The most prominent global health issue in the media in 2016 (so far) has, without a doubt, been Zika virus. On February 1, the World Health Organization (WHO) labeled Zika virus a public health emergency of international concern . This has led to increased media coverage, particularly around the potential link between Zika virus and microcephaly. You may be wondering: what is Zika virus, where did it come from, how is it transmitted, and should you be concerned? Fortunately for you, we answer these questions, and many more, in this blog post!
Zika virus was first identified in rhesus monkeys through a sylvatic yellow fever monitoring network in Uganda in 1947. The first cases in humans were discovered in 1952, in Uganda and the United Republic of Tanzania . Zika virus is vector-borne, meaning that an infected living organism transmits the infectious disease between animals and humans, usually through its bite. The Aedes mosquito is the vector in the case of Zika, the same mosquito that spreads chikungunya, malaria and yellow fever . Other forms of transmission include from mother to child, through sexual contact and through blood transfusion . Approximately 1 in 5 people who are infected with Zika through these channels go on to become ill. The most common symptoms are fever, rash, joint pain and conjunctivitis (red eyes). The time from exposure to experiencing symptoms (the incubation period) is not yet known; however, the CDC estimates that it is likely to be a few days to a week . These symptoms are acute, common to many other illnesses, and rarely severe, meaning that many people who have Zika may not realize they have been infected.
Zika virus has been around for more than 60 years, so why are we suddenly so concerned in 2016? There have been outbreaks in the past in Africa, Southeast Asia and the Pacific Islands, but Zika virus gained international attention in the media due to events in Brazil in the second half of 2015. The ministry of health in Brazil first reported that Zika was circulating within the country on May 15 2015. Seven months later on December 24, the country declared a state of emergency due to a dramatic increase in cases of microcephaly (abnormal smallness of the head which can lead to neurological defects) in newborn babies. There were 150 cases recorded in all of 2014 in Brazil, compared to 2700 cases recorded from January to October 2015. Between October 2015 and January 20 2016, there were an additional 3893 cases of suspected microcephaly reported . Brazil has also reported an increased number of cases of Guillain-Barré syndrome (GBS) in the same time period. GBS is a rare illness in which a person’s own immune system damages the nerve cells, causing muscle weakness, and sometimes, paralysis . A total of eight countries/territories (Brazil, French Polynesia, El Salvador, Venezuela, Colombia, Martinique, Honduras and Suriname) have reported a temporal association between the emergence of Zika virus and microcephaly and/or GBS . Although a causal association between Zika and these neurological disorders has not yet been proven, a growing body of both clinical and epidemiological data suggest this is the case. Further studies are currently underway in order to confirm (or refute) the link .
Stay tuned for Part II, which will examine risk factors, further implications, prevention and control measures and myths around Zika virus.
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