17 Jul The Dreaded Twins….Ophidian Paramyxovirus and Inclusion Body Disease
Article by: Dr Egbert Compion
The Dreaded Twins….Ophidian Paramyxovirus and Inclusion Body Disease
These two are the real deal, the worst of the worst. They are the bad twins you never want to meet in a dark alley. They are not actually related at all, but they are so nasty and sneaky, so devastating and cunning that you would be forgiven for classing them as family. Call them Blood Brothers, at least… Their existence alone is the sole reason to implement strict quarantine protocols and practices when introducing new additions to your prized collection. If you don’t, be prepared to suffer the consequences as severe losses may follow.
Who are these guys?
Inclusion Body Disease
Inclusion Body Disease is caused by a virus resembling and currently classed with the Retroviridae. This group includes more familiar cousins such as the Feline Immunodeficiency Virus (FIV), commonly found in domestic and wild cats and Human Immunodeficiency Virus (HIV), all too familiar in the South African context. Very little is known about this virus. It typically affects species of the Boidae family. It is thought to be spread by the common snake mite (Ophionyssus natricis) and there seems to be definite link to Boa constrictors.
The disease gets its name from eosinophylic (red staining) intracytoplasmic inclusions typically found on microscopy of most tissue types, but especially on examination of brain, kidney and pancreas samples. Samples of the brain typically display a severe inflammatory process involving brain tissue and the membranes surrounding the brain alike and it is this process that will lead to the most severe of symptoms.
Boas will typically show repeated regurgitation as a first symptom followed by light to severe head tremors (often oddly horizontal in nature). Pythons very rarely show regurgitation, but, instead, develop severe central nervous system disease, typified by head tremors, seizures, ataxia (balance and righting reflex dysfunction) as well as ‘stargazing’ (staring upwards, head tilted backwards). The entire disease process can span over several months. Secondary disease such as stomatitis and respiratory infections is fairly common due to the overall debilitated nature and reduced resistance of the patient. Interestingly, lymphosarcoma and other malignant tumors have been found in nonboid snake species. This is a pattern frequently encountered in domestic cats affected by Feline Immunodeficiency Virus.
Diagnosis is typically near impossible in live specimens and only really successful in Boas where the intracytoplasmic inclusions can be seen in liver biopsy samples. In all python and the majority of boa cases, diagnostic work is completed on post mortem findings and microscopy.
Treatment is limited to supportive care and, in reality, suspected or confirmed cases should be isolated from the rest of your collection and humanely euthanized with immediate effect.
Our second customer is a real slippery imposter! This disease affects mostly New World pit vipers, but just about all snake families have been affected in the past. What makes this virus particularly nasty is its changeability. Any weak and debilitated snake should be considered a potential sufferer. It is thought to spread though body fluids and secretions and therefore very easily transferred through the use of contaminated hooks, tongs and cage decorations. Aerosol transmission has been postulated
Infected animals are affected in many ways and roughly grouped as acutely ill, chronically ill and asymptomatic. Acutely ill patients typically display severe respiratory disease followed by head tremors and ‘stargazing’ (very similar to Inclusion Body Disease). Many are found to have passed away acutely without any previous signs of illness. Chronically ill patients are typically run down, emaciated and suffer a multitude of opportunistic chronic complaints. Many struggle if intestinal infections or chronic respiratory disease. The real threat lies with asymptomatic carriers. These individuals shed the virus intermittently, contaminating the environment around them. Inevitably they will too become chronically ill, but not before taking entire collections with them.
Live animals can be screened using a hemagglutination inhibition (HI) test. Positive titres confirm exposure only and the demonstration of a rising titre is necessary to positively expose infected animals. Post mortem findings will include obvious changes in the liver and upper airways, but particularly at a lung tissue level.
Treatment is limited to supportive and care and broad spectrum antibacterial and antiprotozoal cover and restricted to chronic poor performers only. There have been reports of individuals surviving and clearing the infection altogether, but this should be considered a rare occurrence. Again, suspect cases should be isolated from the collection and euthanized once a rising titre has been confirmed.
Despite all the research and trials on vaccines against Ophidian Paramyxovirus and the odd successes in treatment, prevention is still of key importance here. The necessity of proper quarantine facilities and protocols cannot be stressed enough. These diseases are present in South African collections and I personally saw a Boa with Inclusion Body disease not more than a few months ago. Ignorance will wipe out entire collections and, with the love and attention, not to mention financial contribution put into some ventures, these two diseases will always pose a serious threat. Quarantine periods of up to ninety days have been suggested. In contact animals, infected or not, should be isolated for three to five months and monitored for disease. There is a significantly higher incidence of these diseases in poorly kept animals. Therefore, only buy from reputable breeders and distributors and do your homework regarding the environmental needs of the species in question. Lastly, be honest and open about confirmed cases. Reptile forums and groups provide a platform for all of us to cooperate and potentially even eradicate some of the problems we may encounter.
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