Field evaluation of Yorkool ®, a long-lasting insecticidal net after 12 months of use in Seme, Kisumu County, Kenya

Abstract

Background

Physical integrity and insecticidal efficacy of long-lasting insecticide-treated nets (LLINs) is influenced by the handling practices during use. This was an evaluation of Yorkool^® pyrethroid-based LLINs after 12 months of use to determine the washing and drying practices, physical conditions and bio-efficacy. 

Methods

This was a cross-sectional household survey in an area where rectangular Yorkool^® a pyrethroid LLINs were distributed during national mass net distribution campaign in 2021. Questionnaires were used for data collection and bioassay tests were done from thirty randomly selected nets. 

Results

262 household heads were interviewed with their mean age being 46.9 years (SD 17.4 years) and level of education was mainly primary (70.2%). Most households (71.8%) had 1 to 2 sleeping spaces. The households had a total 468 LLINs with 95.1% having been washed at least once. About three-quarters (74.4%) of the LLINs had been washed using local bar soap, with 99.6 % having not been scrubbed on hard surface during washing and 72.1% were dried under a shade. Those evaluated for physical integrity and had at least one hole made up 77.8% of the nets and 57.2% were too torn and requiring replacement. Bio-efficacy test recorded a mean KD of 92% after 1 hour, and mean mortality of 86% after 24 hours. The nets that passed the WHO efficacy cut off for mortality (≥80%) after 24 hours were 83.3% and 70% passed the KD (≥95%) cut off after 1 hour.

Conclusions

While more than a half of the Yorkool^® LLINs needed replacement due to poor physical integrity after one year of use in the households, the bio-efficacy of the LLINs was relatively high with the mortality on vectors meeting the WHO threshold.