We’ve published several articles in Stormwater magazine over the last decade dealing with the question of mosquitoes and stormwater structures. In this article, for instance, the authors—both public health biologists—call on stormwater agencies to work in tandem with the agencies responsible for mosquito control to ensure that infrastructure is maintained to eliminate stagnant water that can serve as a breeding ground for mosquitoes. Recent events in Brazil suggest this is a practice we should take more seriously.
Mosquito-borne diseases include malaria, dengue, yellow fever, chikungunya, St. Louis encephalitis, and West Nile virus, which first appeared in the US in 1999. We don’t often think of these diseases as big problems in this country—in large part because the mosquito control efforts of public health agencies have been so effective—but they are serious threats in many parts of the world. And now there’s a frightening new one.
The Zika virus, found mainly in tropical climates, is transmitted by the Aedes aegypti mosquito—the same one that transmits yellow fever, dengue, and chikungunya. The virus has recently been found in parts of Brazil—the first case was reported in May 2015—and doctors there have linked infection with the Zika virus during pregnancy to a disorder called newborn microcephaly, which results in incomplete brain development and is often fatal. In 2014, Brazil had 147 cases of newborn microcephaly; in 2015, coinciding with the arrival of the virus, it had more than 2,700 cases.
At first the virus was concentrated in the northeastern part of the country, but it is spreading. The Zika virus causes symptoms like rash, fever, headache, and sore joints. Many women who have given birth to children with microcephaly reported experiencing these symptoms early in their pregnancies, and autopsies on some of the children who have died from the disorder have confirmed the presence of the virus. Research to investigate the connection is ongoing, and doctors are monitoring nearly 400 pregnant women who are believed to have been infected.
The Zika virus is so widespread and the consequences potentially so serious that doctors in Brazil are recommending women do not get pregnant until the situation is under control. “If families can put off their pregnancy plans, that’s what we’re recommending,” said one doctor in the state of Pernambuco, which has had the most cases of the virus.
Sometimes the virus causes no symptoms, so it’s difficult to know who has been infected, but the Brazilian Health Ministry believes there have been between half a million and 1.5 million cases in the country so far. There is no vaccine against the virus.
What is the Brazilian government doing about the situation? Officials are advising people—especially pregnant women—to use insect repellant and to stay indoors. In many parts of the country, but especially in Rio de Janeiro, which will host the 2016 Olympics, officials are doing much the same as we’d do: trying to eliminate the mosquitos by getting rid of areas of stagnant water. A recent increase in the country’s mosquito population has, ironically, been linked to the drought Brazil has experienced for the last couple of years, as many residents are storing up water in plastic containers, swimming pools, and other small reservoirs, which become ideal mosquito habitats. Officials are trying to eliminate these areas of standing water, which potentially number in the millions.The mosquito that transmits the Zika virus is found in southern states the US, as well as in Hawaii. Just last week the virus itself was found in Puerto Rico. The US Centers for Disease control says that the connection between the Zika virus and microcephaly is not definitely established but is still advising travelers to Brazil and Latin America to take steps to avoid mosquito bites.