Biology subjects

Alfaro-Alarcon, A.

Publications and source records attributed to Alfaro-Alarcon, A..

3 recordsLinked to original sources

bioRxiv2022

Boid Inclusion Body Disease (BIBD) Is Also a Disease of Wild Boa Constrictors

Reptarenaviruses cause Boid Inclusion Body Disease (BIBD), a potentially fatal disease, occurring in captive constrictor snakes boas and pythons worldwide. Classical BIBD, characterized by the formation of pathognomonic cytoplasmic inclusion bodies (IBs), occurs mainly in boas, whereas in pythons, for example, reptarenavirus infection most often manifests as central nervous system signs with limited IB formation. The natural hosts of reptarenaviruses are unknown, although wild constrictor snakes are among the suspects. Here, we report BIBD with reptarenavirus infection in indigenous captive and wild boid snakes in Costa Rica using histology, immunohistology, transmission electron microscopy, next-generation sequencing (NGS), and RT-PCR. The snakes studied represented diagnostic post mortem cases of captive and wild caught snakes since 1989. The results from NGS on archival paraffin blocks confirm that reptarenaviruses have been present in wild boa constrictors in Costa Rica already in the 1980s. Continuous sequences de novo assembled from the low-quality RNA obtained from paraffin embedded tissue allowed the identification of a distinct pair of reptrarenavirus S and L segments in all studied animals; in most cases reference assembly could recover almost complete segments. Sampling of three prospective cases in 2018 allowed examination of fresh blood or tissues, and resulted in identification of additional reptarenavirus segments and hartmanivirus co-infection. Our results show that BIBD is not only a disease of captive snakes, but also occurs in indigenous wild constrictor snakes in Costa Rica, suggesting boa constrictors to play a role in natural reptarenavirus circulation. IMPORTANCEThe literature describes cases of boid inclusion body disease (BIBD) in captive snakes since the 1970s, and in the 2010s, others and we identified reptarenaviruses as the causative agent. BIBD affects captive snakes globally, but the origin and the natural host of reptarenaviruses remains unknown. In this report, we show BIBD and reptarenavirus infections in two native Costa Rican constrictor snake species, and by studying archival samples, we show that both the viruses and the disease have been present in wild snakes in Costa Rica at least since the 1980s. The diagnosis of BIBD in wild boa constrictors suggests that this species plays a role in the circulation of reptarenaviruses. Additional sample collection and analysis would help to clarify this role further and the possibility of e.g. vector transmission from an arthropod host.

microbiology↗

bioRxiv2022

Experimental infection of Artibeus lituratus bats and no detection of Zika virus in neotropical bats from French Guyana, Peru, and Costa Rica, suggest a limited role of bats in Zika transmission.

Bats are important natural reservoir hosts of a diverse range of viruses that can be transmitted to humans and have been suggested that could play an important role in the Zika virus (ZIKV) transmission cycle. However, the exact role of these animals as reservoirs for Flaviviruses is still controversial. To further expand our understanding of the role of bats in the ZIKV transmission cycle in Latin America, we carried an experimental infection in wild-caught Artibeus bats and sampled several free-living neotropical bats over three countries of the region. Experimental ZIKV infection was made in free-ranging adult bats (4 females and 5 males). The most relevant gross findings were hemorrhages in the bladder, stomach and patagium. Significant histological findings included inflammatory infiltrate consisting of a predominance of neutrophils and lymphocytes, in addition to degeneration in the reproductive tract of males and females. This suggests that bat reproduction might be at some level affected by ZIKV. Leukopenia was also observed in some inoculated animals. Hemorrhages, genital alterations, and leukopenia are suggestive to be caused by ZIKV, however, since these are wild-caught bats, we can not exclude other agents. Excretion of ZIKV by qPCR was detected (low titles) in only two urine samples in two inoculated animals. All other animals and tissues tested negative. Finally, no virus-neutralizing Abs were found in any animal. To determine ZIKV infection in nature, a total of 2056 bats were blood sampled for ZIKV detection by qPCR. Most of the sampled individuals belonged to the genus Pteronotus sp. (23%), followed by the species Carollia sp. (17%); Anoura sp. (14%), and Molossus sp. (13.7 %). No sample of any tested species resulted positive to ZIKV by qPCR. These results together suggest that bats are not efficient amplifiers or reservoirs of ZIKV and may not have an important role in ZIKV transmission dynamics. Author summaryIn previous works made in 2008-2009, we have found the presence of antibodies against Flaviviruses and viral RNA has been detected in Neotropical chiropterans of Mexico, which led us to support the hypothesis that these animals could be reservoirs of Flaviviruses. As controversial opinions have been exposed, and based on a previous (2019) experimental ZIKV infection made in Colorado State University using adult Artibeus males from a captive colony, in this work we also experimentally infected adult Artibeus males complementarily adding females and using free-living animals instead of laboratory bats. We also monitored a diverse range of natural bat populations in Latin America for the presence of viral RNA against ZIKV in blood. A plaque reduction seroneutralization test was used for the detection of antibodies against ZIKV. Similar to the previous work, we found histopathological alteration in male testicles but also in ovaries and oviducts of females, as well as gliosis and multifocal necrosis in pyramidal neurons and Purkinge cells of inoculated animals. Only two urine samples from inoculated animals showed viral RNA. Additionally, leukopenia and lymphoid follicular splenic hyperplasia were evidenced. Differing to what was reported, no neutralizing antibodies against ZIKV were detected in any sample. Viral RNA within the blood was not present in any of the 2056 bat samples collected in French Guyana, Peru and Costa Rica and proceeding from 33 bat genera. These results together suggest that bats are not efficient amplifiers or reservoirs of ZIKV and might not have an important role on ZIKV transmission dynamics.

microbiology↗

bioRxiv2021

Passive epidemiological surveillance in wildlife in Costa Rica identifies pathogens of zoonotic and conservation importance

Epidemiological surveillance systems for pathogens in wild species have been proposed as a preventive measure for epidemic events. These systems can minimize the detrimental effects of an outbreak, but most importantly, passive surveillance systems are the best adapted to countries with limited resources. Therefore, the present study aims to evaluate the technical and infrastructural feasibility to establish this type of scheme in Costa Rica targeting thedetection of pathogens of zoonotic and conservation importance in wildlife. Between 2018 and 2020, 85 carcasses of free-ranging vertebrates were admitted for post mortem analysis and complementary laboratory analysis, representing a solid basis for the implementation of a passive surveillance system for wildlife diseases in the country. However, we encounter during this research significant constraints that affected the availability of carcasses for analysis, mainly related to the initial identification of cases, detection biases towards events in populated- or easily accessible-areas with nearby located wildlife management centers, further associated with financial disincentives, and limited local logistics capacity. Thus resulting in the exclusion of some geographic regions of the country. This epidemiological surveillance scheme allowed us to estimate the general state of health of the countrys wildlife, establishing the cause of death of the analyzed animals as follows: (i) 46 (54.1%) traumatic events, (ii) 23 (27.1%) infectious agents, (iii) two (2.4%) degenerative illness, (iv) three (3.5%) presumably poisoning, and (v) in 11 (12.9%)undetermined. It also allowed the detection of pathogens such as, canine distemper virus, Klebsiella pneumoniae, Toxoplasma gondii, Trypanosoma spp., Angiostrongylus spp., Dirofilaria spp., Baylisascaris spp., among others. As well as recognizing the circulation of these pathogens around national territory and also on those analyzed species. This strategy is crucial in geographical regions defined as critical for the appearance of diseases due to their great biodiversity and social conditions.

pathology↗