Molecular surveillance of potential SARS-CoV-2 reservoir hosts in wildlife rehabilitation centers.

BACKGROUND: The COVID-19 pandemic, caused by SARS-CoV-2 infection, has become the most devastating zoonotic event in recent times, with negative impacts on both human and animal welfare as well as on the global economy. Although SARS-CoV-2 is considered a human virus, it likely emerged from animals, and it can infect both domestic and wild animals. This constitutes a risk for human and animal health including wildlife with evidence of SARS-CoV-2 horizontal transmission back and forth between humans and wild animals. AIM: Molecular surveillance in different wildlife rehabilitation centers and wildlife associated institutions in Chile, which are critical points of animal-human interaction and wildlife conservation, especially since the aim of wildlife rehabilitation centers is to reintroduce animals to their original habitat. MATERIALS AND METHODS: The survey was conducted in six WRCs and three wildlife associated institutions. A total of 185 samples were obtained from 83 individuals belonging to 15 different species, including vulnerable and endangered species. Each specimen was sampled with two different swabs: one oropharyngeal or nasopharyngeal according to the nostril diameter, and/or a second rectal sample. RNA was extracted from the samples and two different molecular assays were performed: first, a conventional RT-PCR with pan-coronavirus primers and a second SARS-CoV-2 qPCR targeting the N and S genes. RESULTS: All 185 samples were negative for SARS-CoV-2. CLINICAL RELEVANCE: This study constitutes the first report on the surveillance of SARS-CoV-2 from wildlife treated in rehabilitation centers in Chile, and supports the biosafety procedures adopted in those centers.

Opportunistic or selective? Stage-dependent feeding behavior in a wild vector of Chagas disease.

The composition and contribution of different host species in the dynamics of vector-borne zoonotic parasites are particularly relevant for public health. Hence, the study of host selection by vectors is fundamental. Developmental stage and infection status are factors that may modulate vector feeding behavior. In the semi-arid Mediterranean ecosystem of South America, the transmission of Trypanosoma cruzi, the protozoan causing Chagas disease, includes the triatomine vector Mepraia spinolai and several vertebrate species. In this field study, we examined whether M. spinolai exhibits an opportunistic feeding behavior dependent upon developmental stage and/or infection status. We found that M. spinolai does not feed according to the relative availability of vertebrate species. In addition, early stage nymphs (first/second instars) fed on twice as many different species as middle (third/fourth instars) and late (fifth instars and adults) M. spinolai, with the former feeding on native rodents and lizards and the latter mostly on rabbits. Infected and uninfected M. spinolai showed similar feeding profiles. Wild triatomine species might be described as stage-dependent selective blood feeders, as a consequence of the temporal and spatial scale at which host-vector interactions occur, highlighting that all developmental stages might be infected and capable of transmitting T. cruzi.

Trypanosoma cruzi could affect wild triatomine approaching behaviour to humans by altering vector nutritional status: A field test.

Hematophagous insects exhibit complex behaviour when searching for blood-meals, responding to several host stimuli. The hematophagous insect Mepraia spinolai is a wild vector of Trypanosoma cruzi, causative agent of Chagas disease in humans, in the semiarid-Mediterranean ecosystem of Chile. In this study, we evaluated the association between the approaching behaviour to a human host, with T. cruzi infection status and nutritional condition of M. spinolai. To this end, we captured 501 individuals in six consecutive 10 min-timespan, using a human as bait. Captured vectors were weighed, photographed and measured to calculate their nutritional status by means of a Standardized Body Mass Index. Trypanosoma cruzi infection was assessed in the intestinal content by using a real-time PCR assay. Ordinal logistic regressions were performed separately for infected and uninfected groups to evaluate if the nutritional status was associated with the approaching behaviour to a human host, recorded as the time-span of capture. Nutritional status of uninfected triatomines was higher than that from infected ones (p < 0.005). Among the infected, those with higher nutritional status approached first (p < 0.01); there was no effect of nutritional status in the uninfected group. Trypanosoma cruzi infection might affect the foraging behaviour of M. spinolai under natural conditions, probably deteriorating nutritional status and/or altering vector detection abilities.