By Julian Barker
This article first appeared in the September 2001 issue of the NGS Journal
Most people who keep gerbils never have a problem with serious illness. However there is a disease that most people know little about which is potentially fatal to your gerbils. Tyzzer’s disease is a serious condition that effects many rodent species and is caused by an organism called Clostridium piliforme. Rats, mice, gerbils and hamsters, and cavies are all susceptible to this potentially fatal illness. Mice and rats can often harbour the disease without any symptoms at all. Because of this it is common for wild mice to carry the disease.
There are various strains of C. pilforme and these are usually species specific. This means that disease in mice will not normally spread to rats etc. However, a major exception to this is gerbils who are susceptible to infection from a wide range of strains. Symptoms are most often observed in suckling or weanling animals, but animals of any age may be affected. Signs of acute disease include rough coat, weakness, lethargy, and death. Animals may also experience watery to pasty diarrhoea or faecal staining. Diarrhoea does not always appear. Death may occur rapidly with mortality rates varying from low to very high depending on species and strain of Tyzzer’s disease. However, in gerbils mortality of 80% or more of animals showing symptoms is common. Death usually occurs within 48 hours of symptoms appearing. Fatality rates for other species are generally lower.
The disease attacks the intestines and the colon. From there it spreads to the liver. The organism produces a toxin that causes widespread necrosis. This can cause failure of almost any organ of the body. Damage to the heart and neurological symptoms such as loss of co-ordination or paralysis are often seen.
C. pilforme produces spores which can live for up to two years in infected bedding. Spores spread though the faeces of the infected animals and infected animals can continue to produce spores in their faeces for up to two weeks if they survive the infection. Ingestion of spores probably occurs as animals clean themselves after coming into contact with contaminated bedding.
Seemingly healthy animals can apparently harbour the infection without symptoms which will develop into acute disease when the animal is subjected to stress, such as overcrowding, change in environmental conditions, or infection. In research facilities, spontaneous outbreaks of clinical Tyzzer’s disease are most commonly seen in gerbils, hamsters, guinea pigs and rabbits. Infections in rats and mice are least likely to show symptoms. A high protein diet has been shown to predispose animals to Tyzzer’s disease. Although there are no records of humans having any symptoms of a Tyzzer’s infection almost all species of mammals tested can become infected and serological tests of humans frequently show antibody counts that suggest that there has been an active infection that has gone unnoticed.
Antibiotic treatment of infected animals has yielded variable results. A number of studies have examined various antibiotics for treatment of Tyzzer’s disease. Although techniques and evaluation methods varied, tetracycline, oxytetracycline, and penicillin were the most effective antibiotics for alleviation of clinical signs due to C. piliforme infection.
Even when treated promptly death is common in gerbils. However, supporting the animal with heat and injected fluids may help give time for the antibiotics to have effect. Treatment of animals before they show symptoms has been effective in increasing survival. However, these antibiotics have not been shown to effectively eliminate this bacterium completely and their use should be restricted to individual or very valuable animals.
Many veterinary books and laboratory manuals do not recommend antibiotic therapy for elimination of Tyzzer’s disease from an infected colony and recommend that destruction of the colony is the only sure way of stopping the infection from spreading. It is not appropriate to simply treat or remove infected animals because spores will already be spread. Infected bedding etc should be destroyed. Anything that may have been in contact with spores needs to be sterilised. Spores are persistent and need to be kept at 80C for 30 minutes to kill them. Contaminated surfaces can be effectively disinfected by treatment with bleach for 5 minutes.
It is important to remember that whilst Tyzzer’s disease is a common cause of illness in rodents there are other conditions like Listeria, Salmonella and E. coli which can also cause serious illness and death. In many cases the symptoms of these can be similar and they should be dealt with in a similar way. These diseases have an important difference from Tyzzer’s disease. All of them are potentially very dangerous for humans and can be fatal to young, ill or elderly people. For this reason no illness of rodents should be treated in a cavalier way. If disease appears it is important to review husbandry practices, treat infected animals if appropriate and to ensure that all sources of illness are destroyed or sterilised.
If you are ever unsure of what you are dealing with veterinary advice should be sought immediately.