Medical Mysteries Still Surrounding Zika Virus
Yellow indicates areas that have had evidence of Zika virus infection.

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Medical Mysteries Still Surrounding Zika Virus

The challenges of understanding, diagnosing, and treating Zika virus: there are more questions than answers.

In the last few months, media outlets have been pumping out stories on Zika virus and a potentially related birth defect, microcephaly, due to outbreaks and its rapid spread in parts of South and Central America. All of these updates say the same key things. Zika is: 1) spreading quickly, 2) transmitted by mosquito bites, 3) the probable cause of a birth defect known as microcephaly, and 4) possibly sexually transmitted.

A number of pieces written about the impact of the outbreak on the travel industry cautions women who are or will be pregnant against traveling to these regions. While these are important highlights for general awareness, there are scientific perspectives that are neglected in the news. Part of the reason for this is the scarcity of established biological and medical information about the virus. In light of recent events, there is a push for new data on the subject and it may be worth looking at the aspects that are otherwise neglected.

Zika is an emerging problem and so scientists do not have clear-cut questions ready to answer about testing and treatment. I personally find it surprising because I can normally go to sources like WebMD for thorough, established information about such conditions. In many instances new information is released, but not much is being said about what still needs to be learned.

One of the predominant mysteries of Zika is its connection to microcephaly. Microcephaly is a birth defect that is characterized by the baby’s head being smaller than expected for his or her age and size. Zika is a suspected cause of the neurological birth defect based on rates of both rising in the same geographic locations over the same period of time. However, this evidence is not definitive, so the connection has not been a concrete claim. Part of the difficulty with drawing this conclusion is that a Zika infection doesn’t always cause symptoms in adults, and when it does, universal treatments such as rest, fluids, and fever-reducers are utilized. Recently, scientists found evidence of the virus in the brains of infants suffering from microcephaly, providing much more direct evidence that the virus is causing the birth defect [1]. Evidence for the connection is rapidly mounting, which will raise more questions about how to intervene than the interaction itself.

Another major challenge is detection of the virus in people. Currently, the only way to positively diagnose a patient with Zika is by testing them for viral genes. The problem with this is that the only way to determine that a person definitely has the virus is during an active infection, while the virus is present in higher quantities in the body and can be readily detected. Other tests used have the problem of cross-reaction with related viruses, resulting in false positives.

This diagnosis dilemma exacerbates the problem of limited knowledge on how infection interacts with pregnancy. Right now, we don’t know whether the timing of infection or the severity somehow influences the birth defect risk. Without more specific tests, solutions for prevention are incredibly difficult to find.

These pieces of information are frustrating not to have, but hopefully with the new attention on the problem, solutions will come quickly. Before we have these answers, there are many ways for the people in affected areas to be cautious: mosquito nets, repellents, and delaying pregnancy. Armed with the right questions, scientists continue to search for answers to diagnose and prevent the spread of Zika virus infection.

References:

[1] Rubin, Eric J., M. F. Greene, and L. R. Baden. 2016. Zika Virus and Microcephaly. The New England Journal of Medicine, 374: 984-5

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