Macacine alphaherpesvirus 1

History

• B virus was identified in 1932.
• Since then, only about 50 people have been documented to have B virus infections; 21 of them died.
• Most of these people got infected after they were bitten or scratched by a macaque monkey.

Cause and Frequency

• B virus infections in people are usually caused by macaque monkeys.
• These kinds of monkeys are commonly infected with B virus, but they usually do not have symptoms, or have just mild disease.
• Other primates, such as chimpanzees and capuchin monkeys, can become infected with B virus and will frequently die from these infections.
• There have not been documented cases of such primates spreading B virus except to macaques.

Human infection

• B virus infections in people are rare. Since B virus was identified in 1932, only 50 people have been documented to have infections; 21 of them died.
• Most of these people got infected after they were bitten or scratched by a 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 bodily fluid from an infected monkey splashed into her eye.

Transmission

• B virus can spread from infected macaque monkeys to people.
• Macaque monkeys commonly have this virus, and it can be found in their saliva, feces (poop), urine (pee), or brain or spinal cord tissue.
• The virus may also be found in cells coming from an infected monkey in a lab.
• B virus can survive for hours on surfaces, particularly when moist.
• Increasingly, free-ranging macaque monkeys infected with B virus are a common source for potentially exposing people to this virus.
• Large colonies of these monkeys are present in some parks in Florida and Puerto Rico.

The Virus

• 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.

Signs and Symptoms

Symptoms typically start within one month of being exposed to B virus, but could appear in as little as three to seven days.

The first indications of B virus infection are typically flu-like symptoms:

• fever and chills
• muscle ache
• fatigue
• headache

Other symptoms may include:

• Shortness of breath
• Nausea and vomiting
• Abdominal pain
• Hiccups

Complications

As the disease progresses, the virus spreads to and causes inflammation (swelling) of the brain and spinal cord. This can lead to:

• Neurologic and inflammatory symptoms (pain, numbness, itching) near the wound site
• Problems with muscle coordination
• Brain damage and severe damage to the nervous system
• Death

Problems with breathing and death can occur one day to three weeks after symptoms appear. It may be possible for people to have mild B virus infection or no symptoms. However, there are no studies or evidence of this.

Diagnosis

• It is critical to be diligent in recognizing symptoms and their progression to help facilitate rapid diagnose of B virus infection in an exposed person.
• Both clinical evaluation of symptoms and laboratory testing (ideally showing antibodies or virus positive case) are needed to diagnose B virus in an exposed person.
• Serological and virological testing are available for diagnosing B virus infection.
• For more information, see Laboratory Testing and Diagnosis section.

Treatment

Specific exposure scenarios and the corresponding urgency for post-exposure antiviral treatment, as proposed in the Recommendations for Prevention of and Therapy for Exposure to B virus (Cercopithecine Herpesvirus 1)External, are as follows:

Treatment is recommended when:

• Skin or mucosal exposure – with or without injury – to a high-risk source (e.g., a macaque that is ill, immunocompromised, known to be shedding virus, or has lesions compatible with B virus infection.)
• Inadequately cleansed skin exposure (where the skin is broken) or mucosal exposure (with or without injury).
• Laceration of the head, neck, or torso.
• Deep puncture bite.
• Needle stick associated with tissue or fluid from the nervous system, lesions suspicious for B virus, eyelids, or mucosa.
• Puncture or laceration with objects (a) contaminated either with fluid from monkey oral or genital lesions or with nervous system tissues or (b) known to contain B virus.
• A culture taken after the wound was cleansed tests positive for B virus.

Treatment should be considered when:

• A break in the skin that has been adequately cleaned.
• Needle stick involving blood from an ill or immunocompromised macaque.
• Puncture or laceration occurring after exposure to (a) objects contaminated with body fluid (other than that from a lesion) or (b) a possibly infected cell culture.

Treatment is not recommended when:

• Skin exposure in which the skin remains intact.
• Exposure associated with non-macaque species of non-human primates, unless they were in a situation where they could have been infected by a macaque.

Antiviral Therapy

• Recommended dosages for specific antivirals are as follows:
• Prophylaxis for exposure to B virus
• Valacylovir—1g by mouth every eight hours for 14 days, or
• Acyclovir—800 mg by mouth five times daily for 14 days
• Treatment of B virus infection
• With no CNS symptoms
• Acyclovir—12.5–15 mg/kg intravenously every eight hours, or
• Ganciclovir—5 mg/kg intravenously every 12 hours
• With CNS symptoms
• Ganciclovir—5 mg/kg intravenously every 12 hours

Prophylaxes

Prophylaxis for exposure to B virus have been shown to effectively protect rabbits from lethal infectious doses of B virus, but no comparable studies of efficacy in humans have been possible.For more detailed information, refer to the Recommendations for Prevention of and Therapy for Exposure to B virus

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.