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SIMULTANEOUS EXTERNAL AND INTERNAL MARKING OF TRIATOMA SORDIDA NYMPHS: TRACE ELEMENT EFFICACY AND MICROGEOGRAPHIC DISPERSAL IN A PERIDOMESTIC BRAZILIAN CERRADO RURAL HOUSEHOLD
Dispersão
Triatoma sórdido
Ninfas
Elemento de rastreamento
Author
Affilliation
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissão de Hematozoários. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Epidemiologia e Sistemática Molecular. Rio de janeiro, RJ, Brasil.
Universidade de Brasília, Campus Universitário Darcy Ribeiro. Faculdade de Medicina. Laboratório de Parasitologia Médica e Biologia de Vetores, Área de Patologia. Brasília, DF, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissão de Hematozoários. Rio de Janeiro, RJ, Brasil / Arbovirology Department, Bernhard-Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Epidemiologia e Sistemática Molecular. Rio de janeiro, RJ, Brasil.
Universidade de Brasília, Campus Universitário Darcy Ribeiro. Faculdade de Medicina. Laboratório de Parasitologia Médica e Biologia de Vetores, Área de Patologia. Brasília, DF, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissão de Hematozoários. Rio de Janeiro, RJ, Brasil / Arbovirology Department, Bernhard-Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Epidemiologia e Sistemática Molecular. Rio de janeiro, RJ, Brasil.
Abstract
Background: Chagas disease (American trypanosomiasis) is an important neglected tropical illness, which has the
flagellate protozoan Trypanosoma cruzi as etiological agent and blood-feeding insects of the Triatominae subfamily
as vectors. Despite its importance for disease epidemiology, field studies targeting microgeographic dispersal of
triatomines in endemic areas are rare. The ability wingless nymphs have to move (crawl) within peridomestic settings
is a key component regarding the design and development of rational control strategies.
Methods: We double-marked Triatoma sordida fourth-instar nymphs (N4) with a reliable fluorescent dye and a trace
element. This new methodology allowed us to simultaneously evaluate (i) nymph dispersal and (ii) the effectiveness
of copper (Cu), chromium (Cr), and cadmium (Cd) trace elements as potential new markers. In the mark-release-recapture
(MRR) experiment, 390 T. sordida N4 were released in the peridomicile of a single rural household, 130 individuals
at each of three release points, at distances of 2, 5, and 10 m from the chicken coop (CC) and 27, 32, and 35 m away
from the horse corral (HC). All specimens were double marked (Cu/blue, Cr/orange, Cd/green). Recaptures occurred in
two intervals: 1–3 days and 15–17 days after release.
Results: Specimens were successfully recaptured at all distances up to 10 m. A total of 19, 23, and 10 specimens
were able to disperse 2, 5, and 10 m, respectively, to reach the CC. No insects were recaptured at the HC. Of the three
analyte/paint combinations tested, Cr/orange gave the most promising results; Cu/blue marker and Cd/green marker
performed very poorly with only 4/19 and 0/10 analyte/paint ratios, respectively.
Conclusions: Triatoma sordida N4 could cover a distance of 10 m in 17 days. This indicates that nymphs seem to
have a reduced dispersal capability compared to adults. Ninety-one percent of the 22 recaptured orange-marked nymphs were still Cr positive after the 17-day period evaluated. This makes this analyte a good candidate for future
investigations that will apply this marking method in MRR studies.
Keywords in Portuguese
Marca-liberação-recapturaDispersão
Triatoma sórdido
Ninfas
Elemento de rastreamento
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