Occurrence of Clostridium tetani in soil and horses.

The research investigates the occurrence of Clostridium tetani, a bacteria causing tetanus, in soil and horses in different parts of the world with a specific focus on the Durban area. The study also explores whether horses can be permanent carriers of the bacteria.

Levels of Soil Contamination

• The study compared the contamination levels of Clostridium tetani in soils from distinct regions. An overall lower contamination rate was observed in the Durban area than in other regions globally.
• For instance, 28% contamination was observed in Durban compared to 31-42% for locales in Japan and Quebec. This suggests that the prevalence of the bacteria in the soil varies across different regions.
• There were specific sites where the contamination was notably higher, such as a rugby field in the Transvaal, which showed 40% contamination, and a pasture that had been used for horses for over 20 years, which displayed 65% contamination.

Tetanus Incidence and Carriage in Horses

• Despite these high contamination rates in some areas, no cases of human or equine tetanus were reported from the infected sites. This suggests that a high soil contamination rate does not necessarily lead to an increased incidence of tetanus.
• The research also inspected the excretion of the bacteria by horses to evaluate if they might be long-term carriers of Clostridium tetani.
• However, the bacteria were found to only be excreted for a short period of 3-4 days, indicating that horses cannot be permanent carriers of the bacteria.
• In a particular observation, only 2 out of 27 horses in a stable were found to be excreting the bacteria at any one time, further supporting this conclusion.

Testing of Faecal Samples

• The research also involved testing 118 faecal samples over a span of four months. ; Only seven of these samples tested positive for Clostridium tetani, representing a 5-9% positivity rate.

In summary, this study reveals that while Clostridium tetani can be found in soil and horses, high soil contamination rates do not necessarily correspond to higher occurrences of tetanus, and horses do not seem to be permanent carriers of the bacteria.