Orally-transmitted Chagas disease

First report of Rhodnius amazonicus Almeida, Santos & Sposina, 1973 (Hemiptera, Reduviidae, Triatominae) invading a dwelling in the state of Amapá, Brazil

Rhodnius amazonicus has been previously reported in the Brazilian states of Amazonas and Pará, as well as in French Guiana. However, this is the first recorded presence of this species in Amapá, which is situated in the northern region of Brazil. The specimen was collected from a house in the rural area of the municipality of Porto Grande. Other triatomines, such as Panstrongylus geniculatus, Rhodnius pictipes, and Eratyrus mucronatus, were also found in the same locality in different houses. These species are vectors of Trypanosoma cruzi, which causes Chagas disease. Therefore, this report may contribute to understanding transmission in the state of Amapá, where new infections and outbreaks of Chagas disease have been recorded.

Phenology and environmental predictors of Triatoma sanguisuga dispersal in east-central Texas, United States

Of 11 triatomine species in the United States (US), Triatoma sanguisuga has the widest distribution across a 23-state region encompassing the southeastern US. This species consistently feeds on humans and dogs and has a high infection prevalence with the Chagas parasite Trypanosoma cruzi, with over 30-60% of adults infected. Little is known about the phenology and environmental predictors of dispersal activity of Triatoma sanguisuga. Using manual searches standardized by effort, we sampled kissing bugs in east central Texas, US every other night from June to November 2020 to determine their phenology and environmental predictors of activity. We found 176 triatomines alive, all of which were T. sanguisuga, with peak collections in early August and cessation of activity by late October; the phenology as determined by this active surveillance matched what has been reported using a passive community science approach. Using a negative binomial regression, we found temperature to have a positive correlation with T. sanguisuga dispersal activity, while wind speed had a significant negative correlation. We identified increased collections during sampling sessions with precipitation during the preceding 22 h. Further, wind from the southwest - the direction of most of the sylvatic habitat in the study area - was correlated with an increased dispersal activity, suggesting wind-facilitated dispersal. Given concerns for human and animal Chagas disease within the distribution of T. sanguisuga, vector control strategies can be adapted based on the factors influencing dispersal behavior.

Central nervous system commitment in Chagas disease

The involvement of the central nervous system (CNS) during human acute and chronic Chagas disease (CD) has been largely reported. Meningoencephalitis is a frequent finding during the acute infection, while during chronic phase the CNS involvement is often accompanied by behavioral and cognitive impairments. In the same vein, several studies have shown that rodents infected with Trypanosoma cruzi (T. cruzi) display behavior abnormalities, accompanied by brain inflammation, in situ production of pro-inflammatory cytokines and parasitism in diverse cerebral areas, with involvement of microglia, macrophages, astrocytes, and neurons. However, the mechanisms used by the parasite to reach the brain remain now largely unknown. Herein we discuss the evidence unravelling the CNS involvement and complexity of neuroimmune interactions that take place in acute and chronic CD. Also, we provide some clues to hypothesize brain infections routes in human and experimental acute CD following oral infection by T. cruzi, an infection route that became a major CD related public health issue in Brazil.

Trypanosoma cruzi, beyond the dogma of non-infection in birds

Trypanosoma cruzi is a protozoan parasite responsible for Chagas disease affecting seven million people. The disease cycle is maintained between Triatominae insects and Mammalia hosts; a refractory effect against infection was noted in birds, but only verified in poultry. This paper presents a new host record for T. cruzi, the American barn-owl (Tyto furcata). Trypanosoma cruzi DTU II molecular evidence was found in heart, intestine, liver, and breast suggesting an established chronic infection based on the parasite DNA presence in multiple organs but absent in spleen, as in the murine model and chronically infected raccoons (Procyon lotor). For birds, the parasite rejection was explained based on the complement and high body temperature, but these mechanisms vary greatly among the members of the avian class. Therefore, there is a need to investigate whether more bird species can become infected, and if T. furcata has a role in disseminating, transmitting and/or maintaining the parasite.

Therapeutic effects of benznidazole in Swiss mice that are orally inoculated with Trypanosoma cruzi IV strains from the Western Brazilian Amazon

Strains of Trypanosoma cruzi, etiological agent of Chagas disease, are classified into different discrete typing units that may present distinct dynamics of infection and susceptibility to benznidazole (BZ) treatment. Mice that were orally inoculated with T. cruzi IV strains exhibited a more intense course of infection compared with intraperitoneally inoculated mice, reflected by higher parasite loads. We evaluated the efficacy of BZ treatment in Swiss mice that were inoculated with T. cruzi IV strains from the Western Brazilian Amazon. The mice were orally (OR) or intraperitoneally (IP) inoculated with 2 × 10⁶ culture-derived metacyclic trypomastigotes of the AM14, AM16, AM64, and AM69 strains of T. cruzi that were obtained from two outbreaks of orally acquired acute Chagas disease in the state of Amazonas, Brazil. The animals were treated with BZ (100 mg/kg/day for 20 days). Fresh blood examination, hemoculture, conventional and quantitative real-time polymerase chain reaction were performed to monitor the therapeutic effects of BZ. Significant reductions in five of 24 parameters of parasitemia and parasite load were found in different tissues in the OR group, indicating worse response to BZ treatment compared with the IP group, in which significant reductions in nine of those 24 parameters were observed. The cure rates in the OR groups ranged from 18.2% (1/11) to 75.0% (9/12) and in the IP groups from 58.3% (7/12) to 91.7% (11/12), for the AM14 and AM69 strains, respectively. These findings indicate that treatment with BZ had fewer beneficial effects with regard to reducing parasitemia and parasite load in different tissues of mice that were OR inoculated with four TcIV strains compared with IP inoculation. Therefore, the route of infection with T. cruzi should be considered when evaluating the therapeutic efficacy of BZ in patients with Chagas disease.

Preliminary Characterization of Triatomine Bug Blood Meals on the Island of Trinidad Reveals Opportunistic Feeding Behavior on Both Human and Animal Hosts

Chagas disease is a neglected tropical disease caused by infection with Trypanosoma cruzi. The parasite is endemic to the Americas, including the Caribbean, where it is vectored by triatomine bugs. Although Chagas disease is not considered a public health concern in the Caribbean islands, studies in Trinidad have found T. cruzi-seropositive humans and T. cruzi-infected triatomine bugs. However, little is known about triatomine bug host preferences in Trinidad, making it difficult to evaluate local risk of vector-borne T. cruzi transmission to humans. To investigate this question, we collected triatomine bugs in Trinidad and diagnosed each one for T. cruzi infection (microscopy and PCR). We then carried out a blood meal analysis using DNA extracted from each bug (PCR and sequencing). Fifty-five adult bugs (54 Panstrongylus geniculatus and one Rhodnius pictipes) were collected from five of 21 sample sites. All successful collection sites were residential. Forty-six out of the 55 bugs (83.6%) were infected with T. cruzi. Fifty-three blood meal hosts were successfully analyzed (one per bug), which consisted of wild birds (7% of all blood meals), wild mammals (17%), chickens (19%), and humans (57%). Of the 30 bugs with human blood meals, 26 (87%) were from bugs infected with T. cruzi. Although preliminary, our results align with previous work in which P. geniculatus in Trinidad had high levels of T. cruzi infection. Furthermore, our findings suggest that P. geniculatus moves between human and animal environments in Trinidad, feeding opportunistically on a wide range of species. Our findings highlight a critical need for further studies of Chagas disease in Trinidad in order to estimate the public health risk and implement necessary preventative and control measures.