Wild cycle approaches Zika from the population and eradicating the disease may become impossible, warns Dr. Maurício Nogueira

Researchers must now understand the role that the monkeys play in the maintenance of the urban cycle of Zika virus and how they can become a channel in the route to establish a non-human animals transmission cycle in tropical Latin America


During the yellow fever epidemic, researchers observed many dead monkeys, killed not by the illness, but by human action. The fact sparked an alert, since when healthy, these primates are very difficult to be captured

An article signed by Dr. Maurício Lacerda Nogueira and researchers from several institutions, recently published in Scientific Reports, Nature group, indicates that there is a potential for a wild cycle of Zika in Brazil, as happens to yellow fever, for example. In the study, entitled Evidence of natural Zika virus infection in non-human primates neotropical in Brazil, the researchers examined carcasses of monkeys and found that they were infected by the Zika virus, in São José do Rio Preto (SP) as in Belo Horizonte (MG).

Dr. Nogueira explains that discovering a potential wild cycle changes the way we perceive Zika virus’ epidemiology. According him, the existence of this cycle potentially places the Zika with its reservoir very close to the population, making it practically impossible to eradicate the disease, meaning an efficient vaccine is needed. The discovery of Zika virus among monkeys can be serious problem for Brazil, because if this cycle is confirmed, we will have more frequent wild Zika epidemics, he points out. The complete sequencing showed that the virus found was very similar to that infecting humans.

Another evidence was that, in the places where the carcasses were found, in the same week, Zika virus-infected mosquitoes were also found. To carry out this research, experimental Zika virus infection was induced in live monkeys. The inoculation provoked viremia, which is the presence of the virus in the blood. Also, monkeys were observed to have behavior changes, confirming the initial hypothesis that an infection would make them more susceptible to being captured and killed. The presence of Zika virus in these monkeys is probably explained by the fact that they are peri urban animals, living very closely to the population and that they were frequently in contact with Aedes aegypti mosquitoes.

Although the discovery happened in Brazil, Dr. Nogueira, who is a researcher at the Medical School of São José do Rio Preto (Famerp) and president of the Brazilian Society of Virology (SBV), believes it is possible to happen in other places. According to him, if the virus is spread in the wild Amazon region, other countries of the Amazon basin are at risk of developing the same situation. In his opinion, the solution to minimize the problem of epizootic diseases, which are always sources of epidemics among humans, begins with a vaccination strategy through the development of an effective vaccine.

The aroboviruses ability to mutate and adapt is still a major challenge for science. To Dr. Nogueira, the only way to defeat these diseases is knowing them deeply enough to develop the vaccine. Its the only way we currently have, he says. Regarding the epidemics perspective, this period preceding the rainy season in the Northeast, when arboviral diseases appear more intensely, the researcher is emphatic to say it is also important to focus in Brazils Southeast, which is extremely vulnerable to Chikungunya. We have never had Chikungunya epidemics in this part of the country, so this is the area that most worries us, he says.

The first part of the study looked at the peri urban environment, and now researchers continue to search for the existence of the wild cycle in forest regions. At the moment were looking for this virus in Manaus, in denser forest regions, with different species of mosquitoes and monkeys, concludes Dr. Nogueira.