Simian B Virus Infection

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Simian B Virus Infection is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • H Simiae Encephalomyelitis
  • Herpesvirus Simiae, B Virus
  • Monkey B Virus

Disorder Subdivisions

  • None

General Discussion

Simian B Virus Infection is caused by a type of herpesvirus. It is an infectious disorder contracted chiefly by laboratory workers exposed to infected monkeys and/or simian tissue cultures. It is characterized by a viral invasion of the brain (Encephalitis) and the membranes (meninges) surrounding the brain. Occasionally, the infection affects the spinal cord structures as well (Encephalomyelitis). Neurological damage may result from this infection. Without treatment, some cases of Simian B Virus may be life- threatening.


Simian B Virus Infection is characterized by fever, headache, vomiting, discomfort (malaise), and a stiff neck and back. These symptoms may be associated with neuromuscular dysfunction, respiratory difficulties, vision problems, cranial nerve abnormalities, alteration of consciousness, personality changes, seizures and/or partial paralysis (paresis). Some patients may go into a coma.


Simian B Virus Infection is caused by herpesvirus simiae (also known as B virus), a type of herpesvirus that is highly prevalent (i.e., enzootic) among macaque monkeys, i.e., certain Asiatic monkeys belonging to the "Macaca" genus. According to some reports, up to 80 or 90 percent of adult macaques may be infected with the virus.

In humans, Simian B Virus Infection may result from exposure to contaminated saliva from infected monkeys (e.g., from bites or scratches) or to simian tissue cultures of the virus, usually in laboratory settings. In addition, there has been at least one instance in which person-to-person transmission occurred.

Affected Populations

According to reports in the medical literature, symptoms associated with Simian B Virus Infection typically occur within approximately two to five weeks after initial exposure.

Simian B Virus Infection usually occurs in an occupational setting in which employees have been bitten or scratched by infected monkeys or exposed to virus-infected simian tissue cultures. The disease was originally reported in a monkey handler in 1932. Through 1973, approximately 17 additional cases were reported in the medical literature. In addition, in 1987, four more individuals were affected by the disease, including the first documented case in which human-to-human disease transmission occurred. Fewer than a total of 40 cases of Simian B Virus Infection have been reported in humans to date. Researchers suggest, however, that the true frequency of Simian B Virus Infection may be difficult to assess, since it is possible that exposure to the virus may result in mild or no apparent symptoms (asymptomatic infection) in some cases.

Since 1975, United States public health regulations have prohibited the importation of primates as pets. However, according to researchers at the Centers for Disease Control and Prevention (CDC), there have been a number of incidents in nonoccupational settings in which individuals were exposed to the saliva of pet macaques (e.g., due to bites or scratches). According to one published CDC report, investigators examined seven nonoccupational exposures involving 24 individuals and eight monkeys. One exposed family had flu-like symptoms and another individual developed symptoms at the wound site suggesting infection. The researchers stress that infection must be assumed as a potential risk of macaque bite or scratch wounds, making macaques unacceptable as pets.

Standard Therapies

The Centers for Disease Control and Prevention (CDC) has published a series of guidelines for the prevention of Simian B Virus Infection among monkey handlers. Such guidelines include receiving training in appropriate methods of restraint and the use of proper protective clothing and equipment when handling potentially infected monkeys. The CDC and the National Institutes of Health (NIH) have also published guidelines concerning appropriate measures for working with the B virus in a laboratory setting. For further information, please contact the CDC and/or the NIH (listed in the "References" section of this report below).

According to reports in the literature, in some affected individuals, the antiviral drug acyclovir may be effective in treating Simian B Virus Infection. In some cases, therapy may include intravenous infusion of ganciclovir, an antiviral medication structurally related to acyclovir.

Other treatment for Simian B Virus Infection is symptomatic and supportive.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



Cecil Textbook of Medicine, 19th Ed.: James B. Wyngaarden et al., Eds.; W.B Saunders Company, 1992. Pp. 1796-97.

Harrison's Principles of Internal Medicine, 14th Ed.: Anthony S. Fauci et al., Eds.: McGraw-Hill Companies, Inc., 1998. P. 836.


Successful Treatment of Experimental B Virus (Herpes Virus Simiae) Infection with Acyclovir. E.A. Boulter et al.; Br Med J (March 8 1980; 280(6215)). Pp. 681-83.

The Spectrum of Antiviral Activities of Acyclovir in Acyclovir in Vitro and in Vivo. P. Collins; J Antimicrob Chemother (Sept 1983; 12 Suppl B). Pp. 19-27.

B Virus, Herpes Virus Simiae: Historical Perspective. A.E. Palmer; J Med Primatol (1987; 16(2)). Pp. 99-130.

Guidelines for Prevention of Herpes Virus Simiae (B Virus) Infection in Monkey Handlers. MMWR Morb Mortal Wkly Rep (Oct 23 1987; 36(41)). Pp. 680-82, 687-89.

Diagnosis and Management of Human B Virus (Herpes Virus Simiae) Infections in Michigan. D.S. Davenport et al.; Clin Infect Dis (Jul 1994; 19(1)). Pp. 33-41.

The Simian Herpes Viruses. R. Eberle et al.; Infect Agents Dis (Jun 1995; 4(2)). Pp. 55-70.

A Controlled Seroprevalence Survey of Primate Handlers for Evidence of Asymptomatic Herpes B Virus Infection. A.G. Freifeld et al.; J Infect Dis (Apr 1995; 171(4)). Pp. 1031-34.

Guidelines for the Prevention and Treatment of B-Virus Infections in Exposed Persons. The B Virus Working Group. G.P. Holmes et al.; Clin Infect Dis (Feb 1995; 20(2)). Pp. 421-39.

Threat to Humans from Virus Infections of Non-Human Primates. D.W. Brown; Rev Med Virol (Dec 1997; 7(4)). Pp. 239-246.

B-Virus From Pet Macaque Monkeys: An Emerging Threat in the United States? S.R. Ostrowski et al.; Emerg Infec Dis (Jan-Mar 1998; 4(1)). Pp. 117-21.

Fatal Cercopithecine Herpes Virus 1 (B Virus) Infection Following A Mucocutaneous Exposure and Interim Recommendations for Worker Protection. MMWR Morb Mortal Wkly Rep (Dec 18 1998; 47(49)). Pp. 1073-76, 1083.

Herpes B Virus Infection. A. Jainkittivong et al.; Oral Surg Oral Med Oral Pathol Oral Radiol Endod (Apr 1998; 85(4)). Pp. 399-403.


Transverse Myelitis Association

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NIH/National Institute of Allergy and Infectious Diseases

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World Health Organization (WHO)

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Encephalitis Global

18 North Broadway #404

Tarrytown, NY 10591


Tel: 604-980-2236

Fax: (604)904-0809



Encephalitis Society

32 Castlegate


North Yorkshire, YO17 7DT

United Kingdom

Tel: 4401653692583


Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223


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