A79.82 Anaplasmosis [A. phagocytophilum]

Name of the Condition

• Anaplasmosis [A. phagocytophilum]

Summary

Anaplasmosis is an infectious disease caused by the bacterium Anaplasma phagocytophilum. It is transmitted through the bite of infected ticks, primarily the black-legged tick (Ixodes scapularis) in the United States. The condition is characterized by systemic symptoms, including fever, headache, and muscle aches, and can range from mild to severe. Early diagnosis and treatment are important to prevent complications.

Causes

Anaplasmosis is caused by Anaplasma phagocytophilum, a bacterium transmitted to humans via the bite of infected ticks. The bacteria infect white blood cells, leading to symptoms. Transmission occurs when an infected tick attaches and feeds on a human host.

Risk Factors

• Exposure to environments with high tick populations (e.g., wooded or grassy areas)
• Outdoor activities without protective measures (e.g., insect repellent, long sleeves/pants)
• Occupations involving outdoor work or animal handling
• Travel to regions endemic for tick-borne diseases

Symptoms

• Fever
• Headache
• Muscle aches
• Fatigue
• Chills
• Gastrointestinal symptoms (e.g., nausea, vomiting)
• Rash (less common)

Diagnosis

Diagnosis is based on clinical evaluation, patient history (including potential tick exposure), and laboratory tests. Blood tests may detect antibodies or the presence of the bacterium. Polymerase chain reaction (PCR) testing can confirm the infection.

Treatment Options

Treatment typically involves antibiotics, such as doxycycline, which is effective if started early. The duration of treatment depends on the severity of the infection and patient response. Supportive care, including rest and hydration, may also be recommended.

Prognosis and Follow-Up

With prompt treatment, most patients recover fully. Delayed treatment can increase the risk of severe illness. Follow-up may involve monitoring for complications, especially in patients with weakened immune systems or other health conditions.

Complications

• Severe illness in untreated or immunocompromised individuals
• Neurological symptoms (e.g., confusion, seizures)
• Respiratory distress
• Organ failure (rare)

Lifestyle & Prevention

• Use insect repellent containing DEET or permethrin
• Wear protective clothing (e.g., long sleeves, pants) in tick-prone areas
• Perform tick checks after outdoor activities
• Remove ticks promptly using fine-tipped tweezers
• Avoid tick-infested areas when possible

When to Seek Professional Help

Seek medical attention if you experience flu-like symptoms after potential tick exposure, especially if symptoms worsen or persist. Early evaluation is critical for effective treatment.

Tips for Medical Coders

Document the specific causative agent (Anaplasma phagocytophilum) and any associated tick exposure when coding. Ensure clinical documentation supports the diagnosis, including symptoms, test results, and treatment. Verify that the code aligns with the patient’s confirmed infection and avoid using this code for unspecified or unrelated conditions.