B Virus (Cercopithecine herpesvirus 1) Infection
B Virus (Cercopithecine herpesvirus 1) Infection
Disease History, Characteristics, and Transmission
Introduction
B virus, also called Cercopithecine herpesvirus 1, is an infectious virus found in macaques (short-tailed monkeys), such as rhesus macaques, pig-tailed macaques, stump-tailed macaques, and cynomolgus monkeys. The virus—which is a member of the herpes group of viruses—possesses origins and causes disease similar to that of the herpes simplex virus in humans. When humans are infected with B virus from macaques, they can become ill with severe and sometimes permanent central nervous system (CNS) involvement or death from encephalomyelitis (inflammation of the brain).
The National Center for Infectious Diseases (NCID), of the U.S. Centers for Disease Control and Prevention (CDC), states that the mortality rate for undiagnosed/untreated B virus disease is historically almost 80%, mostly from complications of the disease. However, since antiviral therapy has become a treatment for B virus, the mortality rate has decreased.
B virus is also called herpes B virus, herpesvirus simiae, and monkey B virus. The last known fatality from B virus in the United States occurred in 1997 at the Yerkes National Primate Research Center, located at Emory University in Atlanta, Georgia. Biological material from a monkey infected the eye of a worker and, eventually, the infection killed the worker.
Because of this incident, the CDC formed a working group to devise recommendations for the evaluation, prevention, and treatment of B virus in humans. The group's report is called “Recommendations for Prevention of and Therapy for Exposure to B Virus (Cercopithecine Herpesvirus 1).” It was published in 2002 in the journal Clinical Infectious Diseases.
Disease History, Characteristics, and Transmission
The first medically documented case of human B virus infection occurred in 1932 when a researcher's hand was bitten by a rhesus macaque. The worker died two weeks later of encephalomyelitis.
Macaques are primates in the family Cercopithecidae (commonly called Old World monkeys), subfamily Cercopithecinae, and genus Macaca. The scientific name of the rhesus macaque is Macaca mulatta, the southern pig-tailed macaque is called M. nemestrina, the northern pig-tailed macaque is called M. leonina, the stump-tailed macaque (or bear macaque) is called M. arctoides, and the cynomolgus monkey (or crab-eating macaque) is called M. fascicularis.
Macaque monkeys infected with B virus usually become infected when oral or genital secretions from other monkeys contact their mucous membranes or skin. Infected monkeys usually have few or no symptoms. When symptoms are present, they usually consist of lesions on the face, genitals, lips, or mouth. Normally, the lesions heal themselves, however, they may re-appear repeatedly, especially during extended periods of stress or anxiety. This condition is called gingivostomatitis, which is a type of stomatitis, an inflammation of the mucous lining within the mouth (specifically on the tongue, lips, or gums). When the inflammation involves the gums (gingiva), it is called gingivostomatitis.
B virus infection in humans is rare. When it does occur, B virus usually comes from cells and tissues (such as in cultures) of monkeys, and less frequently from these animals’ secretions (such as saliva), bites, or scratches. The incubation period is generally between two days and five weeks, although most symptoms appear in five days to three weeks. Symptoms usually limit themselves to the infected areas. They may include itching, numbness, skin lesions, and pain. However, some patients develop serious symptoms in the peripheral nervous system (PNS) or central nervous system (CNS). Some symptoms can initially include dizziness, headache, nausea, vomiting, and, later, seizures, respiratory failure, and coma.
Other patients have influenzalike (flulike) symptoms such as chills, fever, and muscle pain. Additional symptoms include itching, weakness, general pain, tingling, or numbness at the infection site. Often humans come down with acute encephalomyelitis (inflammation of the brain and spinal cord), which causes the death. Groups of people most at risk from B virus include laboratory workers, veterinarians, and other similar groups who have close contact with macaques or their cell cultures.
Scope and Distribution
B virus is found worldwide, but it is more likely to be found in areas inhabited by Asiatic monkeys of the genus Macaca or at locations where they are kept in captivity.
Treatment and Prevention
To prevent the transmission of the disease, protective equipment is recommended when working with macaque monkeys, especially virus-positive animals. Protective equipment includes eyewear (such as goggles or glasses with side shields), disposable head coverings, face shields (such as a welder's mask), gloves, disposable shoe covers, and disposable surgical scrubs or fluid-resistant cloth uniforms.
As recommended by the B Virus Working Group, which is headed by Jeffrey I. Cohen (National Institutes of Health, Bethesda, Maryland), bites, scratches, and any exposures to mucous membranes, including the eyes, must be cleansed immediately. Culture samples from the macaque and human should be sent for B virus diagnostic testing.
Specifically, the minutes after exposure are critical. The skin or mucosa affected by bites, scratches, or monkey fluids should be cleansed for a minimum of 15 minutes. If the eyes are contaminated, they should be irrigated with sterile saline solution or water for 15 minutes. Exposed skin should be washed with a chemical antiseptic (such as chlorhexidine or povidoneiodine) or detergent soap. After cleansing, wounds should be lightly massaged to increase the effectiveness of the cleaning agent. As soon as possible, antiviral medicine should be started in order to prevent severe disease or death from B virus.
WORDS TO KNOW
ENCEPHALOMYELITIS: Simultaneous inflammation of the brain and spinal cord is encephalomyelitis.
HERPESVIRUS: Herpesvirus is a family of viruses, many of which cause disease in humans. The herpes simplex-1 and herpes simplex-2 viruses cause infection in the mouth or on the genitals. Other common types of herpesvirus include chicken pox, Epstien-Barr virus, and cytomegalovirus. Herpesvirus is notable for its ability to remain latent, or inactive, in nerve cells near the area of infection, and to reactivate long after the initial infection. Herpes simplex-1 and -2, along with chickenpox, cause familiar skin sores. Epstein-Barr virus causes mononucleosis. Cytomegalovirus also causes a flu-like infection, but it can be dangerous to the elderly, infants, and those with weakened immune systems.
MACAQUE: A macaque is any short-tailed monkey of the genus Macaca. Macaques, including rhesus monkeys, are often used as subjects in medical research because they are relatively affordable and resemble humans in many ways.
Impacts and Issues
According to the CDC, workers who handle monkeys directly or handle cultures, bones, and other objects that originate from monkeys are potentially at risk for contracting B virus. Since this work is potentially hazardous, the CDC has written a set of guidelines for the care and maintenance of macaques titled “Guidelines for Prevention of Herpesvirus Simiae (B Virus) Infection in Monkey Handlers.”
Although thousands of humans have handled macaques since B virus was first reported, only about 40 cases of human infection have been well-documented as of 2003. Even though only a few cases have been reported, CDC health officials feel that precautions should be instituted to minimize health risks to monkey handlers since B virus is potentially deadly.
An effective vaccine for B virus, even after years of research, is still unavailable. Since the potential for human death from the B virus infection is high, and the handling and exposure to macaques is rising with increased use of the animals in laboratory settings, a better understanding of the infection is necessary. The mechanism by which the B virus lives within the macaque host is still unclear, and further research is needed to gain the knowledge necessary to combat this virus.
See AlsoAntiviral Drugs; Personal Protective Equipment; Viral Disease; Zoonoses.
BIBLIOGRAPHY
Books
Bannister, Barbara A. Infection: Microbiology and Management. Malden, MA: Blackwell Publishing, 2006.
Cohen, Jonathan, and William G. Powderly, eds. Infectious Diseases. New York: Mosby, 2004.
Ryan, Kenneth J., and C. George Ray, eds. Sherris Medical Microbiology: An Introduction to Infectious Diseases. New York: McGraw Hill, 2004.
Periodicals
Huff, Jennifer L., and Peter A. Barry. “B-Virus
(Cercopithecine herpesvirus 1) Infection in Humans and Macaques: Potential for Zoonotic Disease.” Emerging Infectious Diseases 9 (February 2003): 246–250. Also available online at: <http://oacu.od.nih.gov/UsefulResources/resources/emergindis2003.pdf> .
Web Sites
Centers for Disease Control and Prevention. “Recommendations for Prevention of and Therapy for Exposure to B Virus (Cercopithecine Herpesvirus 1).” November 15, 2002. <http://www.cdc.gov/ncidod/diseases/BVIRUS.pdf> (accessed April 16, 2007).
Georgia State University. “National B Virus Resource Center.” <http://www2.gsu.edu/∼wwwvir/> (accessed April 17, 2007).
Morbidity and Mortality Weekly Report. “Guidelines for Prevention of Herpesvirus Simiae (B Virus) Infection in Monkey Handlers.” October 23, 1987. <http://www.cdc.gov/mmwr/preview/mmwrhtml/00015936.htm> (accessed April 18, 2007).