Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2007 Sep 19:6:126.
doi: 10.1186/1475-2875-6-126.

Interdependence of domestic malaria prevention measures and mosquito-human interactions in urban Dar es Salaam, Tanzania

Yvonne Geissbühler  1 , Prosper Chaki, Basiliana Emidi, Nicodemus J Govella, Rudolf Shirima, Valeliana Mayagaya, Deo Mtasiwa, Hassan Mshinda, Ulrike Fillinger, Steven W Lindsay, Khadija Kannady, Marcia Caldas de Castro, Marcel Tanner, Gerry F Killeen
Affiliations

Interdependence of domestic malaria prevention measures and mosquito-human interactions in urban Dar es Salaam, Tanzania

Yvonne Geissbühler et al. Malar J. .

Abstract

Background: Successful malaria vector control depends on understanding behavioural interactions between mosquitoes and humans, which are highly setting-specific and may have characteristic features in urban environments. Here mosquito biting patterns in Dar es Salaam, Tanzania are examined and the protection against exposure to malaria transmission that is afforded to residents by using an insecticide-treated net (ITN) is estimated.

Methods: Mosquito biting activity over the course of the night was estimated by human landing catch in 216 houses and 1,064 residents were interviewed to determine usage of protection measures and the proportion of each hour of the night spent sleeping indoors, awake indoors, and outdoors.

Results: Hourly variations in biting activity by members of the Anopheles gambiae complex were consistent with classical reports but the proportion of these vectors caught outdoors in Dar es Salaam was almost double that of rural Tanzania. Overall, ITNs confer less protection against exophagic vectors in Dar es Salaam than in rural southern Tanzania (59% versus 70%). More alarmingly, a biting activity maximum that precedes 10 pm and much lower levels of ITN protection against exposure (38%) were observed for Anopheles arabiensis, a vector of modest importance locally, but which predominates transmission in large parts of Africa.

Conclusion: In a situation of changing mosquito and human behaviour, ITNs may confer lower, but still useful, levels of personal protection which can be complemented by communal transmission suppression at high coverage. Mosquito-proofing houses appeared to be the intervention of choice amongst residents and further options for preventing outdoor transmission include larviciding and environmental management.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Wards included in the study area of the Urban Malaria Control Program in Dar es Salaam, showing the ten cell units (TCU) of the adult mosquito monitoring system as well as of the detailed survey.
Figure 2
Figure 2
Hourly biting profile of An. gambiae s.l. based on averaged results of routine outdoor human landing catches from across the entire study area covered by the Urban Malaria Control Programme.
Figure 3
Figure 3
Human and mosquito behavioural patterns in Dar es Salaam, Tanzania. A. Number or proportion of time residents spend outdoors, comparing what they reported themselves with direct observations in the field. B. Mean numbers of An. gambiae s.s caught indoors and outdoors. C. Mean number of An. arabiensis caught indoors and outdoors. D. Mean number of An. gambiae s.l. caught indoors and outdoors.
Figure 4
Figure 4
Comparison of exophagic and endophagic behaviour of different mosquito species in urban and rural Tanzania. Degree of exophagy or endophagy is presented as the proportion of mosquitoes caught outdoors so that all mosquitoes with a proportion of outdoor biting significantly greater than 0.5 are considered to be exophagic and all below 0.5 are considered endophagic.
Figure 5
Figure 5
Exposure to biting of An. gambiae s.s. for ITN users and non-users. The shadings represent the proportion of time spend in each compartment (outdoor; 1-πi ; equation 8, indoor awake; πa ; equation 7, indoor asleep; πs ; equation 6). Exposure to biting is shown overall as well as for different house qualities: Screened (Glass windows, screening with no or small holes), unscreened (no screening or badly torn/incomplete screens), ceiling (complete ceiling or partly ceiling), no ceiling (no ceiling board).
Figure 6
Figure 6
Proportion of people present in each compartment and their estimated exposure if not using a bednet (outdoor; 1-πi ; equation 8, indoor awake; πa ; equation 7, indoor asleep; πs ; equation 6), presented as an overall mean and for categories of different house qualities: Screened (Glass windows, screening with no or small holes), unscreened (no screening or badly torn), ceiling (complete ceiling or partly ceiling), no ceiling (no ceiling board).
Figure 7
Figure 7
Mean number of bites received by a person in each of the three domestic and peri-domestic compartments (outdoor; 1-πi ; equation 8, indoor awake; πa ; equation 7, indoor asleep; πs ; equation 6).
Figure 8
Figure 8
Three factors derived through principal component analysis and their association with different protective measures as well as mosquito densities.
See this image and copyright information in PMC

References

    1. WHO . Global Strategic Framework for Integrated Vector Management. Geneva , World Health Organization; 2004. p. 15.
    1. Snow RW, Guerra CA, Noor AM, Myint HY, Hay SI. The global distribution of clinical episodes of Plasmodium falciparum malaria. Nature. 2005;434:214–217. doi: 10.1038/nature03342. - DOI - PMC - PubMed
    1. Hay SI, Guerra CA, Tatem TA, Noor AM, Snow RW. The global distribution and population at risk of malaria: past, present and future. Lancet Infectious Dis. 2004;4:327–336. doi: 10.1016/S1473-3099(04)01043-6. - DOI - PMC - PubMed
    1. RollBackMalariaPartnership . World Malaria Report. Geneva , World Health Organization; 2005.
    1. Kiszewski A, Mellinger A, Spielman A, Malaney P, Sachs SE, Sachs J. A global index representing the stability of malaria transmission. Am J Trop Med Hyg. 2004;70:486–498. - PubMed

Publication types