Probability of Trypanosoma cruzi transmission by Triatoma infestans (Hemiptera: Reduviidae) to the opossum Didelphis albiventris (Marsupialia: Didelphidae).

Rabinovich, Jorge E.; Schweigmann, Nicolás; Yohai, V; Wisnivesky‐Colli, Cristina

doi:10.4269/ajtmh.2001.65.125

Cited by 28 publications

(20 citation statements)

References 12 publications

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“…Both opossums and skunks may acquire T. cruzi infection by eating infected T. infestans, either when they approach houses in search for food, or when adult bugs eventually disperse by flight into sylvatic habitats, or by contamination with bug feces. The probability of experimental opossum infection with T. cruzi by ingestion or contamination was about 6-8% (Rabinovich et al, 2001). Regardless of the exact mechanism and habitat where vector-mediated transmission occurs, if domestic or peridomestic T. infestans infected with T. cruzi were implicated in opossum infections, the observed major decrease in the extent and abundance of infected bugs would imply an insignificant risk of infection for local opossums.…”

Section: Discussionmentioning

confidence: 99%

Long-term reduction of Trypanosoma cruzi infection in sylvatic mammals following deforestation and sustained vector surveillance in northwestern Argentina

et al. 2006

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Long-term variations in the dynamics and intensity of sylvatic transmission of Trypanosoma cruzi were investigated around eight rural villages in the semiarid Argentine Chaco in 2002-2004 and compared to data collected locally in 1984-1991. Of 501 wild mammals from 13 identified species examined by xenodiagnosis, only 3 (7.9%) of 38 Didelphis albiventris opossums and 1 (1.1%) of 91 Conepatus chinga skunks were infected by T. cruzi. The period prevalence in opossums was fourfold lower in 2002-2004 than in 1984-1991 (32-36%). The infection prevalence of skunks also decreased five-fold from 4. 1-5.6% in 1984-1991 to 1.1% in 2002-2004. Infection in opossums increased with age and from summer to spring in both study periods. The force of infection per 100 opossum-months after weaning declined more than six-fold from 8. . The striking decline of T. cruzi infection in opossums and skunks occurred in parallel to community-wide insecticide spraying followed by selective sprays leading to very low densities of infected Triatoma infestans in domestic and peridomestic habitats since 1992; to massive deforestation around one of the villages or selective extraction of older trees, and apparent reductions in opossum abundance jointly with increases in foxes and skunks. These factors may underlie the dramatic decrease of T. cruzi infection in wild reservoir hosts.

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Section: Discussionmentioning

confidence: 99%

Long-term reduction of Trypanosoma cruzi infection in sylvatic mammals following deforestation and sustained vector surveillance in northwestern Argentina

et al. 2006

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“…The only other two reports of observed oral transmission probability involved opossums and different parasite strains, and generated much lower estimates of 0.075 [37] and 0.15 [49]; the differences in host biology, vector species and parasite strain make it difficult to extend them to the two cycles under study here but may signal significant differences in oral transmissibility by strain and/or host. In the scenario in the main text which assumes no adaptation to/from oral transmissibility (AOT), we can take the weighted (by sample size) average of 0.177 from [23].…”

Section: Appendix 1 Parameter Estimationmentioning

confidence: 94%

“…Vertical (congenital) transmission, which has been observed in humans as well as laboratory rats [28,43], may also be significant among other placental hosts (but not in marsupials such as opossums). Furthermore, it has been suggested that oral transmission of T. cruzi via host consumption of infected vectors (raccoons and opossums are both opportunistic feeders whose diets include insects) may be the dominant infection pathway in some cycles, more likely among raccoons than among opossums [32,37,40,49]. Oral transmission has also been documented in laboratory mice as well as in humans [4,7] and other primates [35].…”

Section: Introductionmentioning

confidence: 99%

The role of adaptations in two-strain competition for sylvaticTrypanosoma cruzitransmission

Kribs-Zaleta¹,

Mubayi²

2012

Journal of Biological Dynamics

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This study presents a continuous-time model for the sylvatic transmission dynamics of two strains of Trypanosoma cruzi enzootic in North America, in order to study the role that adaptations of each strain to distinct modes of transmission (classical stercorarian transmission on the one hand, and vertical and oral transmission on the other) may play in the competition between the two strains. A deterministic model incorporating contact process saturation predicts competitive exclusion, and reproductive numbers for the infection provide a framework for evaluating the competition in terms of adaptive trade-off between distinct transmission modes. Results highlight the importance of oral transmission in mediating the competition between horizontal (stercorarian) and vertical transmission; its presence as a competing contact process advantages vertical transmission even without adaptation to oral transmission, but such adaptation appears necessary to explain the persistence of (vertically-adapted) T. cruzi IV in raccoons and woodrats in the southeastern United States.

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“…Vertical transmission has been reported among placental hosts such as rats and mice [22,23], and humans [24]. In addition, sylvatic hosts such as raccoons and opossums are opportunistic feeders whose diet includes insects, and experimental studies have shown that they can get infected by ingesting infected vectors [25,26]. Oral transmission of T. cruzi is likely to be a dominant transmission pathway for sylvatic T. cruzi in the SE US, and explain the high disease prevalence observed among raccoons in particular [27], as suggested by the model of [13].…”

Section: Introductionmentioning

confidence: 99%

The role of the ratio of vector and host densities in the evolution of transmission modes in vector-borne diseases. The example of sylvatic Trypanosoma cruzi

Pelosse

Kribs-Zaleta

2012

Journal of Theoretical Biology

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Pathogens may use different routes of transmission to maximize their spread among host populations. Theoretical and empirical work conducted on directly-transmitted diseases suggest that horizontal (i.e., through host contacts) and vertical (i.e., from mother to offspring) transmission modes trade off, on the ground that highly virulent pathogens, which produce larger parasite loads, are more efficiently transmitted horizontally, and that less virulent pathogens, which impair host fitness less significantly, are better transmitted vertically. Other factors than virulence such as host density could also select for different transmission modes, but they have barely been studied. In vector-borne diseases, pathogen transmission rate is strongly affected by host-vector relative densities and by processes of saturation in contacts between hosts and vectors. The parasite Trypanosoma cruzi which is transmitted by triatomine bugs to several vertebrate hosts is responsible for Chagas' disease in Latin America. It is also widespread in sylvatic cycles in the southeastern U.S. in which it typically induces no mortality costs to its customary hosts. Besides classical transmission via vector bites, alternative ways to generate infections in hosts such as vertical and oral transmission (via the consumption of vectors by hosts) have been reported in these cycles. The two major T. cruzi strains occurring in the U.S. seem to exhibit differential efficiencies at vertical and classical horizontal transmissions. We investigated whether the vector-host ratio affects the outcome of the competition between the two parasite strains using an epidemiological two-strain model considering all possible transmission routes for sylvatic T. cruzi. We were able to show that the vector-host ratio influences the evolution of transmission modes providing that oral transmission is included in the model as a possible transmission mode, that oral and classical transmissions saturate at different vector-host ratios and that the vector-host ratio is between the two saturation thresholds. Even if data on parasite strategies and demography of hosts and vectors in the field are crucially lacking to test to what extent the conditions needed for the vector-host ratio to influence evolution of transmission modes are plausible, our results open new perspectives for understanding the specialization of the two major T. cruzi strains occurring in the U.S. Our work also provides an original theoretical framework to investigate the evolution of alternative transmission modes in vector-borne diseases.

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Probability of Trypanosoma cruzi transmission by Triatoma infestans (Hemiptera: Reduviidae) to the opossum Didelphis albiventris (Marsupialia: Didelphidae).

Cited by 28 publications

References 12 publications

Long-term reduction of Trypanosoma cruzi infection in sylvatic mammals following deforestation and sustained vector surveillance in northwestern Argentina

Long-term reduction of Trypanosoma cruzi infection in sylvatic mammals following deforestation and sustained vector surveillance in northwestern Argentina

The role of adaptations in two-strain competition for sylvaticTrypanosoma cruzitransmission

The role of the ratio of vector and host densities in the evolution of transmission modes in vector-borne diseases. The example of sylvatic Trypanosoma cruzi

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