The Zika virus linked to microcephaly, discovered on the African continent

Researchers from the Department of Zoology at the University of Oxford teamed up with the Angolan Ministry of Health to study the introduction and circulation of the Asian genotype of Zika virus in Angola, southwestern Africa.

Published today in The Lancet Infectious Diseases, they discovered that the Asian genotype of the Zika virus has been circulating in Angola since at least 2016, and is likely linked to an upsurge in microcephaly cases in newborns in the country. Babies born with microcephaly have smaller heads than expected and often have smaller brains that might not have developed properly. The strains circulating there were most likely to be introduced from Brazil, and this migration route reflects the large number of travellers flying between Angola and Brazil.

In 2017 Angola started reporting cases of microcephaly in newborns. Until that point only the African genotype of Zika was known to circulate in Africa. Researchers from Oxford’s and the Instituto Nacional de Investigação em Saúde in Luanda followed up on reports of microcephaly cases in Angola, which they suspected could be caused by Zika virus infection in pregnancy. They carried out molecular testing and genome sequencing to understand the virus’s genetic history and its epidemiology in this genomic work. This ground-breaking research marks the first time that complete virus genomes have been generated on-site in Angola.

The study searched for Zika virus in patients presenting with symptoms compatible with Zika infection in Angola. Zika virus infection often does not cause symptoms, so researchers also screened hundreds of asymptomatic patients for the virus. Zika virus was only detected in a total of five patients, but the use of viral genome sequences to reconstruct the outbreak showed that Zika virus likely circulated in Angola for over 17 months. Therefore, the true scale of the outbreak in Angola was likely larger than the small number of identified cases would suggest.

The research coupled scientific detective work in challenging conditions with the latest, agile technology. The international collaboration with the Ministries of Health in Angola and Portugal and several research institutes in Brazil, used the latest handheld portable sequencing technology, the MinION from Oxford Nanopore Technologies, to investigate the epidemiology of Zika virus in Africa.

By combining molecular testing and genome sequencing to best understand the virus genetic make-up and its epidemiology, they found that the Asian lineage was introduced from Brazil into Angola in 2016, probably by a traveller infected with Zika. This virus then led to the recent upsurge in microcephaly cases in the country.

Dr. Faria, Research Fellow at the Department of Zoology, University of Oxford, and lead author of the study, said “The use of viral sequence analysis is a powerful tool for tracking the global spread of Zika and other viruses of epidemic potential. These results are significant in that they demonstrated the introduction of the Asian genotype into continental Africa, demonstrating the ongoing spread of Zika virus worldwide and our continued need to remain vigilant to Zika virus infection and its impact on pregnant women and infants. This study highlights the need of increased surveillance in areas that are connected by travellers to regions where Zika and other mosquito-borne viruses circulate Improved surveillance is key to anticipate and prevent future epidemics of mosquito-borne viruses, especially in areas connected by air travel that have high abundance of mosquitoes capable of transmitting viruses.”

Bringing rapid genomic sequencing tools to Angola is empowering local academics and is helping us to improve early detection of future virus threats. Ultimately, fostering scientific innovation and research in Angola will help to improve the health of the country.

Further studies are needed to investigate what fraction of the population exposed to Zika and other viruses transmitted by mosquitoes. Researchers are now working on expanding genomic surveillance to dengue, chikungunya and yellow fever and other neglected viral infectious diseases.