The Zika Virus, the next Epidemic?

The Zika virus was virtually unheard of until recent months, but it is now leaving people very concerned due to its possible side effects and rapid spread through the Americas. The World Health Organisation (WHO) has recently classified it as a global emergency. The virus itself has very few, mild symptoms, with the majority of infected people not even realising they carry it.

(Image via Felipe Dana/AP)

The main concern faced by governments is the lack of knowledge surrounding the disease and its potential link to major head deformities in newborn babies. As of yet there are no treatments, vaccines or any natural resistance, and with a lack of research into the virus, there will be many more people affected before we see any improvements. The WHO’s reclassification of the virus, placing it into the same category as Ebola, will hopefully lead to a fast-track response, to provide help and possibly a cure for the virus.

The virus is spread by the Aedes genus of mosquitos, particularly Aedes aegypti – the same mosquito that spreads yellow fever. They breed rapidly in pools of water, so are especially prominent in lesser developed countries where people often store water in tanks around their homes. The primary transfer vector has been the mosquito; however, there are more recent cases involving transmission between humans. The first case of sexual transmission occurred in 2008, and since then the viral RNA has been found in serum, saliva and urine.

When it was first noticed that the migration of the virus had sped up in 2007, there were no new mutations identified in the sequence. However, in 2014, a new sequence of the virus became available which had a faster replication cycle and had the potential to spread to other parts of the body. A slight difference in the production of one protein in the virus may aid this, but there is not enough research to link this finding to the effects in the body.

Only 1-in-5 people infected with Zika have any sort of symptoms. These include a fever, rash, conjunctivitis, muscle weakness and joint pain – relatively mild symptoms with an extremely low chance of hospitalization. It is the effect that has been seen in pregnant women in the past few months that is of grave concern. Microcephaly is a neurodevelopment disorder causing incomplete brain development and an abnormal smallness of the head, present from birth and resulting in brain damage.

Although the virus has not yet been proven to be the causal link, there have been 4000 cases reported in affected areas of Brazil since October 2015, compared to only 150 in the country in 2014. However, the virus is strongly suspected to be the cause, as it has shown up in amniotic fluid, meaning it is possible that it could cross the placenta.

A lesser-known autoimmune neurological disorder associated with the virus is Guillain–Barré syndrome. It causes weakness and a tingling sensation in the muscles and in some severe cases can lead to complete paralysis. The link to Zika virus was first suggested during an outbreak in French Polynesia in 2013, but there has recently been an increase in the number of cases in Brazil in the first 6 months of 2014, with 121 reported cases.

The virus is not yet confirmed as the cause of the disorder, but it has also shown a correlation between the affected areas and those with the syndrome. Most people recover completely from GBS but the time this takes varies. GBS is a lot less common than Microcephaly in people infected but can have very serious effects on people’s lives.

The virus is expected to spread throughout all of the Americas within the next few months, which has led some people to question if we are at risk in Europe. So far there have been very few cases in Europe, and these have all been travel-related.

The real concern is the risk of the virus being passed to Aedes albopictus, a mosquito commonly found in the Mediterranean, which is most likely a competent vector for its transmission to humans. This has not been confirmed, however, and may not be possible due to the low transmission rates during European winter.

The recent drive for research into the virus has provoked some controversy. WHO received a lot of criticism following their late response towards the Ebola virus, so some feel their fast decision to drive research in this area may be to prevent a similar reaction. Their current advice is for pregnant women or those trying to get pregnant to avoid affected areas. For those already there or living there the best protection is mosquito repellent to avoid being bitten.

Some affected countries have even advised women not to get pregnant in the next two years, but this can be difficult when contraceptives are too expensive for most of the population and abortions are illegal. For those who are already pregnant, all they can do is wait until their baby is born and hope the virus has not affected their development.

There are still a lot of questions to be answered about the Zika virus and what effect it will have on populations over the next few years. With research now being undertaken, we should soon be able to answer these questions and hopefully find a way to prevent the disorders associated with it. Unfortunately, for many, it is already too late.

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