A dog-associated primary pneumonic plague in Qinghai Province, China.

BACKGROUND: Primary pneumonic plague (PPP) caused by Yersinia pestis is the most threatening clinical form of plague. An outbreak was reported in July 2009 in Qinghai Province, China. METHODS: This outbreak was investigated by clinical, epidemiological, bacteriological, and immunological methods. Multilocus variable number tandem repeat analysis (MLVA) was used to track the source of the outbreak. RESULTS: The index case, a patient with PPP, contaminated 11 close contacts. All the 12 cases, including the index patient, experienced sudden onset of fever, headache, and productive coughing with bloody sputum. Three of them died. Nevertheless, another 61 direct and 256 indirect contacts were not infected during the 2-week quarantine. Antibodies to F1 antigen were detected in 9 survival cases, with a 4-fold increase in titers in serum samples collected at different periods. Seven strains of Y. pestis were isolated from dogs and patients. Field investigation and MLVA of the isolated strains revealed that this outbreak was started by a deceased dog. CONCLUSION: Dogs are believed to be an indicator animal for plague surveillance, but their association with PPP is rare. Our results provide evidence for this possibility, which suggests the public health significance of dogs as a source of plague.

Serum cytokine responses in primary pneumonic plague patients.

The serum levels of interleukin-2 (IL-2), gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), IL-4, IL-6, and IL-10 of pneumonic plague patients were determined by enzyme-linked immunosorbent assay. IL-6 was the only elevated cytokine in the patients, and its level increased with a clear time course, indicating that IL-6 might be a prognostic marker for predicting the progression of plague.

[A molecular epidemiological study on human plague fulminant epidemic in Qinghai, 2004].

OBJECTIVE: To study the epidemiology of genotyping Yersinia pestis isolated in the fulminant epidemics of human plague in Qinghai province in 2004. METHODS: Primer pairs targeting the twenty-three different identified regions (DFRs) were designed to detect the presence or deletion of each DFR in 13 strains of Yersinia pestis isolated from the fulminant epidemic of human plague in Qinghai province in 2004. RESULTS: There were 4 genomovars, i.e. Genomovar 8, 10, 15 and 16 in the 13 strains of Yersinia pestis identified. The genomovar of all the strains of Yersinia pestis isolated from Nangqian county was Genomovar 10. Among the two strains of Yersinia pestis isolated from Wulan county, the genomovar of one strain was Genomovar 8 and the other was Genomovar 10. The genomovars of all the strains of Yersinia pestis isolated from Qilian, Qumalai and Chengduo county belonged to Genomovar 16. CONCLUSION: It was demonstrated that the genotyping of Yersinia pestis appeared to be a powerful tool for investigating human plague epidemics.