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A new method for forensic DNA analysis of the blood meal in chagas disease vectors demonstrated using Triatoma infestans from Chuquisaca, Bolivia.

Pizarro JC, Stevens L - PLoS ONE (2008)

Bottom Line: (3) Does the rate of T. cruzi infection vary among habitats and is it associated with specific blood meal types?T. cruzi infection was detected in 42% of the specimens.From the epidemiological point of view, the results reveal an overall pattern of movement from peri-domestic structures to human habitations for T. infestans in this region of Bolivia as well as the important role of pigs, dogs, chickens and guinea pigs in the dynamics of T. cruzi infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Vermont, Burlington, Vermont, USA.

ABSTRACT

Background: Feeding patterns of the vector are important in the epidemiology of Chagas disease, the leading cause of heart disease in Latin America. Chagas disease is caused by the parasite, Trypanasoma cruzi, which is transmitted by blood feeding insects. Historically, feeding behaviours of haematophagous insects have been investigated using serological reactions, which have detection limits in terms of both taxonomic resolution, and quantity and quality of the blood meal. They are labor intensive, require technical expertise, need fresh or frozen samples and antibodies often are either not available commercially or the resources for synthesis and purification are not available. We describe an assay to identify vertebrate blood meal sources, and the parasite T. cruzi using species-specific PCR assays from insect vectors and use the method to provide information regarding three questions: (1) Do domestic and peri-domestic (chicken coop and animal corral) habitats vary in the blood meals detected in the vectors? (2) What is the pattern of multiple blood meals? (3) Does the rate of T. cruzi infection vary among habitats and is it associated with specific blood meal types?

Methodology/principal findings: Assays based on the polymerase chain reaction were evaluated for identification of the blood meal source in the heamatophagous Chagas disease vector Triatoma infestans. We evaluate a technique to identify 11 potential vertebrate food sources from the complex mixture extracted from the vector's abdomen. We tested the assay on 81 T. infestans specimens collected from the Andean highlands in the department of Chuquisaca, located in central Bolivia, one of the regions in South America where sylvatic T. infestans have been reported. This area is suggested to be the geographic origin of T. infestans and has very high human infection rates that may be related to sylvatic vector populations.

Conclusion/significance: The results of the assays revealed that a high percentage of insects collected in human dwellings had fed on peri-domestic animals. In contrast, one insect from a chicken coop but no bugs from corrals tested positive for human blood. Forty-eight percent of insects tested positive for more than one vertebrate species. T. cruzi infection was detected in 42% of the specimens. From the epidemiological point of view, the results reveal an overall pattern of movement from peri-domestic structures to human habitations for T. infestans in this region of Bolivia as well as the important role of pigs, dogs, chickens and guinea pigs in the dynamics of T. cruzi infection.

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For domestic and peri-domestic habitats, we show the percentage of each type of blood meal found in that habitat and the T. cruzi prevalence in insect vectors that had fed on each blood source.Vectors from domestic vs. peri-domestic habitats vary in their blood meal source. Almost all the insects that had fed on humans were collected from houses. Detection of cow, chicken pig or goat DNA in vectors collected from houses indicates a migrant from a peri-domestic to domestic habitat. Detection of human DNA in a vector collected from a peri-domestic habitat indicates migration from domestic to peri-domestic habitat.
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pone-0003585-g001: For domestic and peri-domestic habitats, we show the percentage of each type of blood meal found in that habitat and the T. cruzi prevalence in insect vectors that had fed on each blood source.Vectors from domestic vs. peri-domestic habitats vary in their blood meal source. Almost all the insects that had fed on humans were collected from houses. Detection of cow, chicken pig or goat DNA in vectors collected from houses indicates a migrant from a peri-domestic to domestic habitat. Detection of human DNA in a vector collected from a peri-domestic habitat indicates migration from domestic to peri-domestic habitat.

Mentions: Human DNA is more prevalent in insects from houses than insects from peri-domestic habitats (Likelihood Ratio χ2 = 22.14, p<0.0001) and chicken DNA was more common in vectors from peri-domestic vectors than vectors from houses (Likelihood Ratio χ2 = 7.06, p<0.01), DNA of all the other vertebrate species is equally distributed between habitats (Figure 1 and Table 2). Those insects collected in houses that had fed on cow chicken pig or goat were defined as migrants, as were insects that had fed on humans and were found in corrals or chicken coops. Vectors are significantly more likely to migrate from houses to peri-domestic habitats than vise versa (Table 3).


A new method for forensic DNA analysis of the blood meal in chagas disease vectors demonstrated using Triatoma infestans from Chuquisaca, Bolivia.

Pizarro JC, Stevens L - PLoS ONE (2008)

For domestic and peri-domestic habitats, we show the percentage of each type of blood meal found in that habitat and the T. cruzi prevalence in insect vectors that had fed on each blood source.Vectors from domestic vs. peri-domestic habitats vary in their blood meal source. Almost all the insects that had fed on humans were collected from houses. Detection of cow, chicken pig or goat DNA in vectors collected from houses indicates a migrant from a peri-domestic to domestic habitat. Detection of human DNA in a vector collected from a peri-domestic habitat indicates migration from domestic to peri-domestic habitat.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2570791&req=5

pone-0003585-g001: For domestic and peri-domestic habitats, we show the percentage of each type of blood meal found in that habitat and the T. cruzi prevalence in insect vectors that had fed on each blood source.Vectors from domestic vs. peri-domestic habitats vary in their blood meal source. Almost all the insects that had fed on humans were collected from houses. Detection of cow, chicken pig or goat DNA in vectors collected from houses indicates a migrant from a peri-domestic to domestic habitat. Detection of human DNA in a vector collected from a peri-domestic habitat indicates migration from domestic to peri-domestic habitat.
Mentions: Human DNA is more prevalent in insects from houses than insects from peri-domestic habitats (Likelihood Ratio χ2 = 22.14, p<0.0001) and chicken DNA was more common in vectors from peri-domestic vectors than vectors from houses (Likelihood Ratio χ2 = 7.06, p<0.01), DNA of all the other vertebrate species is equally distributed between habitats (Figure 1 and Table 2). Those insects collected in houses that had fed on cow chicken pig or goat were defined as migrants, as were insects that had fed on humans and were found in corrals or chicken coops. Vectors are significantly more likely to migrate from houses to peri-domestic habitats than vise versa (Table 3).

Bottom Line: (3) Does the rate of T. cruzi infection vary among habitats and is it associated with specific blood meal types?T. cruzi infection was detected in 42% of the specimens.From the epidemiological point of view, the results reveal an overall pattern of movement from peri-domestic structures to human habitations for T. infestans in this region of Bolivia as well as the important role of pigs, dogs, chickens and guinea pigs in the dynamics of T. cruzi infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Vermont, Burlington, Vermont, USA.

ABSTRACT

Background: Feeding patterns of the vector are important in the epidemiology of Chagas disease, the leading cause of heart disease in Latin America. Chagas disease is caused by the parasite, Trypanasoma cruzi, which is transmitted by blood feeding insects. Historically, feeding behaviours of haematophagous insects have been investigated using serological reactions, which have detection limits in terms of both taxonomic resolution, and quantity and quality of the blood meal. They are labor intensive, require technical expertise, need fresh or frozen samples and antibodies often are either not available commercially or the resources for synthesis and purification are not available. We describe an assay to identify vertebrate blood meal sources, and the parasite T. cruzi using species-specific PCR assays from insect vectors and use the method to provide information regarding three questions: (1) Do domestic and peri-domestic (chicken coop and animal corral) habitats vary in the blood meals detected in the vectors? (2) What is the pattern of multiple blood meals? (3) Does the rate of T. cruzi infection vary among habitats and is it associated with specific blood meal types?

Methodology/principal findings: Assays based on the polymerase chain reaction were evaluated for identification of the blood meal source in the heamatophagous Chagas disease vector Triatoma infestans. We evaluate a technique to identify 11 potential vertebrate food sources from the complex mixture extracted from the vector's abdomen. We tested the assay on 81 T. infestans specimens collected from the Andean highlands in the department of Chuquisaca, located in central Bolivia, one of the regions in South America where sylvatic T. infestans have been reported. This area is suggested to be the geographic origin of T. infestans and has very high human infection rates that may be related to sylvatic vector populations.

Conclusion/significance: The results of the assays revealed that a high percentage of insects collected in human dwellings had fed on peri-domestic animals. In contrast, one insect from a chicken coop but no bugs from corrals tested positive for human blood. Forty-eight percent of insects tested positive for more than one vertebrate species. T. cruzi infection was detected in 42% of the specimens. From the epidemiological point of view, the results reveal an overall pattern of movement from peri-domestic structures to human habitations for T. infestans in this region of Bolivia as well as the important role of pigs, dogs, chickens and guinea pigs in the dynamics of T. cruzi infection.

Show MeSH
Related in: MedlinePlus