A study by Ifakara Health Institute, in collaboration with partners in Europe and Asia, has underscored the significant impact of well-designed homes and toilets in reducing disease transmission. The research emphasizes how such designs can limit human interaction with disease-carrying flies, which are known to spread illnesses like diarrhoea.

A key innovation in fly control
The study demonstrated how innovative homes, known as "Star homes," specially designed with structural modifications, significantly reduced the presence of domestic flies, particularly those known to spread diarrhoeal diseases. 

Compared to traditional homes, Star homes had 46% fewer Chrysomya putoria flies and 69% fewer Sarcophaga species in their kitchens. These findings published on the Parasites & Vectors journal finding suggests a potential for improved public health outcomes, particularly in sub-Saharan Africa, where fly-borne diseases significantly contribute to childhood diarrhoea.

“This study demonstrated the effectiveness of Star homes in reducing domestic fly populations in both the kitchen and toilets compared to traditional houses. During the 2-year study, there were 46% fewer C. putoria and 69% fewer Sarcophaga species in the kitchens of Star homes compared to traditional houses which is likely to have positive health impacts,” noted the scientists.

Key design features contributing to fly reduction
The study identified key design elements that contributed to the reduction in fly populations, including shade netting on the walls, self-closing doors, and smooth cemented floors that make cleaning easier and reduce food odors that attract flies. These structural modifications proved effective in limiting the entry and presence of flies, especially in kitchens and toilets.

Impact of ‘Star Homes’ on toilet hygiene
The study also examined the impact of Star home toilets, which showed a notable reduction of approximately 50% in the presence of C. putoria, a fly species known for transmitting diarrhoeal pathogens. The protective flap installed under the toilet’s drop hole prevented flies from accessing or exiting the faecal waste chamber, reducing the overall fly population. This reduction is especially significant, as C. putoria accounted for 77% of the flies trapped in toilets.

Recommendations for further improvement
While the findings were promising, the study noted that many families continued to cook outdoors, especially during the dry season, due to size limitations in the Star home stoves. The researchers recommended modifications, such as enlarging the stoves and adding adjustable dish holders, to encourage indoor cooking and further reduce fly exposure.

Future action form broader implications
Despite some study limitations, including the potential bias in fly trap efficiency, the research strongly supports the need for better housing and sanitation infrastructure to address vector-borne diseases. The scientists plan to explore the cost-effectiveness of Star homes and available financing options in future publications.

In conclusion, the study demonstrated how well-screened houses and toilets can reduce the presence of important vectors of diarrhoeal diseases. The scientists recommend that scaling up the quality of housing and toilets on a larger scale would likely yield even greater reductions in fly populations, benefiting public health in sub-Saharan Africa and beyond.

“Our study shows how well-screened houses and toilets which prevent flies entering the faecal collecting pit can reduce the abundance of important vectors of diarrhoeal diseases. Even greater reductions would probably occur if the quality of housing and toilets were improved on a larger scale. Our findings are of relevance to those designing and constructing new homes in sub-Saharan,” they concluded.

Ifakara scientist is lead author
This study was led by Ifakara Health Institute scientist Arnold Mmbando, along with colleagues Amos Ngonzi, Halfan Ngowo and Fredros Okumu – also from Ifakara. Other contributors include experts from Durham University (UK), CSK Research Solutions, (Tanzania), University of Oxford, London School of Hygiene and Tropical Medicine, The Royal Danish Academy, and Mahidol-Oxford Tropical Medicine Research Unit (Thailand).

Read the publication here.