By Rachel Nadelman* and Fulton Armstrong

Photo Credit: Pan American Health Organization / Creative Commons / Flickr

While scientists struggle to confirm their theories over the link between the Zika virus and the dread health conditions it apparently causes, national and regional leaders face the monumental task of addressing popular anxiety that’s spreading faster than the virus itself.  The Health Minister in Brazil – site of the largest outbreak of microcephaly – has said he is “absolutely sure” that the virus is causing women to give birth to babies with the condition, characterized by abnormally small heads and serious developmental deficits.  The head of the World Health Organization’s emergency response team said last week (2/19) that the “virus is considered guilty until proven innocent,” but that it will take four to six months to even potentially be sure.  In the meantime, other questions are emerging:

• Argentine scientists calling themselves “Physicians in the Crop-Sprayed Villages” suspect that the outbreak has been caused by pesticides. They note that thousands of Zika-infected pregnant women in Colombia – where the larvicide pyriproxyfen has not been added to drinking water as in Brazil – have delivered normal babies.  El Salvador, also hard hit by Zika, has not reported Zika-related microcephaly cases.  Other scientific authorities, including the U.S. National Academy of Sciences, question the evidence for this theory, and the later arrival of the disease in these countries means the consequences for infected expectant mothers cannot be fully determined.  Research is ongoing.
• In lowland Colombia, along the Caribbean Coast, the virus is being blamed for an outbreak of Guillain-Barre syndrome, when victims’ immune systems damage nerve cells and cause pain, weakness, sometimes paralysis, and even death. Scientists are investigating.
• Mental health experts say the Zika virus closely resembles some infectious agents that have been linked to autism, bipolar disorder, and schizophrenia. They can’t confirm their suspicions.
• Entomologists and climatologists are warning that global warming will accelerate the spread of Zika and other diseases transmitted by the mosquito Aedes aegypti, which thrives in warmer, more humid environments. They caution that the number of people currently exposed to the mosquito, roughly 4 billion, will grow steadily.  Evidence is inconclusive.
• Other theories include that the birth defects are caused by genetically modified mosquitoes released by a British company in Brazil to combat dengue; and by vaccinations given to pregnant women to prevent rubella and pertussis. But doctors and scientists have so far rejected each one.

Regional organizations and governments are taking whatever actions they can while awaiting more conclusive science.  Briefing the OAS, the Assistant Director of the Pan American Health Organization called on countries to “to mobilize to eliminate mosquito breeding sites in every corner where they may be” and pledged PAHO’s support to do so.  Brazil has formed special teams to travel around the country to rigorously quantify cases of Zika and possible links with microcephaly.  U.S. President Obama has asked Congress for US$1.9 billion and approval to reprogram funds left over from Ebola eradication efforts to deal with Zika in Latin America and the United States.  Cuban President Raúl Castro has mobilized 9,000 troops and police to spray neighborhoods and eliminate standing water in which the mosquitoes breed.

The “epidemic,” as some leaders are calling it, will be difficult to respond to even after scientists certify the mosquito-virus link.  Solving the mystery of the higher concentration of microcephaly cases in Brazil, or linked to Brazil, will also be essential to developing an effective public health response.  Eradicating all mosquitos would be a monumental undertaking – further complicated by the fact that the history of pesticides shows equal or even greater risks to citizen health when used widely.  The Aedes mosquito sucks the blood of both rich and poor, but population density and weak infrastructure — allowing for stagnant water – makes lower-income communities much more vulnerable.  Focusing on the mosquito may not be enough, moreover, because there are early indications that Zika can be sexually transmitted.  Traces of Zika have been found in breast milk, but the implications remain unclear.  Such questions fuel popular panic, increasing the risk that governments will make rash decisions that could have  profound costs.

February 26, 2016

* Rachel Nadelman is a PhD candidate in International Relations at the School of International Service.  Her dissertation research focuses on El Salvador’s decision to leave its gold resources unmined.