Investigation of an epidemic of human brucellosis in population without occupational exposure in Jingzhou, Hubei, 2023

Objective To investigate an epidemic of human brucellosis in population without occupational exposure in Jingzhou, Hubei province in 2023 and provide evidence for brucellosis prevention and control.

Methods The study used field epidemiological investigation methods to analyze the incidence and infection sources of human brucellosis. Tiger-red plate agglutination test and tube agglutination test were conducted for antibody detection. Descriptive epidemiological analysis was conducted. Additionally, a self-designed questionnaire was used for on-site surveys to assess the awareness of brucellosis in local population with occupational exposure.

Results The index case was a fisherman, who had no clear history of contact with suspect sick sheep but was identified through active medical care seeking. Traceback investigations revealed there were sheep flocks near the fishing ground. A total of 61 samples were collected from 77 sheep in the sheepfold, the positivity rate of Brucella was 80.32% (49/61). The positive sheep might be from other area. A total of 34 individuals were surveyed in emergency response, in which 3 positive cases were detected, including the wife of the index case and a couple raising the positive sheep. In the epidemic, 2 confirmed cases and 2 latent infection cases were found. The time intervals between onset and diagnosis for the two confirmed cases were 50 days and 89 days, respectively. Emergency response, with 190 samples being collected from sheep in the town, found no additional positive sheep. A survey of 27 occupational individuals in the town showed a brucellosis-related knowledge awareness rate of 3.70%, with 27.27% of occupational individuals reporting skin cuts in works.

Conclusion This was the first epidemic of brucellosis in population without occupational exposure Jingzhou. The source of infection might be infected sheep from other area. It is necessary to strengthen the training of brucellosis diagnosis and treatment in local medical workers and health education about brucellosis prevention in local population with or without occupation exposure.