Epizootiologic parameters for plague in Kazakhstan

Area of Science:

• Zoonotic disease ecology
• Bacteriology
• Veterinary epidemiology

Background:

• Plague, caused by Yersinia pestis, poses a significant public health threat.
• Understanding plague dynamics in natural reservoirs is crucial for predicting and preventing outbreaks.
• Key epizootiologic parameters for plague in reservoir hosts remain poorly estimated.

Purpose of the Study:

• To investigate plague dynamics in a primary maintenance host, the great gerbil (Rhombomys opimus).
• To estimate key epizootiologic parameters for Yersinia pestis infection in natural populations.
• To assess the impact of Y. pestis infection on host survival and population dynamics.

Main Methods:

• A 3-year longitudinal study was conducted in two great gerbil populations in Kazakhstan.
• Serological surveys were used to assess Y. pestis infection prevalence and antibody titers.
• Host survival rates were monitored to evaluate the impact of infection.

Main Results:

• Serological data indicated a mid-summer peak in infectious host abundance, suggesting potential transmission to humans.
• Antibody titers decreased to undetectable levels without a clear seasonal pattern.
• Yersinia pestis infection was found to reduce the survival of otherwise asymptomatic great gerbils.
• The nitroblue-tetrazolium test was not supported as a reliable method for characterizing plague-infected hosts.

Conclusions:

• The study provides crucial insights into plague epizootiology in a key reservoir host.
• Findings highlight a seasonal risk of plague transmission from great gerbils to humans during summer.
• Y. pestis infection significantly impacts host survival, affecting reservoir population dynamics.