Essential information we need to know about Zika virus and its major effects on health...
Can anything we do make a difference?
By Peter N. Landless and Allan R. Handysides
I am worried because my daughter is pregnant, and all the news about the Zika virus and microcephalic babies is making me nervous. What advice do you have to offer?
The Zika virus was isolated in 1947 from a rhesus monkey in the Zika Forest near Entebbe, Uganda. The recent explosive outbreak of Zika virus infection in Brazil, and the temporally associated spike in the incidence of microcephaly and of the Guillain-Barré syndrome (a paralytic disorder), have caused tremendous anxiety and concern.
Epidemics often have a “tipping point,” where the background rate of an infection is higher than the norm. With the Zika epidemic, this probably corresponds to the increased numbers of infected mosquitoes and, consequently, humans.
The virus belongs to the arboviruses, or arthropod-borne diseases, such as dengue. Additionally, and of concern, the virus may be transmitted by sexual contact.
A large number of infected individuals remain asymptomatic, making control more challenging, because documentation of the disease’s progress in a community becomes difficult.
The symptoms are of a viral infection—with fever, rash, and joint pains—and might have permitted the infection to remain obscure. An association with Guillain-Barré (paralysis) raises significant concern. The potential to damage babies (teratogen) has caught global attention.
Zika is associated with abnormal brain development (microcephaly) in the fetus, which may later be associated with convulsions and learning disabilities.
Many questions have not yet been answered. For example, does the infection have to occur at a specific time in the pregnancy to be associated with fetal damage? What percentage of mothers infected at such a specific time have babies that are affected? Does prior infection offer long-lasting protection, and if so, for how long?
We shall learn a great deal about this Zika virus now that its association with major problems has been described. But for now, what does one do?
Avoidance of mosquito bites becomes the number-one priority. This is particularly true for anyone contemplating pregnancy. This would have been to simply defer going to places where mosquitoes are known to carry the virus. The problem now, however, is that mosquitoes in our own backyards may be carrying the virus.
Public health measures of cleaning up the environment and removing even small amounts of water sufficient for the breeding of mosquitoes need to be implemented.
This reduces the number of mosquitoes. Individual householders may consider spraying the walls of their houses inside and out with a permethrin-containing spray to kill mosquitoes. Insect screens should be checked and repaired.
Programs that include spraying or even the introduction of genetically modified male mosquitoes that produce nonviable larval forms need to be considered by regional health authorities.
Experience with malaria has demonstrated the difficulty of mosquito control, so avoidance of bites is a major strategy. Insect repellents are recommended, especially those containing DEET. A pregnant woman, however, may wish to have more of this on her garments than on large areas of skin. Permethrin-impregnated mosquito netting could become a feature of living even in nonmalaria areas.
The concern for pregnant women also affects their partners because of the potential of person-to-person sexual transmission.
The Brazilian health minister suggested couples might even defer having a family because of present uncertainty. Microcephaly may be associated with cognitive handicap, and this is a lifelong challenge.
In the long term, a vaccine may become available and help to contain the epidemic; in the short term, the concerns we have discussed are important. Some may feel the size and importance of the problem may be exaggerated, but “better safe than sorry.” n