Veterinary Epidemiology and Zoonosis

CLOSTRIDIAL FOOD POISONING

Synonyms

• In humans: Clostridial gastroenteritis, Clostridial toxicosis
• In animals: Yellow lamb disease (Clostridium perfringens type A), Lamb dysentery (Clostridium perfringens type B), Struck (Clostridium perfringens type C), Over eating disease or Pulpy kidney disease (Clostridium perfringens type D)

Type of zoonosis

• Direct anthropozoonosis, Food-borne zoonosis

Definition

• It is an infectious disease, caused by Clostridium perfringens type A. It is clinically characterized by sudden onset, abdominal cramps and diarrhoea.

Etiology

• It is caused by Clostridium perfringens type A, an anaerobic, Gram positive, sporogenic, nonmotile, encapsulated bacillus that produces extracellular toxins.
• It is more resistant to heat when found in foods, but 60ºC is lethal to vegetative form.
• Sporulation occurs in the intestine at the optimum temperature between 35ºC and 40ºC.
• During sporulation in the intestine, it produces large quantities of enterotoxins.

Reservoirs and incidence

• Clostridium perfringens type A is ubiquitous in the soil and in the intestinal tract of animals and humans.
• Soil and intestine of man and animals are the natural reservoirs for clostridial food poisoning.
• Clostridium perfringens type A produces alpha toxin in the intestine and released during sporulation.
• Outbreaks mostly reported in several countries where meals prepared in restaurants or institutions.
• In animals, five types of toxigenic Clostridium identified and designated by the letters A, B, C, D and E.

Transmission

• Ingestion of foods of animal origin (especially red meat or fowl).
• The source of poisoning is food contaminated with spores that survive cooking.
• Cooking (heat shock) of contaminated foods favours germination of spores in to vegetative form, which then multiply rapidly to high concentration at room temperature. But, adequate cooking can destroy the spores.

Disease in animals

• Clostridium perfringens type A is part of the normal flora of the intestine. The pathogens under favourable conditions produce alpha toxin and cause a disease in nursing lambs, is described as “yellow lamb disease”. It is characterized by depression, anaemia, jaundice and haemoglobinuria, finally death in 6 to 12 hours after the onset of clinical symptoms.
• Clostridium perfringens type B causes “lamb dysentery” in lambs less than 2 weeks old. It is characterized by haemorrhagic enteritis.
• Clostridium perfringens type C causes “struck”, the haemorrhagic enteritis in adult sheep, as well as necrotic enteritis in calves, lambs, suckling pigs and fowl.
• Clostridium perfringens type D produces epsilon toxin, which causes enterotoxaemia (Over eating disease, Pulpy kidney disease) in sheep of all ages due to abundant consumption of food, whether milk, pasture or grains.
• Clostridium perfringens type E causes dysentery or enterotoxaemia in calves and lambs.

Disease in humans

• Incubation period ranges from 6 to 24 hours after ingestion, which indicates that the food ingested contained pre-formed toxin. Hence, the clinical signs begin suddenly with abdominal cramps and diarrhoea, but usually not vomiting or fever.
• Colonization of Clostridium perfringens type A in the intestine and the production of enterotoxin results in varied clinical pictures (diarrhoea or bloody stools), that mimicking infection caused by Salmonella or Campylobacter.
• It causes necrotic enteritis in the small intestine, especially jejunum.

Diagnosis

• Based on history and clinical signs.
• Clostridial food poisoning is afebrile, and should be differentiated from other enteric diseases, such as salmonellosis, shigellosis or colibacillosis, which manifest fever.
• Staphylococcal food poisoning causes vomiting, while it is rare or absent in clostridial food poisoning.
• Counting of C.perfringens in food and patient’s stool (within 48 hours of onset of infection). Presence of 10⁵ cells and 10⁶ cells respectively in food and faecal materials is considered significant.
• Mouse inoculation technique to demonstrate the presence of specific toxin.
• Reverse passive latex agglutination test and enzyme immunoassays to detect the toxin.

Treatment

• Clostridial food poisoning does not usually require medical treatment, but symptomatic treatment can be provided.

Prevention and control

• Cooked food should be immediately consumed, or if it takes sometime to eat, it should be rapidly refrigerated.
• Food should be reheated adequately enough to kill the vegetative form of the pathogen, preferably with pressure cooker.
• In animals, good herd management, avoidance of sudden change from poor to rich pasture and active immunization with toxoid should be followed.