Kenya at risk of Zika virus outbreak, new research shows

Kenya could be at risk of an outbreak of the Zika virus, a new study of three major towns shows.

Researchers had previously said that there was no evidence of the virus in the country even when there was a global outbreak in 2016.

However, blood samples taken in Nairobi, Kisumu and Eldoret towns whose results were published in the Transactions of the Royal Society of Tropical Medicine and Hygiene journal in 2019, detected the presence of the virus.

About 577 samples were taken between 2009 and 2014 and were stored at the University of Nairobi’s laboratories.

“There was evidence of low previous exposure to Zika virus in the study population. Of the three regions in Kenya where sera for this study were obtained, only Kisumu County had one case of previous exposure to Zika virus,” states the study.

This new study, published in the scientific journal Cell Reports warns that Kenya should be ready to ensure it is not caught off guard.

 Natural transmission cycle

The study suggests that Zika’s viral nature can increase severity of disease in the areas known to have its populations infected and can as well get to areas not known to have it.

The researchers conducted the study by investigating the natural transmission cycle of the Zika and dengue viruses.

This was done by switching the virus from the mosquito to mice and vice-versa.

“This approach yielded several important results with implications for predicting future Zika virus outbreaks,” the researchers say. “The study reveals that the Zika virus can readily adapt to enhance its virulence not only in a naive host but also in the presence of pre-existing cross-protective dengue virus immunity.”

The scientists want to use the study to enhance research in other related virus sub-types called the flaviviral variants. The study says that early screening to identify the mutations can help to prevent fatal outcomes.

“Of note, our results also suggest that the approach taken here could be a useful tool for the early identification of other flaviviral variants with enhanced infectivity, and provide further evidence that viral infections in mice can be used to interrogate evolution of human-relevant arboviruses (viruses transmitted through mosquitoes, ticks or different insects),” states the study.

Scientists predict that new mutations of the Zika virus could spread faster and infect more people even in countries that were previously not at risk.

“Studies have shown Zika virus to be circulating in Kenya but at very low levels. A study we conducted in western and coastal Kenya in 2020 published in the Journal of Infectious Diseases showed that out of 327 blood samples, four had Zika antibodies and we suggested more surveillance,”  said Prof Walter Jaoko, a microbiologist and specialist in tropical medicine.

Transmission

According to the World Health Organisation, the virus is transmitted by a mosquito called Aedes, which mostly bites during the day. The same mosquito is responsible for the spread of dengue and Chikungunya viruses.

Zika’s main symptoms are fever, rash, conjunctivitis (pink eye), muscle and joint pain, malaise (feeling sick) or headaches that lasts up to seven days. Most infected people are asymptomatic.

The harmful effects are often witnessed in pregnant women who pass it onto their unborn babies that in turn get the congenital Zika syndrome, which leads to physical defects after birth.

Despite more than 3,000 children born in the affected areas in South America with birth defects due to Zika virus, there is no vaccine yet to prevent its spread and severity.

Should one get infected, the Centres for Disease Control and Prevention says that the symptoms are treated separately.

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