Associate professor, Carleton University
A little-known virus called Zika has led to the declaration on Sunday of a state of emergency in Pernambuco, Brazil's sixth most populous state. An unusually large number of suspected cases of microcephalia, a neurodevelopmental disorder, has been detected among newborns here over the last few months. The babies affected have an abnormally small cranium, a condition that is often associated with intellectual and developmental handicaps. This past weekend, Brazil's health ministry has formally established a link between the presence of the virus and that condition, which however may also have a variety of other causes, from syphilis to malnutrition.
Still, the number of suspected cases identified this year so far (more than 1,000 in the country as a whole as of November 30, and around 500 in Pernambuco alone) significantly exceed the normal incidence of cases in Brazil, which have ranged between 139 and 175 per year since 2010. In addition, a small number of infected people have died in recent days, including a few adults, though it is unclear if the virus itself was the cause of death, if it interacted with another disease, or if the person died of an unrelated condition.
The virus is transmitted by a mosquito, aedes aegypti, which is also a vector for two increasingly common diseases in Brazil: Chikungunya and especially dengue fever, which has reached epidemic proportion in the country. The mosquito reproduces in stagnant water and has a larval cycle of five days.
Symptoms of Zika are similar to those of dengue fever: high temperature, headaches, joint and muscular pains as well as spots on the skin. They disappear after a few days. A significant proportion of people infected by dengue fever, however, are asymptomatic, and the same could be true of Zika. Finally, many dengue fever diagnoses have been based on clinical assessments instead of blood tests and an unknown proportion of presumed dengue patients or asymptomatic dengue carriers may thus have been in fact infected by the Zika virus.
Specialists and government officials currently think that foetal infection leading to microcephaly occurs when mothers are inoculated with the viruses in the first three months of pregnancy, in a period crucial for the development of the foetal brain and before the placental barrier is fully formed.
The possibility that Zika is already widespread or that it could quickly expand to the whole country is based on the large number of diagnosed cases of dengue, which increased between 2014 and 2015 from 555,000 to 1.5 million (as of Novemer 16). Such a sharp increase clearly indicates that efforts to get rid of the mosquito are unsuccessful. The prospect that, by infecting pregnant women, aedes aegypti could now produce a large number of cases of microcephaly magnifies the severity of the health challenge that dengue and Chikungunya fevers already represents.
The state of emergency has been declared in Pernambuco, which enables the state government to draw from special federal funds and it may be extended to other states in the coming days. The federal government has set up a cross-ministerial working group to tackle the crisis and is mobilizing research capacities and seeking international support to better understand what remains an extremely poorly known virus (CDC and WHO missions will come to Brazil later this week to discuss the crisis). The effort at this point focuses on the elimination of the mosquito. In addition, the government encourages pregnant women to wear long sleeves and pants, to close windows and doors and to use insect repellent.
The spectre of large-scale microcephaly occurrence is obviously the dominant preoccupation of the government and health specialists. This has led a specialist to make a most extraordinary health recommendation: in an interview posted last week-end on the website of Veja, Brazil's most widely read weekly, Artur Timerman, a virologist and President of the Brazilian Society for Dengue and Arbovirus (mosquito-transmitted), recommended that Brazilian women postpone pregnancies until the risks involved are assessed, which may take months. When asked by the female interviewer what women who were already pregnant should do, he fell back to dress codes and insect repellent recommendations, though noting that the efficacy of the latter was limited.
The elephant in the room is the issue of abortion, which is illegal in Brazil except for cases of rape or danger to the life of the mother. The question is extremely delicate in a country that is much more conservative that its international image would suggest. Given that the surge in dengue fever typically takes place between the end of February and June (week 7-23 of each year), most foetuses affected this year would be due between December and the end of March. This would imply impossible, extremely late or very risky pregnancy interruptions for this cycle, but a significant incidence of microcephaly in coming months would precipitate a huge debate in 2016. The tenor of that debate would be unprecedented, and not just for Brazil.
As the world's governments meet in Paris to talk about climate change and what it could mean for the future, a very ugly side of that future may already be showing at the door. A situation is developing in the planet's fifth largest country that may force its society to consider "postponing" or interrupting pregnancies on a massive scale to avoid the birth of a possibly very large number of severely handicapped babies.
The fact that the vector of that potential epidemic is an insect that has adapted perfectly to the messy and increasingly warm urban context in which much of the population of the world already lives, and the fact that this insect is already showing resistance to common insecticides just boggles the mind. With aedes egypti already roaming a very broad strip of the world's surface, and with the Zika virus quickly spreading well beyond Brazil, a challenge that remains local could very quickly develop into a major global health emergency.