I continue my work in Kenya this week near the Tanzanian border (picture of marker in Masai Mara national park) and an interesting article about the occurrence of malaria in Tanzania was listed in Malaria world this week. ‘Prevalence and drivers of malaria infection among asymptomatic and symptomatic community members in five regions with varying transmission intensity in mainland Tanzania’ by Chacha et al published in Parasites and vectors was carried out in July-August 2023, funded by Bill and Melinda Gates Foundation.
The study tested 10,228 individuals in Kagera, Kigoma, Njombe, Ruvuma and Tanga using rapid diagnostic tests (RDTs). There were differences between districts – varying 21.6% in Tanga to 44.4% in Kagera. There were differences between villages, males had higher positivity than females and school age children had higher rates than under-fives and adults.
Individuals from households with low socio-economic status (SES), or living in houses with open windows and/or holes on the walls, and non-bednet users had statistically higher rates of positive RTD tests (41.5% vs 32.2%). Positive test results were significantly higher among individuals living in households with five or more people (35.4%) compared to those with fewer members (30.0%). Individuals from households with low SES had significantly higher malaria prevalence (37.9%) than those with moderate (33.3%) or higher SES (31.3%). The type of walls of the houses had an effect, where individuals living in houses whose walls were made of mud exhibited a higher prevalence (37.1%) than those from houses constructed with bricks (32.9%). The presence of holes in the walls (39.2%) and open windows (36.3%) had higher prevalence of malaria infections.
The authors link these factors to vector control strategies. Open windows and mud walls are considered more porous to mosquitos. But what is significant is that poor quality of houses and ownership of bed nets are likely factors that correlate with poverty. However, it should be pointed out that most ‘cases’ are asymptomatic, so most people are not really ill.
Malaria disappears from countries when living standards improve. The authors note that the Ministry of health reports a decrease in incidence of malaria in Tanzania. The percentage of children under age 5 who tested positive for malaria according to RDT results has generally decreased over time, from 18% in the 2007-08 Tanzania Health Ministry Indicator Survey (THMIS) to 8% in the 2022 Tanzania Demographic and Health Survey and Malaria Indicator Survey (TDHS-MIS). Also reported is that the percentage of children under age five who are malnourished has decreased steadily from 48% in the 1999 TDHS to 30% in the 2022 TDHS-MIS. And as the country’s economy improves malnutrition will decrease and malaria will eventually disappear completely. This will have nothing to do with anti-mosquito interventions.