Abstract

ZooParc de Beauval houses two groups of western lowland gorillas (Gorilla gorilla gorilla): one familial group of 13 individuals, which coexists with patas monkeys (Erythrocebus patas) and colobus monkeys (Colobus guereza), and a bachelor group of 3 males. In early December 2013, an epidemic of varicella was observed in both groups, starting in the familial group, causing the death of a 10-month-old male, and subsequently to the bachelor group. The first case was a young male showing lethargy, dysorexia, strong nasal discharge and cough, bumps and blisters observed a few hours later. He was monitored for two days with supportive treatment attempts. Anesthesia was scheduled on day four, but he was found dead in the morning. Gross lesions included papular skin lesions on the entire body, ulcerative stomatitis and glossitis, and multifocal necrohemorragic pneumonia. Histologically, lesions showed characteristic vesicular dermatitis, ulcerative glossitis and stomatitis, and fibrinonecrotizing pneumonia, all with intranuclear inclusions and syncytia. Clinical signs for the other animals included bumps and blisters, with some individuals presenting cough and nasal discharge. All observed symptoms resolved within a week. Swabs of skin lesions from several individual were PCR positive for VZV. PCR and virus isolation on organs confirmed the human VZV infection in the dead individual. While case reports of varicella in great apes have previously been published, there rarely is a distinction between VZV and Simian Varicella Virus and, to our knowledge, this is the first fatal VZV infection in gorillas. The origin of the infection remains unknown.