3. ANTHRAX, TETANUS, BOTULISM AND OTHER ANAEROBIC INFECTIONS

contagious

What bacterium causes anthrax?

Bacillus anthracis

How is anthrax transmitted?

Ingestion (most common in animals), inhalation, cutaneous (wound, ++ in Hu) SPORES

What environmental factors are associated with anthrax outbreaks?

Drought/Druness, flooding, soil disturbance (Through excavation, construction, grazing) & Soil characteristics (Alkaline pH, high calcium, and organic content favor spore persistence)

—> dormant spores are reactivated

What is the morbidity and mortality rate of anthrax?

Low morbidity, high mortality

Why do anthrax outbreaks sometimes occur long after initial contamination?

Resistant spores can remain in soil for years

Which cells do anthrax spores infect first?

Macrophages (Inside, spores germinate into vegetative bacilli)

What happens after anthrax spores germinate?

They multiply and release toxins causing local edema and necrosis

What are the systemic effects of anthrax infection?

Bacteremia, toxemia, tissue destruction, organ failure (due to hypoxia, hypotension, and direct cytotoxicity)

What happens when vegetative bacilli in a cadaver come into contact with oxygen?

Sporulation (Bacillus anthracis forms endospores)

What is the incubation period for anthrax?

1-14 days

What is the agent for Botulism

clostridium botulism

What are the clinical signs of botulism?

botulinum neurotoxin (BoNT) from Clostridium botulinum, which blocks acetylcholine release at neuromuscular junctions → flaccid paralysis

Mydriasis, delayed PLR, reduced tone in lips/tongue/throat, salivation, slow chewing, dysphagia, anxiety, muscle weakness, respiratory failure, asphyxia

Death typically results from respiratory muscle failure

How is botulism transmitted?

Alimentary ingestion of spores, inhalation, iatrogenic exposure

What food condition promotes Clostridium botulinum multiplication?

Low acidity

What is the primary pathogenic mechanism of botulism?

Neurotoxins bind to ACh receptors, inhibit acetylcholine release, block nerve impulses, cause paralysis and asphyxia

What is the treatment for botulism?

Antitoxin in early stages, supportive care

How can botulism be prevented?

Vaccination and improved forage quality

At what temperature and duration can botulinum neurotoxins be inactivated?

100°C for 15 minutes

What causes tetanus?

Clostridium tetani

Which species are most sensitive to tetanus?

Horses and lambs

How is tetanus transmitted?

Open wound inoculation, e.g., castration, difficult delivery

What are the primary toxins of tetanus?

Tetanospasmin and tetanolysin

What is the pathogenic effect of tetanus toxins?

Inhibit breakdown of acetylcholine, causing permanent neuromuscular excitation

What are the clinical signs of tetanus?

Tetanic spasms, possible fractures, third eyelid protrusion in horses, dyspnea, hyperthermia, septicemia

How is tetanus diagnosed?

Anamnesis, clinical signs, culture and Gram staining, toxin assay

How is tetanus treated?

Antitoxin in early stages, wound care with peroxide disinfectant, penicillin, supportive care

What causes necrobacillosis?

Mixed infection with Fusobacterium necrophorum and F. nucleatum

Where are Fusobacterium species commonly found?

Commensal in the gastrointestinal and urogenital flora of humans and animals

What is the primary pathogenic characteristic of necrobacillosis?

Necrotic disease associated with poor hygiene

What are the sources of necrobacillosis transmission?

Asymptomatic carrier animals

What are the clinical signs of calf diphtheria in cattle?

Oral form: foul-smelling ulcers, tongue/palate/cheek/pharynx swelling, pneumonia, anorexia, high temperature

What are the clinical signs of laryngeal necrobacillosis in cattle?

Moist painful cough, dysphagia, dyspnea, pneumonia, anorexia, high temperature

What are other forms of necrobacillosis in cattle?

Bovine hepatic necrobacillosis, footrot, post-abortion necrobacillosis, umbilical cord necrobacillosis

What are the clinical forms of necrobacillosis in sheep?

Lamb diphtheria, footrot, omphalophlebitis

What are the clinical forms of necrobacillosis in pigs?

Dysentery, necrobacillosis of the snout/head skin, necrobacillosis of the mammary gland, footrot

How is necrobacillosis diagnosed?

Ante-mortem: clinical signs, culture; Post-mortem: biopsy

What is the treatment for necrobacillosis?

Systemic antibiotics: penicillin, chloramphenicol, tetracycline, sulfonamides, metronidazole

What specific treatments are used for footrot?

5% formalin or 10-20% zinc sulfate baths

How is necrobacillosis prevented?

Isolation of affected animals, improved husbandry conditions

What bacteria cause footrot in sheep and cattle?

Bacteroides nodosus, Bacteroides melaninogenicus

Which animals are most affected by footrot?

Adult sheep and cattle

What environmental factor increases footrot occurrence?

Wet season

How is footrot transmitted?

Direct contact or via contaminated objects

What is the pathogenesis of footrot?

Interdigital tissue inflammation leads to necrosis and joint invasion, causing septic arthritis

What is the first clinical sign of footrot?

Progressive lameness

What additional clinical signs accompany footrot?

Swelling, suppurative necrosis of the foot, strong rotting odor

How is footrot diagnosed?

Clinical examination based on lesions and odor, scoring system from 0 (healthy) to 5 (necrotizing inflammation of deeper tissues)

What is the treatment for footrot?

Footbathing with 10% zinc sulfate for 15-30 minutes, antibiotics (long-lasting tetracycline), relocation to a clean, hard surface

How can footrot be prevented?

Quarantine, clinical examination of new animals, restriction of contact with unknown herds, regular foot trimming (twice per year), vaccination

What bacteria cause clostridial diseases?

Clostridium perfringens

What type of bacterium is Clostridium perfringens?

Gram-positive, commensal, spore-forming

How do clostridial diseases progress?

Production of enterotoxins types A-E

What is a common unfavorable clostridial condition in poultry?

Enterotoxemia

What are the types of clostridial infections in pigs?

Enteritis caused by Clostridium perfringens type A and C

Which age group of pigs is most affected by clostridial infections?

Young pigs, 2-3 weeks old

What are the pathological findings of clostridial enteritis in pigs?

Inflammation, ulceration of the jejunum, kidney damage

What are the treatments for clostridial enteritis in pigs?

Vaccination

What is Clostridia-associated enterocolitis in horses?

A condition caused by Clostridium perfringens and Clostridium difficile

What triggers Clostridia-associated enterocolitis in horses?

Stress

What are the clinical signs of Clostridia-associated enterocolitis in horses?

Diarrhea (sometimes bloody), colic, fever, lethargy, sudden death

What is the treatment for Clostridia-associated enterocolitis in horses?

Antibiotics (metronidazole), supportive care

What animal is most affected by infectious enterotoxemia caused by Clostridium perfringens type D?

Goats

What dietary factor predisposes goats to enterotoxemia?

High-protein, low-fiber food