Bug of the Month: Clostridium piliforme
Tyzzer's disease is a rare but devastating disease caused by the bacterium Clostridium piliforme. This bacterium causes severe liver disease and sudden illness in young, otherwise healthy foals between the ages of 1 and 6 weeks. Usually on any particular farm only one foal is affected at a time, but small outbreaks can occur.
There is still a great deal we don't know about C. piliforme and Tyzzer's disease. It is presumed that foals become infected by ingesting the bacterium from the manure of other horses or from the environment. No one knows how often foals are exposed to the bacterium in this way - it may happen to a lot of foals, but only a few of them get sick, or it may happen very uncommonly, but make most of the exposed foals sick. Tyzzer's disease occurs very suddenly and progresses incredibly fast. Affected foals are often simply found dead, even though they looked completely normal only hours earlier. If they are found alive, foals may be slightly to extremely weak and lethargic, and they may have a fever, diarrhea, and increased heart and respiratory rates. The gums and whites of the eyes may be yellowish (i.e. jaundice), which is sign of liver failure. Even if foals with Tyzzer's disease are found alive, their condition usually worsens very quickly and they often start having seizures before they die.
A diagnosis of Tyzzer's disease is usually made by post mortem (necropsy) examination. Clostridum piliforme cannot be grown on regular culture plates in the lab like most of the disease-causing bacteria with which we deal (this also makes it very difficult to study). Special stains of liver tissue (silver stain) can help identify C. piliforme under the microscope. Real-time PCR, a molecular method that detects the DNA of C. piliforme, is also available.
Unfortunately, most foals with Tyzzer's disease die before, or shortly after, they are found to be ill. In most cases there is hardly enough time to even start treatment because the disease is so severe and progresses so rapidly. There are only three foals ever reported to have survived Tyzzer's disease, or what was strongly suspected to be Tyzzer's disease. Very aggressive therapy (i.e. in a referral hospital) is needed immediately to try to save affected foals, but the prognosis is very grave.
There are no known measures that can be taken to help prevent Tyzzer's disease in foals. Fortunately, the condition is rare, and there is no evidence that it is transmissible to humans.
