A review of food and waterborne parasites in Kenya has highlighted gaps in surveillance, which researchers say means there is limited data to help inform public health interventions.
In Kenya, the prevalence of intestinal infections is high due to the warm tropical climate and socioeconomic factors.
A scoping review evaluated the national prevalence, risk factors, and contamination sources of intestinal protozoa. In total, 67 studies covering from 1966 to 2024 were included. The search focused on keywords related to enteric protozoa, including Cryptosporidium, Giardia, informal settlements, food handlers, and vulnerable groups. Findings were published in the journal China CDC Weekly.
Protozoa, transmitted primarily through the fecal-oral route, are spread by asymptomatic carriers and cause symptoms such as diarrhea, vomiting and abdominal pain. The focus was on pathogens in Kenya’s water intended for domestic consumption. Water treatment mainly relies on chlorination, which is ineffective against many protozoa.
The review found that most studies used stool microscopy, a method with limited sensitivity, and largely focused on vulnerable human populations, with minimal investigation into environmental reservoirs.
Sampling duration was often unspecified. However, 20 percent of the studies were conducted for less than six months, while 24 percent were completed within six to 12 months
Risk factors for three parasites
Key protozoa included Entamoeba histolytica, Cryptosporidium and Giardia, with transmission driven by poor water, sanitation, and hygiene (WASH) conditions, environmental factors, and close human-animal contact. Incidence of most protozoa, including Entamoeba histolytica, Cryptosporidium and Giardia, showed an increasing trend over time, peaking between 2010 and 2020 but this is also the period when more studies were conducted.
Entamoeba histolytica is a significant public health concern, having been isolated from various sources, including food handlers.
Cryptosporidium is the second most prevalent parasite. Cryptosporidium hominis was the most prevalent in human infections, while Cryptosporidium parvum was more common in environmental and animal samples. The presence of livestock and untreated/contaminated water sources were identified as risk factors but some studies suggested transmission because of overcrowding and poor WASH conditions.
Studies have identified unhygienic conditions, improper sewage disposal and low socioeconomic status as significant risk factors for Giardia infections. There is limited information on the prevalence of Giardia in domesticated animals and its national distribution in Kenya.
According to the study, increasing human encroachment into wildlife habitats, tourism, the exotic pet trade and bush meat demand may also create new infection pathways.
Scientists said current research on intestinal protozoa in Kenya relies primarily on patient-based data, often collected through questionnaires. However, studies investigating environmental sources to identify infection pathways are lacking. This limitation may be due to resource constraints.
“This review identifies significant gaps in the surveillance of intestinal protozoa, particularly within the environmental and animal health sectors. To address the rising burden of intestinal protozoan infections in Kenya, large-scale surveillance and comprehensive One Health studies are needed to evaluate the prevalence, synthesize data, and identify risk factors for targeted interventions and informed policymaking,” said researchers.
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