By Siouxsie Wiles 04/03/2016

Brazilian scientists announce Zika could be spread by a different species of mosquito, one more common in Brazil and present in countries like New Zealand.

According to the US Centers for Disease Control (CDC), the Zika virus is currently known to be transmitted by Aedes species mosquitoes, namely A. aegypti and A. albopictus. Media are now reporting that Brazilian scientists say they have succeeded in infecting another mosquito species, Culex quinquefasciatus, with the Zika virus in a laboratory. The report says the researchers injected the mosquitoes with Zika-infected rabbit blood and that the virus circulated through the mosquitoes’ bodies and into their salivary glands, meaning they might be able to transmit Zika to a person when taking a blood meal. What the scientists don’t yet know is if ‘wild’ mosquitoes are carrying the virus. Similar studies will be going on with other mosquito species, as it’s important to know just how many have the potential to transmit this worrying virus.

These latest findings are a concern as the researchers say C. quinquefasciatus is 20 times more common than A. aegypti in Brazil. It also has a different lifestyle so will require a different approach to kill. According to the report, C. quinquefasciatus can survive colder temperatures and prefers to live up trees where it feeds on birds. The relevance to New Zealand is that this IS one of the 16 mosquito species found here. The Science Media Centre quotes Dr José Derraik, a Senior Research Fellow at the University of Auckland, as saying:

“So, while it is correct to say that the known mosquito vectors of Zika virus are not present in New Zealand, it is misguided (and potentially dangerous) to assume that we do not have mosquito vectors capable of transmitting the virus. Zika virus in particular, has been very poorly studied until the outbreak in Brazil, which means that we simply do not know whether the species of mosquitoes in New Zealand are able to transmit the virus to humans.”

José is absolutely right, and I apologise for my sloppy language around this!

Update: José’s  written a paper about Zika in the Pacific which you can read here.

Does this finding mean Zika could establish in New Zealand?

If we have the ‘right’ species of mosquito here, for Zika to establish in New Zealand, we would need those mosquitoes to feed on a person with Zika in their bloodstream, then go on to feed on someone else, who in turn could be fed on by another of the ‘right’ species of mosquito and so on. While we still have relatively small numbers of infected travellers coming in to NZ, the risk is low, but it shows that we can’t be complacent. I think everyone who thinks they may have been exposed to Zika should take all precautions to avoid being bitten by mozzies, even here in NZ, and to make sure they use condoms to minimise the chance of passing the virus on to their partner(s) and creating more cases.

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