Brazil is in a state of emergency. Since October 2015 the number of infants born with microcephaly increased more than 10 times compared to previous years. Microcephaly is a rare condition when babies are born with an unusually small head and brain injury. Health authorities believe that the condition is associated with Zika virus which is being carried by mosquitos.
Zika virus has infected more than a million people in Brazil so far.
Zika virus was first detected more than 70 years ago in African monkeys. The first human case was reported in Nigeria in 1954. By the year 2007 only 14 cases of Zika virus infection had occurred in humans, followed by more frequent infections in remote parts of the world. In 2007, almost three quarters of 11,000 total population of the island Yap was infected. In 2013 Zika appeared on Tahiti and other parts of French Polynesia. 28,000 people searched for medical help. In May, 2015 the virus has arrived to Brazil and has infected more than a million people so far. Last month the virus was first time detected also in the countries of West Africa and in several South and Central American countries (1, 2, 3).
The Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito, the same mosquitoes that spread dengue, yellow fever, West Nile and chikungunya viruses. It normally causes mild flu-like illness or is completely asymptomatic. However, since extreme increase in the number of babies being born with microcephaly in Brazil has been noticed, the authorities started to connect microcephaly cases with Zika virus.
Zika virus was found during autopsy in two babies with microcephaly who died within 24 hours after birth.
Brazil is exploring now at least 3,530 suspicious microcephaly cases and 46 deaths of new-borns, while in previous years fewer than 200 microcephaly cases per year were recorded (4). Scientists at CDC provided the strongest evidence so far of a potential link between Zika virus and microcephaly. Using two different types of tests — polymerase chain reaction (PCR), and immunohistochemistry they found Zika virus during autopsy in two babies with microcephaly who died within 24 hours after birth. The virus was also found in placenta samples of two pregnant women who were carrying fetuses diagnosed with microcephaly. However, several affected babies have also tested negative for Zika using the same test (4, 5).
As microcephaly in babies can be a consequence of different causes (e.g. infections a mother can get during pregnancy, genetic abnormalities, exposure to toxic substances during pregnancy), the connection between microcephaly and Zika virus infection needs further investigations in order to confirm that Zika actually causes microcephaly.
However, until more information is available CDC warns that all pregnant women and women who are trying to become pregnant, should avoid traveling to the affected areas or should try to prevent mosquito bites if the trip cannot be avoided (6). Authorities in Brazil and Jamaica even advise women to delay pregnancy (7).
By Katarina Kovac, PhD, BioSistemika LLC
