Evidence of an infection can also be provided cytologically and histologically.
Inclusion body disease of boid snakes (IBD) is caused by arenaviruses and particularly affects boas and pythons. Clinical signs comprise tremor, opisthotonus and loss of the reflex to turn. In young animals, it is often an acute infection with a mortality rate of nearly 100%. In adult animals, the course of the disease is usually chronic and protracted. Early signs are a slight tremor of the head, apathy and less flickering of the tongue.
Progression of the disease is often faster in pythons than in boas. Many times, regurgitation is the first clinical sign in boas. In pythons, the typical course of the disease is stomatitis accompanied by progressive pneumonia, which, showing signs of CNS disease, leads to death. Over the past years, an increase of the disease has been observed in boas, whereas it does not occur as often in pythons anymore. To date, little is known about the transmission in reptiles. Transmission through close contact as well as through mites is being discussed. In some cases at least, a vertical transmission from infected parents to young animals seems to occur.
Diagnosis is either made through the detection of the characteristic intracytoplasmic inclusions in the tissues of affected animals or through the detection of reptarenaviruses using PCR. In both cases, detection is easier in boas; in pythons, inclusions as well as the virus are often only found in the brain. Particularly in boas, inclusions can be detected histologically, most notably in the pancreas, liver, kidneys, oesophageal tonsils and the brain. The same organs are suitable for PCR virus testing. In live animals, inclusions and viral RNA can be detected through blood smears or whole blood as well as through biopsies of the liver, kidney or the oesophageal tonsils. Oesophageal swabs are also very useful for virus testing. Especially in boas, oesophageal swabs are very useful for PCR virus detection.