Herpesvirus simiae, often known as B virus or monkey B virus, is a herpes virus that may infect monkeys and apes, including macaques and chimpanzees. The virus is predominantly found in Southeast Asia and may be transmitted to humans by interactions with infected animals, such as bites or scratches.

It is unusual among non-human herpesviruses in that it is neurotropic and neurovirulent in a foreign human host. Untreated B virus infections in humans have a high mortality rate (80%), providing unique and potentially fatal challenges for anybody interacting with affected animals. 


The symptoms of human Herpesvirus simiae (B virus) infection differ depending on the severity of the sickness and the part of the body affected. The following are the symptoms caused by the virus:

  • Inflammation or redness in the afflicted area
  • Difficulty moving or walking 
  • Fever
  • Muscle fatigue
  • Headaches
  • Sensation loss or tingling in the afflicted region
  • Vomiting and nausea
  • Tenderness or pain in the afflicted region


Infection with Herpesvirus simiae (B virus) is often diagnosed using the following: 

  • Imaging Studies: CT or MRI scans may be used to search for signs of inflammation or damage in the affected area.
  • Laboratory Testing: Healthcare practitioners often request a range of laboratory tests to confirm the diagnosis of B virus infection; cerebrospinal fluid analysis and blood tests may be performed.
  • Clinical Examination: A physical examination is performed to search for symptoms of infection, such as redness, swelling, or soreness around the exposure site. 


  • Immune globulin: Passive antibody treatment using immunological globulin (Ig) may assist in alleviating symptoms.
  • Intensive care: Patients with encephalitis who have had the infection spread to their neurological system may need quick medical intervention to sustain their breathing and circulation.
  • Hospitalization: People infected with the B virus are often hospitalized for close monitoring and supportive treatment.
  • Antiviral medications: Some antiviral medicines, such as acyclovir, can reduce virus replication; however, they are not very useful in B virus instances and may be ineffective.

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