Microcephaly and Zika virus

microcephalyRecently Brazil has declared state of emergency due to an epidemic of newborn microcephaly. Children with microcephaly have significantly smaller head circumference than the mean for their age and body size. It results from abnormal brain development before birth or during infancy that can be caused by genetic (e.g. Down syndrome) or environmental factors affecting development, for instance craniosynostosis, malnutrition, and infection. Children with this condition may be cognitively impaired and need special medical care throughout their lives. During 2015 Brazil has been registering a drastic increase in the cases of microcephaly, mainly in the northeastern states. For instance in Pernambuco there was 141 cases while the mean is around 10 per year. Coincident with this epidemic, Brazil was also affected by a Zika virus outbreak firstly detected in late April and confirmed in 14 states by November. This virus was first identified in the 1940’s in Uganda, and it is now distributed throughout several tropical countries. It is transmitted to humans by bites of infected mosquitoes of the genus Aedes, the same that transmit dengue and yellow fever. Because symptoms of infection by Zika virus are mild it has not been given much attention. However the coincidence between the virus outbreak and increased microcephaly incidence in Brazil led to a suspicion that there was an association, further reinforced by the confirmation of the virus during an autopsy of a microcephalic baby.

The relationship between microcephaly and Zika virus is now being investigated and the government is taking steps to control the mosquitoes’ population and to assist the children with microcephaly. This virus may have spread from the French Polynesia, where there was an outbreak in 2013-2014, and where the Zika virus was associated with neurological complications like Guillain-Barré syndrome. If an association between a mosquito-transmitted virus and neurological conditions is confirmed, further measures of prevention must be taken as the area favorable for mosquitoes spreading seems to be increasing.

Sofia Pedro

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