Human herpes B virus infection is rare, but often fatal; therefore, prompt management of likely exposure is critical to preventing disease progression.
B virus should be suspected when illness follows exposure to macaque monkeys or their body fluids or tissues.
Any area exposed to macaque monkeys, their body fluids, or tissues should immediately be thoroughly cleansed for 15 minutes.
Untreated B virus infection in humans will often lead to CNS disease and death. The mortality rate with B virus infection is approximately 80% in untreated humans.
Immediate thorough cleansing of the exposed area combined with antiviral prophylaxis may prevent infection.
Early and aggressive antiviral treatment of B virus disease 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). The virus is commonly called the B virus, but is also known as herpes B, monkey B virus, Herpesvirus simiae, and herpesvirus B. The virus is a member of the Alphaherpesvirus subfamily (genus: Simplexvirus ) and is closely related to the human herpes simplex virus (HSV). It is mainly found in macaque monkeys and these appear to be its natural host. Most infected monkeys are asymptomatic or have only mild symptoms; however, in some cases a disease similar to human HSV infection is seen (e.g., vesicular lesions on the tongue and lips, and sometimes on the skin).  
Of all the simplex herpesviruses 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).  The incubation period from confirmed exposure to onset of clinical symptoms ranges from a few days to 5 weeks, but symptoms generally appear between 1 and 3 weeks post-exposure.  B virus 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.   Human infections have been identified in at least 50 instances, with approximately 80% mortality when untreated.   Morbidity and mortality associated with human infection result from invasion of the CNS, leading to ascending paralysis and respiratory failure.  
Centers for Disease Control and Prevention
DSS declares that he has no competing interests. The views included in this topic are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention or the National Institutes of Health.
Medical Officer, Captain, Public Health Service
Division of Public Health Information Dissemination
Center for Surveillance, Epidemiology, and Laboratory Services
Centers for Disease Control and Prevention
LEC is the author of a reference cited in this monograph. The views included in this topic are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention or the National Institutes of Health.
Chief, Laboratory of Infectious Diseases
Chief, Medical Virology Section
National Institutes of Health
JIC is the author of a reference cited in this monograph. The views included in this topic are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention or the National Institutes of Health.
Dr D. Scott Schmid, Dr Louisa E. Chapman, and Dr Jeffrey I. Cohen would like to gratefully acknowledge Dr Julia K. Hilliard for her contributions to this monograph.
Professor of Virology and Infectious Diseases
University of Liverpool
AMG declares that she has no competing interests.
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.
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