Zika virus: Resources, references and recommendations

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The following is a collection of almost 100 links to news stories, resources, references and recommendations associated with mosquito-borne Zika virus and the current outbreak in the Americas.

What is Zika? What are the health threats and why an outbreak now?

Zika virus (CDC). Essential resource. Click.

Zika virus (WHO). Essential resource. Click.

Zika virus spreading explosively, says World Health Organisation (The Guardian). Coverage of statement by WHO Director General that the explosive outbreak of Zika virus in the Americas as “deeply concerning” and that an emergency committee has been convened. Click.

WHO Director-General summarizes the outcome of the Emergency Committee regarding clusters of microcephaly and Guillain-Barré syndrome (WHO). Click.

Zika virus declared a global health emergency by WHO (ABC News). Click.

Zika Virus Spreads to New Areas — Region of the Americas, May 2015–January 2016 (CDC). Click.

WHO early response to Zika virus praised by Australian experts (The World Today). Click.

First report of autochthonous transmission of Zika virus in Brazil (Memórias do Instituto Oswaldo Cruz). Click.

How a Medical Mystery in Brazil Led Doctors to Zika (New York Times). A summary of how health officials investigating a spike in cases of birth defects put together the link to a mosquito-borne disease. Click.

Explainer: where did Zika virus come from and why is it a problem in Brazil? (The Conversation). A good, brief summary of the emergence of Zika virus in Brazil and the health risks it poses. Click.

Zika virus outbreak: What you need to know (New Scientist). A good summary of issues associated with Zika virus outbreak. Click.

Zika outbreak: What you need to know (BBC). A good summary of what is known of Zika virus and its health risks. Click.

What to Know About Zika Virus (The Atlantic). Click.

Zika virus, explained in 6 charts and maps (Vox). Useful collection of infographics on Zika virus, current and historic outbreak distributions and health impacts. Click.

An Illustrated Guide To The Zika Outbreak (Huffington Post). Click.

Why it’s wrong to compare Zika to Ebola (The Conversation). Whats the difference between Ebola and Zika viruses? What are the implications of outbreaks and declarations of public health emergencies? Click.

Zika fever: panic won’t help us (The Guardian). Editorial highlighting the horror and unexpectedness of the Zika virus outbreak in Brazil and how we should move forward in mosquito control. Click.

What we still don’t know about Zika virus (Mashable). There are plenty of gaps in our understanding of Zika virus. Click.

The human cost of Zika is clear, but will Brazil’s economy suffer too? (The Conversation). Outbreaks of infectious diseases can have greater impacts than the human illness alone. Click.

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Zika virus and its vectors

Mosquitoes: The Zika vector (Radio National). Why do we need to know how many mosquitoes can spread Zika virus and what is it about the mosquitoes that do that make them such an important pest? Click.

Natural-born killers: mosquito-borne diseases (SMH). What is it that makes mosquitoes such effective vectors of pathogens? Click.

Zika Virus in Gabon (Central Africa) – 2007: A New Threat from Aedes albopictus? (PLOS Neglected Tropical Diseases). Click.

Oral Susceptibility of Singapore Aedes (Stegomyia) aegypti (Linnaeus) to Zika Virus (PLOS Neglected Tropical Diseases). Click.

Aedes (Stegomyia) albopictus (Skuse): A Potential Vector of Zika Virus in Singapore (PLOS Neglected Tropical Diseases). Click.

Potential of selected Senegalese Aedes spp. mosquitoes (Diptera: Culicidae) to transmit Zika virus (BMC Infectious Diseases). Click.

Genetic Characterization of Zika Virus Strains: Geographic Expansion of the Asian Lineage (PLOS Neglected Tropical Diseases). Click.

Molecular Evolution of Zika Virus during Its Emergence in the 20th Century (PLOS Neglected Tropical Diseases). Click.

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The spike in cases of microcephaly and its suspected links to Zika virus infection of those pregnant has been raising greatest concern. (Image: BBC)

Zika virus, pregnancy and microcephaly

Possible Association Between Zika Virus Infection and Microcephaly — Brazil, 2015 (CDC). Click.

Microcephaly in Brazil: is it occurring in greater numbers than normal or not? (Virology Down Under). Great post highlighting the gaps in our understanding of links between microcephaly and Zika virus. Click.

Proving that the Zika virus causes microcephaly (The Conversation).  What questions must be answered to confirm a link between Zika virus and microcephaly. Click.

Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016 (CDC). Click.

CDC: Link between Zika, microcephaly looks “stronger and stronger” (Reuters). Click.

Facts about Microcephaly (CDC). What are the impacts, causes and treatments associated with microcephaly? Click.

Zika virus outbreak raises Pacific, Americas travel concerns for pregnant women (Stuff NZ). Implications for those travelling in Pacific while pregnant. Click.

Safely avoiding mosquito bites when pregnant (Mosquito Research and Management). My tips on safe and effective avoidance of mosquito bites while pregnant. Click.

13 Things Pregnant Women Should Actually Know About Zika (Buzzfeed). Some good advice, most importantly, don’t panic. Don’t even panic if you’re pregnant and bitten by a mosquito. Click.

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Zika virus and the threat to Australia

Does Zika virus pose a threat to Australia? (The Conversation). An overview of why, and why not, Zika virus poses a risk to Australia. Click.

The Threat to Australia: The Rise Of Zika Virus (Popular Science). Article from 2014 highlighting potential risk to Australia of Zika virus following detection of imported cases. Click.

Zika Virus Explained: Aussie Mozzies, Bali Risks And Pregnancy (Huffington Post). Good summary of risks posed to Australia and Australian travellers. Click.

Zika virus: Risk of a widespread outbreak in Australia ‘low’, experts say (ABC News). A summary of reasons why there won’t be a major outbreak of Zika virus in Australia. Click.

Zika talkback with Dr Karl on Triple J (ABC). I join Dr Karl for talkback on Zika virus, advice to travellers and the risks of outbreak in Australia. Click.

Zika virus alert (NSW Health). Factsheet on Zika virus and risk to NSW. Click.

Little chance of Zika outbreak in NSW (Sky News). There is unlikely to be a major outbreak of Zika virus across Australia’s most populated region. Click.

Two Aussies confirmed with Zika as US records first case of virus transmitted through sex (The Mercury). Click.

Zika virus mosquitoes found in Sydney: Airport increases insecticide spraying of incoming passengers (Daily Telegraph). Report of recent detection of Aedes aegypti at Sydney airport by Department of Agriculture and Water Resources. Click.

Queensland announces $1.4 million program to fight Zika. (Brisbane Times). Queensland authorities announce response plan; increasing monitoring and research into Zika virus.  Click.

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Zika virus entering Australia

Zika virus and Travel Alert for Australians (Smart Traveller). Click.

Imported Zika Virus Infection from the Cook Islands into Australia, 2014 (PLOS Current Outbreaks). Click.

Zika Virus Infection Acquired During Brief Travel to Indonesia (Am J Trop Med Hyg). Published report from 2013 of Australian traveller exposed to Zika virus in Indonesia. Click.

Aussie diagnosed with Zika after Bali monkey bite, experts warn of missed cases (SMH). Report of 2015 case os suspected infection following monkey bite in Bali. Click.

Zika Virus Infection In Australia Following A Monkey Bite In Indonesia (Southeast Asian Journal of Tropical Medicine and Public Health). Abstracted from published case report of suspected Zika virus infection following monkey bite. Click.

Six cases of Zika virus in Australia last year as pregnant women warned not to travel (SMH). Summary of recent imported cases of Zika virus infection in Australian travellers. Click.

Health Department confirms WA Zika case (The West Australian). Report of imported case of Zika virus infection in returning traveller to Western Australia. Click.

Zika virus: Queensland woman, child confirmed as contracting illness (ABC News). Imported cases of Zika virus infection with travellers returning to QLD from El Salvador. (ABC News). Click.

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Zika outbreaks in the Pacific

Zika Virus Outside Africa (Emerging Infectious Diseases). Summary of outbreaks in regions outside Africa with specific discussion of the first outbreak in Pacific. Click.

Zika Virus Outbreak on Yap Island, Federated States of Micronesia (New England Journal of Medicine). Click.

Zika virus: following the path of dengue and chikungunya? (The Lancet). Good paper, including useful maps, of activity of three critical mosquito-borne pathogens. Click.

Rapid spread of emerging Zika virus in the Pacific area (Clinical Microbiology and Infection). Publication reporting on the 2013 outbreak of Zika virus in the Pacific. Click.

Notes on Zika virus – an emerging pathogen now present in the South Pacific (Australian and New Zealand Journal of Public Health). An article assessing the risks of Zika virus to New Zealand. Although no suitable vectors exist there, a relatively larger volume of infected travellers would be expected to occur given the strong links to Pacific Islands. Click.

Tonga declares Zika outbreak (Sky News). Zika is impacting more regions than the Americas in 2016. Click.

Australia to help Pacific fight Zika (SBS News). How can Australian authorities take their expertise in mosquito monitoring, mosquito control and vaccine development to assist outbreak of Zika virus. Click.

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Zika virus and sex: An unusual route of transmission

Probable Non–Vector-borne Transmission of Zika Virus, Colorado, USA (Emerging Infectious Diseases). First documented case of transmission of Zika virus through direct contact between people. Click.

Potential Sexual Transmission of Zika Virus (Emerging Infectious Diseases). Publication from 2015 on suspected sexual transmission of Zika virus. Click.

Zika virus infection ‘through sex’ reported in US (BBC). Suspected case of sexually transmitted Zika virus in Texas in 2016. Click.

CDC: To avoid Zika exposure, consider no sex (The Washington Post). Coverage of CDC guidance on avoiding sexual transmission risk of Zika virus. Click.

Interim Guidelines for Prevention of Sexual Transmission of Zika Virus — United States, 2016 (CDC). Click.

Zika: Why the virus isn’t an STI despite being passed on after sexual contact (Independent).  Only where sex is the predominant route of transmission, and the infection is maintained in the human population by sexual transmission, is a pathogen considered a STI and that definition does not apply to Zika virus. Click.

Brazil finds Zika in saliva, urine; expert warns against kissing (SMH). Detection of Zika virus in saliva and urine doesn’t necessarily mean these are pathways of transmission. Authorities advising against kissing? Click.

Zika and the 2016 Rio Olympics

Zika Outbreak Means It Is Now Time To Cancel Rio Olympics (Forbes). Is the threat of Zika virus really so great that the Rio Olympics should be cancelled? Click.

NYU Bioethicist, Amid Zika Threat, Wants to Reschedule Rio Olympics: ‘What the Hell’s the Difference?’ (New York Magazine). With so many unanswered questions, and little confidence the outbreak is under control, is it really ethical to go ahead with the Rio Olympics? Click.

Brazil minister says no plans to cancel Rio Games (AP). Click.

Zika virus will not hamper Rio Olympics says IOC president Thomas Bach (ABC News). Click.

IOC says it will issue advisory on Zika virus spreading across South America ahead of Rio Olympics (ABC News). Click.

Zika crisis and economic woes bring gloom to Brazil’s Olympic buildup (The Guardian). Click.

Zika scare: Olympic athletes need mosquito nets as Bushman sponsors team (SMH). Click.

Zika Virus Rio Olympics: How Australian Athletes Will Fight Potential Infection (Huffington Post). Click.

Bushman named as official insect repellent of Australian Olympic team (mUmBRELLA). One of Australia’s leading mosquito repellent manufacturers to support the athletes and officials travelling to Rio Olympics. Click.

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Battling mosquitoes and the Zika virus outbreak

How Can We Slow The Epidemic Of Zika Infections? (Forbes). Now that the outbreak of Zika virus has been documented, what strategies are available to slow the spread and increasing numbers of cases? Click.

The world needs a Zika vaccine: Getting one will take years (STAT). We won’t have a Zika virus vaccine anytime soon. Here is an explanation why. Click.

Brazil Zika virus: ‘War’ declared on deadly mosquitoes (BBC). How are authorities battling the outbreak of Zika virus in Brazil? Click.

Mosquito Wars Update: Would You Choose GMO ‘Mutants,’ Pesticides Or Dengue And Zika Viruses? (Forbes). The outbreak of Zika virus has focused the attention of health authorities on options for future mosquito-borne disease management strategies. Click.

Brazil sends in 200,000 soldiers to stop the spread of the Zika virus outbreak which has seen huge numbers of babies born with small heads and cast a shadow over the Olympics (Daily Mail). Click.

Here’s what it will take to stop the Zika virus (Vox). Summary of critical issues to address to better understand and stop the Zika virus outbreak. Click.

Curbing Zika Virus: Mosquito Control (Popular Science). Well supported article on options for mosquito control and mosquito-borne disease management. Click.

7 ways the war on Zika mosquitoes could be won (New Scientist). Overview of the different approaches available to beat the Zika virus outbreak and mosquito-borne disease more generally. Click.

In Australia, a New Tactic in Battle Against Zika Virus: Mosquito Breeding (New York Times). Overview of emerging technologies developed in Australia to battle dengue but could be incorporated into the Zika virus response. Click.

Zika virus: pesticides are not a long-term solution says leading entomologist (The Guardian). Spraying insecticides can sometimes be a blunt instrument unless there is an understanding of where best to target mosquito populations. Click.

Zika outbreak revives calls for spraying with banned pesticide DDT (STAT). Outbreaks of mosquito-borne disease often prompt calls to return to DDT as teh insecticide of choice to control mosquitoes. Click.

Insecticide to be sprayed inside planes from Zika affected regions (The Guardian). Aircraft should already be treated with insecticides to stop movement of mosquitoes from one country to the next, hitchhiking in planes but efforts have been boosted in wake of Zika virus fears. Click.

Bats and Mosquitoes

Illustration by Golly Bard

Be careful what you wish for

Let’s Kill All the Mosquitoes (Slate). Emergence of another mosquito-borne disease, another opportunity to call for killing mosquitoes off completely. Click.

Why Eradicating Earth’s Mosquitoes To Fight Disease Is Probably a Bad Idea (Vice). Don’t be so sure that eradicating mosquitoes is the answer, or at least it won’t have consequences. Click.

Would it be wrong to eradicate mosquitoes? (BBC). What could be the unexpected consequences of sending mosquitoes extinct? Click.

Sights on world’s deadliest animal as Zika virus spreads (The New Daily). Wiping out all mosquitoes is probably a bad idea but perhaps we could knock off just a few and greatly improve the health of the planet? Click.

There’s one (or more) in every crowd…

Is Zika Virus the Next Tool For Forced Sterilization, Vaccination and Depopulation? (Activist Post). Oh boy. Click.

Health experts slam anti-vaxxers’ zika virus conspiracy theory as ‘absurd’ (News.com.au). No, immunization programs didn’t cause the Zika virus outbreak and increases in microcephaly. Click.

Concerning Correlation: GMO Mosquitoes Caused Zika Virus Outbreak? (21st Centuray Wire). Bonkers. Click.

No, GM Mosquitoes Didn’t Start The Zika Outbreak (Discover Magazine). Wonderful article debunking one of the most common conspiracy theories associated with the Zika virus outbreak. Click.

Got any more useful links? Tweet them through to me!

Photo of sign from Zika Forest taken from here.

Does Zika virus pose a threat to Australia?

They’re small, spindly insects but their threat never dwindles – the bites of mosquitoes threaten death and disease in many parts of the world. The emergence of a little-known virus, Zika, from an African forest, is the latest to alarm the public, politicians and health authorities because of its potential link to birth defects.

What is Zika virus?

Zika virus is a mosquito-borne virus closely related to dengue and Yellow Fever viruses. Discovered almost 70 years ago in a Ugandan forest, the virus generally only causes a mild illness. Symptoms include rash, fever, joint pain and conjunctivitis.

Severe symptoms aren’t common and the illness was never thought to be fatal.

Despite detection throughout Africa and Asia, the virus rarely entered the spotlight of scientific research. It was overshadowed by the spread and impact of dengue and chikungunya viruses, which infect millions of people across the regions.

In the last decade, Zika virus outbreaks have occurred in the Pacific, with reports of severe illness. But again, Zika was considered a lesser threat than dengue and chikungunya viruses.

Everything changed in 2015 when Zika virus reached the Americas.

New outbreaks and severe symptoms

Since the first local Zika virus infection, cases have been reported from at least 19 countries or territories in the Americas, with more than one million suspected cases.

Rapid spread of an emerging mosquito-borne pathogen is news enough but people are also panicked by reports of more serious consequences of Zika virus infections, including post-viral Guillain-Barré Syndrome, an autoimmune condition where there person’s nerves are attacked by their own body.

Of most concern has been the rapid rise in rates of microcephaly, a birth defect which causes babies to be born with unusually small heads, in regions where Zika virus has been circulating.

While the role of Zika virus as the cause of microcephaly has not yet been confirmed, there is growing evidence of a connection between the two where pregnant women have been infected with the virus.

Babies born with microcephaly, and those who died shortly after birth, have tested positive for the virus, and there are close regional associations between clusters of birth defects and Zika virus.

There is enough concern for the Centres for Disease Control to issue health warnings to pregnant women planning to travel to these regions. [This also includes the Australian Government] Some health authorities are even advising people to postpone pregnancies.

There is no vaccine for Zika virus. Stopping mosquito bites is the only way to prevent infection.

Is Australia at risk of a Zika virus outbreak?

There is little doubt the virus can make it to Australia. There have already been a number of infections reported in travellers arriving in Australia from the Cook Islands and Indonesia.

Mosquito-borne viruses generally aren’t spread from person to person. Only through the bite of an infected mosquito can the virus be transmitted.

In the case of Zika, there have been some unusual cases of transmission, including through sex and the bite of an infected monkey. Despite these unusual circumstances, mosquitoes will still play the most important role in any local transmission.

While dozens of mosquitoes are capable of spreading local mosquito-borne pathogens, such as Ross River virus, only one of the 300 or so mosquitoes found in Australia can transmit Zika virus: Aedes aegypti, the Yellow Fever Mosquito, which is only found in north Queensland.

The Yellow Fever mosquito, Aedes aegypti, is critical to the spread of Zika virus in many regions of the world, including Australia.

For local Aedes aegypti to spread Zika virus, they must bite an infected traveller shortly after they return from a country where the virus is circulating.

While the chances of this happening are small, there is then a risk of a local outbreak occurring as the infected mosquito bites people who’ve never left the country.

This is the process that occurs in outbreaks of dengue in Far North Queensland. If we can get outbreaks of dengue, there is no reason we cannot, or won’t, get an outbreak of Zika in the future.

How to reduce the risk of transmission

Fortunately, authorities are well placed to contain an outbreak of Zika virus, as the required strategies are the same as management of dengue outbreaks.

Perhaps the real message here for Australian authorities is that they need to work diligently to keep exotic mosquitoes out of the country.

While Aedes aegypti may not become established in southern cities, even with a changing climate, there is great potential that Aedes albopictus, better known as the Asian Tiger Mosquito, could become established in southern cities. As well as a vector of Zika virus, it can spread dengue and chikungunya viruses and be a significant nuisance-biting pest. Keeping this mosquito out of our cities is critical.

Australians planning travel to South and Central America, including the Rio Olympics, should take precautions to avoid mosquito bites. Irrespective of Zika virus, mosquito-borne dengue and chikungunya viruses have infected millions of people, causing thousands of deaths, in the last few years and are reason alone to pack mosquito repellents. Be prepared to cover up with long sleeved shorts and long pants if in regions where risk is high.

The ConversationThis article was originally published on The Conversation. Read the original article.

Lessons from the dengue outbreak in Hawaii

Hawaii_1There are millions of cases of mosquito-borne disease world wide every year so why should we care about a few dozen dengue cases in Hawaii?

Hawaii is no stranger to dengue. There have been outbreaks first dating back to the 1840s. Travellers, including returning residents, are diagnosed with dengue routinely. However, this is the first outbreak of locally-acquired infection since 2011.

As of 17 November 2015, Hawaii Department of Health reports there have been approximately 65 locally acquired cases on Hawaii Island (aka Big Island) including both residents and visitors. Why has this happened and what lessons can be learned from the outbreak?

[update: As of 29 January 2016, there have been 242 confirmed cases of locally acquired dengue.]

Hawaii provides a fascinating example of the implications (as well as study of spread) of exotic mosquito invasions. With no endemic mosquito species, the pest species found in the Hawaiian islands have all been introduced from elsewhere.

The first mosquito to make it to Hawaii was Culex quinquefasciatus. It is thought to have arrived on a boat from Mexico in the mid 1820s. Interestingly, with no native mosquitoes in Hawaii, there was no word to describe them so they were initially referred to as “singing flies”.

In recent years, it has been the role of Culex quinquefasciatus in the spread of avian malaria that’s been grabbing the headlines. However, in the last few weeks, it has been Aedes aegypti and Aedes albopictus playing a role in the local spread of dengue virus in the spotlight. These two container-inhabiting mosquitoes are the key vectors of dengue viruses (as well as chikungunya, yellow fever and zika viruses) internationally. They’re driving the outbreak now as they have in the past.

There was an outbreak of dengue in 2001 with a total of 122 locally acquired cases. Cases were reported from Maui, Oahu and Kauai with the outbreak thought to have been triggered by travellers from French Polynesia where there was a major outbreak underway at the time. Between 1944 and 2001, the only cases of dengue reported in Hawaii were imported with travelers. Firstly, this highlights how important it is to understand the pathways of infected people, this can help guide assessments of risk.

This was also done from the potential introduction of West Nile virus into Hawaii. Analysing the movement of travelers from regions of endemic mosquito-borne disease has also been used to assess the risk of chikungunya virus introduction to North America.

It was believed that Aedes albopictus played an important role in this 2001 outbreak. This mosquito was not a significant presence in Hawaii until the 1940s. More importantly, Aedes albopictus is not exclusively found in water-holding containers in urban area. Unlike the other vector of dengue viruses, Aedes aegypti, Aedes albopictus is also found in bushland habitats. This makes mosquito control just a little more difficult when authorities need to look beyond the backyard.

Previous dengue outbreaks in Hawaii were thought to have been driven by Aedes aegypti. These outbreaks were significant with an estimated 30,000 cases in the early 1900s followed by approximately 1,500 cases around Honolulu in the period 1943-1944. While not necessarily easy to manage, outbreaks of dengue driven primarily by Aedes aegypti can be strategically targeted by residual insecticide treatments and community education. That education focuses on raising awareness of the public health risks associated with mosquitoes and the need to remove opportunities for mosquitoes to be breeding around dwellings. This model is essentially what is in place to address occasional outbreaks of dengue in Far North Queensland, Australia.

The current outbreak has raised concern in the community. Shelves of stores have been emptied of insecticides and repellents. Community meetings have been held by local authorities to provide information on dengue and address concerns on the Big Island. You can watch some of the meetings here. You can see some of the health promotion (aka “Fight the Bite”) flyers here.

Community engagement is important. An indirect impact of this engagement though is that the total number of confirmed cases of dengue on the Big Island is likely to rise over coming weeks. Not necessarily due to new cases but a greater likelihood that older cases will now be diagnosed through blood tests. Even those who may be suffering a mild illness are likely to be tested for infection and may end up in official statistics.

This dengue outbreak is a reminder to authorities across the world that where suitable mosquitoes are present, a risk of mosquito-borne disease outbreak is possible. The mosquitoes provide the tinder and it only takes the spark of an infected traveler to ignite an outbreak. We saw this in 2014 with the first outbreak of dengue in Japan for 70 years. We’ve seen it this year with local transmission of chikungunya virus in Spain and other outbreaks across Europe.

For Australian authorities, ensuring there are strategic responses in place to address the risk of exotic mosquito introduction, as well as outbreaks of disease, is critical. What this outbreak in Hawaii reminds us is that if Aedes albopictus becomes established in our major cities, it is only a matter of time before we see local outbreaks of dengue, chikungunya or Zika viruses.

What is it like if a loved one comes down with dengue? Check out the channel of YouTube stars Charles Trippy and Allie Wesenberg as they document their brush with mosquito-borne disease during this outbreak.

[Update: Implications for potential Zika virus spread] The recent spread of Zika virus in the Americas has raise concerns by health authorities. In particular, the spread of the virus to North America. What about Hawaii? There has already been one case of microcephaly in Hawaii with a baby born on Oahu to a mother who had been residing in Brazil. The pregnant women was infected in South America, not Hawaii. However, authorities should be on alert as travellers from the Americas, or the Pacific, have the potential to introduce the virus and the mosquitoes currently present in Hawaii spreading dengue viruses are the same that spread Zika virus.

 

 

 

 

 

 

 

Perfume won’t protect you from mosquito bites

VictorissecretThe headlines have been awash with claims that a popular perfume may repel as many mosquitoes as those regularly recommended by health authorities. Could it be true?

In short, no. There is little surprise that the results of this recently published study in the Journal of Insect Science has attracted so much attention. Everyone loves the idea that some unexpected substance could be used as a mosquito repellent. Even better if it performs as well, or even better, than those such as DEET or picaridin that are widely recommended by health authorities.

The scientists tested a range of commercial insect repellents. Three formulations of DEET based repellent, an oil of lemon eucalyptus (aka PMD) based repellent, three botanical-based repellents, a mosquito repellent patch (Vitamin B), a product not specifically designed as a repellent but often quoted as being effective (Avon skin so soft) and the perfume. Why include the perfume at all?

The logic behind including the perfume was a good one. It is often said that floral perfumes and other cosmetics attract mosquitoes. I’ve never thought this is actually the case. I mean, there is stronger evidence that mosquitoes re attracted to smelly foot bacteria than pleasant smelling cosmetics! I always suspected that the idea comes from the fact the mosquitoes (mostly the non-biting males) will feed on plant sugars. However, it was worth including in this study. Always good to gather some quantitative evidence on the response of blood-seeking mosquitoes. It could be a good opportunity to bust (or perhaps confirm) some urban myths.

I’ve written before about how you can test mosquito repellents. While the “arm-in-cage” methodology typically provides the best indication of how a mosquito repellent will perform, there are other methods commonly employed. In this case, the researchers used a “Y-tube” setup. This system basically allows mosquitoes to make a choice as to whether they preferentially fly towards one or the other ends of the tube. If you insert a hand treated with a substance into one end and another untreated hand as a control into the other, it is possible to measure the overall repellent effect by tracking the movement of mosquitoes.

Firstly, it is interested to note that the researchers found that some mosquitoes were attracted to the hand treated with DEET. If I was conducting an “arm in cage” test. I would be very surprised if I had any mosquitoes biting a DEET-treated arm within 2h of application. In one study, I found an approximately 7% DEET-based repellent stopped bites for a little under 2h. It makes me wonder how many mosquitoes may fly up to tube towards the treated hand but, given the chance, would actually bite the hand?

Fewer mosquitoes were attracted to hands treated with oil of lemon eucalyptus, not surprising either given this product is regularly recommended as an effective repellent by health authorities.

The testing of the perfume provided the headline grabbing results! For the first couple of hours, there wasn’t much difference in the proportion of mosquitoes repelled by the perfume compared to the other repellents. Why? It may be related to the strength of the odour overpowering the sensory organs of the mosquito. I think this is how some strongly smelling essential oils can provide some protection. It masks the normal chemical cocktails of smells on our skin that attracts mosquitoes.

We all know how overpowering the smell of some cosmetics can be. In this case of this experiment, a relatively high dose of the products as used. The authors make note of this too when they state “It must be noted that the concentration of perfume we used in this test was rather high and that lower concentrations of the same fragrance might have different effects.”

Could this perfume be used as a repellent?

Studies like this provide some fun headlines but they can be misleading to the public. What “works” for a relatively short period in a small laboratory based study does not necessarily stand up the practicalities of real life.

Notwithstanding the expense (the perfume is about AUS$80 for 100ml compared to less than AUS$10 for about the same amount of DEET-based repellent) I must admit that for some of these products, the smell can be so overpowering that applying them to large areas of skin would probably be more unpleasant than the bites of mosquitoes!

When trying to help the public choose and use mosquito repellents more effectively, it is critical that health authorities stick to products that are currently registered for use as a mosquito repellent and that have been demonstrated to provide suitable protection from biting mosquitoes over extended periods of time.

Perhaps the most important finding of the paper is not that the perfume repelled some mosquitoes but that patches infused with Vitamin B provide absolutely no protection from mosquitoes. This is one urban myth that never really seems to go away!

We also know that Victoria’s Secret perfume doesn’t stop bed bugs invading lingerie stores!

[The image used at the top of this piece is taken from here.]

Asian tigers and shifting mosquito control from the swamps to the suburbs

aedes_albopictus_SteveDoggettOne of the world’s most troublesome nuisance-biting mosquitoes is perfectly adapted to summer life in southern cities in Australia. This is bad news for communities in temperate climate regions in Australia that would otherwise be immune from the threats of exotic mosquito vectors of dengue and chikungunya virus otherwise limited to tropical regions of the world.

I’ve been invited to speak in the “Managing Current & Future Exotic Mosquito Threats” symposium at the Australian Entomological Society conference to share some of the experiences in temperate Australia regarding exotic and endemic mosquito threats and how the threat of the Asian Tiger Mosquito is being addressed.

Australia has annual activity of mosquito-borne disease. Around 5,000 people a year fall ill following a mosquito bite each year in Australia, most commonly due to Ross River virus. These pathogens are generally spread by native “wetland” mosquitoes such as Aedes vigilax or Culex annulirositrs). Australia has also had major outbreaks of dengue in the past but the only mosquito in Australia able to spread the viruses, Aedes aegypti, is restricted to far north QLD. It is unlikely to spread to southern cities beyond Brisbane based on temperature change alone but there is another mosquito that may pose a threat of dengue or chikungunya virus transmission in southern regions.

The Asian Tiger Mosquito (Aedes albopictus), poses a significant threat to Australia. It was discovered in the Torres Strait in 2005, having thought to have hitchhiked on fishing boats from Indonesia. Although the mosquito hasn’t yet managed to set up home on mainland Australia, its a more likely a question of when, not if, this mosquito will make its way here.

The container-inhabiting (not wetland living) mosquito has already hitchhiked to Europe and North America with eggs carried with people and their belongings. Movement of people, not shifts in climate is the biggest risk. Should it reach one of our major southern cities, there is little doubt that mosquito could become a persistent summer pest and possible public health threat. The way we respond to water shortages in our cities, by increasing water storage around our homes, may set the scene for this mozzie to move in.

Once the mosquito is established in our cities, all we need are travellers to bring in the viruses. Travellers introduce dengue virus into Far North QLD every year. Last year Japan experienced its biggest outbreak of dengue in over 70 years thanks to a traveller introducing the virus to local mosquitoes in downtown Tokyo. This Tokyo outbreak of dengue has implications for local authorities in Australia.

In my presentation at the Australian Entomological Society conference, I’ll highlight some of the issues to consider when assessing the risks posed by exotic mosquitoes in New South Wales as well as outline some of the problems local authorities may have to face when dealing with these mosquitoes that differ from the current focus of mosquito and mosquito-borne disease surveillance and control strategies.

You can view my presentation slides and abstract below:

Developing a strategic response to exotic mosquito threats in NSW

Cameron E Webb (1,2), Jay Nicolson (3), Andrew van den Hurk (4) & Stephen L Doggett (1)

(1)Department of Medical Entomology, Pathology West – ICPMR Westmead, Level 3, ICPMR, Westmead Hospital, Westmead NSW 2145 Australia; (2) Marie Bashir Institute of Infectious Disease and Biosecurity, University of Sydney, NSW 2006, Australia; (3) School of Pathology and Laboratory Medicine, The University of Western Australia, Nedlands, WA 6009, Australia; (4) Virology, Public and Environmental Health, Forensic and Scientific Services, Department of Health, Queensland Government, Brisbane, QLD 4108, Australia.

Mosquito-borne disease management in Australia faces challenges on many fronts. Home growth threats posed by endemic mosquito-borne pathogens (e.g. Ross River virus (RRV)) may increase with a changing climate but exotic mosquitoes and pathogens are an emerging threat. In the absence of a national strategy to address these exotic threats, local authorities must develop regionally specific surveillance and response programs to identify and respond to exotic mosquito incursion. The Asian tiger mosquito, Aedes albopictus, poses the greatest risk to temperate regions of Australia due to their close ecological associations with urban habitats and ability to transmit exotic pathogens (e.g. dengue viruses (DENV) and chikungunya virus (CHIKV)). The mosquito is widespread in local regions, has been detected at international ports and, given the increasing frequency of local travellers to regions where this mosquito is abundant, it raises the potential that an incursion into metropolitan Sydney in the coming years is probable. When this happens, what is the likelihood that this mosquito becomes established? Laboratory studies have confirmed Ae. albopictus could survive in the egg stage under climatic conditions typical of a Sydney winter. Despite the endemic mosquito, Aedes notoscriptus, sharing the same ecological niche to Ae. albopictus, cohabitation studies demonstrated that no interspecies competition would act to limit the local spread of Ae. albopictus and the mosquito could proliferating in the summer. Critically, vector competence experiments have demonstrated the ability of Ae. albopictus to transmit endemic pathogens and, given their propensity to bite humans, could contribute to human-mosquito-human outbreaks of RRV in urban areas of NSW, complementing the enzootic vectors that currently limit transmission to the metropolitan fringe. Local authorities need to develop a multiagency strategic approach to surveillance concomitant with strategic response to reduce the pest and public health threats associated with exotic mosquitoes.

Make sure you check out the tweets from the Australian Entomological Society Annual Conference in Cairns, QLD, 27 September through 1 October 2015, by clicking on #AusEntoSoc15

Are mosquito coils making us sick?

coilWe burn them to beat the bite of mosquitoes but could they actually be making us sick? Is breathing the smoke from a smouldering mosquito coil really the same as smoking a pack of cigarettes?

In summary, should I use mosquito coils to protect my family from mosquito bites?

  • Only use commercial products that have been registered by local authorities
  • Products that contain pyrethroids will provide better protection from mosquitoes than those that contain only botanical extracts
  • The byproducts of combustion, not insecticides, associated with mosquito coils may pose a health risk in some circumstances
  • Best to limit use of coils to outdoor or well ventilated indoor areas
  • Don’t sleep next to a smouldering mosquito coil
  • Consider plug-in “smokeless” mosquito repellent devices
  • Sleeping under a mosquito net is the best non-chemical approach to overnight mosquito bite prevention
The Saltmarsh Mosquito (Aedes vigilax) (Photo: Stephen Doggett)

The Saltmarsh Mosquito (Aedes vigilax) (Photo: Stephen Doggett)

Here is the background…

For centuries we’ve burnt substances, particularly aromatic plants, to keep mosquitoes away. The clouds of smelly smoke can often ward off the swarms of blood sucking mosquitoes.

The use of pyrethrum in incense gained popularity and became common practice in Asia but it wasn’t until the early 1900s that the mosquito coil was born thanks to Japanese entrepreneurs Eiichiro and Yuki Ueyama and their katori senkō (mosquito-killing incense).

Modern mosquito coils, mostly containing the pyrethroid insecticides, are an almost permanent fixture at camp sites and backyard during summer. Millions of families across the tropics use them as their primary source of mosquito-borne disease prevention. They’re cheap and generally effective. We burn them to reduce the risks of mosquito-borne disease but could they actually be making us sick?

Health concerns of mosquito coils

There is growing concern about the adverse health impacts associated with the burning of mosquito coils and sticks indoors. A recently presentation to the 48th National Conference of Indian College of Allergy, Asthma and Applied Immunology has again raised the issue of potential health impacts associated with mosquito coils with media coverage given to Dr Sundeep Salvi in the lead up to the conference. He is quoted as saying “Burning one mosquito coil in a closed room amounts to smoking roughly 100 cigarettes”. The key point in Dr Salvi’s comment is “closed room”.

When assessing the real risks posed by mosquito coils, it is important to consider not just what is released by these smouldering products but actual likelihood it poses a serious health risk. How do you balance these potential health risks of burning coils with those posed by the bite of infected mosquitoes?

Total daily rainfall recorded at Sydney Olympic Park (Data source Bureau of Meteorology)

Do you really need to weigh up the risks of breathing in smoke from a mosquito coil with the risks of mosquito bites? (Image: Joel Sartore, National Geographic)

Who checks the safety of mosquito coils?

In Australia, all substances that purport to kill or repel mosquitoes must be registered by the Australian Pesticides and Veterinary Medicines Authority (APVMA). Similar regulatory authorities exist in other jurisdictions.

Mosquito repellents, whether they’re topical or spatial or whether they contain “chemical” or “natural” substances will need to be tested for efficacy and safety. Check the packaging for a registration number. There are dozens of different variations on “mosquito coils” including sticks, coils, candles and a variety of “plug in” devices. You’ll find the shelves of the local supermarket, camping and hardware store fully stocked almost all year round!

Despite the wide range of products available, the active ingredients (that is the mosquito repelling or killing products) don’t vary too much. There are either synthetic pyrethroids or botanical extracts (e.g. citronella oil, eucalytpus oil). You may be surprised to know that some contain a combination of the two. Just because “citronella” is written in bold on the packaging, it may still contain one of the synthetic pyrethroids. Check the label.

repellentrackDoes burning mosquito coils really make us sick?

A study of mosquito coils sold in the U.S. and found that some mosquito coils contain octachlorodipropyl ether (s-2) that, during the smouldering of the coils, produces an extremely potent lung carcinogen as a byproduct called (bis(chloromethyl)ether (BCME)). Fortunately, s-2 is banned in many countries. It is no longer used commercially in the U.S. and prompted by reports of the risks associated with mosquito coils, Hong Kong authorities released a statement in 2005 regarding the recall of mosquito coils containing s-2.

It is not listed as an active ingredient in mosquito coils registered for use in Australia. Given that in most circumstances, particularly in Australia, mosquito coils don’t contain s-2, it is the particulate matter that is of greatest concern.

An often quoted study published in 2003 titled “Mosquito coil emissions and health implications” analysed the components of commercially available mosquito coils from China and Malaysia and found that burning mosquito coils in an enclosed room may pose “significant acute and chronic health risks” with the fine and ultra fine particulate matter released from a single mosquito coil equaling that of up to 137 cigarettes!

In addition, they found that emission of formaldehyde (a by product of the combustion process) from burning one coil can be as high as that released from burning 51 cigarettes.

Doesn’t sound too good does it? The combustion of the coil itself is the main concern, not the insecticides used.

More recent studies have indicated that changing the base materials used in mosquito coils (i.e. switching to charcoal from other organic material) can reduce the volume of particulate matter substantially. Would these “smokeless” mosquitoes be more “healthy”? Probably.

Does what happens in the lab stays in the lab?

Billions of mosquito coils are sold across Asia every year. Millions of families use them as their primary mosquito bite prevention strategy. Why aren’t we seeing more substantial health impacts in local communities?

It is worth noting that two papers published in 2006 investigated the different methods used to assess the health risks associated with burning mosquito coils. The researchers tested different methods to expose laboratory rats to particulate matter from mosquito coils. They firstly reported that “protocols devised evaluate and assess the acute inhalation toxicity of mosquito coil smoke demonstrating that the nose-only mode of exposure of rats to the smoke of mosquito coils is suitable to assess the toxic potency of different coils.

The nose-only mode has clear advantages over the whole-body exposure mode.” Then, using the “nose-only” exposure method that they proposed, the researchers concluded that “overnight exposure to the smoke from burning mosquito coils (manufactured in Indonesia) is unlikely to be associated with any unreasonable health risk.” This is a noteworthy conclusion given that the level of exposure to those rats (6 h a day, 5 days a week for 13 weeks) was substantial.

What about “smokeless” mosquito coils?

There is a paucity of studies investigating the potential human health impacts of “smokeless” mosquito repellents. The few studies that do exist are inconclusive or use animals to test health impacts under conditions unlikely to occur in most circumstances.

A 2005 review of pyrethroid poisoning reported “Despite their extensive world-wide use, there are relatively few reports of human pyrethroid poisoning. Less than ten deaths have been reported from ingestion or following occupational exposure. Occupationally, the main route of pyrethroid absorption is through the skin. Inhalation is much less important but increases when pyrethroids are used in confined spaces.” Again, this highlights the critical issue here, exposure to insecticides in confined and/or enclosed situations.

It is worth remembering that pyrethroids are over 2000 times more toxic to insects than mammals. That means that the concentrations used to kill insects are unlikely to have adverse health impacts on humans, particularly if commercial formulations are used as recommended. Given the billions of people who use mosquito coils to prevent mosquito bites, perhaps the more important question to ask is, does burning mosquito coils actually prevent mosquito-borne disease? Perhaps that is a discussion for another time….

sp-breweries-mozzie-boxPerhaps one of the most interesting ideas this year was the “mosquito repellent beer carton”. More marketing than public health initiative but I like the idea. The carton is infused with citronella so that when you’re sitting about the campfire enjoying a few beers, you can toss bits of the carton into the fire and keep mosquitoes away. It is unlikely many mosquitoes will be actively repelled. However, I do like the idea of using the beer carton as an opportunity to raise awareness of mosquito-borne disease.

Perhaps it is this little bit of public health communication that will actually stop a few people becoming infected.

Do you use mosquito coils and sticks to prevent mosquito bites? Join the conversation on Twitter and let me know what you think.

Want to learn more about the amazing world of Australian mosquitoes? Check out “A Field Guide to Mosquitoes of Australia” out now through CSIRO Publishing. Over 200 pages containing a pictorial guide to almost 100 different mosquitoes along with tips on beating their bite and protecting your family from the health risks of mosquitoes. You can order online or through your favourite local bookstore or online retailer.

Why would a Californian drought trigger an outbreak of mosquito-borne disease?

CalifornianBushfireSunset_DawnEllnerMosquitoes need water almost as much as they need blood so why is it a drought could cause an outbreak of mosquito-borne disease? Why does the drought in California mean less water but more mosquito-borne disease?

More than just water

All mosquitoes need water. It could be a teaspoon of water in a pot plant base or an expanse of wetlands inundated by tides. Following flooding, health authorities are typically quick to issue public health warnings about increased risk of mosquito-borne disease. However, more mosquitoes doesn’t always mean more mosquito-borne disease.

Mosquitoes need blood. As well as biting people, they also bite animals. Outbreaks of mosquito-borne disease typically requires the presence of wildlife, animals that act as reservoirs for the disease-causing viruses.

CaliforniaDrought_EPA

Drought is hitting California hard (Source EPA via Huffington Post)

Mosquitoes, drought and West Nile virus

West Nile virus is a mosquito-borne pathogen generally spread between birds and people by mosquitoes. Culex mosquitoes they appear to play the most important role in West Nile virus transmission in urban environments, particularly Culex pipiens.

These mosquitoes are generally not breeding in wetlands. They’re found in artificial structures ranging from backyard containers and neglected swimming pools to stormwater pipes and drains. These mosquitoes have moved out of the swamps and into the suburbs! They’ve also moved into the constructed wetlands popping up throughout the suburbs too.

Rather than water birds associated with wetland environments, the birds playing a key role in West Nile virus transmission are small songbirds common in urban areas. These birds roost in large numbers and are the target the the Culex mosquitoes that preferentially feed on birds. It is important to keep in mind that there is still a lot of learn about how the roosting behaviour of birds influences their exposure to West Nile virus.

During “dry” conditions, bird populations are concentrated in urban areas (where humans provide water and food) and mosquito populations associated with urban water-holding structures increase. During “wet” summers, bird populations may be more widely dispersed through the environment with many birds roosting and foraging well away from residential areas and reducing the contact between birds, mosquitoes and people. When the “dry” summers arrive, birds move back close to the people. People who provide water.

Culex_molestus_Photo_StephenDoggett

The Culex pipiens group of mosquitoes play an important role in the transmission of West Nile virus and are closely associated with urban environments. They like biting birds. (Photo: Stephen Doggett, NSW Health Pathology)

In the absence of rain, water stagnates in stormwater pipes and drains providing favourable conditions for mosquitoes. During “wet” summers, the mosquitoes are flushed out by increased water flows and, even if they don’t, permanent habitats are more likely to support populations of mosquito predators such as fish.

During “dry” summers, people also start storing water around the home. Once water restrictions kick in, the desire to keep the garden looking healthy can potentially pose an indirect health risk to the homeowner as they hoard water around the home that provides habitat for mosquitoes.

In short, dry conditions help concentrate mosquitoes and birds in close proximity to people and increase the risk of mosquito-borne disease outbreaks.

WestNileSign

Mosquito control in Texas in response to an outbreak of West Nile virus raised much concern within the community. It can sometimes be difficult to balance the need for mosquito control with community engagement to allay fears of insecticide -based human health risks (Source: CDC)

An outbreak in Texas in 2012

West Nile virus was first introduced into North America in 1999. Despite rapidly spreading across the continent in the subsequent years, the numbers of outbreaks steadily declined and, to some extent, it fell of the radar as a serious public health concern. There was a resurgence of the disease in 2012 with an outbreak primarily focused in Texas.

There was a substantial increase in the number of cases compared to previous years with an unusually warm spring thought to have played an important role in driving the outbreak. Health authorities were warned that outbreaks of this nature may continue.

USDroughtMonitors_7April2015West Nile virus and the Californian drought

For the past couple of years, California has been hit with one of its worst droughts in decades. It is having widespread impacts and may also be increasing mosquito-borne disease. Californian authorities have been battling potential public health risks associated with mosquitoes on many fronts. There were record numbers of deaths due to West Nile virus disease in 2014 and exotic mosquitoes were detected. This included an Australian mosquito that was found in Los Angeles.

It is relatively early in California’s mosquito season but West Nile virus has already been detected. Health authorities are warning that another bad year for West Nile virus activity could be ahead despite the ongoing drought. There is already a suggestion that the severity of the current drought may be exacerbated by climate change and that climate change may be playing a role in future West Nile virus risk internationally.

There is little doubt that prolonged drought will impact Californian residents in many ways and an increased risk of mosquito-borne disease is just one of them. Fortunately, mosquito and vector control agencies in California work closely with local health authorities to monitoring mosquito and pathogen activity to provide warnings of increased risk. However, there is responsibility for everyone to ensure that the ways in which water is conserved around the home doesn’t increase the risks associated with mosquitoes.

potplantsaucer

If you’re worried about keeping your pot plants well watered but don’t want to provide a home for mosquitoes, fill the saucer with sand. It will keep the moisture in place but there is no “free water” for mozzies to use!

If you’re not able to “dump and drain” water holding containers, make sure that they’re covered to stop mosquitoes getting in or out. If you’ve got a swimming pool that’s neglected, start chlorinating it or release fish to eat through any mosquitoes. There are also a few mosquito control products that could be used, the most appropriate would probably be the insect growth regulator methoprene, it will stop mosquitoes emerging from the water holding container.

Why not share your tips on saving water around the home while not increasing opportunities for mosquitoes on Twitter?

The photo at the top of this post is taken by Dawn Ellner (see original photo here)