Anopheles gambiae distribution and insecticide resistance in the cities of Douala and Yaoundé (Cameroon): influence of urban agriculture and pollution

• Published in: Malaria journal Vol. 10; no. 1; p. 154
• Main Authors: Antonio-Nkondjio, Christophe, Fossog, Billy Tene, Ndo, Cyrille, Djantio, Benjamin Menze, Togouet, Serge Zebaze, Awono-Ambene, Parfait, Costantini, Carlo, Wondji, Charles S, Ranson, Hilary
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 08.06.2011; BioMed Central; BMC
• Subjects: Agricultural pollution; Agricultural practices; Agriculture; Agriculture - methods; Alkalinity; Aluminium; Aluminum; Ammonia; Animals; Anopheles; Anopheles - drug effects; Anopheles - growth & development; Anopheles gambiae; Aquatic insects; Breeding sites; Cameroon; Culicidae; DDT; Deltamethrin; Disease transmission; Distribution; Environmental Pollution; Gene frequency; Hardness; Health aspects; Human diseases; Humans; Insecticide Resistance; Insecticides; Insecticides - pharmacology; Iron; Magnesium; Malaria; Malathion; Manganese; Mortality; Mosquitoes; Nitrates; Nitrites; Parameters; Permethrin; Pesticide resistance; Phosphates; Pollution; Potassium; Public health; Risk factors; Rural areas; Selection, Genetic; Suburban areas; Turbidity; Urban agriculture; Urban areas; Urban farming; Urban Population; Vector-borne diseases; Vectors; Water - chemistry; Water - parasitology; Water analysis; Water hardness; Water sampling; France; Cameroon; Cameroon, Yaounde; Africa
• ISSN: 1475-2875; 1475-2875
• DOI: 10.1186/1475-2875-10-154

Urban malaria is becoming a major health priority across Africa. A study was undertaken to assess the importance of urban pollution and agriculture practice on the distribution and susceptibility to insecticide of malaria vectors in the two main cities in Cameroon. Anopheline larval breeding sites were surveyed and water samples analysed monthly from October 2009 to December 2010. Parameters analysed included turbidity, pH, temperature, conductivity, sulfates, phosphates, nitrates, nitrites, ammonia, aluminium, alkalinity, iron, potassium, manganese, magnesium, magnesium hardness and total hardness. Characteristics of water bodies in urban areas were compared to rural areas and between urban sites. The level of susceptibility of Anopheles gambiae to 4% DDT, 0.75% permethrin, 0.05% deltamethrin, 0.1% bendiocarb and 5% malathion were compared between mosquitoes collected from polluted, non polluted and cultivated areas. A total of 1,546 breeding sites, 690 in Yaoundé and 856 in Douala, were sampled in the course of the study. Almost all measured parameters had a concentration of 2- to 100-fold higher in urban compare to rural breeding sites. No resistance to malathion was detected, but bendiocarb resistance was present in Yaounde. Very low mortality rates were observed following DDT or permethrin exposure, associated with high kdr frequencies. Mosquitoes collected in cultivated areas, exhibited the highest resistant levels. There was little difference in insecticide resistance or kdr allele frequency in mosquitoes collected from polluted versus non-polluted sites. The data confirm high selection pressure on mosquitoes originating from urban areas and suggest urban agriculture rather than pollution as the major factor driving resistance to insecticide.