The Chagas disease domestic transmission cycle in Guatemala: Parasite-vector switches and lack of mitochondrial co-diversification between Triatoma dimidiata and Trypanosoma cruzi subpopulations suggest non-vectorial parasite dispersal across the Motagua valley

Triatoma dimidiata, domestic animals and acute Chagas disease: A 10 year follow-up after an eco-bio-social intervention

Introduction

Trypanosoma cruzi, the causative agent of Chagas disease, is primarily transmitted by triatomine insects, including Triatoma dimidiata. In Central America, vector control programs have significantly reduced transmission; however, certain regions, such as Comapa, Jutiapa, Guatemala, continue to experience persistent T. dimidiata infestation. This study presents a 10-year follow-up assessment of triatomine infestation, T. cruzi infection, and acute Chagas disease cases after an eco-bio-social intervention.

Methods

Between June and August 2022, entomological surveys were conducted in four communities of Comapa. Seventy six households were systematically searched for triatomines using the one-person hour method, which were collected and processed for T. cruzi detection using qPCR. Bloodmeal analysis was performed to assess host feeding patterns. Dog samples and environmental DNA from household surfaces were also processed for T. cruzi detection. Additionally, surveillance for acute Chagas disease cases was carried out in collaboration with the Ministry of Health.

Results

Persistent infestation of T. dimidiata was observed across all communities, with infestation rates ranging from 17-38% and colonization levels between 9-29%. The mean household triatomine density remained low, suggesting a possible reduction in transmission risk. A total of 86 triatomines were collected, of which 26% tested positive for T. cruzi (all TcI strain). Amplicon deep sequencing analysis from triatomines identified seven vertebrate species and one insect family as hosts upon which triatomines have previously fed, with chickens being the most common blood source (occurring in 57% of triatomines), along with rats, dogs, humans, cats, pigs, ducks, and one genus of cockroach. Of the 132 dogs processed 22% were positive for T. cruzi (all TcI). One acute Chagas disease case detected in a child in 2015 remained seropositive in 2022, emphasizing the need for continued surveillance.

Conclusions

Despite multiple interventions over a decade, T. dimidiata infestation remains high in Comapa with sustained evidence of actue disease in humans, necessitating continued vector control efforts. The persistence of T. cruzi transmission among triatomines and dogs and the predominant role of chickens in supporting the vector population highlights the need for innovative control strategies including those that target domestic animals to mitigate Chagas disease risk.

Differential Epigenetic Status and Responses to Stressors between Retinal Cybrids Cells with African versus European Mitochondrial DNA: Insights into Disease Susceptibilities

Mitochondrial (mt) DNA can be classified into haplogroups, which represent populations with different geographic origins. Individuals of maternal African backgrounds (L haplogroup) are more prone to develop specific diseases compared those with maternal European-H haplogroups. Using a cybrid model, effects of amyloid-β (Amyβ), sub-lethal ultraviolet (UV) radiation, and 5-Aza-2'-deoxycytidine (5-aza-dC), a methylation inhibitor, were investigated. Amyβ treatment decreased cell metabolism and increased levels of reactive oxygen species in European-H and African-L cybrids, but lower mitochondrial membrane potential (ΔΨM) was found only in African-L cybrids. Sub-lethal UV radiation induced higher expression levels of CFH, EFEMP1, BBC3, and BCL2L13 in European-H cybrids compared to African-L cybrids. With respect to epigenetic status, the African-L cybrids had (a) 4.7-fold higher total global methylation levels (p = 0.005); (b) lower expression patterns for DNMT3B; and (c) elevated levels for HIST1H3F. The European-H and African-L cybrids showed different transcription levels for CFH, EFEMP1, CXCL1, CXCL8, USP25, and VEGF after treatment with 5-aza-dC. In conclusion, compared to European-H haplogroup cybrids, the African-L cybrids have different (i) responses to exogenous stressors (Amyβ and UV radiation), (ii) epigenetic status, and (iii) modulation profiles of methylation-mediated downstream complement, inflammation, and angiogenesis genes, commonly associated with various human diseases.

Efficiently sparse listing of classes of optimal cophylogeny reconciliations

Background

Cophylogeny reconciliation is a powerful method for analyzing host-parasite (or host-symbiont) co-evolution. It models co-evolution as an optimization problem where the set of all optimal solutions may represent different biological scenarios which thus need to be analyzed separately. Despite the significant research done in the area, few approaches have addressed the problem of helping the biologist deal with the often huge space of optimal solutions.

Results

In this paper, we propose a new approach to tackle this problem. We introduce three different criteria under which two solutions may be considered biologically equivalent, and then we propose polynomial-delay algorithms that enumerate only one representative per equivalence class (without listing all the solutions).

Conclusions

Our results are of both theoretical and practical importance. Indeed, as shown by the experiments, we are able to significantly reduce the space of optimal solutions while still maintaining important biological information about the whole space.