Scientists have ruled out Zika infection in the many babies born with microcephaly (unusually small head) along the Kenyan coast.
If a mother contracts the virus during pregnancy, it can cause microcephaly and damaged brain tissue in the newborn.
Surveys from 2017 to 2019 show the level of microcephaly on the Kenyan Coast is at least nine times higher than in Europe and Latin America.
It is also 1.5 times higher than reported in Brazil at the peak of the Zika virus outbreak in 2016.
“None of the newborns with microcephaly in our study had evidence of Zika Virus and only one had confirmed Dengue Virus exposure,” the Kenyan researchers said, ending speculation that the virus has quietly been spreading infections in the country.
“Nonetheless, the low number of infections in our study means that we cannot exclude an association.”
However, the researchers say microcephaly can be caused by other infections such as rubella, herpes simplex virus, immunodeficiency virus, syphilis, cytomegalovirus, and toxoplasmosis.
There are also environmental and genetic causes.
The researchers come from the University of Nairobi, Ministry of Health, Washington State University, Coast General Hospital, Port Reitz Hospital – Mombasa, Institute of Tropical Medicine, Antwerp, CDC and the Kenya Medical Research Institute.
Zika virus was first discovered in Uganda in 1947, re-emerged globally in 2013 and was later associated with microcephaly and other birth defects.
The Kenyan researchers recruited and followed up on pregnant women in three hospitals in Mombasa from October 2017 to July 2019.
In total, among 1,236 newborns whose heads were measured, 11 (0.9 per cent) had microcephaly and three (0.2 per cent) had severe microcephaly.
Only three women tested positive for Zika virus infection during pregnancy but their babies did not report any problems.
“The prevalence of severe microcephaly among newborns in coastal Kenya was high relative to published estimates from facility-based studies in Europe and Latin America, but little evidence of Zika virus transmission.,” the researchers said.
They called for improved surveillance for microcephaly and other congenital malformations in Kenya.
Zika is spread by bites from infected Aedes mosquitoes, which are also prevalent on the Kenyan Coast.
While for most people Zika is a mild illness, with no lasting effects, it can have catastrophic consequences for babies in the womb.
Although the virus is mostly spread by mosquitoes, it can also be sexually transmitted.
Scientists say few people die from Zika and only one in five people infected is thought to develop symptoms, which include fever, a rash and joint pain.
Since there is no treatment, the only option is to reduce the risk of being bitten.
Scientists have since begun work on a Zika vaccine to help protect pregnant women.
