B virus
- Virus
- Enveloped
- For completeness
A herpesvirus that macaque monkeys carry harmlessly. In people, a bite or scratch can rarely lead to a brain and spinal cord infection that is often fatal.
Also called: Macacine alphaherpesvirus 1, herpes B, monkey B virus, herpesvirus simiae
Quick facts
- Type
- Virus · Human herpesviruses
- Gram / shape
- Icosahedral capsid inside a tegument and envelope
- Spread
- Bite or scratch from a macaque · Monkey saliva
- Causes
- Infection after a monkey bite or scratch
- Treatment
- Antiviral nucleoside analogues
At a glance
- Shape
- Icosahedral capsid inside a tegument and envelope
- Genome
- Double-stranded, linear DNA
- Envelope
- Enveloped
- Family
- Orthoherpesviridae (alphaherpesvirus subfamily), genus Simplexvirus
- Size
- About 150 to 200 nm
Morphology
- Closely related to herpes simplex viruses 1 and 2, with which it cross-reacts in antibody tests
- Like other alphaherpesviruses it becomes latent in sensory nerve ganglia of its natural host
Transmission
- Bite or scratch from a macaque (rhesus, pig-tailed, cynomolgus)
- Monkey saliva, tissue or fluids on broken skin, eyes, nose or mouth
- Needle sticks and cuts from contaminated cages or equipment; handling monkey brain, spinal cord or skull
- Person-to-person spread has been documented only once
Reservoir: Macaque monkeys: most adult animals carry the virus, usually without signs, and shed it intermittently like HSV in humans
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- In macaques it causes mild oral or genital lesions, as HSV does in people
- In humans it replicates at the entry site, then travels along peripheral nerves to the spinal cord and brain
- Ascending myelitis and encephalomyelitis lead to respiratory failure, the usual cause of death
Diseases it causes
- B virus encephalomyelitis after macaque exposure Viral encephalitis (herpes simplex encephalitis) →
- Infection after a monkey bite or scratch Mammalian bites (dog, cat, human) →
Clinical picture
- Incubation usually under a month, sometimes as short as 3 to 7 days
- Early: flu-like fever, myalgia, fatigue, headache; vesicles, pain or itching at the wound; regional lymphadenitis
- Neurological: numbness near the wound, ataxia, diplopia, agitation, then ascending paralysis
- Death can follow 1 day to 3 weeks after symptoms start; survivors often keep severe neurological deficits
Diagnosis
- Exposure history is the key clue: any macaque bite, scratch or splash in a lab, zoo, temple or tourist site
- Serology and virus detection (PCR) in reference laboratories; HSV cross-reactivity complicates antibody tests
- Swabs from the wound and the monkey, plus CSF and blood if symptoms appear
Treatment
Antiviral nucleoside analogues: valaciclovir or aciclovir as post-exposure prophylaxis after a high-risk exposure; intravenous aciclovir or ganciclovir once disease is suspected, especially with neurological signs. Prompt wound cleansing matters most.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Immediate first aid: wash skin with soap, povidone-iodine or chlorhexidine and rinse eyes or mucosa with water or saline for about 15 minutes
- Protective equipment and safe handling protocols for lab and animal workers
- Do not touch or feed monkeys at tourist sites
- No vaccine exists
Test yourself
Think of the answer, then tap the question to see it.
Which animal is the natural host of B virus?
Macaque monkeys (such as rhesus and cynomolgus), which usually carry it without illness.
What is the first step after a macaque bite in a laboratory?
Wash the wound thoroughly for about 15 minutes (soap, povidone-iodine or chlorhexidine), then seek medical evaluation for antiviral prophylaxis.
What usually causes death in B virus infection?
Respiratory failure from ascending paralysis caused by encephalomyelitis.
Connections
← Back to the group: Human herpesviruses
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: About B Virus (CDC, 2024); Clinical Overview of B Virus (CDC, 2024).
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Representative model, for educational purposes only.