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    Natural ecotope of Triatoma longipennis composed of large rocks in the agro-pastoral area of the Ameca Valley, which is highly infected with Trypanosoma cruzi. A, General view of the site. B, Mice bait-trap with triatomines that consisted of a cylindrical wire-netting bait-trap covered with double-coated adhesive tape 20 cm long and 7 cm diameter. C, Example of sites where the traps are hidden. This figure appears in color at www.ajtmh.org.

  • 1

    Lent H, Wygodzinsky P, 1979. Revision of the Triatominae (Hemiptera:Reduviidae), and their significance as vectors of Chagas disease. Bull Am Mus Nat Hist 163 :125–520.

    • Search Google Scholar
    • Export Citation
  • 2

    Magallón-Gastélum E, Magdaleno-Peñaloza NC, Kattahain-Duchateau G, Trujillo-Contreras F, Lozano-Kasten FJ, Hernández-Gutiérrez RJ, 1998. Distribución de los vectores de la enfermedad de Chagas (Hemiptera:Reduviidae:Triatominae), en el estado de Jalisco, México. Rev Biomed 9 :151–157.

    • Search Google Scholar
    • Export Citation
  • 3

    Magallón-Gastélum E, Lozano-Kasten F, Gutiérrez MS, Flores-Perez A, Sanchez B, Espinoza B, Bosseno MF, Brenière SF, 2006. Epidemiological risk for Trypanosoma cruzi transmission by species of Phyllosoma complex in the occidental part of Mexico. Acta Trop 97 :331–338.

    • Search Google Scholar
    • Export Citation
  • 4

    Brenière SF, Bosseno MF, Magallón-Gastélum E, Castillo Ruvalcaba EG, Gutierrez MS, Montaño Luna EC, Basulto JT, Mathieu-Daudé F, Walter A, Lozano-Kasten F, 2007. Peridomestic colonization of Triatoma longipennis (Hemiptera, Reduviidae) and Triatoma barberi (Hemiptera, Reduviidae) in a rural community with active transmission of Trypanosoma cruzi in jalisco state, Mexico. Acta Trop 101 :249–257.

    • Search Google Scholar
    • Export Citation
  • 5

    Magallón-Gastélum E, Lozano-Kasten F, Bosseno MF, Cárdenas-Contreras R, Ouaissi A, Brenière SF, 2004. Colonization of rock pile boundary walls in fields by sylvatic triatomines (Hemiptera: Reduviidae) in Jalisco State, Mexico. J Med Entomol 41 :484–488.

    • Search Google Scholar
    • Export Citation
  • 6

    Bosseno MF, Barnabé C, Magallón Gastélum E, Lozano Kasten F, Ramsey J, Espinoza B, Brenière SF, 2002. Predominance of Trypanosoma cruzi lineage I in Mexico. J Clin Microbiol 40 :627–632.

    • Search Google Scholar
    • Export Citation
  • 7

    Noireau F, Abad-Franch F, Valente S, Dias-Lima A, Lopes CM, Cunha V, Valente VC, Palomeque FS, de Carvalho-Pinto CJ, Sherlock I, Aguilar M, Steindel M, Grisard EC, Jurberg J, 2002. Trapping triatominae in silvatic habitats. Mem Inst Oswaldo Cruz 97 :61–63.

    • Search Google Scholar
    • Export Citation
  • 8

    Moser DR, Kirchhoff LV, Donelson JE, 1998. Detection of Trypanosoma cruzi by DNA amplification using the polymerase chain reaction. J Clin Microbiol 27 :1477–1482.

    • Search Google Scholar
    • Export Citation
  • 9

    Bosseno MF, García LS, Baunaure F, Magallón GE, Soto GM, Lozano KF, Dumonteil E, Brenière SF, 2006. Identification in triatomine vectors of feeding sources and Trypanosoma cruzi variants by heteroduplex assay and a multiplex miniexon polymerase chain reaction. Am J Trop Med Hyg 74 :303–305.

    • Search Google Scholar
    • Export Citation
  • 10

    Fernandes O, Santos SS, Cupolillo E, Mendonca B, Derre R, Junqueira AC, Santos LC, Sturm NR, Naiff RD, Barret TV, Campbell DA, Coura JR, 2001. A mini-exon multiplex polymerase chain reaction to distinguish the major groups of Trypanosoma cruzi and T. rangeli in the Brazilian Amazon. Trans R Soc Trop Med Hyg 95 :97–99.

    • Search Google Scholar
    • Export Citation
  • 11

    Canals M, Cruzat L, Molina MC, Ferreira A, Cattan PE, 2001. Blood host sources of Mepraia spinolai (Heteroptera: Reduviidae), wild vector of Chagas disease in Chile. J Med Entomol 38 :303–307.

    • Search Google Scholar
    • Export Citation
  • 12

    World Health Organization, 1991. Control of Chagas disease. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser 811 :1–95.

    • Search Google Scholar
    • Export Citation
  • 13

    Pietrzak SM, Pung OJ, 1998. Trypanosomiasis in raccoons from Georgia. J Wildl Dis 34 :132–136.

  • 14

    Hancock K, Zajac AM, Pung OJ, Elvinger F, Rosypal AC, Lindsay DS, 2005. Prevalence of antibodies to Trypanosoma cruzi in raccoons (Procyon lotor) from an urban area of northern Virginia. J Parasitol 91 :470–472.

    • Search Google Scholar
    • Export Citation
  • 15

    Yabsley MJ, Noblet GP, 2002. Seroprevalence of Trypanosoma cruzi in raccoons from South Carolina and Georgia. J Wildl Dis 38 :75–83.

  • 16

    Brenière SF, Pietrokovsky S, Magallón GE, Bosseno MF, Soto GM, Ouaissi A, Lozano KF, Wisnivesky-Colli C, 2004. Feeding patterns of Triatoma longipennis Usinger (Hemiptera, Reduviidae) in peridomestic habitats of a rural community in Jalisco State, Mexico. J Med Entomol 41 :1015–1020.

    • Search Google Scholar
    • Export Citation
  • 17

    Lozano Kasten F, Hernández Gutiérrez R, Kasten Monges M, Magallón Gastélum E, Soto Gutiérrez M, Ramírez García MA, 1997. Manifestaciones digestivas en la fase crónica de la enfermedad de Chagas. Cirugía Cirujanos 65 :10–14.

    • Search Google Scholar
    • Export Citation
  • 18

    Clark CG, Pung OJ, 1994. Host specificity of ribosomal DNA variation in sylvatic Trypanosoma cruzi from North America. Mol Biochem Parasitol 66 :175–179.

    • Search Google Scholar
    • Export Citation

 

 

 

 

Wild Ecotopes and Food Habits of Triatoma longipennis Infected by Trypanosoma cruzi Lineages I and II in Mexico

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  • 1 Département Société et Santé, Unité de Recherche 016 and Unité de Recherche 165, Institut de Recherche pour le Développement, Montpellier, France; Centro Universitario de Ciencias de la Salud, Instituto Regional de Investigación en Salud Pública, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico; Laboratorio de Parasitología, Centro de Investigaciones Regionales, Universidad Autónoma de Yucatán, Yucatán, Mexico

The control of wild triatomine populations that can invade dwellings is a major challenge for Chagas disease control in Mexico, but a better knowledge of the biology of these populations is required to develop appropriate control methods. We describe a new terrestrial ecotope of Triatoma longipennis, a principal vector in the occidental part of Mexico, in addition to its previously identified niche in rock pile boundary walls. Analysis of feeding hosts in the two ecotopes showed that this species is able to diversify its food sources outside of the principal hosts, Dasypus novemcinctus and Procyon lotor, and to disperse in search of new meals. Moreover, T. longipennis are strongly infected not only by the Trypanosoma cruzi I lineage found in the domestic cycle, but also by T. cruzi lineage II. The impact of T. cruzi II on human infection remains to be determined.

In Mexico, at least 31 primarily wild (sylvatic) triatomine species have been described, of which 21 are found naturally infected with Trypanosoma cruzi.1 Among these species, Triatoma longipennis is the principal vector in the state of Jalisco and this vector infests villages where peridomestic colonization can be high.24 However, few studies are available on the ecology, geographic distribution, and behavior of the vector in the natural environment of T. longipennis. Invasion or incursion in villages by wild populations is a permanent threat in the region. We previously reported on the colonization by T. longipennis of rock pile boundary walls that separate the culture fields in the Ameca Valley, whereas here we describe a new natural ecotope.5 Also, we identified blood meal origins and strains of T. cruzi in the two ecotopes, and provided evidence of the presence of the T. cruzi II lineage in addition to T. cruzi I, which is the only lineage identified in the domestic cycle.6

Triatomines were collected in the Ameca Valley(20°22′55.46″ N, 103°53′15.78″ W, altitude = 1,345 meters) in the municipality of San Martin de Hidalgo. The site was composed of large rocks at the top of a small hill located in an agro-pastoral area. In surrounding area, the main agricultural crops were corn (Zea mays) and Maguey tequilero (Agave tequilana); grazing of animals is also common (Figure 1A). The climate in this region is semi-arid, with an average annual temperature of 20.9°C and an rainfall between 829 mm and 964 mm. The rainy season is between June and September; winter and spring are very dry. Many mammals have disappeared from this region but raccoons, armadillos, opossums, rabbits, hares, squirrels, and other species of small rodents are still abundant (www.e-local.gob.mx/work/templates/enciclo/jalisco/mpios/14077a.htm).

Collections were made by using a modified Noireau mice bait-trap (Figure 1B).7 Traps were placed in small caves and cracks between the rocks for four nights at the beginning of June 2006 and for one night at the end of August 2007 (Figure 1C). Mice enclosed in a trap that contains food and bedding and are generally removed alive the next day. A total of 254 triatomines were captured at this site. The percentage of positive traps was 24.3% (total of traps = 485) with a mean ± SD of 2.1 ± 1.1 triatomines per positive trap. Triatoma longipennis was the dominant species (95.7%); other species were T. pallidipennis (3.4%) and T. picturata (0.9%). Age groups of the triatomines consisted of adults (46%), fourth and fifth stages (40.6%), and first and second nymphs (13.4%). The sex ratio was slightly biased toward females (1:1.2), but the difference was not significant (degrees of freedom = 1, χ2 = 0.5, P > 0.05). The infection rate determined by microscopic observations of feces ranged from 25% in first and second nymphs to 66.7% in adults; no significant differences were observed between sexes. We did not observe differences in infestation and infection rates between 2006 and 2007 triatomine collections.

To identify mammal reservoirs in large rocks and in rock pile boundary walls, mammals were captured at these sites (the boundary wall was previously studied and was 8.2 km away from large rocks; 20°23′56.73″ N, 103°58′00.30″ W).5 At each site, 100 traps (live traps, 8 cm × 9 cm × 23 cm; H. B. Sherman Trap Co., Tallahassee, FL) were set. Similar numbers of mammals were captured in the two ecotopes (16 at the rock site and 17 in the boundary wall). Baiomys sp. (Pygmy mouse) was the dominant species (28 animals of which only six were adults); the others were Liomys irroratus (Mexican spiny pocket mouse, two adults) and Reithrodontomys fulvescens (fulvous harvest mouse, three adults). Blood samples were taken on site after animals were anesthetized using gloves, a protective shield, and mask. Blood smears and thick drops were microscopically negative for parasites. However, T. cruzi was detected in blood by a polymerase chain reaction (PCR) in 45.5% of the animals by using primers that amplified specifically T. cruzi minisatellites.8 The three species were positive by PCR.

Blood meal origins were identified in 47 triatomines captured in large rocks (35 samples) and in several rock pile boundary walls in the Ameca Valley (12 samples) by using the cytochrome b heteroduplex essay and sequencing of PCR products (Genome Express, Meylan, France) directly or after cloning (TOPO TA kit; Invitrogen, Cergy-Pontoise, France).9 A total of 14 heteroduplex patterns were observed. The most frequent pattern (57.5%) corresponded to a sequence best aligned with that of Procyon lotor (raccoon) (GenBank accession no. AB297804.1, 98% identity). The second most frequent pattern (25%) corresponded to a sequence best aligned with that of Dasypus novemcinctus (nine-banded armadillo) (Y11832.1, 97% identity). Similarly, other sequences showed the closest similarity with Philander opossum (DQ236275.1, 91% identity), Lynx rufus (AY499332.1, 89% identity), Sigmodon mascotensis (AY041203.1, 97% identity), Megasorex gigas (AB175150.1, 79% identity), Reithrodontomys fulvescens (AY041206, 96% identity), Mephitis macroura (usually called zorrillo) (L27301.1, 88% identity), Sceloporus occidentalis (western fence lizard, AB079242, 86% identity), and Homo sapiens (AY50968.1, 99% identity).

Four samples had multiple blood meal origins. Dasypus novemcinctus was identified in the four samples with other blood meals (S. mascotensis [2 samples], Bos taurus [cattle, one sample, best alignment with AY819734.1, 99% identity], and S. occidentalis [one sample]). Most blood meals for triatomines in rock pile boundary walls were from armadillo (D. novemcinctus, 7 of 13 [54%]), whereas the principal feeding host captured in large rocks was the raccoon (P. lotor, 25 of 38 [66%]) for those captured in large rocks (Table 1). Among identified species, P. opossum and S. occidentalis have not been reported in the Jalisco State.

Triatomines with flagellate-positive feces were also processed by using mini-exon, multiplex, PCR-based typing for direct detection of T. rangeli and T. cruzi sub-groups according to methods based on PCR sizes.10 Among 129 triatomines (31 from rock pile boundary rocks and 98 from the large rocks site), T. cruzi I (200-basepair band) was the major lineage (84.5% of the blood meals), 13.2% corresponded to T. cruzi II (150-basepair [bp] band, DTU 2a and 2c), two samples (1%) had two bands (200 bp and 150 bp), which suggested a mixture of the two lineages, and one sample had a band of approximately 300 bp, which was not previously described. Sequencing of PCR products of the entire intergenic region of the mini-exon gene and the NADH dehydrogenase subunit 1 gene from current T. cruzi II samples showed the greatest homology with strains from the United States belonging to DTU 2a. The frequencies of T. cruzi I and T. cruzi II were not significantly different between the two ecotopes (Table 1) (P > 0.05). However, T. cruzi II was not detected in armadillo blood meals but was found in 27% of raccoon blood meals (χ2 = 3.66, P = 0.055).

Our results and those of previous studies show that T. longipennis colonizes agro-pastoral environments and can form large colonies in artificial structures such as rock pile boundary walls, but can also colonize the natural ecotope, such as large rock formations that provide shelters for many host feeders.5 Recent discovery of a second site equally composed of large rocks infested with T. longipennis at the edge Guadalajara (20°46′06.36″ N, 103°22′54.15″ W) suggests that such ecotopes are common. The success of the adaptation of T. longipennis to these sites may be caused by the abundance of mammals and the capacity of T. longipennis to diversify its food source to many species of mammals and reptiles (Iguana family), which has been rarely observed. 11

These breeding sites, when highly infested, could serve as the spreading origins of triatomines to villages and could maintain transmission of the disease. A blood meal obtained from a man was identified in a T. longipennis female captured in a rock pile boundary in a grazing field located 500 meters from the nearest dwelling. Because work in fields is conducted during the day, it is likely that this triatomine entered a house, and then left the house after feeding. Also, the cow blood meal origin shows the capacity of triatomines to get out from their hiding sites and go into the fields.

The sylvan triatomines analyzed in this study were heavily parasitized, which suggests that the two principal blood meal hosts, D. novemcinctus and P. lotor, are important reservoirs in the region. 12 Also, as shown in our study, several rodent species are heavily infected. Raccoons are important reservoirs in the United States; extensive seroprevalence surveys showed infection rates ranging from 20% to 30%. 1315 These host species are also able to approach human dwellings and play a role in linking sylvatic and domestic cycles. The previous identification of one armadillo blood meal in the peridomiciliary area also supports this role. 16

We report circulation of the T. cruzi II parasite lineage in Mexico. This lineage had not been previously identified in domestic and peridomestic cycles. Also, no human infection with T. cruzi II has been reported in Mexico. However, few human strains have been characterized, especially in the studied area where several cases of mega-esophagus have been described, unlike in other parts of Mexico where only cases of chagasic myocardiopathy were reported. 17 Therefore, the implication of the T. cruzi II lineage in Chagas disease remains to be explored. A previous report suggested T. cruzi lineage II–raccoon specificity in the United States (Georgia) but other results suggest that these stocks can infect other hosts. 18

Table 1

Identification of blood meal origins and Trypanosoma cruzi lineage in sylvatic Triatoma longipennis according to sites of capture

Table 1
Figure 1.
Figure 1.

Natural ecotope of Triatoma longipennis composed of large rocks in the agro-pastoral area of the Ameca Valley, which is highly infected with Trypanosoma cruzi. A, General view of the site. B, Mice bait-trap with triatomines that consisted of a cylindrical wire-netting bait-trap covered with double-coated adhesive tape 20 cm long and 7 cm diameter. C, Example of sites where the traps are hidden. This figure appears in color at www.ajtmh.org.

Citation: The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg 80, 6; 10.4269/ajtmh.2009.80.988

*

Address correspondence to Simone Frédérique Brenière, Unité de Recherche 016, Caractérisation et Contrôle des Populations de Vecteurs, IRD, Institut de Recherche pour le Développement, Avenida Hernando Siles No. 5290, Esq. Calle 7, Obrajes, CP 9214, La Paz, Bolivia. E-mail: breniere@ird.fr

Authors’ addresses: Marie-France Bosseno, Christian Barnabé, Pierre Kengne, and Simone Frédérique Brenière, Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France. Maria Jesus Ramirez Sierra, Laboratorio de Parasitología, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán, Avenida Itzaes No. 490 × 59, 97000, Mérida, Yucatán, Mexico. Sergio Guerrero, Centro de Estudios en Zoología, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Apartado Postal 1-1919, CP 44101, Guadalajara, Jalisco, Mexico. Felipe Lozano, Kasten Ezequiel, and Magallón Gastelúm, Centro Universitario de Ciencias de la Salud, Instituto Regional de Investigación en Salud Pública, Universidad de Guadalajara, Guadalajara, Jalisco, México.

Acknowledgments: We thank the biology students working in the laboratory of Dr. Sergio Guerrero for helping capture mammals in field.

Financial support: This study was supported by the Institut de Recherche pour le Développement.

REFERENCES

  • 1

    Lent H, Wygodzinsky P, 1979. Revision of the Triatominae (Hemiptera:Reduviidae), and their significance as vectors of Chagas disease. Bull Am Mus Nat Hist 163 :125–520.

    • Search Google Scholar
    • Export Citation
  • 2

    Magallón-Gastélum E, Magdaleno-Peñaloza NC, Kattahain-Duchateau G, Trujillo-Contreras F, Lozano-Kasten FJ, Hernández-Gutiérrez RJ, 1998. Distribución de los vectores de la enfermedad de Chagas (Hemiptera:Reduviidae:Triatominae), en el estado de Jalisco, México. Rev Biomed 9 :151–157.

    • Search Google Scholar
    • Export Citation
  • 3

    Magallón-Gastélum E, Lozano-Kasten F, Gutiérrez MS, Flores-Perez A, Sanchez B, Espinoza B, Bosseno MF, Brenière SF, 2006. Epidemiological risk for Trypanosoma cruzi transmission by species of Phyllosoma complex in the occidental part of Mexico. Acta Trop 97 :331–338.

    • Search Google Scholar
    • Export Citation
  • 4

    Brenière SF, Bosseno MF, Magallón-Gastélum E, Castillo Ruvalcaba EG, Gutierrez MS, Montaño Luna EC, Basulto JT, Mathieu-Daudé F, Walter A, Lozano-Kasten F, 2007. Peridomestic colonization of Triatoma longipennis (Hemiptera, Reduviidae) and Triatoma barberi (Hemiptera, Reduviidae) in a rural community with active transmission of Trypanosoma cruzi in jalisco state, Mexico. Acta Trop 101 :249–257.

    • Search Google Scholar
    • Export Citation
  • 5

    Magallón-Gastélum E, Lozano-Kasten F, Bosseno MF, Cárdenas-Contreras R, Ouaissi A, Brenière SF, 2004. Colonization of rock pile boundary walls in fields by sylvatic triatomines (Hemiptera: Reduviidae) in Jalisco State, Mexico. J Med Entomol 41 :484–488.

    • Search Google Scholar
    • Export Citation
  • 6

    Bosseno MF, Barnabé C, Magallón Gastélum E, Lozano Kasten F, Ramsey J, Espinoza B, Brenière SF, 2002. Predominance of Trypanosoma cruzi lineage I in Mexico. J Clin Microbiol 40 :627–632.

    • Search Google Scholar
    • Export Citation
  • 7

    Noireau F, Abad-Franch F, Valente S, Dias-Lima A, Lopes CM, Cunha V, Valente VC, Palomeque FS, de Carvalho-Pinto CJ, Sherlock I, Aguilar M, Steindel M, Grisard EC, Jurberg J, 2002. Trapping triatominae in silvatic habitats. Mem Inst Oswaldo Cruz 97 :61–63.

    • Search Google Scholar
    • Export Citation
  • 8

    Moser DR, Kirchhoff LV, Donelson JE, 1998. Detection of Trypanosoma cruzi by DNA amplification using the polymerase chain reaction. J Clin Microbiol 27 :1477–1482.

    • Search Google Scholar
    • Export Citation
  • 9

    Bosseno MF, García LS, Baunaure F, Magallón GE, Soto GM, Lozano KF, Dumonteil E, Brenière SF, 2006. Identification in triatomine vectors of feeding sources and Trypanosoma cruzi variants by heteroduplex assay and a multiplex miniexon polymerase chain reaction. Am J Trop Med Hyg 74 :303–305.

    • Search Google Scholar
    • Export Citation
  • 10

    Fernandes O, Santos SS, Cupolillo E, Mendonca B, Derre R, Junqueira AC, Santos LC, Sturm NR, Naiff RD, Barret TV, Campbell DA, Coura JR, 2001. A mini-exon multiplex polymerase chain reaction to distinguish the major groups of Trypanosoma cruzi and T. rangeli in the Brazilian Amazon. Trans R Soc Trop Med Hyg 95 :97–99.

    • Search Google Scholar
    • Export Citation
  • 11

    Canals M, Cruzat L, Molina MC, Ferreira A, Cattan PE, 2001. Blood host sources of Mepraia spinolai (Heteroptera: Reduviidae), wild vector of Chagas disease in Chile. J Med Entomol 38 :303–307.

    • Search Google Scholar
    • Export Citation
  • 12

    World Health Organization, 1991. Control of Chagas disease. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser 811 :1–95.

    • Search Google Scholar
    • Export Citation
  • 13

    Pietrzak SM, Pung OJ, 1998. Trypanosomiasis in raccoons from Georgia. J Wildl Dis 34 :132–136.

  • 14

    Hancock K, Zajac AM, Pung OJ, Elvinger F, Rosypal AC, Lindsay DS, 2005. Prevalence of antibodies to Trypanosoma cruzi in raccoons (Procyon lotor) from an urban area of northern Virginia. J Parasitol 91 :470–472.

    • Search Google Scholar
    • Export Citation
  • 15

    Yabsley MJ, Noblet GP, 2002. Seroprevalence of Trypanosoma cruzi in raccoons from South Carolina and Georgia. J Wildl Dis 38 :75–83.

  • 16

    Brenière SF, Pietrokovsky S, Magallón GE, Bosseno MF, Soto GM, Ouaissi A, Lozano KF, Wisnivesky-Colli C, 2004. Feeding patterns of Triatoma longipennis Usinger (Hemiptera, Reduviidae) in peridomestic habitats of a rural community in Jalisco State, Mexico. J Med Entomol 41 :1015–1020.

    • Search Google Scholar
    • Export Citation
  • 17

    Lozano Kasten F, Hernández Gutiérrez R, Kasten Monges M, Magallón Gastélum E, Soto Gutiérrez M, Ramírez García MA, 1997. Manifestaciones digestivas en la fase crónica de la enfermedad de Chagas. Cirugía Cirujanos 65 :10–14.

    • Search Google Scholar
    • Export Citation
  • 18

    Clark CG, Pung OJ, 1994. Host specificity of ribosomal DNA variation in sylvatic Trypanosoma cruzi from North America. Mol Biochem Parasitol 66 :175–179.

    • Search Google Scholar
    • Export Citation
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