Here's what travellers need to do to avoid contracting Zika virus

The dreaded Zika virus is named after the place where it was identified- the Zika forest in Uganda, close to the Entebbe airport in Kampala. It was detected in 1947 by Alexander Haddow and George Dick as a fever in rhesus monkeys during their study of yellow fever. It has since been noted in many parts of the world, but has not been of consequence as a major human pathogen. In fact, antibodies to it had been identified in Indians way back in 1953 by the National Institute of Virology, Pune. This was not considered of importance given the mildness of the disease.

What changed? Well, the strain of Zika identified in Yap island in Micronesia seemed different. It appeared to be associated with more problems than recognised earlier. There was a sharp increase in the number of children born with small heads- microcephaly- since 2007. Also noted was the rise in neurological illness like Guillian Barre syndrome.  

The concern is that Zika is going the way of West Nile virus and Chikungunya. West Nile, for example, had been known to be around for more than 50 years when it suddenly entered North America and swept the nation causing neurological disease, like meningitis. Zika virus has entered the South American continent and has proceeded to spread across all of Latin America at remarkable speed. Most persons have a mild disease, and only about one fifth have a febrile illness. Some have a rash or redness of the eye, but tends to improve. A small number can have a severe neurological illness called Guillian-Barre syndrome, and some hospitals have reported a higher than usual risk to death.

The most worrisome association is with the risk of developing a baby with a small head in pregnant women who get the infection. 1 in 2 pregnant women contracting Zika virus infection may have a child with microcephaly. While a direct link between the virus and brain damage in babies has not been proven yet, experts believe that the evidence is mounting. The speed of spread of the problem has not given us enough time to study it thoroughly. It is carried and spread by the same mosquito that carries dengue and chikungunya, Aedes aegypti and Aedes albopictus. Given the prevalence of this species, it is expected to sweep the Americas, stopping short only of Canada and Chile. It has also been noted to be present in genital fluid and saliva independent of its presence in blood, and at least 2 cases of sexual transmission have documented in the United States.

Patients are infectious 10 days before the onset of symptoms and remain so for another 12 days. This is a problem as patients could transmit the infection without knowing that they present a risk. This can also contaminate the blood supply, and blood products could also become a source of infection.  

Precautions you need to take:
1. Non-essential travel to the affected areas must be avoided. Pregnant women should pay specific attention, as this concerns the unborn baby.
2. Given the risk of spread, travel to the affected areas should be postponed till we have better information. At this point, WHO and CDC have issued a warning only for pregnant women, but this could change. CDC is investigating the possibility that it could be transmitted through sex. 
3. Mosquito repellant methods make sense if travel to these areas is not avoidable. Of course, it should be kept in mind that this is a day time biter, and the precautions are mandatory in the morning and evening. 
4. Pregnant women should avoid contact with returning travellers with any illnesses. 
5. In the event of any type of sickness in a returning traveller, immediate consultation with an infectious disease expert is prudent.

Dr Subramanian Swaminathan is MD DNB MNAMS, AB (Internal Medicine, Infectious Diseases), Infectious Diseases Consultant, Global Hospital