Anopheles Stephensi Invasion Threatens Malaria Elimination in Africa

Strategic Insights -

Researchers in Ethiopia have published a new report highlighting the significant threat posed by the invasion of Anopheles stephensi to malaria elimination in Africa. This mosquito species is less impacted by rainfall seasonality, allowing it to thrive in artificial containers and pose a substantial risk to public health. The study, conducted in the city of Kebri Dehar, Somali Region of Ethiopia, found that An. stephensi productivity significantly concentrated in large water reservoirs as the dry season progressed.

Key Takeaways:

  • Anopheles stephensi, a mosquito species native to Asia, has invaded Africa and poses a significant threat to malaria elimination.
  • This species is less impacted by rainfall seasonality, allowing it to thrive in artificial containers and human-made habitats.
  • The study found that An. stephensi productivity significantly concentrated in large water reservoirs, such as drinking and construction water cisterns, as the dry season progressed.
  • Larval productivity was significantly overdispersed, with 77% of all larvae originating from 23% of the sites, which were primarily water cisterns.
  • The metapopulation model predicted that larval control targeted on superproductive water reservoirs may lead to An. stephensi elimination when implemented at coverages higher than 60%.
  • The partial overlap between An. stephensi and Ae. aegypti, particularly during the dry season, poses challenges to control both species if only large containers are treated.

Statistics:

  • 77% of all An. stephensi larvae originated from 23% of the sites, which were primarily water cisterns.
  • Larval productivity was significantly overdispersed, with a parameter k of the negative binomial distribution ranging between 0.28 and 0.43.
  • The metapopulation model predicted that implementing larval control at coverages higher than 60% may lead to An. stephensi elimination.

Sources:

  • Anopheles stephensi larval habitat superproductivity and its relevance for larval source management in Ethiopia. Malaria Journal, 2025;24(1):357.
  • Bmc, Campus, 4 Crinan St, London N1 9XW, England. (BioMed Central - www.biomedcentral.com/; Malaria Journal - www.malariajournal.com)
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