What are Iridoviruses?
There are several types of Iridoviruses such as the Chloriridovirus, Ranavirus, Lymphocystivirus, and Megalocytivirus. The Lymphocystivirus, Megalocytivirus, and Chloriridovirus only affect fish or insects, but the Iridovirus and Ranavirus are often found in snakes as well. These viruses are often lethal and are known to cause die-offs of certain species of reptiles, fish, and amphibians. The damage and destruction done to the kidney, liver, spleen, lungs, esophagus, and stomach is irreversible and lethal. The Iridoviruses belong to a group of DNA viruses called Nucleo-Cytoplasmic Large DNA viruses (NCLDV), that can affect many different types of hosts from insects to mammals.
Iridoviruses (erythrocyte viruses) in snakes are DNA viruses that are capable of destroying the tissues of the heart, spleen, liver, and kidneys, and can also damage the red blood cells which causes severe anemia. Iridoviruses can be enveloped or nonenveloped viruses. Nonenveloped viruses (Ranaviruses) are more potent and contagious, and damage the cells of the host while being more resistant to drying, acids, and heat. These types of viruses are also easier to spread through dust, saliva, and objects such as doorknobs and furniture. Enveloped viruses are less contagious, easier to kill, and can only be spread through blood.
Symptoms of Iridoviruses in Snakes
The symptoms of Iridoviruses depends on the type your snake has. However, all of these viruses can be lethal so you should be sure to take your snake to see a veterinarian as soon as you can if you notice any of these symptoms:
- Ulcers in the mouth
- Refusal to eat
- Inflammation of the tongue
- Sore and inflamed mouth
- Ulcers of the skin anywhere on the body
- Nasal irritation
- Conjunctivitis (red eyes)
- Tracheitis (infection of the trachea with possible airway blockage)
- Respiratory distress
- Swelling anywhere on the body
Although there are many types of Iridoviruses, only Ranaviruses and the original Iridoviruses are able to infect snakes.
- Chloriridovirus mainly affects insects
- Lymphocystivirus is a deadly virus that affects fish
- Megalocytivirus is also a virus that affects fish
- Ranavirus is an extremely infectious and fatal virus that causes tissue swelling, internal hemorrhaging, and behavioral changes
Causes of Iridoviruses in Snakes
The cause of Iridoviruses is due to a cytoplasmic DNA morphology. In some cases, the cause is thought to be a hereditary DNA defect, but this is not verified. The majority of cases seem to be transferred by direct contact. However, the cause of other types of Iridoviruses may be from ingesting prey that are infected by the virus.
Diagnosis of Iridoviruses in Snakes
If you believe your snake has a virus, you should find a veterinarian that specializes in reptile care, and one with experience handling snakes is even better. Although any veterinarian should be able to handle your snake, a specialist will have the expertise to know exactly what is going on with your pet. Tell the veterinarian as much as you can about your snake’s history and the symptoms you have seen that brought you there. A physical examination with a snake is similar to any other veterinary examination, but the veterinarian will need to be prepared to handle your snake as little as possible to prevent too much stress. The best way to do this is for the veterinarian to start at the head and work down to the tail, examining your snake’s eyes, ears, mouth, etc. looking for abnormalities or lesions. Each vital organ (heart, spleen, pancreas, stomach, gallbladder, lungs) will be palpated and auscultated and any lesions found will be swabbed for testing.
While a presumptive diagnosis can be made from finding inflamed fibroblasts that can reach up to 1 millimeter, the virus has to be confirmed by microscopic examination. The Iridovirus should be able to be isolated in a cell culture or found in a sensitive polymerase chain reaction (PCR) test. Oral and cloacal swabs and liver samples are sometimes necessary for a definitive diagnosis.
Treatment of Iridoviruses in Snakes
Some forms of Iridoviruses are fatal within a short period of time and there is no treatment that can stop the progression once it gets to a certain point. In those cases, the veterinarian will likely suggest euthanization to prevent suffering. Other types of these viruses move slowly and are not fatal, the symptoms barely noticeable. In fact, many snakes and other reptiles test positive for the virus but do not have any signs of illness at all. The only treatment that has been tried successfully are antivirals such as Acyclovir (Zovirax 5%).
Recovery of Iridoviruses in Snakes
These viruses have a high mortality rate in those snakes that show symptoms. However, if treatment is begun right away and continued as directed, there is a fair chance for your pet to recover.