The World Health Organization wants to set the record straight about Zika.
The virus has been making headlines since the start of 2016 due to its rapid spread and its possible connection to cranial defects in infants whose mothers contract the virus while pregnant. Earlier this month, the WHO declared Zika to be a global health emergency, only the fourth time it has declared such a crisis in its 68-year history.
Until this epidemic, only a limited amount of research had been conducted on Zika. It was such a minor, infrequently occurring virus there was wasn’t much of a need.
We do have some insights. We know, for example, that the virus’ primary mode of transmission is through the Aedes aegypti mosquito, and less frequently, other species of mosquito. We also know that people who contract Zika are asymptomatic. The 20% of patients that do show symptoms have relatively mild complaints that include a fever, rash, joint pain, and conjunctivitis. The biggest threat is to pregnant women and their fetuses is believed to be a condition called microcephaly, which causes babies to be born with smaller than average heads, and is associated with both cognitive and physical disabilities. There have also been reports that the virus can be spread through sexual contact, but it’s exceedingly difficult to prove that Zika (or any infection, for that matter) is transmitted sexually. To do so requires proof of a similar active strain of the virus in the genital secretions of both infected individuals.
But still, there are many unknowns about the virus, the CDC’s Thomas Frieden recently acknowledged. Though the virus has been associated with a growing number of babies born with microcephaly, so far it’s been impossible to prove a direct causal link. The same can be said for the even more rare Guillain-Barré syndrome, a neurological condition that has also been connected, but not proven to be caused by, the virus.
The vacuum caused by this limited knowledge has resulted in a lot of anxious speculation. In order to combat this, WHO recently released a statement dispelling rumors about the virus to try to better inform the public, saying that:
- There is no evidence that vaccines and insecticides, not Zika, are causing microcephaly. The fact that the virus has primarily affected babies has fueled speculation that microcephaly is actually linked to vaccines, instead of Zika. The same has been said about the chemical pyriproxyfen, an insecticide manufactured by Sumimoto Chemical which kills mosquito larvae. The WHO says that there no evidence for either of these claims.
- Genetically modified mosquitos are not responsible for the spread of Zika in Brazil. In an effort to curb the spread of Zika and other mosquito-borne illnesses, scientists have been working on genetically modifying mosquitos to produce offspring with shortened lifespans that are unable to reproduce. In January of this year, the bio-tech company Oxitec reported that when the GM mosquitos were released in Brazil in a trial to combat dengue fever, the total number of mosquitos in the area decreased by 82% over about eight months. Contrary to some concerns, WHO reiterated that the mosquitos aren’t contributing to the outbreak of Zika, but are actually helping to fight the spread of the virus.
- Zika’s spread is not because of sterilized male mosquitos. An alternative method of curbing mosquito populations is to alter the existing male population in a way that prevents them from generating viable offspring. Scientists can use low levels of radiation or infect male mosquitos with a bacterial parasite called Wolbachia to stop them from reproducing successfully, or living long enough to do so. Like genetically modifying mosquitos, these tactics are helping combat Zika, not spreading it.
- Chemical strategies are not the only means of combatting Zika. The most-affected countries are using biological methods as part of an ”integrated approach” to fighting the virus—like fish, WHO said. Mosquitos lay their eggs in standing bodies of water. El Salvador is currently introducing fish that feed on mosquito larvae (pdf) into its water storage containers to create an uninhabitable environment for mosquito eggs.