Tanapox: a new disease caused by a pox virus.

Area of Science:

• Virology
• Epidemiology
• Zoonotic Diseases

Background:

• Two epidemics of a new viral disease, tanapox, occurred in Kenya in 1957 and 1962.
• The disease affected several hundred individuals with a short febrile illness, headache, prostration, and a characteristic single pock-like lesion.

Purpose of the Study:

• To identify the causative agent of tanapox.
• To characterize the tanapox virus and its relationship to other pox viruses.
• To investigate the potential zoonotic nature and transmission of tanapox.

Main Methods:

• Isolation and characterization of the causative pox virus.
• In vitro studies using human and monkey tissue cultures.
• Animal susceptibility studies in monkeys.
• Histopathological and electron microscopic examination.
• Serological testing to compare with known pox viruses.
• Human volunteer studies to reproduce lesions.

Main Results:

• A novel pox virus, unrelated to the vaccinia-variola group, was identified as the cause of tanapox.
• The virus demonstrated a limited host range, successfully grown in human and monkey cells, with monkeys being the only susceptible animals in laboratory settings.
• Histopathological and electron microscopic analyses confirmed the virus belongs to the pox group.
• Serological tests indicated distinct differences from other animal pox viruses, including monkey yabapox virus.
• Lesions were successfully reproduced in a human volunteer.
• A similar pox virus was implicated in primate colony epidemics in the USA.

Conclusions:

• Tanapox is caused by a distinct pox virus that differs from known pox viruses.
• The virus has a limited host range, primarily affecting humans and monkeys.
• Evidence suggests tanapox is a zoonosis, likely transmitted from monkeys to humans in Kenya.