• Outbreaks of cholera, typhoid, and hepatitis A usually come when floods affect water availability, quality and sanitation
• Even before the WHO announcement, Kenya had indicated it is monitoring Rift Valley Fever, cholera and malaria among other diseases ahead of the expected El nino rains
Image: REUTERS
The World Health Organisation has asked countries to prepare for possible outbreak of diseases, such as dengue and malaria, due to the "very high probability" of the El Niño weather phenomenon in 2023 and 2024.
In his weekly briefing, director general Tedros Ghebreyesus said the phenomenon could influence the breeding of mosquitoes, spiking the spread of diseases such as malaria, dengue, Zika and chikungunya.
"WHO is preparing for the very high probability that 2023 and 2024 will be marked by an El Nino event, which could increase transmission of dengue and other so called arboviruses, such as Zika and chikungunya,” Dr Tedros said.
The El Niño — warmer water in the central and eastern Pacific Ocean — influences weather globally and is likely to cause heavy rains in Kenya from September or October, according to the Kenya Meteorological Department.
Dr Tedros further said climate change is already fuelling the breeding of mosquitoes, and the incidence of dengue has already risen sharply in recent decades.
Malaria, chikungunya virus and dengue virus are endemic causes of fever among children in Kenya, and outbreaks are common in wet seasons.
Both chikungunya and dengue are transmitted by Aedes aegypti mosquitoes, while malaria is transmitted by the Anopheles mosquito.
Even before the WHO announcement, Kenya had indicated it is monitoring Rift Valley Fever, cholera and malaria among other diseases ahead of the expected El nino rains.
The Kenya Meteorological Department earlier reported that some regions of the North Eastern region of Kenya had received three times the normal rainfall between March and May 2018.
For RVF, flooding provides ideal conditions for mosquito multiplication and, consequently, disease emergence.
KMD also said if El Niño brings heavy rains this year, those effects will be most significant from October.
“The public is advised to stay informed by updating themselves with weather reports issued by KMD, and seeking expert advice in relevant sectors to minimise adverse weather impacts,” KMD director Dr David Gikungu said.
Health CS Susan Nakhumicha said they are keen to distribute 10 million treated mosquito nets before the October rains.
She spoke last week after inaugurating the board of the Kenya Medical Supplies Authority.
“We want to achieve this before the end of this year so that Kenyans who need to benefit should not miss it,” she said. “Remember, it's a rainy season, we don't want Kenyans to suffer.”
In Kenya, RVF is a priority zoonotic disease because of the high morbidity and mortality.
The last major outbreak in 2006–07 resulted in about 340 human cases, 90 human deaths and economic losses of more than $32 million (Sh4.4 billion) in direct livestock mortality and indirect losses, partly due to impediments to trade, according to studies.
Data from the 2016 El Nino around the world showed cholera outbreaks were elevated in eastern Africa, and dengue was indeed more frequent than usual in Brazil and Southeast Asia.
Outbreaks of cholera, typhoid and hepatitis A usually come when floods affect water availability, quality and sanitation.
Kenya managed to avert an RVF outbreak during the 2016 El Nino through a mass vaccination programme for domestic livestock.
Livestock can pass the disease to certain mosquito species and directly to humans through milk and blood.
There is currently no human vaccine to prevent RVF.
Model predictions and expert assessments globally indicate a moderate probability (60 per cent chance) for the onset of El Niño during May-July 2023.
This probability is expected to increase to 60-70 per cent during June-August, and it is highly likely (with a chance of 70-80 per cent) in July-through October 2023.
El Niño conditions are expected to persist up to the October-December 2023 rainfall season and may extend to the November to January season.
Dr Gikungu said while El Nino can result in heavier-than-normal rainfall, this can vary significantly between events.
For instance, the 1987 October-December season was an El Niño event that did not result in heavy rainfall over the country, he said.
Additionally, in 2015, the El Niño index was higher than that of 1997, but the country did not experience as much rainfall as it did in 1997.