Experts warn killer diseases may add more misery as rains pound

Patients on queue seeking to be served at Muhila Mission Hospital on December 17,2020. [Benjamin Sakwa, Standard]

It is raining heavily in many parts of the country. Raging waters are coursing down many rivers as overflow invades nearby homes. Damage and risk to life and resources are unimaginable.

Experts warn that the risks will extend beyond immediate injuries, displacement, and deaths, based on scientific prediction and evidence from previous disasters.

Floodwaters are likely to seep into septic tanks, causing waste to ooze out into houses, especially in low-income urban neighbourhoods, posing great health risks.

In areas that rely on wells, the floods could contaminate the water.

An advisory from the Ministry of Health has sounded the alarm on water-borne diseases, notably cholera, typhoid, and diarrhoeal diseases.

The ministry is also warning that respiratory infections are going to increase due to prevailing cold and damp conditions.

A 2018 survey by the Kenya Institute for Public Policy Research and Analysis (KIPPRA) conducted from February to March showed a surge in both waterborne and respiratory illnesses following the floods of December 2017.

That year, cholera cases were reported in various parts, including Garissa, Isiolo, Kiambu, Meru, Murang’a, Nairobi, Turkana, and West Pokot.

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Cholera cases in Southern Africa have risen by over seven times in the first six weeks of 2026 compared with the same period last year due to severe flooding, infrastructure damage, and inadequate water and sanitation among displaced populations, an analysis by the World Health Organisation (WHO) shows.

A total of 4,320 cases and 56 deaths from cholera were reported between January 1 and 15 February in five countries from the region, up from 586 cases and 11 deaths in the same period in 2025.

The increase, WHO notes, contrasts with a general decline in cholera cases across the continent, which reported a drop of 47 percent in 2025.

“The sharp rise in cholera cases in Southern Africa is a clear reminder of how climate-related shocks are intensifying public health risks,” Dr. Marie Roseline Belizaire, Emergencies Director at the WHO Regional Office for Africa, said in a WHO bulletin.

Due to excess rainfall, the organisation is reporting that 13 countries in the African region are currently reporting cholera outbreaks.

Other notable waterborne diseases linked to floods are E. coli infection, bilharzia, dysentery, and typhoid.

Cold and damp conditions are also predicted to lead to respiratory illnesses such as flu, pneumonia, and measles, among others. They are also likely to trigger chronic diseases such as asthma.

But perhaps more importantly, in the immediate-to-long-term, the floods are expected to spur vector-borne diseases, key among them mosquito-borne diseases such as malaria, dengue fever, yellow fever, and chikungunya.

Excess rainwater forms pools and enhances vegetation growth, both of which are ideal breeding grounds for mosquitoes.

According to the KIPPRA survey, an average of 37 percent of people in households suffered from malaria during drought and floods in 2017.

Mombasa County also reported an outbreak of chikungunya, caused by the Aedes eagypti mosquito, which also causes yellow fever, dengue fever, and Zika virus infection.

An outbreak of Rift Valley fever (RVF) was also reported in 2018. It affects animals but spreads to humans on contact with the animal fluids.

Yellow fever, malaria, dengue, and Rift Valley fever outbreaks are expected to become more frequent as global temperatures rise and rainfall becomes more erratic.

Drought followed by heavy rains, notes Dr. Benard Chege, usually causes a Rift Valley fever outbreak.

“In 2017, we had a severe drought followed by heavy rainfall, which progressed into the 2018 March-April-May rains. In June 2018, an active RFV in animals was identified. So was the case with drought from 2020 to 2022; followed by rains in 2023, which led to an outbreak starting August of the same year,” says Dr. Chege, the Disease Surveillance Coordinator for Marsabit County.

The MoH advisory is inviting Kenyans to report any disease developments to help authorities respond quickly.

“The ministry calls upon communities, local leaders, and all stakeholders to remain vigilant and cooperate with health authorities by reporting unusual disease occurrences and adhering to public health advisories,” says Public Health Principal Secretary Mary Muthoni.

According to the Kenya Meteorological Department, the highlands east and west of the Rift Valley, the Lake Victoria basin, the Rift Valley, the South Coast, north-western and some parts of the south-eastern lowlands and north-eastern Kenya are likely to receive near-average to above-average rainfall.

May is expected to mark the end of the rainfall season for much of the country except the highlands west of the Rift Valley, the Lake Victoria basin, and the Coast, where the rains are likely to continue into June.

According to the WHO analysis, Southern Africa faces a critical period between March and August, with a projected 12,000 to 22,000 additional cholera cases under most probable scenarios.

As floods continue to ravage, another expected risk involves dangerous and poisonous wildlife such as snakes and crocodiles, which may be forced out of their usual habitat into human dwellings and/or farms, exposing people to danger. Experts also warn about rodent-borne diseases such as leptospirosis: a bacterial disease spread through water or soil contaminated with rodent urine and can lead to liver and kidney damage.