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Busselman RE, Curtis-Robles R, Meyers AC, Zecca IB, Auckland LD, Hodo CL, Christopher D, Saunders AB, Hamer SA. Abundant triatomines in Texas dog kennel environments: Triatomine collections, infection with Trypanosoma cruzi, and blood feeding hosts. Acta Trop 2024; 250:107087. [PMID: 38061614 DOI: 10.1016/j.actatropica.2023.107087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 11/26/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023]
Abstract
Triatomine insects are vectors of the protozoan parasite Trypanosoma cruzi- the causative agent of Chagas disease. Chagas disease is endemic to Latin America and the southern United States and can cause severe cardiac damage in infected mammals, ranging from chronic disease to sudden death. Identifying interactions among triatomines, T. cruzi discrete typing units (DTUs), and blood feeding hosts is necessary to understand parasite transmission dynamics and effectively protect animal and human health. Through manual insect trapping efforts, kennel staff collections, and with the help of a trained scent detection dog, we collected triatomines from 10 multi-dog kennels across central and south Texas over a one-year period (2018-2019) and tested a subset to determine their T. cruzi infection status and identify the primary bloodmeal hosts. We collected 550 triatomines, including Triatoma gerstaeckeri (n = 515), Triatoma lecticularia (n = 15), Triatoma sanguisuga (n = 6), and Triatoma indictiva (n = 2), with an additional 10 nymphs and 2 adults unable to be identified to species. The trained dog collected 42 triatomines, including nymphs, from areas not previously considered vector habitat by the kennel owners. Using qPCR, we found a T. cruzi infection prevalence of 47 % (74/157), with T. lecticularia individuals more likely to be infected with T. cruzi than other species. Infected insects harbored two T. cruzi discrete typing units: TcI (64 %), TcIV (23 %), and mixed TcI/TcIV infections (13 %). Bloodmeal host identification was successful in 50/149 triatomines, revealing the majority (74 %) fed on a dog (Canis lupus), with other host species including humans (Homo sapiens), raccoons (Procyon lotor), chickens (Gallus gallus), wild pig (Sus scrofa), black vulture (Coragyps atratus), cat (Felis catus), and curve-billed thrasher (Toxostoma curviostre). Given the frequency of interactions between dogs and infected triatomines in these kennel environments, dogs may be an apt target for future vector control and T. cruzi intervention efforts.
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Affiliation(s)
- R E Busselman
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - R Curtis-Robles
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - A C Meyers
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - I B Zecca
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - L D Auckland
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - C L Hodo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States; Michale E. Keeling Center for Comparative Medicine and Research, The University of Texas MD Anderson Cancer Center, Bastrop, TX, United States
| | | | - A B Saunders
- Department of Small Animal Clinical Sciences, Texas A&M University, College Station, TX, United States
| | - S A Hamer
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States.
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Fiatsonu E, Deka A, Ndeffo-Mbah ML. Effectiveness of Systemic Insecticide Dog Treatment for the Control of Chagas Disease in the Tropics. BIOLOGY 2023; 12:1235. [PMID: 37759635 PMCID: PMC10525078 DOI: 10.3390/biology12091235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/05/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023]
Abstract
Chagas disease, caused by Trypanosoma cruzi and transmitted by triatomines, can lead to severe cardiac issues and mortality in many mammals. Recent studies have shown that systemic insecticide treatment of dogs is highly effective in killing triatomines. Here, we assessed the impact of dog treatment on T. cruzi transmission. We developed a mathematical model of T. cruzi transmission among triatomines, dogs, humans, and rodents. We used the model to evaluate the impact of dog treatment regimens on T. cruzi transmission dynamics to determine their effectiveness in reducing T. cruzi infection among hosts. We show that a 3-month treatment regimen may reduce T. cruzi incidence among humans by 59-80% in a high transmission setting, and 26-82% in a low transmission setting. An annual treatment may reduce incidence among humans by 49-74% in a high transmission setting, and by 11-76% in a low transmission setting. However, dog treatment may substantially increase T. cruzi prevalence among dogs if dog consumption of dead triatomines increases. Our model indicates that dog treatment may reduce T. cruzi infections among humans, but it may increase infections in dogs. Therefore, a holistic approach targeting different hosts is necessary for Chagas elimination.
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Affiliation(s)
- Edem Fiatsonu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845, USA; (A.D.); (M.L.N.-M.)
| | - Aniruddha Deka
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845, USA; (A.D.); (M.L.N.-M.)
| | - Martial L. Ndeffo-Mbah
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845, USA; (A.D.); (M.L.N.-M.)
- Department of Epidemiology and Biostatistics, School of Public Health, Texas A&M University, College Station, TX 77845, USA
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Rokhsar JL, Raynor B, Sheen J, Goldstein ND, Levy MZ, Castillo-Neyra R. Modeling the impact of xenointoxication in dogs to halt Trypanosoma cruzi transmission. PLoS Comput Biol 2023; 19:e1011115. [PMID: 37155680 PMCID: PMC10194993 DOI: 10.1371/journal.pcbi.1011115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 05/18/2023] [Accepted: 04/19/2023] [Indexed: 05/10/2023] Open
Abstract
BACKGROUND Chagas disease, a vector-borne parasitic disease caused by Trypanosoma cruzi, affects millions in the Americas. Dogs are important reservoirs of the parasite. Under laboratory conditions, canine treatment with the systemic insecticide fluralaner demonstrated efficacy in killing Triatoma infestans and T. brasiliensis, T. cruzi vectors, when they feed on dogs. This form of pest control is called xenointoxication. However, T. cruzi can also be transmitted orally when mammals ingest infected bugs, so there is potential for dogs to become infected upon consuming infected bugs killed by the treatment. Xenointoxication thereby has two contrasting effects on dogs: decreasing the number of insects feeding on the dogs but increasing opportunities for exposure to T. cruzi via oral transmission to dogs ingesting infected insects. OBJECTIVE Examine the potential for increased infection rates of T. cruzi in dogs following xenointoxication. DESIGN/METHODS We built a deterministic mathematical model, based on the Ross-MacDonald malaria model, to investigate the net effect of fluralaner treatment on the prevalence of T. cruzi infection in dogs in different epidemiologic scenarios. We drew upon published data on the change in percentage of bugs killed that fed on treated dogs over days post treatment. Parameters were adjusted to mimic three scenarios of T. cruzi transmission: high and low disease prevalence and domestic vectors, and low disease prevalence and sylvatic vectors. RESULTS In regions with high endemic disease prevalence in dogs and domestic vectors, prevalence of infected dogs initially increases but subsequently declines before eventually rising back to the initial equilibrium following one fluralaner treatment. In regions of low prevalence and domestic or sylvatic vectors, however, treatment seems to be detrimental. In these regions our models suggest a potential for a rise in dog prevalence, due to oral transmission from dead infected bugs. CONCLUSION Xenointoxication could be a beneficial and novel One Health intervention in regions with high prevalence of T. cruzi and domestic vectors. In regions with low prevalence and domestic or sylvatic vectors, there is potential harm. Field trials should be carefully designed to closely follow treated dogs and include early stopping rules if incidence among treated dogs exceeds that of controls.
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Affiliation(s)
- Jennifer L. Rokhsar
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
- Department of Epidemiology and Biostatistics, Dornsife School of Public Health, Drexel University, Philadelphia, Pennsylvania, United States of America
- ORISE Fellow, Emerging Leaders in Data Science and Technologies Program Fellowship, National Institute of Allergy and Infectious Diseases (NIAID), NIH, United States of America
| | - Brinkley Raynor
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Justin Sheen
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Neal D. Goldstein
- Department of Epidemiology and Biostatistics, Dornsife School of Public Health, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - Michael Z. Levy
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- One Health Unit, School of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Ricardo Castillo-Neyra
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- One Health Unit, School of Public Health and Administration, Universidad Peruana Cayetano Heredia, Lima, Peru
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