Background: What is Nido: The order Nidovirales is a large group of diverse enveloped positive-strand RNA viruses (1). Nidoviruses are known to infect a range of vertebrate and invertebrate hosts, several of which have caused serious diseases in both humans and animals. In humans, prominent nidoviruses belong to the family Coronaviridae and infections can result in a wide range of presentations from asymptomatic infections to significant morbidity and mortality associated with severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome (MERS-CoV) (2, 3). This family also includes the virus responsible for the current COVID-19 global pandemic, severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) (1).

Signs of infection: Infection of the respiratory tract appear to be the most common feature of nidovirus infection. Initial clinical signs in captive pythons include increased amounts of clear or mucoid material in the nose and mouth and oral inflammation (stomatitis). This proceeds to wheezing, open mouth breathing, increased respiratory rate, or coughing. Additional clinical signs include inappetence, weight loss, lethargy, dehydration, inappropriate skin shedding, difficulty perching in arboreal snakes, and speculitis.

There is evidence that reptiles can be asymptomatic when infected with nidoviruses.There is also some evidence that animals may remain infected and asymptomatic for prolonged periods. Five pythons (Morelia spp.) that were nidovirus PCR positive for over 2 years with serial testing at ~4 month intervals remained asymptomatic for the duration (2)

How is it spread? The natural route(s) of transmission of nidoviruses in reptiles remains unclear. Multiple transmission routes are possible, including faecal-oral, fomite, and aerosolization. This is supported by detection of virus in respiratory epithelium, tissues of the gastrointestinal tract and on various antemortem swabs. “Vertical” transmission is also possible (1).

How to test for Nido:

PCR swabs of the oral cavity can be done at home and sent to RAL. These must be sent overnight priority post.