Vigilance—But Not Panic—Needed in US Reaction to the Zika Virus.

A researcher at the School of Public Health and Boston Medical Center warns that the Zika virus could spread quickly to, and potentially within, the US. He also states that people in the US shouldn’t panic; they should be aware and vigilant.

In an article online in the Annals of Internal Medicine, senior author Davidson Hamer, professor of global health and of medicine at the School of Medicine, says that the risk of Zika’s introduction into the US is “substantial, given the presence of (Aedes species) mosquitoes in many states.” The warning comes as the World Health Organization announced Monday that microcephaly, which may be associated with Zika infection during pregnancy, is a public health emergency of international concern.

Hamer and co-author Lin Chen of the Mt. Auburn Hospital Travel Clinic say that a total of 20 countries and territories in the Americas have Zika virus circulation, and that its “explosive spread” mirrors the emergence of chikungunya, which was first detected in St. Martin in 2013 and rapidly disseminated throughout the Americas.

“If you are pregnant, put off travel to the endemic areas,” he urged. “If you absolutely must go, be sure to protect yourself against mosquitoes. For those who are not pregnant, it’s still a good idea to delay travel so that you don’t risk getting infected and transferring the virus back home. There are many unknowns about its transmission, so there is still a risk.”

The mosquito-borne Zika virus, which is believed to cause microcephaly in infants who are exposed in utero, causes rash and flu-like symptoms in adults and children who have been infected. The virus dates back to 1947; however, the first well-documented outbreak in humans was not reported until 2007. An outbreak in French Polynesia in 2013 was responsible for 19,000 suspected cases, and since October 2015, nearly 4,000 cases of Zika virus-related microcephaly have been reported in Brazil.

Microcephaly is abnormal smallness of the head, a congenital condition associated with incomplete brain development and a range of neurological complications.

Zika virus has been rapidly emerging in the Western Hemisphere in the last few months, Hamer and Chen note. Currently, it can be found in Central America, the Caribbean and Mexico, and transmission has occurred in travelers to these areas returning to non-endemic countries including the US, Canada, Japan, Western Europe, and Israel.

“At this time, we believe that Zika virus is primarily transmitted via infected mosquitoes, and therefore people living in or traveling to impacted areas are strongly encouraged to protect themselves against mosquitoes by using an effective insect repellent (containing DEET or picaridin),” said Hamer, director of the Travel Clinic at Boston Medical Center. “However, there is now strong evidence to suggest that the Zika virus can be transmitted via sexual activity, and possibly blood transfusion. This means that safe sexual practices are necessary, especially for woman who are currently pregnant.”

There is also evidence of mother-to-child transmission, which appears to be responsible for the surge in cases of microcephaly being seen in Brazil. But showing how much is still unknown about this virus, other researchers at SPH have written that the WHO emergency may be premature, and that there is an emerging reconsideration of the data about the potential association between Zika and microcephaly.