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Germs that infect humans

Clostridium tetani

Clostridium tetani

© Dennis Kunkel Microscopy, Inc.

Microorganism: the bacterium Clostridium tetani

Disease: tetanus

Occurrence of the disease

Current situation: a hundred cases of tetanus are reported each year in the United States. The majority of reported cases occur among intravenous drug users. In Canada there were two cases of tetanus reported in Ontario in 1998.

Prevention: control measures are difficult to implement as the bacteria are widely present in soil.

Mechanism of action of the microorganism: when the bacteria die they produce a toxic substance (neurotoxin) which damages the cells of the nervous system of the infected individual.

Symptoms of the disease: cramps and muscle contractions around a wound and stiffness in the jaw muscles are the first symptoms. At a more advanced stage the disease causes contractions of the facial muscles, which develops into an inability to open the mouth. The later symptoms include contraction of the muscles from the heel to the back resulting in a curvature of the body. Death may result from involuntary contractions of the respiratory muscles.

Incubation period: normally three to 21 days but may start in as little as one day and last for several months.

Contagious period: this disease is not transmissible from one human to another.

Hosts: the intestine of several animal species.

Transmission: the bacteria may only enter an organism by means of open wounds. The death rate varies between 30% and 90%.

Discoverer of the microorganism: Nicolaier (1885)

Treatment: treatment for this disease is not particularly effective, which is why vaccination against tetanus is so important. If you are injured and you feel a stiffness in the muscles surrounding the wound, it is important to disinfect the area immediately, obtain a booster shot of the vaccine, and begin a course of penicillin. Immediate treatment is crucial.

Geographical distribution of the microorganism: this bacterium can be found in hospitals, in the soil, in dust, and in the excrement of humans and farm animals.

Prevention: The tetanus vaccine is combined with other vaccines. The T of DPT represents the vaccine against tetanus. Several injections and booster shots are required because the immune system forgets the information obtained from previous inoculations (DPT-Polio-Hib at 2, 4, 6 and 18 months, vaccine DPT-Polio at 4 and 6 years and d2T5 at 14 to 16 years and at 10-year intervals for adults).

Vaccine: the vaccine consists of the inactivated toxin produced by the bacterium. Following the injection of the six recommended doses, the tetanus vaccine is approximately 90% effective.

Side effects of the vaccine: in 60% of cases the child feels a little discomfort or pain at the site of the injection and in 50% of cases fever may appear within 48 hours of the injection.