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

Abstract

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, this research aimed to evaluate the technical and infrastructural feasibility of establishing this type of scheme in Costa Rica by implementing a pilot program targeting the detection of pathogens of zoonotic and conservation importance in wildlife. Between 2018 and 2020, 85 carcasses of free-ranging vertebrates were admitted for post-mortem and microbiology analysis. However, we encountered obstacles mainly related to the initial identification of cases and limited local logistics capacity. Nevertheless, this epidemiological surveillance scheme allowed us to estimate the general state of health of the country's wildlife by establishing the causes of death according to pathological findings. For instance, 60% (51/85) of the deaths were not directly associated with an infectious agent. Though in 37.6% (32/85) of these cases an infectious agent associated or not with disease was detected. In 27.1% (23/85) of the cases, death was directly related to infectious agents. Furthermore, 12.9% (11/85), the cause of death was not determined. Likewise, this wildlife health monitoring program allowed the detection of relevant pathogens such as Canine Distemper Virus, Klebsiella pneumoniae, Angiostrongylus spp., Baylisascaris spp., among others. Our research demonstrated that this passive surveillance scheme is cost-effective and feasible in countries with limited resources. This passive surveillance can be adapted to the infrastructure dedicated to monitoring diseases in productive animals according to the scope and objectives of monitoring wildlife specific to each region. The information generated from the experience of the initial establishment of a WHMP is critical to meeting the challenges involved in developing this type of scheme in regions with limited resources and established as hotspots for emerging infectious diseases.

Fig 1. Pilot WHMP work scheme design proposal.

DVM-MC: Doctor of veterinary medicine of wildlife management centers; MC: Wildlife management centers; PD: Pathology Department of Escuela de Medicina Veterinaria, Universidad Nacional.

Fig 2. Geocoding of the cases analyzed by conservation area.

The number corresponds to the cases analyzed in each conservation area. Wildlife management centers shown are those that collaborated with the WHMP.

Fig 3. Infectious agents in lesions identified in wild animals.

A) Lung (Alouatta palliata-howler monkey). Lymphoplasmacytic pneumonia with the presence of tissue cyst, morphology compatible with Toxoplasma gondii, confirmation by PCR (arrowhead; H&E 600x). B) Lung (Alouatta palliata-howler monkey). Pyogranulomatous abscessing bronchopneumonia with intralesional bacteria Klebsiella pneumonia, confirmation by culture (arrowhead; H&E 200x). C) Brain (Didelphis marsupialis-opossum). Presence of nematode Angiostrongylus spp. identified by morphology (arrowhead; H&E 400x). Inset: Nematode magnification (H&E 200x). D) Lung (Cebus imitator-white-faced monkey). Bronchopneumonia associated to multiple Nematodes, Filariopsis spp. identified by morphology (more cuts of the female in microphotograph) (arrowhead; H&E 40x). E) Stomach (Herpailurus yagouaroundi-jaguarundi). Nodular and sclerosing gastritis associated with multiple Cylicospirura spp. Nematodes identified by morphology (arrowhead; H&E 40x). F) Skin (Sphiggurus mexicanus-porcupine) Pyogranulomatous and eosinophilic dermatitis associated with massive infestation of Sarcoptex spp. (arrowhead; H&E 400x). Inset: Mites magnification (H&E 100x).

Fig 4. Geographical distribution of the most frequently identified infectious agents in the referred specimens.

The individuals reported as negative were depicted even though the infectious agent was not detected in the complementary analyzes or no lesions suggestive of the disease were found in the pathological analysis.