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A neglected aspect of the epidemiology of sleeping sickness: the propensity of the tsetse fly vector to enter houses.

Vale GA, Chamisa A, Mangwiro C, Torr SJ - PLoS Negl Trop Dis (2013)

Bottom Line: Doors and windows seemed about equally effective as entry points.Houses are attractive in themselves.Some of the tsetse attracted seem to be in a host-seeking phase of behavior and others appear to be looking for shelter from high temperatures outside.

View Article: PubMed Central - PubMed

Affiliation: Natural Resources Institute, University of Greenwich, Chatham, United Kingdom. valeglyn@gmail.com

ABSTRACT

Background: When taking a bloodmeal from humans, tsetse flies can transmit the trypanosomes responsible for sleeping sickness, or human African trypanosomiasis. While it is commonly assumed that humans must enter the normal woodland habitat of the tsetse in order to have much chance of contacting the flies, recent studies suggested that important contact can occur due to tsetse entering buildings. Hence, we need to know more about tsetse in buildings, and to understand why, when and how they enter such places.

Methodology/principal findings: Buildings studied were single storied and comprised a large house with a thatched roof and smaller houses with roofs of metal or asbestos. Each building was unoccupied except for the few minutes of its inspection every two hours, so focusing on the responses of tsetse to the house itself, rather than to humans inside. The composition, and physiological condition of catches of tsetse flies, Glossina morsitans morsitans and G. pallidipes, in the houses and the diurnal and seasonal pattern of catches, were intermediate between these aspects of the catches from artificial refuges and a host-like trap. Several times more tsetse were caught in the large house, as against the smaller structures. Doors and windows seemed about equally effective as entry points. Many of the tsetse in houses were old enough to be potential vectors of sleeping sickness, and some of the flies alighted on the humans that inspected the houses.

Conclusion/significance: Houses are attractive in themselves. Some of the tsetse attracted seem to be in a host-seeking phase of behavior and others appear to be looking for shelter from high temperatures outside. The risk of contracting sleeping sickness in houses varies according to house design.

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Related in: MedlinePlus

Seasonal pattern of catches of the trap (A) refuges (B) and House 1 (C).The monthly mean daily catch of each bait is expressed as a percent of the annual mean daily catch of that bait. The refuge data refer to the pooled catches of all three refuges. Sample sizes are shown in Table 1.
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pntd-0002086-g003: Seasonal pattern of catches of the trap (A) refuges (B) and House 1 (C).The monthly mean daily catch of each bait is expressed as a percent of the annual mean daily catch of that bait. The refuge data refer to the pooled catches of all three refuges. Sample sizes are shown in Table 1.

Mentions: The monthly catches at the trap and refuges (Fig. 3, A and B) followed the patterns typically observed at Rekomitjie, with the refuge catches being by far the greatest in the hot-dry season of Sep–Nov and smallest in the cool-dry season of mid-year, and with the trap catches being more evenly distributed [6]. The pattern with the house catches was intermediate, giving support to the mixed sample hypothesis, above.


A neglected aspect of the epidemiology of sleeping sickness: the propensity of the tsetse fly vector to enter houses.

Vale GA, Chamisa A, Mangwiro C, Torr SJ - PLoS Negl Trop Dis (2013)

Seasonal pattern of catches of the trap (A) refuges (B) and House 1 (C).The monthly mean daily catch of each bait is expressed as a percent of the annual mean daily catch of that bait. The refuge data refer to the pooled catches of all three refuges. Sample sizes are shown in Table 1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585122&req=5

pntd-0002086-g003: Seasonal pattern of catches of the trap (A) refuges (B) and House 1 (C).The monthly mean daily catch of each bait is expressed as a percent of the annual mean daily catch of that bait. The refuge data refer to the pooled catches of all three refuges. Sample sizes are shown in Table 1.
Mentions: The monthly catches at the trap and refuges (Fig. 3, A and B) followed the patterns typically observed at Rekomitjie, with the refuge catches being by far the greatest in the hot-dry season of Sep–Nov and smallest in the cool-dry season of mid-year, and with the trap catches being more evenly distributed [6]. The pattern with the house catches was intermediate, giving support to the mixed sample hypothesis, above.

Bottom Line: Doors and windows seemed about equally effective as entry points.Houses are attractive in themselves.Some of the tsetse attracted seem to be in a host-seeking phase of behavior and others appear to be looking for shelter from high temperatures outside.

View Article: PubMed Central - PubMed

Affiliation: Natural Resources Institute, University of Greenwich, Chatham, United Kingdom. valeglyn@gmail.com

ABSTRACT

Background: When taking a bloodmeal from humans, tsetse flies can transmit the trypanosomes responsible for sleeping sickness, or human African trypanosomiasis. While it is commonly assumed that humans must enter the normal woodland habitat of the tsetse in order to have much chance of contacting the flies, recent studies suggested that important contact can occur due to tsetse entering buildings. Hence, we need to know more about tsetse in buildings, and to understand why, when and how they enter such places.

Methodology/principal findings: Buildings studied were single storied and comprised a large house with a thatched roof and smaller houses with roofs of metal or asbestos. Each building was unoccupied except for the few minutes of its inspection every two hours, so focusing on the responses of tsetse to the house itself, rather than to humans inside. The composition, and physiological condition of catches of tsetse flies, Glossina morsitans morsitans and G. pallidipes, in the houses and the diurnal and seasonal pattern of catches, were intermediate between these aspects of the catches from artificial refuges and a host-like trap. Several times more tsetse were caught in the large house, as against the smaller structures. Doors and windows seemed about equally effective as entry points. Many of the tsetse in houses were old enough to be potential vectors of sleeping sickness, and some of the flies alighted on the humans that inspected the houses.

Conclusion/significance: Houses are attractive in themselves. Some of the tsetse attracted seem to be in a host-seeking phase of behavior and others appear to be looking for shelter from high temperatures outside. The risk of contracting sleeping sickness in houses varies according to house design.

Show MeSH
Related in: MedlinePlus