Zika virus is now “implicated” in the large numbers of brain-damaged babies in Brazil and the increase in the nerve disorder Guillan-Barré syndrome, according to experts at the World Health Organisation, who say urgent action is needed to deal with a growing crisis.
WHO’s director general, Margaret Chan, said on Tuesday the association was still not officially scientifically proven but a shift was needed from looking at individual cases to planning for the possible impact on health systems of the birth of many thousands of babies who will need care, treatment and support for life.
Speaking in Geneva, Chan said nobody could predict how far the Zika virus would spread, causing more and more cases of Guillan-Barré and microcephaly, but “if this pattern is confirmed in and beyond Latin America and the Caribbean, the world will face a severe public health crisis”.
A substantial proportion of the babies diagnosed with microcephaly because of their small head circumference in north-east Brazil, whose mothers had been infected by the Zika virus, are being confirmed by CT scans as brain-damaged, said Anthony Costello, WHO’s director of maternal and child health. Out of 6,480 suspected cases in Brazil, most of them in the north-east, 2,212 have been fully investigated and 863 confirmed with brain abnormalities, a rate of 39%.
“If that rate continues, we would expect just over 2,500 cases will emerge of babies with brain damage and the clinical signs of microcephaly,” said Costello. More and more suspect cases will be reported as time goes on. “We must expect the burden to increase substantially.”
The proportion of pregnant women infected with Zika giving birth to a baby with microcephaly is much lower – a study in French Polynesia estimated it at 1%. That study, however, looked only at women infected in the first three months of pregnancy and microcephaly only defined as a small head circumference.
“There is a changing pattern of defects in Brazil,” said Costello. “Children are born with unusual brain scans as well as microcephaly and hearing and visual defects.”
Chan has asked member states for $56m (£39m) to help WHO tackle the crisis, but only $3m has so far been handed over to the Pan-American Health Organisation, the regional division which deals with Latin America. She said she was in discussions over $4m more. If necessary, she said, she would borrow from other WHO departments and repay them later.
The implications for health systems in affected countries are severe, she said. “We need a whole systems approach and a much longer term approach [to help] countries to prepare the capacity to deal with it. It would be very difficult to estimate what would be the funding requirement.”
More than half the world’s population lives in countries where the Aedes aegypti mosquito, which transmits the virus, breeds. WHO’s experts say there are effective tools against mosquitoes, but are recommending “carefully planned” pilot studies of two of the most novel approaches. One is infecting mosquitoes with Wolbachia, a bacteria that lives only in insect cells and impairs the mosquito’s ability to transmit infections such as dengue and Zika. The other is the use of genetic manipulation to reduce the populations of mosquitoes.