AUTHOR=Su Chao , Duan Biao , Duan Qun , He Zhaokai , Sha Hanyu , Liang Yun , Pu Ennian , Qin Shuai , Duan Ran , Lyu Dongyue , Li Wenbao , Tang Deming , Zhang Peng , Xiao Meng , Xia Lianxu , Jing Huaiqi , Wang Xin , Gao Zihou , Kan Biao TITLE=Status and analysis of undetected plague cases in Yunnan Province, China JOURNAL=Frontiers in Public Health VOLUME=Volume 12 - 2024 YEAR=2024 URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2024.1408025 DOI=10.3389/fpubh.2024.1408025 ISSN=2296-2565 ABSTRACT=Background

The virulence of Yersinia pestis strains in the Rattus flavipectus plague focus is relatively low. The purpose of this study was to investigate the undetected, sporadic plague cases in plague foci and provide the basis for plague prevention and control.

Methods

A 3-year-old plague-confirmed case was investigated in the R. flavipectus plague focus of Yunnan Province in 2020 due to the intensive screening for fever symptoms during the coronavirus disease 2019 (COVID-19) pandemic. Epidemiological investigation, laboratory testing, and clinical treatment were conducted for the case. The expanded survey was carried out around the case within a 7-km radius, including the resident population, domesticated dogs, and rats. PCR and indirect hemagglutination tests were performed on the collected samples.

Results

The isolation rates of Y. pestis were 100.0% (7 out of 7) in dead rats and 4.00% (3 out of 75) in live rats in the survey area of the foci. A total of 5.00% (6 out of 120) of the domesticated dogs were F1 antibody positive. Nine local people were determined for plague infection recently (0.92%, 9 out of 978). The locations of human cases coincided with the Y. pestis epidemic area among the animals.

Conclusion

This study discovered the existence of plague cases that had not been detected by routine surveillance in the R. flavipectus plague focus, and the actual epidemic of human infection may be underestimated.