Dr Nyamai Mutono is a Senior Research Fellow at the Centre for Epidemiological Modelling and Analysis (Cema) at the University of Nairobi and the modelling and training lead at the Africa Modelling Network for Neglected Tropical Diseases.
Researchers are urging Kenya to rethink its long-running
mass drug administration (MDA) programme for intestinal worms.
They are calling for targeted, region-specific interventions
to replace the blanket approach that has been used for years to control
infectious diseases.
MDA has been credited with major public health gains in
Kenya, including sharp reductions in diseases such as elephantiasis, trachoma
and soil-transmitted helminths (STH).
However, scientists behind a new national study say
declining funding and clear regional differences in worm infections mean the
one-size-fits-all model is no longer efficient.
The study, published in the International Journal of
Infectious Diseases, mapped the distribution of three main intestinal worms in
Kenya, collectively known as soil-transmitted helminths. These are hookworm,
whipworm and roundworm.
It analysed data from 146,668 school-going children sampled
in 3,752 schools across 207 subcounties between 2021 and 2024.
Using geostatistical modelling, the researchers found that
infection burdens vary sharply by region and by worm species.
Hookworm prevalence was generally low, with a national mean
of 0.6 per cent. However, six per cent of subcounties, mainly in coastal areas,
exceeded the two per cent threshold used to guide treatment decisions.
Whipworm infections were higher, with increased risk in
south-western and coastal regions. Roundworm had the highest prevalence of the
three, clustering mainly in western Kenya, where some subcounties were
estimated to have prevalence above 10 per cent.
According to the study, continuing to treat all regions in
the same way risks wasting scarce resources while missing hotspots that require
more intensive intervention.
“Intestinal worms primarily affect people living in poor,
rural communities and contribute to school absenteeism, malnutrition and
delayed developmental milestones in children,” said Dr Nyamai Mutono, the study’s
lead author.
“With Kenya’s healthcare system now devolved, tailoring
intervention strategies at subcounty level is essential to optimising partner
resources and achieving elimination of each STH species. Targeted approaches
would allow Kenya to move away from the blanket application of a single
treatment strategy across all subcounties,” she said.
Dr Nyamai is a senior research fellow at the Centre for
Epidemiological Modelling and Analysis at the University of Nairobi and the
modelling and training lead at the Africa Modelling Network for Neglected
Tropical Diseases.
The study is titled Geostatistical modelling of
soil-transmitted helminth prevalence in Kenya: Informing targeted interventions
to accelerate elimination efforts.
Kenya has set a national goal of reducing STH prevalence to
below two per cent by 2027, signalling a shift towards breaking transmission.
The study estimates the probability of regions exceeding
prevalence thresholds of two, 10 and 20 per cent. Across all three worm
species, the probability of exceeding 20 per cent remained below 0.5 per cent
nationally.
However, for roundworm and whipworm, several western,
south-western and coastal subcounties showed a high likelihood of exceeding
lower thresholds that trigger more frequent or alternative treatment regimens.
The researchers argue this level of detail should guide
decisions on which drugs to use, who to treat and how often treatment should be
administered.
“Such precision allows resources to be reallocated to areas
with high-prevalence infections, while reducing treatment intensity where the
likelihood of exceeding disease thresholds is low,” Dr Nyamai said.
“This promotes more efficient use of limited resources and
aligns with the global move towards precision public health,” she added.
She said smarter targeting was also key to
cost-effectiveness.
“Resource targeting ensures the most appropriate and
cost-effective treatment methods are adopted, minimising wastage on ineffective
interventions and maximising the impact of every shilling spent on deworming
programmes,” she said.
Mass drug administration has been a cornerstone of Kenya’s
fight against neglected tropical diseases for more than a decade, largely
through school-based programmes using donated medicines.
The approach has helped Kenya come close to eliminating some
diseases and earn certification for eliminating Guinea worm in 2018.
However, the study notes that blanket deworming does not
account for differences in drug effectiveness across worm species. For
instance, commonly used benzimidazole drugs are less effective against
whipworm, meaning some high-burden areas may require alternative medicines or
strategies.
The authors also point to Kenya’s devolved health system as
an opportunity to tailor interventions more closely to local conditions, using
high-resolution data rather than national averages.
Beyond drugs, the study stresses the importance of investing
in water, sanitation and hygiene, particularly in regions where roundworm and
whipworm persist. Without these complementary measures, reinfection is likely
even after repeated treatment rounds.
The findings come as Kenya works towards its goal of
reducing soil-transmitted helminth prevalence to below two per cent by 2027, in
line with the World Health Organization roadmap for neglected tropical
diseases.
According to the researchers, achieving that goal will
require moving beyond blanket solutions and embracing data-driven, targeted
action that reflects Kenya’s diverse epidemiological landscape.