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The Zika virus, explained

News headlines are swarming with concern over outbreaks of the mosquito-borne Zika virus. First discovered in 1947, the Zika virus is part of the flavivirus family and was believed to pose no threat to humans; however, this virus is the recent cause of over 4,000 cases of microcephaly in infants—an illness causing underdevelopment of the brain and an irregularly small head. Microcephaly can lead to impaired vision and hearing, as well as other neurological abnormalities.

The virus is prevalent in South America, where it has spread to 21 countries through the mosquito carrier Aedes aegypti. This species is known to carry other viruses such as dengue and yellow fever—two other members of the flavivirus family—and are known to have various neurological effects including Parkinson’s-like symptoms and encephalitis.

Zika virus appears to be less severe than dengue or yellow fever; infection ranges from asymptomatic to fairly mild symptoms—aches, inflammation in the eyes, joint pain, rash; however, pregnant women appear to be at high risk of transmitting the infection to their fetuses, causing the increasing rates of microcephaly.

The virus was first discovered in Uganda and was possibly carried to South America during the 2014 World Cup. The upcoming Olympic Games in Rio de Janeiro pose a threat to the rest of the world population, opening up the possibility of global outbreaks. In an attempt to prevent this, the Brazilian government just announced it will deploy 220,000 soldiers to bring pamphlets door-to-door, advising people—especially pregnant women—on ways to prevent infection.

Virology professor Selena Sagan, from the McGill Department of Microbiology and Immunology, focuses her research on other flaviviruses, such as hepatits C and dengue. The Zika virus, however, presents new difficulties.

“We don’t know enough about transmission to the fetus,” Sagan said. “Zika virus is a very new virus being studied.”

Development of a vaccine doesn’t seem to be in the near future—scientists believe it may be 10 years before a vaccine for Zika virus could be developed.

“It is difficult to predict how quickly research and development will take to produce an effective vaccine,” Sagan explained. “We’ve studied dengue virus for much longer and approval for vaccine trials just began last year; however, since Zika is closely related, there may be things we’ve learned in studying viruses like dengue and Chikungunya [a related virus] that can be used in developing a Zika vaccine.”

In the meantime, governments in Colombia, El Salvador, and Ecuador are urging women to avoid pregnancy until the outbreaks end. This raises ethical concerns over women’s reproductive rights, especially in countries with stricter laws surrounding birth control and abortion.

Luckily, humans appear to be a dead-end host for Zika, so infection control focuses on preventing mosquito populations from spreading. Possible solutions include releasing genetically modified mosquitos that are sterile or resistant to the virus, as was recently proposed to prevent mosquitos from carrying malaria. Pesticides are another option, but similarly to the problems antibiotics face, mosquitos may evolve to become resistant.

According to the World Health Organization (WHO), the virus is likely to spread to the United States. Four million cases of infection are estimated to occur in the Americas within the next year, and this year’s El Niño weather appears to be speeding up the process.

“Since [Canada doesn’t] have the [mosquito carrier], it’s unlikely we’ll have an outbreak [here], but the southern United States [is] at risk,” Sagan explained. “With global warming, these vectors seem to be traveling north, so it’s difficult to say if it will be a problem years from now.”

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