populations.

Interestingly, after Hurricane Katrina hit New Orleans in 2005, there was an increase in mosquito-borne disease with more than a 2-fold increase in West Nile neuroinvasive disease. However, other reports noted no significant increase in cases of either West Nile or St. Louis encephalitis viruses. Surveillance for 6 weeks following the hurricane, authorities found no arboviruses circulating in local mosquito populations. These results highlight that much more than water and mosquitoes are required for outbreaks of disease.

In Australia, a recent review looked at the influence of flooding on cases of Ross River virus disease. They found that the evidence to support a positive association between flooding and RRV outbreaks is largely circumstantial. The trouble in predicting outbreaks of Ross River virus disease is that there can be complex biological, environmental and climatic drivers at work and, irrespective of local flooding, there may be other region-specific issues that either increase or decrease the potential for an outbreak.

What should we expect in Australia as summer approaches?

There is no doubt mosquito repellent will come in handy over the coming months. There are already reports of increased mosquito populations in some parts of the country. While nuisance-biting impacts will be a worry, if mosquito populations further increase following flooding, authorities need to remain mindful of a range of other health risks too.

The good news is that unless higher than normal mosquito populations persist into the warmer months, we may not see major outbreaks of disease. It typically isn’t until November-December that we start to see pathogens circulate more widely among wildlife and mosquitoes. Hopefully, if some hot weather arrives, the flood waters will quickly evaporate and abundant mosquitoes populations won’t continue.

Current outlooks suggest that between now and December 2016, south-eastern regions of Australia are likely to receive above average rainfall. Temperatures, though, are likely to be a little cooler than normal. We’re probably lucky that this cooler weather will keep the really big mosquito population increases that we saw a few years ago at bay.

On balance, we’re expecting plenty of mosquitoes to be about as summer starts, hopefully not “mozziegeddon” but enough to ensure the community should stay aware of the health risks associated with mosquito bites and how best to avoid their bites.

Have you seen mosquitoes about already this season? Join the conversation and tweet some shots of local mosquitoes!

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Can social media help translate research to practice and promote informed public health messages?

I’m a Senior Investigator with the Centre for Infectious Diseases and Microbiology – Public Health. One of our primary focuses is translating research into improved public health outcomes. With NSW Population Health and Health Services Research Support Program assisting our work, we’re exploring new ways to achieve this objective. My experience of using social media was selected to be showcased among other case studies in 2015. 


Nuisance-biting mosquitoes and mosquito-borne disease are concerns for local authorities in Australia. 2015 saw the largest outbreak of mosquito-borne Ross River virus disease for more than 20 years with over 9,500 cases nationwide. In NSW, there were 1,633 cases compared to the annual average since 1993 of 742 cases per year. Notwithstanding the current outbreak, other endemic, as well as exotic, mosquito-borne pathogens represent future threats to public health.

As there is no large-scale mosquito control program in NSW, reducing the contact between mosquitoes and people is primarily achieved through the promotion of personal protection measures. NSW Health promotes the use of topical insect repellents in combination with behavioural change to avoid natural mosquito habitats and the creation of mosquito habitats around the home. This information is typically provided in the form of posters, brochures, online factsheets, and seasonal or outbreak-triggered public health messages issued by Local Health Districts or the NSW Ministry of Health.

With the emergence of new communications technologies, particularly the rise in popularity of social media, there are new opportunities for public health communications.

The aim of the current research was to determine the reach of public health messages through social media by tracking engagement, audience and relative value as assessed by media monitoring organisations and metrics provided by hosting services of social media platforms.

Assessing activities and processes

Dr Cameron Webb (CIDM-PH) has focused much attention on filling the gaps between current public health messages and findings from recent research into topical mosquito repellents.[1] For example, while public health messages provide accurate information on the insect repellents that provide the best protection, there is a paucity of information provided on how best these products should be used by individuals and those they care for.

Dr Webb’s engagement with mass media, online media (e.g. The Conversation), a personal blog (e.g. Mosquito Research and Management) and social media (e.g. Twitter) has resulted in substantial exposure of focused and informed public health messages. From mid-2014 through to the end of 2015, Dr Webb participated in over 80 mass media articles and interviews in print, online, radio and television media with public health information reaching an estimated audience of over 10 million people.[2] The focus of his messaging around mosquito-borne disease was to highlight the best way for the community to choose and use mosquito repellents; stressing the importance of active ingredients and application methods. This fills a gap in the current provision of public health information while also augmenting public health alerts and messages associated with the 2015 outbreak of Ross River virus disease.

Social media has become a “go to” source of information for much of the community. Information shared on Facebook, Twitter, Instagram, and YouTube has the potential to shape the habitats and behaviour of the community. Dr Webb is active on Twitter (currently followed by over 4,500 people); he uses the platform to engage with the social media accounts of journalists and broadcasters to establish a voice of authority in the field of mosquito-borne disease prevention and extend the reach and exposure of public health messages broadcast through mass media. Using Twitter to share links to informed articles following interviews reached hundreds of thousands of people by being shared by the social media accounts of journalists, media outlets, government organisations and community groups. During the 2014-2015 summer, tweets by Dr Webb reached an estimate 1.28 million people.[3]

Dr Webb regularly writes open access articles on his website, attracting around 250 daily visitors with over 117,000 article views.[4] In addition to his personal website, Dr Webb regularly contributes articles to The Conversation (a website for academics to share expert opinion and write about their latest research). His articles have attracted over 120,000 readers. However, one article “why mosquitoes seem to bite some people more” (published 26 January 2015) has alone been read by over 1.3 million people.[5] This “non-scholarly” writing not only establishes CIDM-PH scientists as authorities in public health matters but can also assist in directing the public to official health guidance provided on official websites and other sources.

Dr Webb’s activities provide a framework for how health authorities may engage with social media to extend public health messages. Organisations or individuals can connect health authority information with the community through media outlets. He has been invited to share his experiences in this field at local and international conferences and workshops including those coordinated by the Public Health Association of Australia, Australian Entomological Society and Entomological Society of America. In addition, Dr Webb has been invited to provide lectures on the benefits of social media for public health advocacy to undergraduate and post-graduate students at the University of Sydney.

While traditional messaging provided by health authorities will remain a staple in public health campaigns, social media provides a connection between traditional and emerging media and communication organisations. This increased connectivity between public health advocates, the media and community has the potential to greatly improve the awareness of mosquito-borne disease and increase the rate of uptake and application of strategic personal protection measures.

References

  1. Webb C.E. (2015). Are we doing enough to promote the effective use of mosquito repellents? Medical Journal of Australia, 202(3): 128-129.
  2. Estimated audience reported by Kobi Print, Media and Public Relations, University of Sydney, 23 April 2015, based on data provided by media monitoring organisation isentia.
  3. Estimated from total “tweet impressions” for the period October 2014 through April 2015 provided by Twitter Analytics (https://analytics.twitter.com/user/Mozziebites/home accessed 30 April 2015)
  4. Data provided by WordPress statistics (accessed 18 December 2015)
  5. Data provided by The Conversation metrics (accessed 18 December 2015)

This article was originally published by NSW Health showcasing some of the work within the NSW Population Health and Health Services Research Support Program. You can see the original article here.

Managing ‘Mozziegeddon’, Media and Public Health Messages

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Beer, high tides, public holidays and blood thirsty mozzies. The perfect mix to set the media into a spin. How can you get the best public health messages out about mosquito bite protection?

It was almost as tricky managing the media this summer as it was the mozzies. Since late October, I’ve been interviewed on almost 50 occasions. A mix of pre-dawn calls from radio stations to live crossed to nationally broadcast breakfast televsion to taking talkback and dealing with mobile phone dropouts. It was a sweaty and stressful couple of months….and ‘mozzie season’ still isn’t over just yet.

The last few years have followed a pretty similar pattern. I get my first few calls around August/September. This is usually when we get our first blast of unseasonal heat and there are typically a few stories about people noticing bugs about their home and are worried about an early start to the mozzie season.

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Mozzie season kicked off early

This year we genuinely did have an early start to the mozzie season. The warmest spring on record kicked off the mozzie season early and one of the first big stories I did for Channel 9 News was almost derailed by swarms of mozzies! A few of the crew needed to retreat to the safety of their car. You can listen to me speaking with ABC New Radio here.

Following plenty of rain in early December, mosquito populations starting jumping up along the coast. Just in time for the Christmas holidays. During this period it is pretty common to respond to requests from media to talk about mozzies, particularly if there have been some public health alters from local health authorities.

Getting ready for a live cross to Weekend Today (Channel 9) but what you cannot see in this shot is the hundreds of mosquitoes that were swarming around me, standing in the middle of the mangroves for 20min getting ready for the segment attracted plenty of mozzie attention!

Getting ready for a live cross to Weekend Today (Channel 9) but what you cannot see in this shot is the hundreds of mosquitoes that were swarming around me, standing in the middle of the mangroves for 20min getting ready for the segment attracted plenty of mozzie attention!

A few things helped keep mozzies in the news. There were health warnings from local authorities after the detection of Ross River virus in southern Sydney. There were warnings about a new outbreak of dengue in Far North QLD. Flooding in central Australia also prompted warnings of outbreaks of mosquito-borne disease.

Then there was this piece I wrote on why mosquitoes bite some people more than others that attracted plenty of attention too….over 1.2 million readers in fact (thanks to republication by IFLS, SBS and Mamamia)!

Moztralia Day Mozziegeddon

As we headed towards our national holiday weekend and Australia Day celebrations, there were warnings that a big boost in mosquito populations were on their way. Yes, “mozziegeddon” was coming and the pesky little biters were set to turn our long weekend into a “moztralia day bloodbath“. Worse still, those taking part in the traditional Australia Day past time of beer drinking were being scared off the booze by fears of becoming “mozzie magnets“.

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“Mozzigeddon” turns Australia Day into Mozztralia Day! Great cartoon by Paul Zanetti accompanying a story at News.com

There is little surprise that stories about beer drinking and mozzies attract plenty of attention. It does almost every year. However, this year was a little different because health authorities were concerned about potential increases in mosquito populations and given recent detections of mosquito-borne pathogens such as Ross River virus, there was concern about public health risks. Those risks range from both the north coast of NSW to north-west of WA!

There was plenty of mosquito media coverage from SE QLD too. Local authorities were battling big mosquito populations and trying to control “3000 known mosquito breeding sites” the next generation of mosquitoes hatching following heavy rain and tidal flooding of local wetlands.

Local insect repellent manufacturers were also taking advantage of the boost in mosquito numbers. I’ve noticed an increase in tv and radio ads spruiking mosquito repellents and Aerogard also sent out “swat” teams to local parklands around Sydney on Australia Day promoting their “Mozzie Index“* website!

Aerogard "Bite Busters" hit the prime picnic spots around Sydney on Australia Day

Aerogard “Bite Busters” hit the prime picnic spots around Sydney on Australia Day

How could this media interest help spread the word on effectively stopping mosquito bites?

In the lead up to the long weekend I spoke with the breakfast show on 2UE (you can listen to the interview via link), Angela Catterns on 2UE, Chris Smith on 2GB as well as Robbie Buck and Linda Mottram on 702 Sydney. I provided a couple of brief grabs for news bulletins and even did my first live cross for the Sunrise breakfast program on Channel 7. You can also listen to interviews with 2SER, ABC Perth and ABC South East SA. [update 26 February 2015. There were a few more interviews, one fun one was with Richard Stubbs for 774 ABC Melbourne and you can listen in below, another was with Dom Knight on 702 ABC Sydney and you can read about that here. and I also chatted with Patricia Karvelas on Radio National Drive and you can listen here.]

It can be tricky getting good public health messages out during these very brief interviews, particularly for television. Radio can be pretty good as there is often plenty of time to get the message out (sometimes even time for talk back callers and questions) but for some of the commercial stations, time can be brief. Television is particularly challenging, I usually spend more time in the make up chair than being interviewed!

This summer I’ve been determined to ensure some key messages get out, particularly about choosing and using insect repellents most effectively. This is an issue I feel strongly about and I have an article coming out shortly in the Medical Journal of Australia on how local health authorities can do this a little better.

The two key messages were “if you’re using botanical based topical repellents, they need to be reapplied more frequently than the recommended DEET and picaridin based repellents” and “when using repellents, they must be applied as a thin coat over all exposed skin to get the best protection, not a dab here and there”.

Overall, I think I managed to get these two points into most radio and television interviews and I was happy to see that the general message got through in a lot of the print/online media too.

Below are some of my tips on getting a specific message out while dealing with the media.

1. Prepare. You would practice giving a conference presentation ahead of time so why not prepare for media? Think about the messages and how you can deliver them. What questions might you get asked? What will be the style of the presenter? Are there any questions you may be asked that you may want to avoid answering (e.g. questions of a political nature or something that could embarrass your employer)? How can you do that?

2. Learn from the professionals. If know you’re going to do some media in the coming weeks or months. Spend some time listening to talk back radio and reading newspapers. Take note of the number and length of quotes journalists use in articles. Make their job a little easier by providing concise quotes where possible. How do radio broadcasters conduct interviews? Listen to politicians and journalists being interviewed. How do they get their message across (or don’t in some circumstances). What makes you “switch off” from an interview – is it the topic or interviewee?

3. Create bridges between questions and your message. This is the thing I’ve found quick tricky but once you’ve got the hang of it, you can more effectively get the message out. There may not be a question asked that specifically relates to the message you need to get out. Learn how to transition from a brief response to the question asked onto the key messages you want to get out there. Don’t just launch off into your spiel at first chance, it is important to engage with presenter too, its a subtle art but like all things, it is only hard before it becomes easy.

4. Post-interview review. I’ll often take notes after an interview that help prepare for the next one. Things like the type of questions asked or how I answered questions, particularly if I feel my responses were clunky or I rambled a little! I’ve always found it interesting that slight differences in the way that questions are asked can often throw you off balance in an interview. If there are talkback callers, what questions were asked, especially if there was something out of left field! Making a note of these can help when preparing for the next batch of media.

5. Keep track of media activity. You never know when it may come in handy when applying for a promotion, grant or new job. I try to keep track of all media activities by recording the date, journalist, media outlet and brief description of topic. You can also speak to your local media and communications unit to see if they gather statistics on these things too. The team at the University of Sydney are great and it is fascinating to compare the analysis of different media activities, their reach and estimated value.

Perhaps the trickiest thing in all this is assessing whether this media activity actually helped the community prevent mosquito bites. It will be almost impossible to tell from human notification data on mosquito-borne disease given the numbers jump around so much from year to year anyway. What really need is some more attitudinal studies to see how people seek out and follow advice provided by local health authorities on mosquito-bone disease prevention strategies. Another thing for the “to do” list

Webb_NineNews_March2015[update 21 March 2015] Following the detection of Ross River virus amongst mosquitoes collected in NSW combined with a dramatic increase in human notifications of Ross River virus disease, there was another wave of interest by local media. You read a piece at the Sydney Morning Herald and watch a segment with me from Nine News.

Why not join the conversation on Twitter?

*A disclaimer: I provided some assistance to a local PR company back in 2012 that developed the “Mozzie Index” for Aerogard, particularly some info on the associations between mosquitoes and local environmental conditions.