Herpes B virus infection in humans is rare, but often fatal; therefore, prompt management of likely exposure is critical to preventing disease progression.
Should be suspected when illness follows exposure to macaque monkeys or their body fluids or tissues. Immediate thorough cleansing of the exposed area combined with antiviral prophylaxis may prevent infection.
Untreated infection often leads to central nervous system disease and death, with a mortality rate of approximately 80%. Early and aggressive antiviral treatment may prevent death.
Herpes B virus infection in humans is caused by the zoonotic Macacine herpesvirus 1 (MHV-1), previously known as Cercopithecine herpesvirus 1 (CHV-1). It is mainly found in macaque monkeys and they appear to be its natural host. Of all the herpes simplex viruses identified in non-human primates, only B virus is known to be pathogenic for humans.
Infection in humans is usually caused by the bite or scratch from an infected animal, a percutaneous injury contaminated by macaque body fluids, or from mucosal or non-intact skin contact with infected body fluid or tissue (e.g., in a laboratory or animal handling facility).
Infection in humans is rare, but when it does occur it often presents with flu-like symptoms (fever, muscle aches, fatigue, and headache). Neurological symptoms usually develop, which result in fatal encephalomyelitis or severe neurological impairment if not treated early.
History and exam
Key diagnostic factors
- presence of risk factors
- fever (≥37.5°C)
- flu-like symptoms
- severe persistent headache
- ocular pain
- gait disturbances
- muscle weakness (paresis)
- persistent hiccups
- ascending or acute flaccid paralysis
- vesicular lesions
Other diagnostic factors
- abdominal pain
- occupational exposure
- travel to countries with free-roaming macaques
- keeping macaques as pets
- exposure to non-macaque species that have been housed with macaques
1st investigations to order
- polymerase chain reaction (PCR)
Investigations to consider
- viral culture
- brain MRI
- brain CT
- CSF tests
- brainstem auditory evoked responses
- somatosensory evoked potentials
- laboratory testing of animal specimen
confirmed infection and/or symptomatic
Richard Whitley, MD
Professor of Pediatrics
Professor of Microbiology, Medicine, and Neurosurgery
University of Alabama
RW is a retired Board Member for Gilead Sciences, Inc., and a current member of Scientific Advisory Boards or Data Management Committees for Clear Creek Biosciences, Merck, Virios Therapeutics, Visby Medical, Evrys BioSciences, Enochian Biosciences, and Leyden Laboratories.
Professor Richard Whitley would like to gratefully acknowledge Dr D. Scott Schmid, Dr Jeffrey I. Cohen, and Dr Louisa E. Chapman, previous contributors to this topic, and Dr Julia K. Hilliard for her contributions to this topic. Unfortunately, we have been made aware that Dr Louisa E. Chapman is now deceased.
JKH, JIC, and LEC are the authors of several references cited in this topic. DSS declared that he had no competing interests. The views included in this topic are those of the authors (DSS and JIC) and do not necessarily represent the views of the Centers for Disease Control and Prevention or the National Institutes of Health.
Anna Maria Geretti, MD, PhD, FRCPath
Professor of Virology and Infectious Diseases
University of Liverpool
AMG declares that she has no competing interests.
Deanna Saylor, MD, MHS
Assistant Professor of Neurology
Johns Hopkins University School of Medicine
DS has received research funding from the National Institutes of Health, the World Federation of Neurology, and the Johns Hopkins Center for AIDS Research.
- Herpes simplex encephalitis
- Herpes zoster encephalitis
- West Nile virus
- Health information for international travel (Yellow Book): B virus
- Recommendations for prevention of and therapy for exposure to B virus (Cercopithecine Herpesvirus 1)
- Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer