Project Lead(s): Humphrey Mazigo
Almost 40% of the world population is exposed to malaria, with 215 million malaria cases reported in the year 2015, the majority in children under age five in Africa.
Activities such as rice irrigation farming are known to increase malaria vector breeding sites and, often, these communities carry the largest burden of malaria.
The use of biolarvicides (Bacillus thuringiensis var israeliensis) to control malaria vectors at the larvae stage has been proposed as a safe and effective measure, but larviciding is challenged by the need for trained personnel to apply and monitor.
This study in Tanzania aimed to integrate biolarvicidal activities, with biolarvicides applied concurrently with fertilizers by farmers in their rice fields to target the malaria vectors’ aquatic stages, while at the same time increasing rice productivity.
The study first sought to determine malaria mosquito vectors’ abundance and transmission intensity in Study Area B, sampling indoor host-seeking malaria vectors using Centers for Disease Control light traps (CDC light traps) from fifteen houses selected from five sub-villages for three consecutive nights.
A total of 5,131 female mosquitoes were collected and, of these, malaria mosquitoes (Anopheles gambiae and An. Funestus) accounted for 64.4% of the total.
A total of 1,154 inhabitants, with median age 13 years, were examined for malaria infection. The overall malaria prevalence was 14.2% and 17.5%, based on microscopic examination and rapid diagnostic testing, respectively.
To assess community knowledge, perceptions and practices regarding malaria, a total of 248 households from five sub-villages were surveyed. Heads of the households had knowledge about malaria and intervention measures, but their knowledge of the use of biolarvicides as malaria intervention measures was poor.
Finally, the project team set out to evaluate the effect of biolarvicide–fertilizer application on mosquito transmission indices and to determine community acceptability of integrating larviciding applications during applications of fertilizers on farms.
The project successfully demonstrated that it is feasible to combine biolarvicidal activities with the farmers’ use of fertilizers.
Farmers who used a mix of biolarvicides and fertilizer had a significantly higher rice grain output.
A 4.17% decline in malaria parasitaemia (a measure of the malaria transmission level) was noted at the intervention site, Upogoroni, as was a decline in malaria larvae density.
There was also a significant decline in mean density of indoor malaria-seeking vectors, Anopheles gambiae s.l. between baseline and follow-up after the intervention (88.29 mean versus 46.14) in the study village.
Results of the work have been disseminated through publications and the research team has applied for additional funding to carry out further validation studies.