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Domestic animals and epidemiology of visceral leishmaniasis, Nepal.

Bhattarai NR, Van der Auwera G, Rijal S, Picado A, Speybroeck N, Khanal B, De Doncker S, Das ML, Ostyn B, Davies C, Coosemans M, Berkvens D, Boelaert M, Dujardin JC - Emerging Infect. Dis. (2010)

Bottom Line: On the Indian subcontinent, visceral leishmaniasis (VL) is considered an anthroponosis.Data were georeferenced and entered into a geographic information system.The bivariate K-function results indicated spatial clustering of Leishmania spp.-positive persons and domestic animals.

View Article: PubMed Central - PubMed

Affiliation: BP Koirala Institute of Health Sciences, Dharan, Nepal.

ABSTRACT
On the Indian subcontinent, visceral leishmaniasis (VL) is considered an anthroponosis. To determine possible reasons for its persistence during interepidemic periods, we mapped Leishmania infections among healthy persons and animals in an area of active VL transmission in Nepal. During 4 months (September 2007-February 2008), blood was collected from persons, goats, cows, and buffaloes in 1 village. Leishmania infections were determined by using PCR. We found infections among persons (6.1%), cows (5%), buffaloes (4%), and goats (16%). Data were georeferenced and entered into a geographic information system. The bivariate K-function results indicated spatial clustering of Leishmania spp.-positive persons and domestic animals. Classification tree analysis determined that among several possible risk factors for Leishmania infection among persons, proximity of Leishmania spp.-positive goats ranked first. Although our data do not necessarily mean that goats constitute a reservoir host of L. donovani, these observations indicate the need for further investigation of goats' possible role in VL transmission.

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Related in: MedlinePlus

Classification tree results, showing interplay between risk factors of Leishmania positivity, determined by PCR, for A) humans and B) goats, in Dharan-17, Nepal, September 2007–February 2008.
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Related In: Results  -  Collection


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Figure 3: Classification tree results, showing interplay between risk factors of Leishmania positivity, determined by PCR, for A) humans and B) goats, in Dharan-17, Nepal, September 2007–February 2008.

Mentions: The bivariate K-function analyzes only the relationship between Leishmania spp.–positive households for persons and domestic animals in Dharan. The results of this function have no meaning other than a spatial grouping of households with positive animals and persons. In a second stage, we used a CT model to analyze risk factors for Leishmania spp.–positive households. First we analyzed households in which Leishmania spp.–positive persons had been encountered. These results showed that the minimum distance to a household with a Leishmania spp.–positive animal (any species) was the variable with the highest discriminatory power. It appears first in the tree (Figure 3, panel A) and gets a relative importance score of 100% (data not shown). Discriminating distance was 22.8 m: households <22.8 m from a household with Leishmania spp.–positive animals showed a 37% probability of hosting Leishmania spp.–positive persons versus 7.9% if they were >22.8 m from a household with Leishmania spp.–positive animals. The next variables appearing on the tree were the density in poultry (higher risk for Leishmania spp.–positive persons if density <8.55/km2), the number of persons per room (higher risk if >2.88 persons/room), and density of goats (higher risk if >0.05 goats/ km2). A second CT analysis was conducted for households in which Leishmania spp.–positive animals had been encountered. The generated tree differed from the previous one in that the first discriminating variable was the density of goats per km2; risk for Leishmania spp. positivity associated with a density >5.2 (36.8% vs. 1.5%; Figure 3, panel B) was higher, and a relative importance score was 100% (data not shown). The next variables appearing on the tree were the density of birds and poultry per km2 (higher risk for Leishmania spp.–positive goats if >6.14) and the maximum distance to a household with a Leishmania spp.–positive person (higher risk if <334.6 m). All these variables also appeared with highest predictor ranking scores (data not shown).


Domestic animals and epidemiology of visceral leishmaniasis, Nepal.

Bhattarai NR, Van der Auwera G, Rijal S, Picado A, Speybroeck N, Khanal B, De Doncker S, Das ML, Ostyn B, Davies C, Coosemans M, Berkvens D, Boelaert M, Dujardin JC - Emerging Infect. Dis. (2010)

Classification tree results, showing interplay between risk factors of Leishmania positivity, determined by PCR, for A) humans and B) goats, in Dharan-17, Nepal, September 2007–February 2008.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2958000&req=5

Figure 3: Classification tree results, showing interplay between risk factors of Leishmania positivity, determined by PCR, for A) humans and B) goats, in Dharan-17, Nepal, September 2007–February 2008.
Mentions: The bivariate K-function analyzes only the relationship between Leishmania spp.–positive households for persons and domestic animals in Dharan. The results of this function have no meaning other than a spatial grouping of households with positive animals and persons. In a second stage, we used a CT model to analyze risk factors for Leishmania spp.–positive households. First we analyzed households in which Leishmania spp.–positive persons had been encountered. These results showed that the minimum distance to a household with a Leishmania spp.–positive animal (any species) was the variable with the highest discriminatory power. It appears first in the tree (Figure 3, panel A) and gets a relative importance score of 100% (data not shown). Discriminating distance was 22.8 m: households <22.8 m from a household with Leishmania spp.–positive animals showed a 37% probability of hosting Leishmania spp.–positive persons versus 7.9% if they were >22.8 m from a household with Leishmania spp.–positive animals. The next variables appearing on the tree were the density in poultry (higher risk for Leishmania spp.–positive persons if density <8.55/km2), the number of persons per room (higher risk if >2.88 persons/room), and density of goats (higher risk if >0.05 goats/ km2). A second CT analysis was conducted for households in which Leishmania spp.–positive animals had been encountered. The generated tree differed from the previous one in that the first discriminating variable was the density of goats per km2; risk for Leishmania spp. positivity associated with a density >5.2 (36.8% vs. 1.5%; Figure 3, panel B) was higher, and a relative importance score was 100% (data not shown). The next variables appearing on the tree were the density of birds and poultry per km2 (higher risk for Leishmania spp.–positive goats if >6.14) and the maximum distance to a household with a Leishmania spp.–positive person (higher risk if <334.6 m). All these variables also appeared with highest predictor ranking scores (data not shown).

Bottom Line: On the Indian subcontinent, visceral leishmaniasis (VL) is considered an anthroponosis.Data were georeferenced and entered into a geographic information system.The bivariate K-function results indicated spatial clustering of Leishmania spp.-positive persons and domestic animals.

View Article: PubMed Central - PubMed

Affiliation: BP Koirala Institute of Health Sciences, Dharan, Nepal.

ABSTRACT
On the Indian subcontinent, visceral leishmaniasis (VL) is considered an anthroponosis. To determine possible reasons for its persistence during interepidemic periods, we mapped Leishmania infections among healthy persons and animals in an area of active VL transmission in Nepal. During 4 months (September 2007-February 2008), blood was collected from persons, goats, cows, and buffaloes in 1 village. Leishmania infections were determined by using PCR. We found infections among persons (6.1%), cows (5%), buffaloes (4%), and goats (16%). Data were georeferenced and entered into a geographic information system. The bivariate K-function results indicated spatial clustering of Leishmania spp.-positive persons and domestic animals. Classification tree analysis determined that among several possible risk factors for Leishmania infection among persons, proximity of Leishmania spp.-positive goats ranked first. Although our data do not necessarily mean that goats constitute a reservoir host of L. donovani, these observations indicate the need for further investigation of goats' possible role in VL transmission.

Show MeSH
Related in: MedlinePlus