Evidence for a mass community effect of insecticide-treated bednets on the incidence of malaria on the Kenyan coast

Abstract

The use of insecticide-treated bednets (ITBNs) has been shown to be effective in reducing mortality and morbidity from malaria. However, there is mixed evidence as to whether or not community-wide use of ITBNs engenders a 'mass effect', such that those not sleeping under bednets are offered protection from widespread ITBN use in the area in which they live. We have analysed data collected in Kilifi, Kenya, from a cohort of children followed from birth to investigate how the degree of net usage in the locality of a child affects the risk of developing malaria. This effect was explored using a Cox proportional hazards model. For those not using ITBNs, we found that an increasing level of ITBN usage within the area surrounding each child was associated with a decreasing risk of developing malaria, thus providing evidence in support of a mass community effect. The size and significance of this effect were found to decrease as non-overlapping areas of increasing distance away from a child's home were considered. The effect was significant for areas at distances of up to 1.5 km away from each child.

N-player mosquito net game: Individual and social rationality in the misuse of insecticide-treated nets

“…Proper ITN users provide the community effect which indirectly protects all players from malaria [9,7,10]. By free riding on the community effect, each improper ITN user can decrease its infection probability without abandoning extra income from ITN misuse.…”

“…On the contrary, the community effect decreases every player's infection probability regardless of strategy. Properly-used ITNs repel or kill mosquitoes when they approach or contact the nets, likely reducing the entomological risk of malaria infection [9,7,10]. We assume that when m-players, m ∈ {0, 1, .…”

“…ITN use for malaria prevention decreases mosquito population size around the community, and indirectly protects the whole community from malaria [9,7,10]. This community effect plays a role similar to public goods.…”

Insecticides for Vector-Borne Diseases: Current Use, Benefits, Hazard and Resistance

“…the proportion of houses in a given area with ITNs Gimnig et al, 2003). Eighth, evidence for the existence of a community-wide effect due to marked reduction in vector populations (Howard et al, 2000;Hii et al, 2001;Maxwell et al, 2002), implying that ITNs have substantial effects at the population level. Finally, all these public health benefits of ITNs were sustained for up to 6 years and there is no evidence that bed-net use from birth increases all-cause mortality in older children (Lindblade et al 2004).…”

Malaria and dengue vector biology and control in West and Central Africa

“…Experimental surveys have confirmed efficacy of these methods in terms of reduction of incidence of malarial disease (Carnevale et al 1991;Lengeler 1998), and overall infant mortality in Ghana (Binka et al 1996), Kenya (Nevill et al 1996), Burkina Faso (Habluetzel et al 1997) and The Gambia (D'Alessandro et al 1995). Moreover, recent trials showed a mass effect of permethrin-impregnated nets in Ghana (Binka, Indome and Smith 1998), in Kenya (Howard et al 2000) and with impregnated curtains in Burkina Faso (Diallo et al 2004) with no rebound mortality even after several years of ITN usage (Binka et al 2002;Hawley et al 2003;Maxwell et al 2003). It was noticed that when some coverage of the population (60 to 80%) was maintained, even people not covered by ITNs can be protected from malaria if they are living inside 'treated' compounds or in their vicinity (less than 300m).…”