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Culicoides (Diptera: Ceratopogonidae) midges, the vectors of African horse sickness virus--a host/vector contact study in the Niayes area of Senegal.

Fall M, Diarra M, Fall AG, Balenghien T, Seck MT, Bouyer J, Garros C, Gimonneau G, Allène X, Mall I, Delécolle JC, Rakotoarivony I, Bakhoum MT, Dusom AM, Ndao M, Konaté L, Faye O, Baldet T - Parasit Vectors (2015)

Bottom Line: The monthly variation in host/vector contact was determined in the Niayes area, Senegal, an area which was severely affected by the 2007 outbreak of AHS.Nineteen of the 41 species collected were new distribution records for Senegal.This increased the number of described Culicoides species found in Senegal to 53.

View Article: PubMed Central - PubMed

Affiliation: ISRA, Laboratoire National de l'Elevage et de Recherches Vétérinaires, Route Front de Terre, Dakar, Senegal. moussafall08@yahoo.fr.

ABSTRACT

Background: African horse sickness (AHS) is an equine disease endemic to Senegal. The African horse sickness virus (AHSV) is transmitted to the mammalian hosts by midges of the Culicoides Latreille genus. During the last epizootic outbreak of AHS in Senegal in 2007, 1,169 horses died from this disease entailing an estimated cost of 1.4 million euros. In spite of the serious animal health and economic implications of AHS, very little is known about determinants involved in transmission such as contact between horses and the Culicoides species suspected of being its vectors.

Methods: The monthly variation in host/vector contact was determined in the Niayes area, Senegal, an area which was severely affected by the 2007 outbreak of AHS. A horse-baited trap and two suction light traps (OVI type) were set up at each of five sites for three consecutive nights every month for one year.

Results: Of 254,338 Culicoides midges collected 209,543 (82.4%) were female and 44,795 (17.6%) male. Nineteen of the 41 species collected were new distribution records for Senegal. This increased the number of described Culicoides species found in Senegal to 53. Only 19 species, of the 41 species found in light trap, were collected in the horse-baited trap (23,669 specimens) largely dominated by Culicoides oxystoma (22,300 specimens, i.e. 94.2%) followed by Culicoides imicola (482 specimens, i.e. 2.0%) and Culicoides kingi (446 specimens, i.e. 1.9%).

Conclusions: Culicoides oxystoma should be considered as a potential vector of AHSV in the Niayes area of Senegal due to its abundance on horses and its role in the transmission of other Culicoides-borne viruses.

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Dynamics of monthly abundances of females for the three main species (C. oxystoma, C. imicola and C. kingi) in the horse-baited trap by season at 5 sites of the Niayes area in Senegal. (RS = rainy season; CDS = cold dry season; HDS = hot dry season). NB: a log10 (n + 1) transformation was applied to the abundance data; the Pout site was not plotted due to the low abundances observed.
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Fig3: Dynamics of monthly abundances of females for the three main species (C. oxystoma, C. imicola and C. kingi) in the horse-baited trap by season at 5 sites of the Niayes area in Senegal. (RS = rainy season; CDS = cold dry season; HDS = hot dry season). NB: a log10 (n + 1) transformation was applied to the abundance data; the Pout site was not plotted due to the low abundances observed.

Mentions: Overall, biting rates on horses were high at Mbao, medium at Hann, Niague and Thies and relatively low at Pout (Table 3). For C. oxystoma, the mean value at Mbao was 772 females/trap/night as compared to 15 or 30 females/trap/night at the Hann Pony Club and at Thies, and close to 0 at Niague and Pout. The highest attack rates on horses were observed in the second half of the rainy season (September and October) at Parc Hann, Mbao and Thies for C. oxystoma, C. imicola and C. kingi (Figure 3). At these three sites, the primary peak of attack rates was accompanied by a secondary peak during the hot dry season before the rains set in. These species had low abundances during the cold dry season (November to February). In contrast, at Niague, C. kingi appeared to be attracted by the horse all year round, and C. imicola during the dry seasons (Figure 3).Figure 3


Culicoides (Diptera: Ceratopogonidae) midges, the vectors of African horse sickness virus--a host/vector contact study in the Niayes area of Senegal.

Fall M, Diarra M, Fall AG, Balenghien T, Seck MT, Bouyer J, Garros C, Gimonneau G, Allène X, Mall I, Delécolle JC, Rakotoarivony I, Bakhoum MT, Dusom AM, Ndao M, Konaté L, Faye O, Baldet T - Parasit Vectors (2015)

Dynamics of monthly abundances of females for the three main species (C. oxystoma, C. imicola and C. kingi) in the horse-baited trap by season at 5 sites of the Niayes area in Senegal. (RS = rainy season; CDS = cold dry season; HDS = hot dry season). NB: a log10 (n + 1) transformation was applied to the abundance data; the Pout site was not plotted due to the low abundances observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307892&req=5

Fig3: Dynamics of monthly abundances of females for the three main species (C. oxystoma, C. imicola and C. kingi) in the horse-baited trap by season at 5 sites of the Niayes area in Senegal. (RS = rainy season; CDS = cold dry season; HDS = hot dry season). NB: a log10 (n + 1) transformation was applied to the abundance data; the Pout site was not plotted due to the low abundances observed.
Mentions: Overall, biting rates on horses were high at Mbao, medium at Hann, Niague and Thies and relatively low at Pout (Table 3). For C. oxystoma, the mean value at Mbao was 772 females/trap/night as compared to 15 or 30 females/trap/night at the Hann Pony Club and at Thies, and close to 0 at Niague and Pout. The highest attack rates on horses were observed in the second half of the rainy season (September and October) at Parc Hann, Mbao and Thies for C. oxystoma, C. imicola and C. kingi (Figure 3). At these three sites, the primary peak of attack rates was accompanied by a secondary peak during the hot dry season before the rains set in. These species had low abundances during the cold dry season (November to February). In contrast, at Niague, C. kingi appeared to be attracted by the horse all year round, and C. imicola during the dry seasons (Figure 3).Figure 3

Bottom Line: The monthly variation in host/vector contact was determined in the Niayes area, Senegal, an area which was severely affected by the 2007 outbreak of AHS.Nineteen of the 41 species collected were new distribution records for Senegal.This increased the number of described Culicoides species found in Senegal to 53.

View Article: PubMed Central - PubMed

Affiliation: ISRA, Laboratoire National de l'Elevage et de Recherches Vétérinaires, Route Front de Terre, Dakar, Senegal. moussafall08@yahoo.fr.

ABSTRACT

Background: African horse sickness (AHS) is an equine disease endemic to Senegal. The African horse sickness virus (AHSV) is transmitted to the mammalian hosts by midges of the Culicoides Latreille genus. During the last epizootic outbreak of AHS in Senegal in 2007, 1,169 horses died from this disease entailing an estimated cost of 1.4 million euros. In spite of the serious animal health and economic implications of AHS, very little is known about determinants involved in transmission such as contact between horses and the Culicoides species suspected of being its vectors.

Methods: The monthly variation in host/vector contact was determined in the Niayes area, Senegal, an area which was severely affected by the 2007 outbreak of AHS. A horse-baited trap and two suction light traps (OVI type) were set up at each of five sites for three consecutive nights every month for one year.

Results: Of 254,338 Culicoides midges collected 209,543 (82.4%) were female and 44,795 (17.6%) male. Nineteen of the 41 species collected were new distribution records for Senegal. This increased the number of described Culicoides species found in Senegal to 53. Only 19 species, of the 41 species found in light trap, were collected in the horse-baited trap (23,669 specimens) largely dominated by Culicoides oxystoma (22,300 specimens, i.e. 94.2%) followed by Culicoides imicola (482 specimens, i.e. 2.0%) and Culicoides kingi (446 specimens, i.e. 1.9%).

Conclusions: Culicoides oxystoma should be considered as a potential vector of AHSV in the Niayes area of Senegal due to its abundance on horses and its role in the transmission of other Culicoides-borne viruses.

Show MeSH
Related in: MedlinePlus