What is the recommended treatment for a patient potentially exposed to Herpes B virus, particularly one who works with primates?

Herpes B Virus Post-Exposure Management

For any person exposed to macaque monkeys through bites, scratches, or mucosal contact, immediately initiate antiviral prophylaxis with valacyclovir or acyclovir within hours of exposure, as untreated Herpes B virus infection carries a 70% mortality rate from fatal encephalomyelitis. 1

Immediate First Aid (Within Minutes)

• Wash the wound aggressively with soap and water for 15 minutes, scrubbing vigorously to mechanically remove viral particles 2
• Flush mucous membranes with water or saline if there was splash exposure to eyes, nose, or mouth 2
• Do not squeeze the wound or apply caustic agents like bleach 3

Risk Assessment

All exposures to macaque monkeys should be considered high-risk regardless of whether the animal appears healthy, as Herpes B virus is endemic in macaque populations and causes asymptomatic infection in the natural host while being highly lethal in humans 1, 4

• Transmission occurs through bites, scratches, needle sticks with monkey tissue/cells, or mucosal splash exposure to monkey saliva, blood, or tissue fluids 2, 4
• The virus causes mild localized lesions in macaques but progresses to fatal encephalomyelitis in 70% of untreated humans 1
• Even capuchin monkeys housed near macaques can become asymptomatic carriers and transmit the virus 5

Antiviral Prophylaxis (Within Hours)

Start prophylactic antiviral therapy immediately—do not wait for symptom development or test results 2, 6

Preferred Regimen

• Valacyclovir 1 gram orally three times daily for 14 days (preferred due to better bioavailability) 2
• Alternative: Acyclovir 800 mg orally five times daily for 14 days 2, 6

Critical Timing

• Prophylaxis must begin within hours of exposure for maximum effectiveness 2
• The window for preventing fatal encephalomyelitis closes rapidly after exposure 6
• Patient 1 in the Michigan series died despite acyclovir treatment because therapy was delayed until respiratory arrest occurred 6

Clinical Monitoring

Monitor closely for early signs of central nervous system involvement, as subtle symptoms can rapidly progress to fatal brain stem dysfunction 6

Warning Signs Requiring Immediate Hospitalization

• Headache (even without meningismus) 6
• Fever, malaise, or flu-like symptoms 6
• Any neurological symptoms including paresthesias at the exposure site 6
• Altered mental status or cranial nerve deficits 6

Diagnostic Testing

• Viral culture from lesions if present 6
• ELISA and Western blot antibody testing 6
• MRI imaging if neurological symptoms develop (highly useful for diagnosis) 6

Treatment of Established Infection

If symptoms develop, immediately escalate to intravenous ganciclovir, as this has shown superior outcomes compared to acyclovir in symptomatic patients 6

• Patient 2 in the Michigan series survived with IV ganciclovir after presenting with subtle brain stem encephalitis signs 6
• Acyclovir alone may be insufficient once encephalomyelitis begins 6

Prevention and Occupational Safety

All personnel working with macaque monkeys must use rigorous personal protective equipment including face shields, double gloves, and bite-proof sleeves 1

• Routine training on first aid protocols and immediate reporting systems is essential 1
• Never house capuchin monkeys or other New World primates near macaques, as cross-species transmission can create asymptomatic carriers 5
• Routine repeated testing of all primates in research facilities is mandatory 5

Critical Pitfalls to Avoid

• Never delay antiviral prophylaxis while waiting for animal testing or symptom development—the mortality rate is 70% without prompt treatment 1
• Do not dismiss mild headache or flu-like symptoms as these may represent early encephalitis that will rapidly progress 6
• Do not assume only macaques pose risk—capuchins and potentially other primates housed near macaques can be asymptomatic carriers 5
• Do not rely on acyclovir alone if neurological symptoms develop—escalate to IV ganciclovir immediately 6