GENEVA—Evidence is piling up of a causal link between the Zika virus and both microcephaly…
If all goes well and as expected, the validation process of the first diagnostic test kit capable of diagnosing Zika, dengue and chikungunya simultaneously will be completed by the end of this month. The test has already been created. And if the final validation process also goes off well, about 5,00,000 test kits could be available in Brazil by the end of the year, Dr. Ana Bispo, Head of the Flavivirus Laboratory at the Oswaldo Cruz Foundation (Fiocruz), in Rio de Janeiro, Brazil told the WHO Bulletin.
“The test has great potential for improving epidemiological vigilance because it shows which virus is circulating at a specific time in a given area. The test could also be particularly useful in the first days of infection, when the symptoms of Zika, chikungunya and dengue are so similar that it is difficult for doctors to distinguish between dengue and Zika,” she was quoted as saying.
The diagnostic test is a simple, ready to use PCR test — Nucleic Acid Test for Dengue, Chikungunya and Zika viruses. All that has to be done is for a technician to extract the RNA of the virus and add it to the three different reagents meant for Zika, dengue and chikungunya.
A causal link between Zika virus and microcephaly is yet to be established despite a strong association found between the virus and microcephaly — the virus has been found in the placenta and amniotic fluid of mothers and in the brains of foetuses and newborns. “The latest evidence suggests that Zika virus infection during pregnancy may be linked to microcephaly in newborn babies. No scientific evidence to date confirms a link between Zika virus and microcephaly,” a February 12 ‘WHO Zika situation report’ notes. Even the February 26 WHO Zika situation report states: “Evidence that neurological disorders, including microcephaly and GBS [Guillain-Barré syndrome], are linked to Zika virus infection remains circumstantial, but a growing body of clinical and epidemiological data points towards a causal role for Zika virus”.
In November 2015, Dr. Bispo’s team was the first to detect Zika virus genome in the amniotic fluid of two pregnant women (from Paraíba state) who had a medical condition consistent with Zika virus infection. Though ultrasound images initially showed that both the foetuses were normal, microcalcifications of the brain were soon seen. Amniocentesis tests to check for the virus in the amniotic fluid turned a positive result for Zika virus.
Dr. Bispo is doubtful if anything other than Zika virus could be causing the increasing number of microcephaly cases seen in Brazil. “The majority of women who have delivered babies with microcephaly report that they have had a medical condition consistent with Zika, especially during the first trimester,” she said. “It is hard to establish a causal link between Zika and microcephaly, because it is difficult to detect the virus when the baby is born.”
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