Key points
- Although extremely rare, B virus can spread from infected macaque monkeys to people.
- If the virus spreads to the central nervous system, most patients with complications will die, even with antiviral therapy.
- There are no vaccines available for B virus.
Introduction
B virus is an alphaherpesvirus commonly found among macaques—a genus of Old World monkeys that serve as the natural host. The virus is found among rhesus macaques, pig-tailed macaques, and cynomolgus monkeys (also called crab-eating or long-tailed macaques).
B virus is also commonly referred to as herpes B, monkey B virus, herpesvirus simiae, and herpesvirus B.
Incubation period
Symptoms of B virus infection typically occur within 1 month of the patient being exposed; although the actual incubation period can be a little as 3 to 7 days.
Clinical features
Recognizing symptoms and their progression is critical!
Patients with B virus infection will initially present with flu-like symptoms such as:
- Fever
- Muscle ache
- Fatigue
- Headache
Disease progression depends on the location of the exposure (usually a bite or scratch); and the number of infectious particles spread during exposure. The patient can have:
- Vesicular skin lesions at the exposure site
- Lymphadenitis (inflamed lymph nodes)
- Lymphangities (infection of lymph vessels)
- Nausea and vomiting
- Abdominal pain
- Hiccups
The virus can spread to the central nervous system (CNS) and cause additional symptoms. The patient can also have:
- Hyperesthesias (increase in sensitivity to stimuli)
- Ataxia (lack of voluntary control of muscle movements)
- Diplopia (double vision)
- Agitation
- Ascending flaccid paralysis (extreme weakness due to reduced muscle tone)
Prevention
There are no vaccines available protect against B virus infection.
Experimental vaccines have been evaluated in animal models, but none are being considered for use in people.
Testing and diagnosis
Diagnostic testing resources
Both clinical evaluation of symptoms and laboratory testing are needed to diagnose B virus in an exposed person. Ideally, the test should show antibodies or virus positive case.
Serological and virological testing are available for diagnosing B virus infection.
Treatment and recovery
When a patient has been in contact with a macaque, immediately wash and gently scrub the patient's exposed wound or area.
- Wash area thoroughly with soap, detergent, or iodine for 15 minutes.
- Then run water over the area for 15 to 20 minutes more.
Patients with a known risk of exposure should be monitored for symptoms. Monitor their symptoms regardless of whether an antiviral treatment regimen has been implemented.
Prognosis
Most patients with CNS complications will die, even with antiviral therapy and supportive care. Those who survive usually suffer serious long-term neurologic problems. Respiratory failure associated with ascending paralysis is the most common cause of death. Respiratory involvement and death can occur 1 day to 3 weeks after symptom onset.
Some people might have a delay in developing acute disease. In rare cases, such delays may range from months to years.
Case studies
Since B virus was identified in 1932, only 50 people have been documented to have B virus infections. Of these people, 21 died. Most of these people got infected after they were bitten or scratched by a macaque monkey; or when tissue or fluids from a monkey got on their broken skin, such as by needle stick or cut.
In 1997, a researcher died from B virus infection after biological material (probably stool) from an infected monkey splashed into her eye.
Hundreds of bites and scratches occur every year in monkey facilities in the United States, but people rarely get infected with B virus. A study of more than 300 animal care workers showed that none had B virus infection, including the 166 workers who had possible exposures to monkeys.
Only one occurrence has been documented of an infected person spreading B virus to another person through direct physical contact with the infected person’s wounds.
Among the four patients involved, three were animal handlers. Two suffered bite wounds and one had close contact with the sick macaque. The one who had contact was not injured or exposed to other bodily fluids, and did not develop symptoms.
The fourth person was the wife of one of the animal handlers. She used an ointment to treat her husband’s wounds and subsequently used it on herself to treat dermatitis. She produced antibodies for B virus but never developed symptoms.
The study found no evidence of B virus infection among 130 close contacts of the four patients, healthcare workers, or primate workers. Although over 70% of adult macaques have B virus, only a few people developed laboratory evidence of B virus exposure. Thus, transmission of this virus is quite rare, both human-to-human and primate-to-human.