Research Article |
Corresponding author: Nancy Gabriela Santos-Hernandez ( nancy.santos@unicach.mx ) Corresponding author: José A. De Fuentes-Vicente ( jose.defuentes@unicach.mx ) Academic editor: Jader Oliveira
© 2022 Eliza F. Gómez-Sánchez, Héctor Ochoa-Díaz-López, Eduardo E. Espinoza-Medinilla, D. Daniel Velázquez-Ramírez, Nancy Gabriela Santos-Hernandez, Christian Ruiz-Castillejos, Dolores G. Vidal-López, Adriana Moreno-Rodríguez, Any Laura Flores-Villegas, Eduardo López-Argueta, José A. De Fuentes-Vicente.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Gómez-Sánchez EF, Ochoa-Díaz-López H, Espinoza-Medinilla EE, Velázquez-Ramírez DD, Santos-Hernandez NG, Ruiz-Castillejos C, Vidal-López DG, Moreno-Rodríguez A, Flores-Villegas AL, López-Argueta E, De Fuentes-Vicente JA (2022) Mini-exon gene reveals circulation of TcI Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae) in bats and small mammals in an ecological reserve in southeastern Mexico. ZooKeys 1084: 139-150. https://doi.org/10.3897/zookeys.1084.78664
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A wide variety of mammals are involved in the sylvatic cycle of Trypanosoma cruzi, the causative agent of Chagas disease. In many areas in Latin America where T. cruzi is endemic, this cycle is poorly known, and its main reservoirs have not been identified. In this study we analyzed T. cruzi infection in bats and other small mammals from an Ecological Reserve in southeastern Mexico. From January through March 2021, we captured wild individuals to extract cardiac and peripheral blood, and infection was detected by PCR of the mini-exon gene. In bats, the prevalence of infection was 16.36%, while in small mammals the prevalence was 28.57%. All of the samples that were positive for T. cruzi were identified as the TCI genotype. Our findings suggest that this zone, situated at the periphery of urban zones might have epidemiological relevance in the sylvatic cycle of T. cruzi and needs to be monitored. The infection of bats in this area is particularly concerning since the flight pattern of this populations overlaps with human settlements. Despite being subject to conservation protections, there continue to be anthropogenic actions that disturb the study area, which could exacerbate risks to public health.
Chagas disease, molecular epidemiology, reservoirs, sylvatic cycle
The protozoan Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae) is the causative agent of Chagas disease, a neglected tropical infection affecting ~6 million people (
Trypanosoma cruzi exhibits high genetic variability and has recently been classified into six discrete typing units (DTUs; TCI–TCVI) and an additional unit named TC Bat (see Zingales et al. 2018). Under natural conditions, T. cruzi is transmitted by blood-sucking insects of the subfamily Triatominae (Hemiptera, Reduviidae) known as kissing bugs (
Historically, the domestic and peridomestic cycles have been the most studied, and little is known about the sylvatic cycle, especially in the southeastern region of Mexico (e.g.,
Although “El Zapotal” is subject to conservation protections, anthropogenic actions may have already caused irreversible damage (
The “El Zapotal” Ecological Reserve, decreed as an Ecological and Recreational Park, is located 2 km southeast of Tuxtla Gutiérrez, Chiapas (Fig.
Wild mammals were captured from January through March 2021 in areas of the “El Zapotal” Ecological Reserve near bodies of water and fruit trees. To capture bats, we deployed three 12 × 2.5 m mist nets from dusk to dawn (eight sampling hours per net) for five consecutive nights. The captured specimens were deposited in canvas bags for identification and blood sampling. The identification was performed as described by Díaz (2021). Meanwhile, the blood sample was obtained by intracardiac puncture (100 μL) and deposited in microcentrifuge tubes with 500 μL 3.8% sodium citrate pH 7.2 for their transportation to the laboratory. Finally, the bats were marked on the wings with ink and released on site.
For the capture of smalls mammals 20 Tomahawk type traps and 15 Sherman traps were used (
Animal handling was carried out in accordance with the provisions of Mexican Animal Welfare Law. The capture of animals was approved by the Mexican Secretariat of the Environment and Natural Resources (Secretaría de Medio Ambiente y Recursos Naturales, SEMARNAT (minute 07 / K6-0095 / 10/189)). No individuals were sacrificed or removed from the site.
Total DNA was extracted using a modified phenol-chloroform isoamyl alcohol protocol (
A total of 152 mammals were captured: 110 bats and 42 small mammals. Among bats, eight species were identified, and Artibeus jamaicensis Leach, 1821 (Chiroptera, Phyllostomidae) was the most common species. Only two hematophagous individuals (Desmodus rotundus É. Geoffroy, 1810) (Phyllostomidae) were captured. We captured four species of small mammals, of which Didelphis marsupialis Linnaeus, 1758 (Didelphimorphia, Didelphidae) was the most common (Table
Bats and smalls mammals captured in “El Zapotal” ecological reserve and infected individuals.
Bats | |||
---|---|---|---|
Family | Species | # individuals | Infected indivuals (% prevalence) |
Phyllostomidae | Artibeus jamaicensis | 64 | 10 (15.6) |
Artibeus lituratus | 16 | 3 (18.7) | |
Sturnira lillium | 3 | 2 (66.6) | |
Centurio senex | 2 | 0 | |
Leptonycteris yebabuenae | 2 | 0 | |
Carollia perspicillata | 7 | 2 (28.5) | |
Desmodus rotundus | 2 | 0 | |
Glossophaga soricina | 8 | 1 (12.5) | |
Pteronotus davyi | 1 | 0 | |
Mormoopidae | Pteronotus parnelli | 3 | 0 |
Mormoops megallophyla | 2 | 0 | |
Total | 110 | 18 (16.3) | |
Small mammals | |||
Didelphidae | Didelphis marsupialis | 18 | 6 (33.3) |
Cricetidae | Peromyscus mexicanus | 7 | 4 (57.1) |
Heteromyidae | Heteromys desmarestianus | 10 | 1 (10) |
Dasyproctidae | Dasyprocta mexicana | 7 | 1 (14.2) |
Total | 42 | 12 (28.5) |
Of the total bat samples examined, 18 were positive for T. cruzi infection (16.36%). Sturnira lilium É. Geoffroy, 1810 had the highest prevalence among the bat species (66.6%), though only three individuals were captured. Meanwhile, the most commonly captured bat species, A. jamaicensis, had a prevalence of 15.62% (10/64) (Table
PCR products of the mini-exon gene in blood of bats from the “El Zapotal” Ecological Reserve. Amplification resulted in a PCR product of 350 bp and this confirms that these parasites belong to the TCI group. L: Ladder; Samples: 1 positive control (Qro. strain); 2–11 A. jamaicensis; 12–14 A. lituratus; 15–16 C. perspicillata; 17–18 S. lilium; 19 G. soricina.
For smalls mammals there was an overall prevalence of 28.57% (12/42), when combining all four mammal species. Peromyscus mexicanus (Saussure, 1860) (Rodentia, Cricetidae) presented the highest prevalence with 57.14% (4/7), while the most commonly captured species, D. marsupialis, had a prevalence of 33.33% (6/18) (Table
PCR products of the mini-exon gene in blood of smalls mammals from the “El Zapotal” Ecological Reserve. Amplification resulted in a PCR product of 350 bp and this confirms that these parasites belong to the TCI group. L: ladder; samples: Q positive control (Qro. strain); 1–6 D. marsupialis; 7–10 P. mexicanus; 11 H. desmarestianus; 12 D. mexicana.
We show evidence of the circulation of T. cruzi in wild mammals from an ecological reserve in southeastern Mexico. Although other studies have demonstrated the presence of the parasite in small mammals from “El Zapotal” (Domínguez-Vázquez et al. 1990;
Overall, the prevalence of T. cruzi infection was 19.73% in all captured individuals (30/152). The overall infection prevalence in small mammals (28.57%) was similar to previous findings in a recent study (26.66%) in the same area (
To date, it is largely unknown how the sylvatic cycle interacts with the peridomestic and domestic cycles, but it is inferred that some synanthropic animals may be the link between them. For example, some synanthropic rodents captured in Yucatán have shown histological lesions associated with T. cruzi infection (
In Mexico, the dynamics of T. cruzi in bats in the sylvatic cycle has been little studied, even though bats have wide distributions that may overlap with urbanized environments (
High prevalence of T. cruzi infection in bats have been previously reported in southern Mexico:
Maintaining biodiversity has been shown to be an important – if not the most important – action to prevent the spread of zoonotic parasites (
We thank the Miguel Alvarez del Toro Zoo (ZOOMAT) for its support in the logistics of animal captures. Funding for our study was contributed by the Consejo Nacional de Ciencia y Tecnología (CONACyT) (SEP-CONACYT A1-S-47901). We are grateful to the reviewers and academic editor for their comments.