Transmission of malaria in relation to distribution and coverage of long-lasting insecticidal nets in central Côte d’Ivoire

Ouattara, Allassane F, Dagnogo, Mamadou, Constant, Edi, Koné, Moussa, Raso, Giovanna, Tanner, Marcel, Olliaro, Piero L, Utzinger, Jürg and Koudou, Benjamin (2014) 'Transmission of malaria in relation to distribution and coverage of long-lasting insecticidal nets in central Côte d’Ivoire'. Malaria Journal, Vol 13, e109.

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Abstract

Background

The use of long-lasting insecticidal nets (LLINs) is an effective malaria control strategy. However, there are challenges to achieve high coverage, such as distribution sustainability, and coverage keep-up. This study assessed the effect of LLINs coverage and contextual factors on entomological indicators of malaria in rural Côte d’Ivoire.

Methods

The study was carried out between July 2009 and May 2012 in three villages (Bozi, N’Dakonankro and Yoho) of central Côte d’Ivoire. In Bozi and Yoho, LLINs were distributed free of charge by the national malaria control programme in 2008. In Bozi, an additional distribution was carried out in May 2011. No specific interventions were done in N’Dakonankro. Entomological surveys were conducted in July 2009 and July 2010 (baseline), and in August and November 2011 and in February 2012. Frequency of circumsporozoite protein was determined using an enzyme-linked immunosorbent assay. Regression models were employed to assess the impact of LLINs and changing patterns of irrigated rice farming on entomological parameters, and to determine associations with LLINs coverage and other contextual factors.

Results

In Bozi, high proportion of LLIN usage was observed (95-100%). After six months, 95% of LLINs were washed at least once and 79% were washed up to three times within one year. Anopheles gambiae was the predominant malaria vector (66.6% of all mosquitoes caught). From 2009 to 2012, in N’Dakonankro, the mean annual entomological inoculation rate (EIR) increased significantly from 116.8 infectious bites/human/year (ib/h/y) to 408.8 ib/h/y, while in the intervention villages, the EIR decreased significantly from 514.6 ib/h/y to 62.0 ib/h/y (Bozi) and from 83.9 ib/h/y to 25.5 ib/h/y (Yoho). The risk of an infectious bite over the three-year period was significantly lower in the intervention villages compared to the control village (p <0.001).

Conclusion

High coverage and sensitization of households to use LLINs through regular visits (particularly in Bozi) and abandoning irrigated rice farming (in Yoho) resulted in highly significant reductions of EIR. The national malaria control programme should consider household sensitization and education campaigns and other contextual factors to maximize the benefit of LLINs.

Item Type:	Article
Additional Information:	The electronic version of this article is the complete one and can be found online at: http://www.malariajournal.com/content/13/1/109
Subjects:	QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases WA Public Health > Preventive Medicine > WA 240 Disinfection. Disinfestation. Pesticides (including diseases caused by) WC Communicable Diseases > Tropical and Parasitic Diseases > WC 750 Malaria
Faculty: Department:	Biological Sciences > Department of Tropical Disease Biology Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI):	https://doi.org/10.1186/1475-2875-13-109
Depositing User:	Lynn Roberts-Maloney
Date Deposited:	22 Apr 2015 08:27
Last Modified:	06 Feb 2018 13:09
URI:	https://archive.lstmed.ac.uk/id/eprint/5097

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