bubble_chart Overview

Anthrax is an acute pestilential disease that occurs in both humans and livestock, and can be divided into three types: cutaneous anthrax, pulmonary anthrax, and intestinal anthrax.

bubble_chart Etiology

The pathogen is the anthrax bacillus (Bacillus anthracis). It is a Gram-positive, encapsulated, non-flagellated, large bacillus. On artificial culture media, it forms long chains resembling bamboo joints and easily forms spores. It can survive for over 20 years in dry, room-temperature environments and several years in leather. Boiling for 10 minutes or dry heat at 140°C for 3 hours may destroy the spores; a 1:2500 iodine solution can kill the spores in 10 minutes.

This disease is commonly seen in pastoral areas and is prevalent among livestock such as cattle, horses, and pigs. These animals develop intestinal anthrax by ingesting feed contaminated with the bacillus or spores, and cutaneous anthrax through contact of the face, nose, or mouth with contaminated soil or feed. Humans may develop cutaneous anthrax through contact with infected or dead animals, or with contaminated skin and hair, soil, or leather products via broken skin. Inhalation of dust containing spores may lead to pulmonary anthrax, while ingestion of meat from infected or dead animals, contaminated water, or milk from infected animals may cause intestinal anthrax. Direct transmission of the disease between humans is possible.

bubble_chart Pathological Changes

The skin lesion shows an epidermal defect, with edema and intraepidermal blisters around the necrotic tissue. The dermal edema is pronounced, and collagen fiber bundles are separated. There are abundant red blood cells, neutrophils, dilated blood vessels in the dermis and subcutaneous tissue. Numerous anthrax bacilli are visible within the necrotic tissue and dermis.

The lungs may exhibit congestion and hemorrhage, with many anthrax bacilli present in the sputum. The intestinal wall may show edema and necrosis. The spleen is often enlarged, and anthrax meningitis frequently presents hemorrhagic and septic changes.

bubble_chart Clinical Manifestations

The incubation period ranges from several hours to 2 days. Due to different routes of infection, anthrax is clinically classified into three types:

1. Cutaneous anthrax: Usually occurs on exposed areas such as the face, neck, hands, or shoulders. Initially, a small red papule appears at the site of bacterial invasion, which quickly develops into a blister containing clear or bloody serous fluid. The surrounding tissue shows significant swelling and infiltration. Soon, the blister suppurates and ruptures naturally, discharging serous fluid or pus. The center of the lesion undergoes necrosis and forms a hard, black eschar. The skin around the eschar becomes red and swollen, with small blisters and pustules. Lymph nodes near the affected area often swell and may suppurate. Patients commonly experience symptoms such as headache, arthralgia, fever, and general malaise. Most patients have mild symptoms, and after the necrotic skin tissue falls off, an ulcer forms, eventually healing with scarring.

In a few severe cases, local redness and swelling are pronounced, with large blisters and severe necrosis. Patients often exhibit persistent high fever, nausea, vomiting, and systemic pain due to toxemia. Within days or weeks, metastatic lesions may occur in internal organs such as the lungs, intestines, liver, spleen, and brain, leading to rapid death.

2. Intestinal anthrax: Relatively rare. Patients suddenly develop high fever, followed by severe gastrointestinal symptoms such as vomiting and diarrhea. In some cases, hepatosplenomegaly or peritonitis may occur. Patients may die within a short period due to toxemia, septicemia, and exhaustion.

3. Pulmonary anthrax: Has an even higher mortality rate. The onset is abrupt, with toxic symptoms such as chills and high fever. Cough, chest pain, difficulty breathing, and expectoration of blood may occur. Death due to respiratory and circulatory failure can happen within 24 hours. In very rare cases, anthrax meningitis may develop.

bubble_chart Diagnosis

Based on the central necrotic black eschar and the surrounding significant redness and swelling, combined with the patient's occupation and exposure history, diagnosis is generally not difficult. Confirmation can be made by detecting anthrax bacilli from the lesion.

bubble_chart Treatment Measures

Sick animals should be strictly isolated or slaughtered. Dead animals must not be skinned or cooked and must be burned or buried deeply. Livestock should be vaccinated against anthrax, and potentially contaminated leather or other animal products must be thoroughly disinfected. When handling dead animals with the virus or caring for patients, personal protective measures such as wearing isolation gowns should be taken, and isolation must be observed. Patients' excreta and used dressings should be incinerated.

Veterinarians, breeders, and leather workers in epidemic areas should receive preventive anthrax vaccinations.

Patients should rest in bed and be isolated, with attention paid to drinking plenty of fluids. The affected area should not be squeezed, nor should incisions be made for drainage or skin lesions excised, to prevent the spread of the virus and the onset of sepsis.

Penicillin is the most effective antibiotic. Sulfonamides are also often effective. For cutaneous anthrax, the total daily dose of penicillin should be 1–2 million units. Tetracycline, streptomycin, chloramphenicol, or neomycin can be added concurrently. For pulmonary anthrax and intestinal anthrax, the total daily dose of penicillin should exceed 6 million units; for anthrax meningitis and sepsis, the total daily dose of penicillin should exceed 10 million units.

For cutaneous anthrax, sulfonamide ointment or ammoniated mercury ointment can be applied topically. A 1:8000 potassium permanganate dilute solution can be used for wet compresses. Lesions on the face that destroy underlying tissues and affect appearance may require plastic surgery.