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Zika is Found in Common Culex Mosquitos, Signaling a Potentially Larger Risk


Jamilly Vitoria Santos da Silva, center, stands next to her mother, Rebeca Arruda as they wash a dog in a bucket in a favela as members of the Brazilian military along with health care workers to talk to residents about the threat of Zika virus. (Matt McClain/The Washington Post)

CLICK HERE - Oswaldo Cruz Foundation (Fiocruz) - Fiocruz identifies Culex in Recife with the potential to transmit the virus zika (translation to English provided below) - by Dom Phillips - July 21, 2016

RIO DE JANEIRO — Brazilian researchers said Thursday they have found Zika in Culex mosquitoes in the northeastern city of Recife in what could prove to be an important discovery. But they cautioned that more study was needed.



via Google Translate

Fiocruz identifies Culex in Recife with the potential to transmit the virus zika

unpublished research conducted by the Oswaldo Cruz Foundation (Fiocruz) detected the presence of zika virus in mosquito Culex quinquefasciatus (the popular muriçoca or house mosquito) collected in the city of Recife. This finding confirms the species as a potential vector of the virus that zika, a situation which, according to scientific literature, had not been proven to date.

The survey was conducted by Fiocruz Pernambuco in the metropolitan area of ​​Recife, where the population of Culex quinquefasciatus is about twenty times greater than the population of Aedes aegypti. Preliminary results of field research identified the presence of Culex quinquefasciatus naturally infected zika virus in three of the 80 pools * (groups) of mosquitoes analyzed to date. In two of these samples they were not fed mosquitoes, indicating that the virus was widespread in the insect body and not in a recent power in an infected host.

The technique used in the experiment was quantitative RT-PCR based detection of RNA (genetic material) virus. The material of these positive pools was used to isolate the circulating virus strains in Reef, in cell culture, where it was observed cytopathic effect induced in the cells - i.e., destruction or damage of vero cells was observed, which proves the presence viral activity.

The collection of mosquitoes was made based on the addresses of the reported cases of zika in the cities of Recife and Arcoverde, obtained from the Health Department of Pernambuco State (SES-PE). The total number of mosquitoes examined in the study was approximately 500. The aim of the project is to compare the role of some species of mosquitoes in Brazil of arbovirus transmission. Priority was given to zika virus because the epidemic of the disease in Brazil and its connection with microcephaly.

In the laboratory stage, in order to investigate the vector competence of the species Culex quinquefasciatus and Aedes aegypti mosquitoes were fed a mixture of blood and viruses, allowing the monitoring of pathogen replication process within the insect. There were two mosquito infections each infection with two different virus concentrations (104 and 106) of Ziku BRPE243 / 2015 lineage. "The smallest simulates viremia condition of a real patient. Then the mosquitoes were collected at different times: at time zero (after infection), three days, seven days, 11 and 15 days after virus infection, "says Constance Ayres, coordinator of the study.

A control group with mosquitoes fed on blood without the virus, was also maintained. Each mosquitoes was dissected to extract the intestine, and salivary gland tissues that present barriers to the development of the virus. The procedure takes place so that, if species vector is not at a given moment the development of the virus is blocked by the mosquito. However, if it is vector, virus replication occurs, spreads in the insect body and just infecting the salivary gland, from which can be transmitted to other hosts during the blood meal, the release of saliva containing virus. According Constancia, from the third day after artificial feeding has been possible to detect the presence of the virus in the salivary glands of both species of mosquito investigated. After seven days, it was observed the peak of infection in the salivary glands which was confirmed by electron microscopy.

Besides the detection of virus in these tissues (intestine, and salivary gland), saliva samples were investigated expelled by mosquitoes infected by quantitative RT-PCR. The viral load found in two species (Aedes aegypti and Culex quinquefasciatus) was similar.

From the data obtained will require additional studies to assess the potential participation of Culex in the spread of zika virus and its role in the epidemic. The current study is very important, since the vector control measures are different. Until the results of new evidence, the zika epidemic control policy will remain guided by the same guidelines, with its central focus on the control of Aedes aegypti.

* A pool of mosquitoes consists of 1 to 10 mosquitoes collected in each location, separated by sex and species.



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Comments - by Maggie Fox - July 21, 2016

. . . Separately, Brazilian researchers said they'd found that a much more common mosquito, a species called Culex quinquefasciatus, has been infected with Zika. The same team of researchers, at Brazil's Oswaldo Cruz Foundation, reported in March that they had infected Culex mosquitoes with Zika in the lab.

Now they say they found the virus in live mosquitoes. . . .

. . . But just this week another team, led by Scott Weaver at the University of Texas Medical Branch, said they had tried and been unable to infect Culex mosquitoes with Zika.

"Without access to the methods and data (it is not published in a peer-reviewed journal yet) there is not much that I can say about this Brazilian study," Weaver told NBC News by email.

"An effective vector requires not only susceptibility to infection and ability to transmit (virus replication in salivary glands) but a high rate of biting humans in the case of Zika virus." . . .

. . . "If they found Zika in the Culex mosquitoes, it could be they had taken a blood meal from someone with Zika and then you would find the virus. It doesn't mean they transmit the virus," Hotez said.


CLICK HERE - Journal of Infectious Diseases - Outbreak of Zika virus infection, Chiapas State, Mexico, 2015, and first confirmed transmission by Aedes aegypti mosquitoes in the Americas (28 page .PDF file)

ALSO SEE RELATED ARTICLE HERE - UTMB researchers find first direct evidence that Aedes aegypti mosquito transmits Zika virus

ALSO SEE RELATED ARTICLE HERE - CDC - EID - Culex pipiens and Aedes triseriatus Mosquito Susceptibility to Zika Virus


Early data from new lab tests reopen question of non-Aedes vectors - by Susan Milius - September 28, 2016

ORLANDO, Fla. — New evidence from separate labs supports the controversial idea that an overlooked and unexpected Culex mosquito might spread Zika virus.

The southern house mosquito, Culex quinquefasciatus, is common in the Americas. Constância Ayres, working with Brazil’s Oswaldo Cruz Foundation in Recife, previously surprised Zika researchers with the disturbing proposal that this mosquito might be a stealth spreader of Zika. But two U.S. research groups tested the basic idea and couldn’t get the virus to infect the species.

Now, preliminary results from Ayres’ and two other research groups are renewing the discussion.


CLICK HERE - Emerging Microbes & Infections - Culex pipiens quinquefasciatus: a potential vector to transmit Zika virus


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