The Zika Virus and its Global Impact

By Beatrice Endler ’17

In May 2015, Zika, an RNA virus, emerged in Latin America and recently, it has gained international notoriety for its possible association with microcephaly, a rare disease that affects the brain development of a fetus. Those at risk for this serious malformation, due to the Zika virus, are primarily children of pregnant women living in or visiting Latin American countries. However, it is possible that the Zika virus could spread globally.  

The Zika virus, prior to 2015, was only known to have occurred in Africa, Southeast Asia, and the Pacific Islands, but cases of the virus were confirmed in Brazil in May 2015 and later in other Latin American countries.

Brazil has been the epicenter of the Zika virus outbreak. Brazil’s Ministry of Health has revealed data suggesting a link between pregnant women infected with the Zika virus and cases of microcephaly, although no connection has been confirmed. Microcephaly is “the condition of having an abnormally small head and brain,” as described by the OED, and it relates to incomplete brain development.

Assumptions supporting the causal relationship began to appear when a hospital in Recife, Brazil, questioned women who delivered babies with microcephaly and found that 70 percent of these women had experienced the symptoms of the Zika virus during pregnancy. These symptoms include a fever, rash, joint pain, headaches, muscle pain, and conjunctivitis (redness of the eyes).

The Pan American Health Organization (PAHO) discovered more evidence to support this association when, in Dec. 2015, it identified Zika virus RNA in the fluid surrounding the fetuses of two pregnant women, who had had the Zika virus during their pregnancies. These women later delivered babies with microcephaly. Another infant with microcephaly, who died after birth, was found to have Zika virus RNA in its body tissues, including the brain. Additionally, there is evidence suggesting that viral infections can cause microcephaly, as other maternal viral infections, such as rubella (German measles), have been proven to be a cause of microcephaly.

The validity of this connection between the Zika virus and microcephaly, however, has recently been called into question. In 2014, before the Zika virus epidemic, Brazil recorded 147 cases of microcephaly, and since Oct. 2015, Brazil has reported 4,180 suspected cases of microcephaly. These reported cases are currently being investigated, and of the 732 so far examined, 462 were incorrectly diagnosed as microcephaly or were not caused by a maternal Zika virus infection.

An illustration of a baby with microcephaly, a condition which causes neurological disability. (Photo: the CDC)​

An illustration of a baby with microcephaly, a condition which causes neurological disability. (Photo: the CDC)​

Despite the doubts regarding this investigation, the spike in microcephaly, which is a rare condition, and the spread of the Zika virus throughout the Americas are still major concerns.

Other ongoing areas of investigation include the Zika virus’ possible connection to Guillain-Barré syndrome, a neurological disorder that can lead to paralysis, and the virus’ possible transmission via bodily fluids (sexual transmission and spread through blood donations for transfusions).

Cases of the virus have also appeared among travelers who visited Latin America, causing the Center for Disease Control (CDC) to issue travel warnings for certain Latin American countries directed at pregnant women in any trimester or women planning to become pregnant.

Fears that the virus will affect participants and spectators of the 2016 Rio summer Olympics have prompted fumigation of outdoor grounds and inspections at or near Olympic facilities for stagnant water, such as cisterns or pools. These bodies of standing water are prime breeding areas for the species of mosquitos that are vectors for the Zika virus, including Aedes aegypti and Aedes albopictus.

Although the Zika virus causes relatively mild symptoms, the more people that are infected, the greater the chance that more uninfected mosquitoes can bite these infected humans, become carriers of the virus, and cause more local transmission. With the Olympics in August, there is the potential for this local transmission to lead to large numbers of international carriers of the Zika virus.

According to the New York Times,  half a million people are expected to attend the Olympics in Rio this summer. However, with ticket sales already low, the emergence of the Zika virus, which has had a lot of media coverage, and the refundable cancellations that many airlines are now offering to certain Latin American countries, Olympic attendance doesn’t look promising. This is an additional problem for Brazil, which is already facing an economic crisis.  

According to the CDC, an estimated 80 percent of people infected with the virus will show no symptoms. This is beneficial for the four fifths of people who are bitten but don’t experience the few days to a week of sickness.

So many asymptomatic cases, however, can also have negative repercussions, since locals who don’t know they have the virus won’t know that it’s crucial that they avoid more mosquito bites (by wearing long, protective clothing and applying insecticide, which they don’t always have access to), and travelers, who are unaware of their viral infection, can potentially transmit the virus locally when they return to their respective countries. There is currently no test for the virus, although one is currently being developed.

The virus has the potential to spread to and throughout countries that share Zika’s primary vectors, the two species of mosquitos, and the Olympics in Brazil could likely become an event that facilitates the international expansion of the virus. This is because the mosquitos that carry the Zika virus, much like many other mosquitos, like to be near people, whether inside or outside, making the large crowds that attend the Olympics targets for mosquito bites.

It is also important to remember that the Zika virus is an RNA virus, meaning that as it replicates in humans and in mosquitoes, there is a greater potential for mutations, as compared to a DNA virus. So not only is there potential for international extension of the virus, outside of the Americas, but there is also the possibility for mutation, which would make the creation of a vaccine even more difficult if multiple strains emerge, and potentially make the virus cause more harmful symptoms or alter its mode of transmission.

The World Health Organization (WHO) met on Feb. 1 to discuss the Zika virus for the second time, and the WHO director general, Margaret Chan, declared the Zika virus outbreak to be a “public health emergency of international concern.” The WHO’s slow response to the Ebola crisis in 2014, and the criticism it received from that decision, has also prompted this faster reaction to the Zika virus, even though evidence of the connection between the virus and microcephaly has not been definitively confirmed.