Assessing the bio-efficacy of mosquito nets in Santchou and Bertoua 1 year after the mass distribution campaign of 2019

Malaria continues to pose a significant public health challenge in Cameroon, requiring effective prevention strategies. Long-lasting insecticide-treated nets (LLINs) are widely distributed as a key control measure, but their physical integrity and effectiveness need to be monitored. This study aimed to assess the condition and bio-efficacy of LLINs in 2 regions of Cameroon, namely Santchou in the West and Bertoua in the East. The study evaluated LLIN use and care using a structured questionnaire, following World Health Organization (WHO) guidelines for assessing physical integrity. Bio-efficacy was measured using the 3-min WHO cone assay. The results showed that the ownership and usage rates of mosquito nets were 93.91% and 72.70% in Santchou and 60.68% and 41.11% in Bertoua, respectively. In Santchou, 5.26% of LLINs were damaged, with 21.05% rendered unusable while in Bertoua, 29.41% of the used LLINs were damaged with 16.47% unusable. The knockdown rate with field mosquito populations was 65.49% with mortality rate of 61.24% in Bertoua. In Santchou, knockdown rate was 10.23%, and mortality rate 14.97%. The LLINs tested were found highly effective against susceptible strain. These findings urgently require the National Malaria Control Program of Cameroon to improve public awareness on consistent and proper LLIN usage and address the decline in LLIN effectiveness, particularly in cities like Bertoua and Santchou. Targeted interventions should focus on improving LLINs distribution, educating the population on correct usage practices, and implementing regular monitoring of physical integrity and bio-efficacy of insecticide-treated bed nets as these LLINs get degraded.