Investigation article published in Veterinary Pathology

February 18^th, 2026

Canine distemper virus (CDV) is a multi-host pathogen capable of infecting a wide range of domestic and wild mammals, however, reports of infection in squirrels and porcupines remain scarce. As part of the wildlife rabies surveillance programme in Costa Rica, six wild ammals (four Sciurus variegatoides and two Coendou mexicanus) with neurological signs were evaluated to rule out rabies. All brain samples tested negative for rabies by direct immunofluorescence and RT-PCR. Rapid distemper antigen tests of ocular and nasal secretions were positive in both porcupines, which were subsequently euthanised. Advanced autolysis prevented histopathological evaluation in five of the animals; however, one squirrel showed severe neutrophilic pneumonia with necrosis and haemorrhage, a moderate lymphoplasmacytic infiltrate in the pulmonary interstitium, intracytoplasmic inclusion bodies in bronchial epithelium, and a focal neutrophilic infiltrate in the midbrain. The findings were consistent with CDV infection accompanied by severe systemic bacterial infection. CDV was confirmed in two of the four squirrels and in the two porcupines by RT-PCR and sequencing. Phylogenetic analysis revealed that the Costa Rican sequences grouped into two distinct clusters: one containing both squirrels and another with both porcupines. All four sequences shared a common ancestor with CDV strains detected in domestic dogs in the United States (2012–2013), and more distantly with a dog strain from Argentina (2005). These cases represent one of the few documented occurrences of CDV in squirrels and porcupines worldwide and the first reported in Costa Rica, underscoring the need for continued molecular surveillance to clarify lineage dynamics and spillover pathways

Leon B., Wiederkehr-Bruno CM., Cruz R., Cordero M., Chinchilla-Rodríguez B., Solorzano-Scott T., Brenes L. and Aguilar-Vargas F.

First detection of canine distemper virus infection in variegated squirrels (Sciurus variegatoides) and porcupines (Coendou mexicanus) in Costa Rica

	Servicio Nacional de Sanidad y Calidad Agroalimentaria (SENASA).
	Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Sol Sanctuary Rescue Center.
	Santuario y Centro de Rescate Las Pumas.
	Hospital Veterinario Cavallini.
	Escuela de Medicina Veterinaria. Universidad Nacional de Costa Rica (UNA).
	Departamento CUSBSE. Sistema Nacional de Áreas de Conservación.
	Laboratorio Nacional de Servicios Veterinarios (LANASEVE). Laboratorio de Patología Servicio Nacional de Salud Animal. Ministerio de Agricultura y Ganadería.