Canada - Mosquito Surveillance Reveals the Aedes aegypti Species in Southern Ontario.

We need a new Map.

Canada - Mosquito Surveillance Reveals the Aedes aegypti Species in Southern Ontario. (Wechu). HT: Crof.

In the United States, the Aedes aegypti mosquito primarily exists in the southern states and along the eastern seaboard, where temperatures are more favourable for its survival. There are records of this mosquito being found in some northern states, including Michigan and New Hampshire; however, these were only temporary summer incursions, as the relatively cold winters prevented establishment. To our knowledge, this is the first time Aedes aegypti has been collected in Canada.  

Although it is unknown exactly how the larvae arrived in Ontario, one possibility is that the eggs were transported from the U.S. in shipping containers or other cross-border vehicle traffic. Aedes aegypti eggs could also have been imported in recycled products, such as tires or other containers. Given that this is a tropical mosquito, the extremely hot temperatures this past summer allowed for the species to exist in Windsor. 

“We will continue to ensure that our community stays informed about infectious diseases and the local mosquito surveillance program. It is a key public health service that we provide to Windsor-Essex County residents. The discovery of the yellow fever mosquito larvae through enhanced surveillance of the Aedes albopictus mosquito is an important reminder that we should continue to protect ourselves and our families from mosquito bites,” said Dr. Kirk.   

The Aedes aegypti mosquito is even less cold tolerant than the Aedes albopictus and will not survive the cold winter temperatures. For Zika virus transmission to occur, the Aedes aegypti mosquito would need to feed on an infected person, within the first several days of infection, and then feed upon another susceptible person. 

The greatest risk to contracting Zika virus continues to be centered on those who have travelled to Zika-risk areas (such as South America, the Caribbean and Florida) or who are or have been in sexual contact with these travelers. Read the full story here. More on this story here.

Medical research charity warns: "Expect ZIKA to spread to India and Africa".

Global map of the predicted distribution of Aedes albopictus, another mosquito of the Aedes family that researchers believe transmits the Zika virus. (1 = Full presence of Aedes mosquito, 0= No presence of Aedes mosquito) Source

Medical research charity warns:  "Expect ZIKA to spread to India and Africa". (Guardian).

The Zika virus, which causes brain damage in babies, is likely to spread to India and the continent of Africa, according to the director of the Wellcome Trust, a medical charity deeply involved in research to try to limit the damage.  

“I think we can anticipate global spread,” said Jeremy Farrar, speaking to the Guardian alongside Sue Desmond-Hellmann, the chief executive officer of the Bill and Melinda Gates Foundation. “Given the [Aedes aegypti] mosquito’s availability across the world, I think the spread will next be across Asia and I think we really have to be prepared for it spreading in Africa. I don’t see any reason why it wouldn’t.” 

Last month, 16 pregnant women in Singapore were confirmed to have zika virus. “You can anticipate reports from Vietnam, from Indonesia, from India. I don’t think we’re even at the start of the Zika knowledge base yet,” said Farrar.

The two philanthropic organisations, together with the Brazilian, US and UK governments, have announced $18m (£14.7m) funding for an ambitious project to release mosquitoes infected with Wolbachia bacteria in two urban areas of Brazil and Colombia. The bacteria renders the mosquitoes unable to transmit viruses. They breed with local mosquitoes, producing offspring with Wolbachia, a bacteria carried by 60% of insects that is harmless to humans. 

If it works, it will help limit not just Zika but also other flaviviruses, including dengue and yellow fever. Read the full story here.

'Zika uncontrollable, will become endemic': CDC Director Tom Frieden.

'Zika uncontrollable, will become endemic': CDC Director Tom Frieden. (MiamiHerald). HT: Crof.

The nation’s highest ranking infectious disease expert delivered some sobering news on Zika to a Miami audience on Tuesday, telling them that the mosquito-borne virus is more widespread than Florida health officials have reported and that the rapid spread of pathogens such as Zika represents “the new normal” in an age of global travel and trade, booming cities and climate change.

“Here’s the plain truth: that Zika and other diseases spread by Aedes aegypti [mosquito species] are really not controllable with current technologies. So we will see this become endemic,” Tom Frieden, a physician and director of the Centers for Disease Control and Prevention told a group of about 100 people gathered at the InterContinental Miami hotel for The Atlantic magazine’s CityLab conference.  

Frieden’s takeaway advice for public officials tasked with protecting the public from disease outbreaks: “Invest in public health,” he said. “It pays off.” 

Unprecedented in its ability to spread by sexual contact as well as mosquito bites, and to cause birth defects — most notably microcephaly in children born to mothers infected while pregnant — Zika took health officials by surprise this year, Frieden said, noting that there’s still a lot that scientists do not know about the virus’s effects. 

“Zika has surprised us,” he said. “It’s been difficult to predict. It’s had characteristics that we have not seen with other diseases before. What we anticipate will happen is that this season will calm down within the continental United States. We hope that Miami-Dade will stop having cases, but we can't promise that. ... We will see parts of the hemisphere where it will be endemic. It will come back every year.” 

And though Florida has reported 1,064 Zika cases, including 190 mosquito-borne infections, Frieden said the real number likely is much higher. 

“A rule of thumb,” he said, “is for every case you diagnose you’ve probably got 10 more.” Read the full story here.

Frieden's case total is correct, according to today's Florida Health Zika update, which mentions six new cases—two of them local.

Projecting the spread of Zika virus in the Americas.

Projecting the spread of Zika virus in the Americas: Three scenarios. (ZikaModel). HT: Crof.

Zika Model displays a map of the Americas (the US is not yet active on it), and when you click on a country you get a range of estimates for the number of possible cases of both Zika and microcephaly. 

The "reference scenario" assumes both Aedes aegypti and Aedes albopictus are competent vectors, and offers mid-range estimates based on the literature. The "aegypti scenario" assumes only Ae. aegypti is a competent vectors and again offers mid-range estimates. The "sensitivity analysis" scenario assumes both species are competent vectors and explores "the longest and shortest serial interval allowed by the range of parameters reported in the literature."

Click on Haiti, for example, and you find that the reference scenario projects a Zika attack rate of 46.8% by the end of 2016. Microcephaly cases by then could range from 294 to 1,399.

The site still doesn't include Cuba or the US, but I expect it will get a great deal of traffic when it does. In the meantime, I'm putting a permanent link to it in the Chikungunya, Dengue, Zika Resources list.

"Projections of Zika virus local transmission in the Continental US"

US reviews plan to infect mosquitoes with 'benign' bacteria to stop Zika, dengue, chikungunya.

 

US reviews plan to infect mosquitoes with bacteria to stop Zika, dengue, chikungunya. HT: Crof.

Via Nature News & Comment:  US reviews plan to infect mosquitoes with bacteria to stop disease. Excerpt:

The United States could soon become the first country to approve the commercial use of a common bacterium to fight the spread of mosquitoes that can transmit viruses such as Zika, dengue and Chikungunya. 

The US Environmental Protection Agency (EPA) is reviewing an application from the biotechnology start-up MosquitoMate to use the bacterium Wolbachia pipientis as a tool against the Asian tiger mosquito (Aedes albopictus). The company plans to market Wolbachia as a pesticide — one that kills only mosquitoes, and leaves other insects untouched. The EPA’s decision on the matter will come after a public-comment period that ends on 31 May. 

MosquitoMate’s strategy involves rearing mosquitoes infected with a particular strain of Wolbachia and releasing the males into the environment. When these male mosquitoes mate with wild females who do not carry the same strain of Wolbachia, the resulting fertilized eggs don’t hatch, because the paternal chromosomes do not form properly. As infected male mosquitoes continue to be released to breed with wild partners, the pest population dwindles. 

Eight countries have now reported cases of microcephaly or other fetal birth defects that are probably caused by Zika, leading officials in many areas to consider new options for reducing mosquito populations. “We need as many effective tools as we can get, so we need to give Wolbachia a try,” says Tom Scott, an entomologist at the University of California, Davis. “That will require a well-developed plan for how trials would be done.” 

MosquitoMate, which was started by researchers at the University of Kentucky in Lexington, has tested Wolbachia in A. albopictus mosquitoes in three states over the past three years. The approach has reduced the wild mosquito population by more than 70% in those areas, says Stephen Dobson, an entomologist at the University of Kentucky and founder of the company. Hmmm......Sorry West Nile you're not a club member. Read the full story here.

Zika - Predicted distribution of of A. aegypti and A. albopictus, February 23.

Source and Download here

This does not bode well for much of the southern and eastern US, or for much of the Midwest and central California. Or, for that matter, for the most densely populated region of Canada, from Windsor, Ontario to Montreal. We're not on the map, yet, but we'll have our hands full even if we have to deal only with imported cases of Zika, dengue, and chikungunya. HT & Source: Crof.

Based on the Agency's Rapid Risk Assessment, the overall risk to Canadians, in Canada, is very low, as mosquitoes known to transmit the virus are not established in Canada and are not well-suited to our climate.  http://www.cdc.gov/chikungunya/resources/vector-control.html

The primary risk of autochthonous transmission in Canada would arise from Aedes albopictus mosquitoes becoming established here. Our knowledge of its current whereabouts is based on informal surveillance. More field research is needed in North America to better understand and predict the climatic limits of this species ^{Footnote 10}.

Several factors could alter this assessment. Temperatures suitable for chikungunya virus transmission are achieved at times in many parts of Canada during the summer ^{Footnote 9}, and it is possible that in some circumstances housing conditions and densities of uninfected people would be sufficient to sustain limited outbreaks. Furthermore, it is possible that genetic plasticity of mosquito species could improve their capacity to survive in cooler, more northerly climates, although this is difficult to predict ^{Footnote 10}. Finally, viral mutations could theoretically result in viruses becoming transmissible by other vectors that are established in Canada ^{Footnote 2}.

In conclusion, our observations suggest that the current risk of autochthonous spread of chikungunya virus in Canada is very low, but there are gaps in our knowledge and several factors could alter this risk assessment. 

This suggests the need for ongoing risk assessment, consideration of the projected effects of climate change, surveillance for human cases of chikungunya, enhanced surveillance for mosquito vectors, and the development of plans for prevention and control of outbreaks of this and other exotic vector-borne diseases that may threaten the health of Canadians in the coming decades.