Herpes B Clinical Presentation

Following potential exposure to herpes B virus in humans, the wound and the at-risk individual should be monitored because of the potential for severe infection, a protocol involving the exposing primate (see Lab Studies). An incubation period of 2-30 days has been described, with progression of symptoms over 7-10 days.

• Early symptoms (variably present)

  • Pain or pruritus at exposure site
  • Vesicles or ulcers at or near exposure site
  • Local lymphadenopathy
• Intermediate symptoms (variably present)

  • Fever
  • Malaise
  • Diffuse myalgias
  • Headache
  • Numbness or paraesthesias at or near exposure site
  • Nausea and/or abdominal pain
  • Persistent hiccups
• Late manifestations

  • Persistent headache
  • Alteration of mentation
  • Focal neurological symptoms

Findings of herpes B virus infection primarily include progressive neurologic deterioration that suggests a multifocal hemorrhagic encephalitis or encephalomyelitis. This finding contrasts with the temporal lobe localization of herpes simplex encephalitis. The progression of signs and symptoms may be modified by early antiviral therapy. Asymptomatic human herpes B virus infection is rare, if not nonexistent. Typical physical signs include the following:

• Meningismus
• Confusion progressing to coma
• Brain stem findings, which may include the following:

  • Diplopia
  • Dysarthria
  • Dysphagia
  • Cerebellar signs, including ataxia
  • Cranial nerve palsies
• Signs of meningoencephalomyelitis, which may include the following:

  • Seizures
  • Hemiparesis or hemiplegia
  • Progressive ascending paralysis
  • Transverse myelitis
• Non–central nervous system signs, which may include the following:

  • Conjunctivitis or chorioretinitis
  • Sinusitis

Information regarding the epidemiology and transmission of herpes B virus in primates is vital in order to understand how to prevent this high-mortality infection.

• Macaques transmit the herpes B virus to each other through oral, ocular, or genital contact of mucous membranes or lesioned skin. The herpes B virus can be shed asymptomatically, including through bodily fluids (eg, semen, mother's milk, saliva, perhaps even in aerosol form). The animal stools could also conceivably transmit the herpes B virus. In captive macaques, transmission may often occur during routine colony management protocols involving tube sharing, common instrumentation, or contaminated gloves. Animals usually become infected as juveniles, at the onset of sexual activity; however, younger animals can become infected through contact with another virus-shedding animal. For example, a nursing mother has repeated opportunities to transmit herpes B virus in buccal or conjunctival fluids to a nursing infant during grooming.
• Conclusively determining transmission pathways may not be possible because most human cases of herpes B virus infection involve individuals who regularly work with monkeys, thus providing many potential means of exposure. Suspected transmission modes include monkey bites, monkey scratches, or cage scratches; direct contamination of a preexisting wound with macaque saliva; respiratory exposure to aerosol macaque saliva; mucosal splash exposure; cuts sustained from culture bottles containing macaque kidney cells; needle-stick injuries following needle use in macaques; and cleaning a rhesus macaque skull without gloves. In addition, one apparent case of human-to-human herpes B virus transmission involved a woman with dermatitis on her finger; she touched her husband's herpetiform lesion (resulting from a monkey bite).^[1]
• Given the myriad potential transmission pathways and abundance of macaques in contact with people, the fact that relatively few documented cases of B virus infection occur in humans may seem surprising. Nevertheless, although most macaques test positive for herpes B virus antibodies, only a small percentage (ie, 0-2%) shed the virus at any given time. In most animals, the human B virus is latent in the trigeminal ganglia and becomes reactivated only when the macaque experiences psychological stress, pharmacological stress, or diminished immunocompetence.
• The widely observed pattern of increasing frequency with age suggests that horizontal transmission is far more common than vertical transmission (ie, mother to offspring). Whether this horizontal transmission occurs most commonly via oral or genital contact, including sexual behavior, is unresolved.