The Zika virus has spread across much of Brazil and Latin America, and cases have also been confirmed in the United States, Germany, Denmark, Great Britain and Italy. An alarm has recently been raised among health officials because the virus is thought to be linked to a dangerous condition known as microcephaly, which since October of last year has affected more than 4,000 children in Brazil. With the Rio de Janeiro Olympics just around the corner, the need to contain the virus is more urgent than ever, as the World Health Organization (WHO) has declared that it is spreading in an explosive manner.

Where the Zika virus comes from

The virus takes its name from the Zika forest in Uganda, where it was first found in a monkey in 1947. The first cases of disease caused by the mosquito that transmits the virus date back to the 1950s: the first human case was recorded in Nigeria in 1954. But it is only in recent years that the virus has spread like wildfire, "infecting a couple of thousand people" across Latin America and the Caribbean, as Professor Scott Weaver, director of the Institute for Human Infections and Immunity in Texas, United States, states.

Why it is so feared

The suspected link between the virus and microcephaly was first put forward by Dr Vanessa Van der Linden of the Barao de Lucena hospital in Recife, Brazil. Newborns affected by this condition are born with a smaller-than-normal skull and have very low brain function and life expectancy. There is no vaccine or cure for the virus, which sometimes presents symptoms such as fever and joint pain, and sometimes none at all.

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Dr Chan: Last year, [#ZikaVirus] was detected in the Americas, where it is now spreading explosively #Zika #EB138

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How it spreads

The alarm has grown because while initially the only vector of the virus was the Aedes aegypti, the more common Culex mosquito now also transmits it, broadening its potential range of distribution. There are approximately twenty times more Culex mosquitoes than Aedes aegypti, and the former are present in a greater number of countries. There is also a suspicion that the virus can be transmitted through sexual intercourse.

Why it has spread

What for some could become an "explosive pandemic" has hit Brazil particularly hard. Due to the country's tropical and subtropical climate, the spread of poverty and the critical conditions of its slums, mosquitoes find fertile ground here in which to breed (such as stagnant water). Female mosquitoes lay up to 100 eggs at a time, three times a week.

What is being done to eradicate it

The governments of Brazil, El Salvador and Colombia have strongly advised women not to get pregnant, hoping in this way to reduce the likelihood of children being born with microcephaly. The WHO has called for the destruction of mosquito breeding sites and the use of standard insect bite protection to slow the spread of the virus. Meanwhile, Brazilian president Dilma Rousseff convened a summit to invite the 33 members of the Community of Latin American and Caribbean States (Celac) to "work together to combat the Zika virus". In Brazil, the army has been called upon to help defeat the virus and to reassure the public.

In a situation like this, where the epidemic is continually proliferating, it is clear that health is a public good that concerns everyone equally. It is easy to say that the virus would not spread so rapidly if living standards in Brazil and other countries were higher. "When the United States catches a cold, the whole world gets the flu" goes a saying that alludes to the nation's economic power; in this case, one might instead say that "when Brazil gets bitten, the whole world catches the Zika virus".

Featured image: Pest control operators working against the Zika virus in Rio de Janeiro © EPA

Translated by Francesca Clemente