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PLOS BLOGS Speaking of Medicine and Health

Culex Mosquitoes and Zika Virus Infection? Nah.

PLOS Neglected Tropical Diseases co-Editors-in-Chief Peter J Hotez and Serap Aksoy discuss new research reporting that Culex mosquitos apparently cannot transmit Zika.

As Zika infects large numbers of immunologically naïve populations in the Americas, significant concern has been raised about the possibility that Culex mosquitoes could be responsible for transmitting the virus.  In the continental United States, this is of particular concern given that Culex are far more numerous and widely distributed than Aedes mosquitoes, explaining why West Nile Virus transmission has been observed in most US states.

Could Culex mosquitoes transmit Zika virus and spread microcephaly cases across the US?  This week’s PLOS Neglected Tropical Diseases article by Ricardo Lourenco-de-Oliveira and his colleagues at Brazil’s Instituto Oswaldo Cruz so far indicates that Culex quinquefasciatus, the “southern house mosquito,” is not competent to transmit local strains of Zika and “there is no experimental evidence that Cx. quinquefasciatus likely plays a role in [Zika] transmission”.  In this study they determined that Zika virus infection rates were minimal to totally absent in all Cx. quinquefasciatus, whereas they were significantly higher for Aedes aegypti mosquitoes, which exhibit the ability to disseminate and transmit Zika Virus [1].

So the good news is that Cx quinquefasciatus, which is responsible for WNV transmission in the southern US, is not a competent vector for Zika.  The bad news of course is that Ae. aegypti  remains an important vector, currently responsible for Zika transmission in South Florida and possibly elsewhere in other areas known to host this species, especially Texas,  Louisiana, and Arizona, and even in small pockets in Southern California.   We still have several weeks left of arbovirus transmission season in the southern US and the possibility remains that outbreaks will continue in Florida and may have already begun on the Gulf Coast or elsewhere.


Featured image credit: James Gathany, William Brogdon, USCDCP 

  1. Peter Hotez has made an incorrect call on a very important aspect of the Zika+ virus outbreak. The jury is still out on the Culex Q. as Zika+ virus vector question. And as time rolls on it is looking more and more likely that Culex Q. is a competent vector for the Zika+ virus.

    See what Michael Coston wrote about the Culex Q. vector question.

    I wrote on the 15/12/15:

    “The question of how many mosquitoes in the world can be Zika+ vectors is extremely important !”

    I wrote 21/6/2016:

    “Culex Q. is a vector for Zika+. Joins the club with Aegypti & Albopictus !”

    (Don’t rely on Google Translate. Get a fluent Portuguese speaker to check all Brazilian media & sources like I’ve done since 2014. You need to have reliable contacts on the ground in Brazil to know what is really going on. I do !)

    This latest paper bolsters my claim months ago that Culex Q. is a capable vector for the Zika+ virus.

    See what Fiocruz Medical Entomologist Dr. Ayres said about Culex Q. on this report from Sunday 25/7

    “Zika virus replication in the mosquito Culex quinquefasciatus in Brazil”

    Does WHO’s 18/8 AFRICA report suggest a fourth vector for Zika+ has been found?

    Aedes Luteocephalus

    Scott Weaver’s latest presentation on Zika, vectors etc. is full of errors & contradictions. I rate it 5/10.

    Proof of Vertical Transmission of Zika+ virus from adult f’s > eggs = Increased Global Threat Potential

    FACT : On Oct. 30th 2015 I first warned publically of the dangers to the world of the Zika+ virus outbreak in Brazil ! I am used to being ahead of the curve on key global issues. What will unfold with the global Zika+ pandemic now?

    Stay tuned…

  2. Sorry Adam, but claims and other written musings are not data. It may be better for you to get on the bench and examine your hypotheses with some experimental data.

    Healthy discussion in science is always welcomed. But at some point it also becomes very useful if you show some evidence that examine your beliefs.

    Happy to talk more on Twitter if you’d like to unblock me.


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