Malaria Transmission Intensity (PfEIR) in Female Anopheles gambiae s.l. Across Different Ecological Zones in Bauchi State, Nigeria.

Abstract

This study quantified the Plasmodium falciparum Entomological Inoculation Rate 
(PfEIR) across selected Local Government Areas (LGAs) in Bauchi State, Nigeria, 
using the pyrethrum spray catch (PSC) technique for indoor-resting mosquito 
collections. PfEIR, a key metric of malaria transmission intensity representing the 
number of infective bites per person per unit time, exhibited marked spatial 
heterogeneity across the study area. The highest PfEIR values were recorded in 
Bauchi and Dass LGAs, whereas comparatively lower rates were observed in Kirfi, 
Ganjuwa, and Dambam LGAs. Ecologically stratified analysis revealed mean PfEIR 
values of 10.19 and 12.33 infective bites per person per unit time in the Sudan and 
Sahel savannah zones, respectively, indicating relatively higher transmission 
potential in the more arid Sahelian belt. Despite observable spatial variations, 
statistical analysis showed that differences in PfEIR across the LGAs were not 
significant at the 95% confidence level (p = 0.075). Nonetheless, the spatial trends 
are epidemiologically relevant and suggest that environmental drivers—particularly 
rainfall variability, humidity, and temperature regimes—play a critical role in 
modulating vector abundance and parasite transmission dynamics. The findings are 
consistent with established malaria transmission models in West African savannah 
ecosystems, where seasonal climatic factors strongly influence vector breeding 
habitats and vectorial capacity. The elevated PfEIR observed in Bauchi and Dass 
LGAs underscores the need for spatially targeted and ecologically informed malaria 
control interventions, including intensified vector control measures and surveillance 
in high-transmission foci. Such targeted strategies are essential for optimizing 
resource allocation and reducing malaria burden in Bauchi State.