Biogeography and<i>Trypanosoma cruzi</i>Infection Prevalence of Chagas Disease Vectors in Texas, USA

Kjos, Sonia A.; Snowden, Karen F.; Olson, Jimmy K.

doi:10.1089/vbz.2008.0026

Cited by 115 publications

(116 citation statements)

References 38 publications

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“…T. rubida could be considered an efficient vector, whereas T. recurva and T. protracta would be of secondary importance, as previously suggested in other field studies (Kjos et al 2009, Breniere et al 2010, Licón-Trillo et al 2010, Reisenman et al 2010.…”

Section: Discussionmentioning

confidence: 57%

The biology of three Mexican-American species of Triatominae (Hemiptera: Reduviidae): Triatoma recurva, Triatoma protracta and Triatoma rubida

Martínez-Ibarra

Paredes-González

Licón-Trillo

et al. 2012

Mem. Inst. Oswaldo Cruz

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Biological information is widely available for the 13 most common domestic triatomines (Hemiptera: Reduviidae: Triatominae) among the 30 species described in Mexico (Martínez-Ibarra et al. 2007, Salazar-Schettino et al. 2010). Information about the remaining species is scarce, primarily because these species have rarely been collected and are difficult to raise under laboratory conditions. Three of these rare species are Triatoma recurva (Stal), Triatoma protracta (Uhler) and Triatoma rubida (Uhler). Although these three species are considered to be of low epidemiological importance, specimens of at least two of these species (T. recurva and T. rubida) collected from inside human dwellings were found to be infected with Trypanosoma cruzi (Paredes-González et al. 2001, Licón-Trillo 2006, Breniere et al. 2010, Licón-Trillo et al. 2010. Studies on the behaviour of triatomine species provide a greater understanding of the habits of these insects and therefore facilitate improved decision-making regarding the priorities for vector control. To our knowledge, there has been no study of the biological parameters (life cycle and feeding and defecation behaviours) of T. recurva; in contrast, two recent studies were devoted to the examination of certain behaviours of T. protracta (Martínez-Ibarra et al. 2007, Klotz et al. 2009) and three studies focused on T. rubida (Martínez-Ibarra et al. 2005, Klotz et al. 2009, Reisenman et al. 2011. Even though the biological parameters of the two latter species have been studied previously, it is necessary to determine the particular behaviours of geographically distinct populations of the same species because it is likely that differing environmental conditions result in different behaviours for distinct populations of the same triatomine species (Licón-Trillo et al. 2010).As part of a series of studies on the biology of Mexican Triatominae, a study of the feeding and defecation behaviours and the life cycles of three Triatominae species of secondary importance in the transmission of T. cruzi to human populations in Mexico was conducted. MATERIALS AND METHODSA laboratory colony of T. recurva established in 2009 from specimens collected in Jesús María, Nayarit, Mexico, was used. A colony of T. protracta (morphologically similar to the synonymised subspecies protracta) was established in 2008 with specimens originally obtained from Caborca, Sonora, Mexico. In addition, a colony of T. rubida (morphologically similar to the synonymised subspecies uhleri) from Saucillo, Chihuahua, was included. The colonies were maintained at 25ºC ± 1ºC and 50% relative humidity (RH) ± 5% RH to match the typical habitat conditions of the three species. The colonies were fed on immobilised and anaesthetised New Zealand rabbits on a weekly basis. These rabbits were anaesthetised following the Norma Official Mexicana regulations with 0.25 mL/kg of ketamine delivered intramuscularly (SAGARPA 1999

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Section: Discussionmentioning

confidence: 57%

The biology of three Mexican-American species of Triatominae (Hemiptera: Reduviidae): Triatoma recurva, Triatoma protracta and Triatoma rubida

Martínez-Ibarra

Paredes-González

Licón-Trillo

et al. 2012

Mem. Inst. Oswaldo Cruz

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“…As a result, the sylvatic cycles in the USA have been less studied despite the often high (over 50%) prevalence of infection observed in some sylvatic US hosts. Only recently have studies begun to examine the characteristics particular to the sylvatic infection cycles that keep T. cruzi in zoonosis in the USA (some recent relevant summaries include [12,19,23,41]). …”

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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“…Stercorarian transmission is therefore quite a hazardous route of transmission compared to transmission through the salivary glands that takes place in other vector-borne diseases such as malaria. In addition, in the SE US, the two main vectors involved in T. cruzi transmission, Triatoma sanguisuga and Triatoma gerstaeckeri [20], appear to display cautious behaviors when they feed on their hosts (in particular they avoid climbing completely onto the host) and a longer delay between feeding and defecating compared to South American species (e.g., [21]). …”

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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Biogeography andTrypanosoma cruziInfection Prevalence of Chagas Disease Vectors in Texas, USA

Cited by 115 publications

References 38 publications

The biology of three Mexican-American species of Triatominae (Hemiptera: Reduviidae): Triatoma recurva, Triatoma protracta and Triatoma rubida

The biology of three Mexican-American species of Triatominae (Hemiptera: Reduviidae): Triatoma recurva, Triatoma protracta and Triatoma rubida

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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