Human monkeypox: clinical features of 282 patients

Area of Science:

• Epidemiology
• Infectious Diseases
• Viral Diseases

Background:

• Human monkeypox is a zoonotic viral disease endemic in parts of Africa.
• Clinical manifestations can resemble smallpox, posing diagnostic challenges.
• Understanding disease course and risk factors is crucial for public health interventions.

Purpose of the Study:

• To describe the clinical features and disease course of human monkeypox in a large cohort.
• To identify differentiating clinical signs between monkeypox, smallpox, and chickenpox.
• To evaluate the impact of prior smallpox vaccination on monkeypox presentation and outcomes.

Main Methods:

• Retrospective analysis of clinical data from 282 human monkeypox patients in Zaire (1980-1985).
• Comparison of clinical features and outcomes between vaccinated and unvaccinated individuals.
• Assessment of age distribution and mortality rates.

Main Results:

• The study included 282 patients, with 90% under 15 years old.
• Early lymphadenopathy was a key differentiator from smallpox and chickenpox.
• Vaccinated patients showed altered disease presentation (pleomorphism, cropping) and improved prognosis, with zero mortality.
• Unvaccinated patients had an 11% crude case-fatality rate, higher in young children (15%).

Conclusions:

• Human monkeypox shares clinical similarities with smallpox but is distinguished by early lymphadenopathy.
• Prior smallpox vaccination significantly modifies the clinical course and improves outcomes, preventing mortality.
• Age and vaccination status are critical factors influencing monkeypox prognosis.