Relationship Between Climate Change and Marmot Plague of Marmota himalayana Plague Focus - the Altun Mountains of the Qinghai-Xizang Plateau, China, 2000-2022.

Introduction: Plague is a zoonotic disease that occurs naturally in specific geographic areas. Climate change can influence the populations of the plague host or vector, leading to variations in the occurrence and epidemiology of plague in animals. Methods: In this study, we collected meteorological and plague epidemiological data from the Marmota himalayana plague focus in the Altun Mountains of the Qinghai-Xizang Plateau. The data spanned from 2000 to 2022. We describe the climatic factors and plague epidemic conditions and we describe their analysis by Pearson's correlation. Results: During the period from 2000 to 2022, the isolation rates of Yersinia pestis (Y.pestis) from marmots and fleas were 9.27% (451/4,864) and 7.17% (118/1,646), respectively. Additionally, we observed a positive rate of F1 antibody of 11.25% (443/3,937) in marmots and 18.16% (142/782) in dogs. With regards to climate, there was little variation, and a decreasing trend in blowing-sand days was observed. The temperature in the previous year showed a negative correlation with the Y. pestis isolation rate in marmots (r=-0.555, P=0.011) and the positive rate of F1 antibody in marmots (r=-0.552, P=0.012) in the current year. The average annual precipitation in the previous two years showed a positive correlation with marmot density (r=0.514, P=0.024), while blowing-sand days showed a negative correlation with marmot density (r=-0.701, P=0.001). Furthermore, the average annual precipitation in the previous three years showed a positive correlation with the isolation rate of Y. pestis from marmots (r=0.666, P=0.003), and blowing-sand days showed a negative correlation with marmot density (r=-0.597, P=0.009). Conclusions: The findings of this study indicate that there is a hysteresis effect of climate change on the prevalence of plague. Therefore, monitoring climate conditions can offer significant insights for implementing timely preventive and control measures to combat plague epidemics.

Pasteurella multocida strains of a novel capsular serotype and lethal to Marmota himalayana on Qinghai-Tibet plateau in China.

Pasteurella multocida is a zoonotic pathogen causing serious diseases in humans and animals. Here, we report P. multocida from wildlife on China's Qinghai-Tibet plateau with a novel capsular serotype, forming a single branch on the core-genome phylogenetic tree: four strains isolated from dead Himalayan marmot (Marmota himalayana) and one genome assembled from metagenomic sequencing of a dead Woolly hare (Lepus oiostolus). Four of the strains were identified as subspecies multocida and one was septica. The mouse model showed that the challenge strain killed mice within 24 h at an infectious dose of less than 300 bacteria. The short disease course is comparable to septicemic plague: the host has died before more severe pathological changes could take place. Though pathological changes were relatively mild, cytokine storm was obvious with a significant rise of IL-12p70, IL-6, TNF-αand IL-10 (P < 0.05). Our findings suggested P. multocida is a lethal pathogen for wildlife on Qinghai-Tibet plateau, in addition to Yersinia pestis. Individuals residing within the M. himalayana plague focus are at risk for P. multocida infection, and public health warnings are necessitated.

Case report: A case of brucellosis misdiagnosed as coronavirus disease 2019/influenza in China.

Brucellosis is an important zoonosis and a multisystem disease. The signs and symptoms of brucellosis are not specific. In the clinical, brucellosis is often ignored and misdiagnosed. We report a case of brucellosis who was misdiagnosed as coronavirus disease 2019 (COVID-19)/influenza and received delayed treatment during strict COVID-19 control. The neglect of other diseases due to COVID-19 and empirical diagnosis and treatment by medical staff are part of the reasons for misdiagnosis. Otherwise, the normal erythrocyte sedimentation rate (ESR), increased white blood cell count (WBC), and increased neutrophil count (NEUT) of this patient was also a cause of misdiagnosis, which is an important reminder for diagnosis. For patients with the unknown origin of fever and other symptoms related to brucellosis, especially those from endemic areas of brucellosis, brucellosis screening is a priority item, and grassroots doctors should be vigilant and standardize the diagnosis and treatment based on epidemiology history, clinical manifestation, and laboratory tests according to the diagnostic criteria of brucellosis.

Identification of Novel Bartonella washoensis Sequence Type 22 in Marmota himalayana - Jiuquan City, Gansu Province, China, 2021-2022.

What is already known about this topic?: The prevalence of rodent-adapted Bartonella species has been increasing significantly. However, the specific Bartonella species carried by Marmota himalayana (M. himalayana), a large rodent species, and the potential risk it poses to human populations remain unknown. What is added by this report?: Bartonella washoensis (B. washoensis), associated with human endocarditis, was initially identified in M. himalayana, exhibiting a detection rate of approximately one-third and demonstrating a predilection for the heart and lungs. The discovery of the novel Sequence Type 22 has expanded both the isolation source and genetic lineage of B. washoensis. What are the implications for public health practice?: Individuals residing within the M. himalayana plague focus are at an elevated risk for B. washoensis infection. Consequently, there is a pressing need for public health warnings and efficient clinical case identification in this population.

Serological investigation of plague and brucellosis infection in Marmota himalayana plague foci in the Altun Mountains on the Qinghai-Tibet Plateau.

The Altun Mountains are among the most active regions of Marmota himalayana plague foci of the Qinghai-Tibet Plateau where animal plague is prevalent, whereas only three human cases have been found since 1960. Animal husbandry is the main income for the local economy; brucellosis appears sometimes in animals and less often in humans. In this study, a retrospective investigation of plague and brucellosis seroprevalence among humans and animals was conducted to improve prevention and control measures for the two diseases. Animal and human sera were collected for routine surveillance from 2018 to 2021 and screened for plague and brucellosis. Yersinia pestis F1 antibody was preliminarily screened by the colloidal gold method at the monitoring site to identify previous infections with positive serology. Previous plague infection was found in 3.2% (14/432) of the studied human population having close contact with livestock, which indicates evidence of exposure to the Yersinia antigen (dead or live pathogenic materials) in the Altun Mountains. Seroprevalence of brucellosis was higher in camels (6.2%) and sheepdogs (1.8%) than in other livestock such as cattle and sheep, suggesting a possible transmission route from secondary host animals to humans.

Plague Outbreak of a Marmota himalayana Family Emerging from Hibernation.

In April 2021, a plague outbreak was identified within one Marmota himalayana family shortly after emerging from hibernation, during plague surveillance in the M. himalayana plague foci of the Qinghai-Tibet Plateau. A total of five marmots were found dead of Yersinia pestis near the same burrow; one live marmot was positive of Y. pestis fraction 1 (F1) antibody. Comparative genome analysis shows that few single nucleotide polymorphisms were detected among the nine strains, indicating the same origin of the outbreak. The survived marmot shows a high titer of F1 antibody, higher than the mean titer of all marmots during the 2021 monitoring period (W = 391.00, Z = 2.81, p < 0.01). Marmots live with Y. pestis during hibernation when the pathogen is inhibited by hypothermia. But they wake up during or just after hibernation with body temperature rising to 37°C, when Y. pestis goes through optimal growth temperature, increases virulence, and causes death in marmots. A previous report has shown human plague cases caused by excavating marmots during winter; combined, this study shows the high risk of hibernation marmot carrying Y. pestis. This analysis provides new insights into the transmission of the highly virulent Y. pestis in M. himalayana plague foci and drives further effort upon plague control during hibernation.