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Individual exposure to Simulium bites and intensity of Onchocerca volvulus infection.

Jacobi CA, Enyong P, Renz A - Parasit Vectors (2010)

Bottom Line: In our study, we counted the actual number of attacking and successfully feeding S. damnosum s.l. flies landing on individual villagers during their routine day-time activities in two villages of the Sudan-savannah and rainforest of Cameroon.The Effective Annual Transmission Potential (EATP) for individual villagers was about 20 fold higher in the rainforest compared to the savannah.These data are important for the development of future treatment strategies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Tropenmedizinisches Institut der Universität Tübingen, Wilhelmstrasse 27, D-72074 Tübingen, Germany. Alfons.Renz@uni-tuebingen.de.

ABSTRACT

Background: Onchocerca volvulus, the causative agent of river blindness, is transmitted through the black fly Simulium damnosum s.l., which breeds in turbulent river waters. To date, the number of flies attacking humans has only been determined by standard fly collectors near the river or the village. In our study, we counted the actual number of attacking and successfully feeding S. damnosum s.l. flies landing on individual villagers during their routine day-time activities in two villages of the Sudan-savannah and rainforest of Cameroon. We compared these numbers to the number of flies caught by a standard vector-collector, one positioned near the particular villager during his/her daily activity and the other sitting at the nearest Simulium breeding site.

Results: Using these data obtained by the two vector-collectors, we were able to calculate the Actual Index of Exposure (AIE). While the AIE in the savannah was on average 6,3%, it was 34% in the rainforest. The Effective Annual Transmission Potential (EATP) for individual villagers was about 20 fold higher in the rainforest compared to the savannah.

Conclusions: Here we show for the first time that it is possible to determine the EATP. Further studies with more subjects are needed in the future. These data are important for the development of future treatment strategies.

No MeSH data available.


Related in: MedlinePlus

Surroundings of Bolo.
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Figure 1: Surroundings of Bolo.

Mentions: Observations were carried out in localities situated in the rainforest (Bolo, Additional Files 2 and 3) and the savannah (Galim, Additional File 4) regions of Cameroon, Africa. In the rainforest, the survey was performed in the village of Bolo (4° 52'N × 9° 28'E), located near the Dilolo river (Additional Files 5 and 6), a tributary of the river Mungo (Figure. 1). There, onchocerciasis is hyperendemic with a microfilarial (mf) prevalence of 95% and an arithmetic mean mf density of 60 mf/mg of skin (all ages), reflecting a very intense transmission (Annual Biting Rate (ABR) = 158775 flies/person-year, Annual Transmission Potential (ATP) = 10162 L3 O. volvulus larvae/person-year, data from [7]). In the savannah, the study was conducted near the village of Galim (7° 13'N × 13° 34'E), situated at the river Vina du Sud (Figure 2, Additional File 7). The ABR at the river bank was 119720 and the ATP was 2,394 [6].


Individual exposure to Simulium bites and intensity of Onchocerca volvulus infection.

Jacobi CA, Enyong P, Renz A - Parasit Vectors (2010)

Surroundings of Bolo.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2910011&req=5

Figure 1: Surroundings of Bolo.
Mentions: Observations were carried out in localities situated in the rainforest (Bolo, Additional Files 2 and 3) and the savannah (Galim, Additional File 4) regions of Cameroon, Africa. In the rainforest, the survey was performed in the village of Bolo (4° 52'N × 9° 28'E), located near the Dilolo river (Additional Files 5 and 6), a tributary of the river Mungo (Figure. 1). There, onchocerciasis is hyperendemic with a microfilarial (mf) prevalence of 95% and an arithmetic mean mf density of 60 mf/mg of skin (all ages), reflecting a very intense transmission (Annual Biting Rate (ABR) = 158775 flies/person-year, Annual Transmission Potential (ATP) = 10162 L3 O. volvulus larvae/person-year, data from [7]). In the savannah, the study was conducted near the village of Galim (7° 13'N × 13° 34'E), situated at the river Vina du Sud (Figure 2, Additional File 7). The ABR at the river bank was 119720 and the ATP was 2,394 [6].

Bottom Line: In our study, we counted the actual number of attacking and successfully feeding S. damnosum s.l. flies landing on individual villagers during their routine day-time activities in two villages of the Sudan-savannah and rainforest of Cameroon.The Effective Annual Transmission Potential (EATP) for individual villagers was about 20 fold higher in the rainforest compared to the savannah.These data are important for the development of future treatment strategies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Tropenmedizinisches Institut der Universität Tübingen, Wilhelmstrasse 27, D-72074 Tübingen, Germany. Alfons.Renz@uni-tuebingen.de.

ABSTRACT

Background: Onchocerca volvulus, the causative agent of river blindness, is transmitted through the black fly Simulium damnosum s.l., which breeds in turbulent river waters. To date, the number of flies attacking humans has only been determined by standard fly collectors near the river or the village. In our study, we counted the actual number of attacking and successfully feeding S. damnosum s.l. flies landing on individual villagers during their routine day-time activities in two villages of the Sudan-savannah and rainforest of Cameroon. We compared these numbers to the number of flies caught by a standard vector-collector, one positioned near the particular villager during his/her daily activity and the other sitting at the nearest Simulium breeding site.

Results: Using these data obtained by the two vector-collectors, we were able to calculate the Actual Index of Exposure (AIE). While the AIE in the savannah was on average 6,3%, it was 34% in the rainforest. The Effective Annual Transmission Potential (EATP) for individual villagers was about 20 fold higher in the rainforest compared to the savannah.

Conclusions: Here we show for the first time that it is possible to determine the EATP. Further studies with more subjects are needed in the future. These data are important for the development of future treatment strategies.

No MeSH data available.


Related in: MedlinePlus