Health and Science

Three big things experts don’t yet know about Zika

The Zika virus outbreak is now considered an international public health emergency by the World Health Organization, a rare move that illustrates the severity of Zika and the desire to encourage further research and tackle some of the biggest unanswered questions about the virus.

Personnel of Peruvian Health Ministry analyzes the larvae that causes Zika virus in Lima, Peru on January 30, 3016.
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1. Does Zika cause microcephaly?

As Zika gained the media spotlight over the past few weeks, there are still many unknowns about the mosquito-borne virus. The most well-documented, although yet unconfirmed, aspect of Zika is its association with microcephaly — brain damage in infants born to infected mothers. Brazil has reported nearly 4,000 suspected cases of microcephaly, in which infants were born with smaller-than-usual brains.

"The Brazilians believe there is a strong connection with microcephaly that we are seeing in their population," said Dr. Ron Warner, director of the Texas Tech Physicians Travel Medicine Clinic. "I suspect it will be several weeks before they are able to be more definitive about this link."

Adding a layer of speculation to this possible connection, Colombia, which has the second largest number of confirmed cases of Zika after Brazil, reported no cases of microcephaly in its population of more than 2,100 pregnant women infected with the virus, Dr. Warner added.

WHO declares Zika virus an international health emergency

2. What prompted the outbreak?

Another major question is what started the Zika outbreak. The first reported cases of Zika in humans occurred in 1947 in Uganda, though the exact reason for the virus' proliferation today has not been specified. While some point to an infected traveler spreading the virus to other attendees of the 2014 World Cup in Brazil, others note that the outbreak of Zika is related to chance rather than a certain event. 

"Why the virus has spread now as opposed to not before is largely a matter of chance," said Alex Perkins, a biological science professor at Notre Dame University. "It is likely the wrong person at the wrong time happened to be in Brazil to start a local outbreak that we see today."

Recently, a claim that the virus was supposedly spread through genetically modified mosquitoes notes the Zika outbreak epicenter is the same location where mutant mosquitoes were released in 2015. Blogs circulated this story criticizing the biotech firm Oxitec that headed the experiment by releasing GM mosquitoes in Brazil to compete with normal Aedes aegypti mosquitoes that transmit the virus.

Oxitec vehemently denied this claim, explaining that the first cases in Brazil were reported in May 2015 in the city of Camaçari in Bahia State, where no trials have taken place. The trial sites are therefore over 400 kilometers (about 249 miles) from the centers of disease outbreak, which is significantly more than the 200-yard distance the mosquitoes can travel in their lifetime. 

A worker fumigates the Sambadrome ahead of Carnival celebrations in Rio de Janiero, Brazil, on Tuesday, Jan. 26, 2016. The operation is part of the Health Ministry's efforts to eradicate the Aedes aegypti mosquito, which is thought to spread the Zika virus being blamed for causing birth defects.
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The forearm of a public health technician is seen covered with sterile female Aedes aegypti mosquitoes after leaving a recipient to cultivate larvae, in a research area to prevent the spread of Zika virus and other mosquito-borne diseases, at the entomology department of the Ministry of Public Health, in Guatemala City, January 26, 2016.
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A banner is seen during an information campaign on the Zika virus by the Chilean Health Ministry at the departures area of Santiago's international airport, Chile, January 28, 2016.
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"Even if an Oxitec mosquito 'hitched a lift,' it would die and not be able to establish a population," said Oxitec CEO Hadyn Parry.

The link between the release of genetically modified mosquitoes and Zika is also "complete nonsense" because Oxitec releases male mosquitoes that cannot transmit the disease as they do not bite, added Parry. 

"I think this connection is completely implausible for all sorts of reasons," said Perkins. "It is unfortunate that this conspiracy is spread because it has negative health consequences as these mosquitoes can get rid of the Aedes."

As the exact origin of the virus is unclear, blaming a type of technology or a single event can provide an easy explanation for Zika's global presence. 

3. How bad will a Zika outbreak be in the U.S.?

Forward-looking questions about Zika's spread are also top of mind within the scientific community. Thus far, local transmission of the Zika virus has not been identified in the continental U.S., so a common question being asked of the research community is how severe the outbreak of the virus might be if it is transmitted to the states. 

"I don't think Zika will be well-established in the U.S.," said Dr. Anna Durbin, an associate professor at the Johns Hopkins Bloomberg School of Public Health. "We will probably see outbreaks in areas like the Florida Keys and the Gulf Coast. The infrastructure we have in most of our buildings will prevent the virus from establishing itself in the same way that it has in Brazil."

Though this mosquito is typically found in tropical locations, the mainland U.S. does have Aedes species mosquitoes that can become infected with and spread Zika virus, according to the CDC. The virus is transmitted when an Aedes mosquito bites a person with an active infection and then spreads the virus by biting other individuals. During the time when those people have symptoms, they can then become carriers. Transmission in the U.S. may start to happen as the weather becomes warmer, however, the propagation of the virus is less predictable.

"As much attention as Zika is getting in the media, it is still difficult to ascertain what is really going on and exactly how bad the problem is," said Perkins. "The ongoing nature of this threat and the limited capability we have to diagnose and confirm 80 percent or more of Zika infections pose challenges to studying it and responding to it, but this WHO declaration is a step in the right direction."