Zika Virus: The Lowdown

Aedes aegypti, one of the species of mosquito responsible for the spread of Zika virus.

It doesn’t seem long since images of weary health workers dressed in yellow suits, gloves and airtight helmets carrying dead bodies to be buried, appeared on television, in newspapers and on all aspects of social media. The culprit of course, was Ebola. In March 2014, a disease originating in Sudan and Zaire that was once rare, causing only sporadic minor outbreaks, went on to become a public health nightmare. It spread panic amongst not just the countries directly affected but also across much of the western world, killing an estimated 11,315 people including one in the US and six in Mali. Fast forward almost two years and whilst the Ebola outbreak seems to be contained, news of another public health threat has surfaced.

On the 5th February 2016 the WHO released its first situation report on what they are calling a ‘world health emergency’, prompted by a rise in microcephaly (a congenital condition linked to incomplete brain development) and Guillain-Barré syndrome linked to a virus known as Zika. Unlike Ebola, very little is actually known about this virus, to such an extent that it was only this month that we learned that Zika might have the capacity to be sexually transmitted. This was in response to the news of an infected patient in Texas, acquiring the disease through sexual contact. With uncertainty spreading, questions about the severity of infection and whether we should be worried in the western world need to be asked, especially considering that the corpses of Ebola rest vivid in the memory of many. So what actually is the Zika virus?

Zika virus, a member of the Flavivirus genus, was first identified in 1947 during experiments monitoring Rhesus monkeys in Uganda and five years later it was detected in humans. Two major outbreaks have since been reported in the last three years in French Polynesia and Brazil. The latter was first detected in May 2015 and has caused great concern as almost 1.5 million cases have already been recorded, an epidemic which has been described as spreading in an ‘explosive manner’ and one that could reach an international magnitude. However, some might argue that a distinction must be made between virulence and transmission. Whilst a virus may spread pretty quickly, if the effects of that disease are minor then the potential threat may be reduced. Indeed, in the majority of cases, infection with Zika virus causes no symptoms and often doesn’t leave any lasting harm if the characteristic Zika fever is treated effectively. According to the WHO website, common symptoms include mild fever, skin rash and conjunctivitis, all of which normally last for just 2–7 days. For the majority of us this is potentially good news but the problem arises when pregnant women are thrown into the equation. Alarmingly, journalists for the British newspaper The Independent have reported that local health authorities in northeast Brazil have noted a correlation between an increase in Zika virus infections and the number of babies born with microcephaly which can cause mental retardation, seizures and hyperactivity amongst other things. Paralysis has also been noted in other patients although no confirmed correlation has been proved thus far. As a consequence, women in the affected El Salvador have been warned not to get pregnant until 2018 to avoid potential complications. The practicality of this proposal is, of course, questionable considering abortion laws in many Latin American countries are highly restrictive.

Nevertheless, all this information harbours the question as to whether this virus poses a significant effect upon us in the western world. The transmission of Zika virus is via mosquitoes, mainly the species Aedes aegypti, which also just so happens to be the same mosquito that transmits diseases such as Dengue and Yellow fever. As a consequence of the type of vector which carries this disease, Zika virus is known to circulate in the tropics across the Americas, Asia, Africa and the Pacific (typically near the equator)- so quite a big area! What’s more, according to the New York Times, the Asian tiger mosquito (Aedes albopictus) is also known to transmit the virus and with a range as far north as New York and Chicago during summer months it is clear that more developed countries in the West do not have a ‘get out of jail free card’. Scientific concern also rests upon the issue of climate change and its effects on range expansion of certain mosquitoes responsible for illnesses such as Lyme disease which could potentially create a wider rate of infection in the United States. These factors could also apply in the case of Zika virus. Add on the potential of sexual transmission and suddenly the problem becomes a lot more evident.

So how can this viral outbreak be contained? Well unfortunately there is currently no specific treatment or vaccine available to combat Zika virus and so the best form of protection promoted by health authorities in affected areas is to avoid being bitten, namely through the use of mosquito nets, insect repellent and the avoidance of breeding sites such as stagnant water. There is hope though in the form of scientific research pioneered by a British biotechnology company known as Oxitec who have genetically engineered male mosquitoes to compete with wild-type males for female mating partners. The only difference is that the offspring of this OX513A brand do not survive into adulthood and so their release onto the streets of Brazil could help tackle the spread of the virus. Of course, the thought of genetically manipulated mosquitoes being set free into the wild is perhaps a worrying one for some but it provides a viable solution to the current pandemic whilst other ideas are being tested. The question is are we more prepared this time or is Zika just another virus which reminds us of the continuous battle we face with disease?

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