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All You Need to Know About the Zika Virus

All You Need to Know About the Zika Virus

Aedes aegypti. Credit: Wikimedia Commons

It started with a monkey named Rhesus 766
In a jungle called Zika in the Ugandan abyss
A terrible fever it caught
(It was a scientific plot)
Good reason and more to give mosquitoes a miss.

Is this the first ever Zika virus outbreak?

Location of the Zika Forest, near Entebbe, Uganda, close to the shores of Lake Victoria. Source: Google Maps
Location of the Zika Forest, near Entebbe, Uganda, close to the shores of Lake Victoria. Source: Google Maps

No. The Zika virus was discovered in 1947 by researchers studying yellow fever in Uganda. As part of their tests, they caged a rhesus monkey at a location known to be infested by a mosquito called Aedes aegypti. The monkey did contract a fever, only it wasn’t the one they expected (yellow fever). They named the rogue virus after the forest, Zika (‘zika’ means overgrown in Lugandan).

Since then, there have been sporadic outbreaks of Zika in Africa and South Asia. Most of them were short-lived and showed relatively mild symptoms like fever and body pain.

What makes this outbreak different?

The current outbreak, the first ever in the western hemisphere, is a bigger deal for a number of reasons. The main one is that we now know that it’s not adults who have most to lose but their unborn babies.

Microcephaly is a condition where a baby is born with an abnormally small head and brain defects. Worldwide it affects only 1 in 30,000 to one in 250,000 newborns. In Brazil there are usually a few hundred cases annually at most, but since October 2015, there have been 3,500 new microcephaly cases.

The authorities started panicking when it started to become clear that this was linked to another spreading disease – Zika. It seems mothers infected by Zika have a much higher chance of giving birth to babies with microcephaly.

How bad is it?

As of January 23, 2016, the Zika virus has spread to 21 countries and territories of the Americas. It’s speculated that the virus must have arrived in Brazil along with the throngs that swept in during the 2014 FIFA World Cup.

Countries where the Zika virus has been detected.
Countries where Zika virus infections have been found.

Things look so grim that governments of four South American countries are now advising women to not get pregnant until the situation is brought under control. And in a first-of-its-kind warning, the United States’ Centres for Disease Control & Prevention (CDC) advised pregnant women not to travel to Zika-ridden areas. The World Health Organisation (WHO) has predicted that the virus is likely to spread all over North and South America, except for Chile and Canada where the Aedes aegypti mosquito is not present.

The reason that the WHO thinks these countries are so susceptible is that their populations have not been exposed to the virus before and hence have no immunity.

Is there a cure?

No, there isn’t. There exists medication for symptomatic relief but these are quite useless now that we know about the microcephaly link.

Research on the Zika virus is still quite primitive. Given its generic symptoms in adults, it’s very easy to miss or misdiagnose. Moreover, the virus doesn’t seem to show effects in common lab animals like mice and rats. Getting monkeys is extremely tough because of restrictions on primate research. Vaccine development and antiviral drug discovery efforts are on but this takes time, and with the Zika virus, we’ll be starting from scratch.

How does the Zika virus spread?

Through an old foe of humankind – the Aedes aegypti mosquito. This mosquito is also the carrier of the dengue fever, yellow fever and chikungunya viruses. In all diseases, the mechanism is the same: the mosquito becomes a carrier when it bites an infected individual and transmits the virus into the bloodstream of its future victims.

Though mosquitoes are the major mode of Zika virus infections, there have been a couple of cases of apparent sexual transmission. However, these cases have been too rare and inconclusive for any major health agency to take seriously. Transmission via blood is another remote possibility.

Does Brazil have a way out?

Brazil needs an immediate plan of action for more than one reason. Rio de Janeiro is frantically spraying insecticides at the parade grounds where the annual carnival celebrations will commence soon. In August, the city is due to host the Olympics.

As can be seen from the official warnings, Brazilian authorities are pulling no punches when it comes to preventive measures. Since an emergency was declared in December 2015, thousands of workers have been deployed in a mosquito-eradication drive and erstwhile bureaucratic procedures slowing down insecticide purchase have been removed.

But the elephant in the room is South America’s abortion laws. Abortion is completely banned in seven Latin American nations, while another eight (including Brazil) only allow it in cases where it could save the life of the mother. Illegal abortions continue to take place, but are often dangerous. The Zika epidemic may result in more pregnant women being forced to resort to this racket. It remains to be seen if governments are even considering a change in legislation in response to the emergency.

What about India?

India is one of the Aedes aegyptis’s many homes but the Zika virus itself has not ever been detected in our country so far. However, in a study in the 1950s, healthy individuals from six Indian states showed passive immunity to the virus. This means that though their blood contained antibodies against the virus, this was not because they were exposed to the virus. Usually passive immunity is acquired through vaccines, from mother-to-child transmissions or breastmilk.

In the case of India, where the Zika virus is not known to exist, the antibodies probably arose from exposure to similar viruses. One likely candidate for this similar virus is the dengue virus, also carried by the same mosquito and prevalent here.

Nevertheless, theoretically, Zika can spread anywhere that the mosquito exists. That means India, too. Indians are just as susceptible if they travel to high-risk countries. The best case scenario is that we remain as lucky as we have so far with yellow fever (another Aedes aegypti cargo), as Dr. Jayanthi Shastri, head of microbiology at the Nair Hospital, Mumbai, told The Times of India in a report this week.

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