Emerging Infectious Diseases (May 2017)

Insecticide-Treated Nets and Protection against Insecticide-Resistant Malaria Vectors in Western Kenya

  • Eric Ochomo,
  • Mercy Chahilu,
  • Jackie Cook,
  • Teresa Kinyari,
  • Nabie M. Bayoh,
  • Philippa West,
  • Luna Kamau,
  • Aggrey Osangale,
  • Maurice Ombok,
  • Kiambo Njagi,
  • Evan Mathenge,
  • Lawrence Muthami,
  • Krishanthi Subramaniam,
  • Tessa Knox,
  • Abraham Mnavaza,
  • Martin James Donnelly,
  • Immo Kleinschmidt,
  • Charles Mbogo

DOI
https://doi.org/10.3201/eid2305.161315
Journal volume & issue
Vol. 23, no. 5
pp. 758 – 764

Abstract

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Insecticide resistance might reduce the efficacy of malaria vector control. In 2013 and 2014, malaria vectors from 50 villages, of varying pyrethroid resistance, in western Kenya were assayed for resistance to deltamethrin. Long-lasting insecticide-treated nets (LLIN) were distributed to households at universal coverage. Children were recruited into 2 cohorts, cleared of malaria-causing parasites, and tested every 2 weeks for reinfection. Infection incidence rates for the 2 cohorts were 2.2 (95% CI 1.9–2.5) infections/person-year and 2.8 (95% CI 2.5–3.0) infections/person-year. LLIN users had lower infection rates than non-LLIN users in both low-resistance (rate ratio 0.61, 95% CI 0.42–0.88) and high-resistance (rate ratio 0.55, 95% CI 0.35–0.87) villages (p = 0.63). The association between insecticide resistance and infection incidence was not significant (p = 0.99). Although the incidence of infection was high among net users, LLINs provided significant protection (p = 0.01) against infection with malaria parasite regardless of vector insecticide resistance.

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