ICD 10 Codes From A20-A28

Zoonotic bacterial diseases represent a significant category of infectious diseases transmitted from animals to humans. These conditions, classified under ICD-10-CM codes A20-A28, encompass various bacterial infections that pose serious health risks. Understanding these diseases is crucial for healthcare professionals, veterinarians, and individuals working in high-risk occupations.

Overview of Zoonotic Bacterial Diseases (A20-A28)

The following table provides a summary of the eight major zoonotic bacterial diseases covered in this classification:

Detailed Disease Profiles

1. Plague (A20)

Historical Significance: Plague has been one of the most devastating diseases in human history, with the “Black Death” of the 1300s killing approximately one-third of Europe’s population.

Disease Description: Plague is a gram-negative bacterial infection transmitted primarily through bites from infected rodent fleas. The disease persists in sylvatic rodent-flea ecosystems worldwide, though modern living conditions and antibiotics have made it uncommon today.

Clinical Forms:

Treatment: Strong antibiotics are effective. No vaccine is currently available.

2. Tularemia (A21)

Alternative Names: Deer-fly fever, Rabbit fever

Disease Description: Tularemia is a plague-like disease affecting rodents that can be transmitted to humans. It is caused by the gram-negative bacterium Francisella tularensis and is characterized by serious systemic symptoms.

Transmission Routes:

• Bites from infected insects (deer flies, Chrysops discalis)
• Inhalation of airborne bacteria
• Handling infected animals (rabbits are important reservoir hosts)
• Consuming contaminated food or water

Clinical Forms:

Common Symptoms: Prolonged fever, lymph node swelling, chills, headache, backache, weakness, skin ulcers, mouth sores, sore throat.

3. Anthrax (A22)

Disease Description: Anthrax is an acute infection caused by the spore-forming bacteria Bacillus anthracis, which lives in soil. While it commonly affects hoofed animals like sheep and goats, it can cause serious disease in humans. The 2001 bioterror attacks in the United States brought significant attention to this disease.

Important Note: Anthrax is not contagious between humans and can be treated with antibiotics if diagnosed early.

Clinical Forms:

Prevention: A vaccine is available for military personnel and others at high risk.

4. Brucellosis (A23)

Alternative Names: Malta fever, Mediterranean fever, Undulant fever

Disease Description: Brucellosis is a gram-negative bacterial infection caused by bacteria of the genus Brucella. It primarily involves the mononuclear phagocyte system and is characterized by recurring symptoms.

Transmission: Humans are infected by ingesting unpasteurized milk or meat from infected animals.

Clinical Forms by Species:

Common Symptoms: Fever, sweating, weakness, headache, malaise, muscle pain, arthritis, anemia, weight loss.

5. Glanders and Melioidosis (A24)

Disease Classification:

6. Rat-bite Fevers (A25)

Disease Description: Rat-bite fever is a syndrome that develops days to weeks after a rat bite, characterized by recurring symptoms.

Clinical Forms:

Characteristic Symptoms: Recurring fever, rash, arthralgias (joint pain).

7. Erysipeloid (A26)

Disease Description: Erysipeloid is an occupational disease caused by Erysipelothrix rhusiopathiae, almost exclusively affecting individuals who handle infected fish, shellfish, poultry, or meat in their work.

Clinical Forms:

At-Risk Occupations: Fish handlers, shellfish workers, poultry workers, meat processors.

8. Leptospirosis (A27)

Disease Description: Leptospirosis is a contagious bacterial infection caused by spirochetes of the genus Leptospira. It is transmitted through contact with water and soil contaminated with animal waste products.

Clinical Progression:

1. Initial Phase: Flu-like symptoms
2. Second Phase: May develop meningitis, liver failure, and renal failure

Clinical Forms:

Common Symptoms: Initial flu-like phase followed by potential complications including meningitis, liver failure, and kidney failure.

Risk Factors and Prevention

Occupational Risk Groups

General Prevention Strategies

1. Avoid Contact: Minimize exposure to potential animal vectors
2. Protective Equipment: Use appropriate PPE when handling animals or animal products
3. Food Safety: Consume only pasteurized dairy products and properly cooked meat
4. Hygiene: Practice thorough handwashing after animal contact
5. Vaccination: Utilize available vaccines (e.g., anthrax for high-risk individuals)
6. Environmental Control: Implement rodent control measures
7. Water Safety: Avoid contaminated water sources

Conclusion

Zoonotic bacterial diseases remain a significant public health concern despite advances in modern medicine. Early recognition and prompt treatment are essential for favorable outcomes. 

Healthcare providers should maintain a high index of suspicion for these diseases, particularly in patients with relevant occupational exposures or animal contact history. 

While many of these diseases are rare in developed countries due to improved sanitation and veterinary care, they continue to pose risks in endemic areas and certain occupational settings.

Understanding the transmission routes, clinical presentations, and appropriate diagnostic codes is essential for proper disease management and public health surveillance. Continued education, appropriate preventive measures, and early intervention remain the cornerstones of controlling these ancient yet persistent threats to human health.

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