Plague, caused by a bacterium called Yersinia pestis, is transmitted from rodent to rodent by infected fleas.
Plague is characterized by periodic disease outbreaks in rodent populations, some of which have a high death rate. During these outbreaks, hungry infected fleas that have lost their normal hosts seek other sources of blood, thus increasing the increased risk to humans and other animals frequenting the area.
Plague is an ancient disease that is not likely to disappear, its continued outbreaks throughout the world attest to its tenacious presence. Since the first descriptions, many studies have examined the transmission, epidemiology and pathogenesis of the disease (Gage, 1998). Plague is a bacterial infection of small mammals transmitted from animal to animal by the bite of infected fleas. Plague cycles naturally in its enzootic foci, circulating between small mammals and fleas without human involvement. The quiescent periods, during which few or no human cases are detected, may last for years, leading to mistaken declarations of plague eradication. However long the silent periods last, plague may suddenly reappear. The combination of false assurance of its eradication, and the failure of public health vigilance, sets the stage for the panic that may ensue when enzootic plague spills over from its natural cycle into the peridomestic and commensal rodent populations (and their fleas), bringing plague into closer human contact. Poor sanitation, overcrowding and high numbers of rodents are conditions that enhance urban plague transmission. Thus, a plague outbreak has come to represent an indictment of social, environmental and political changes in the modern world.
Perspective and history: Plague has a remarkable place in history. For centuries, plague represented disaster for those living in Asia, Africa and Europe, where, it has been said, populations were so affected that sometimes there were not enough people left alive to bury the dead (Gross, 1995). Because the cause of plague was unknown, plague outbreaks contributed to massive panic in cities and countries where it appeared. The disease was believed to be delivered upon the people by the displeasure of the gods, by other supernatural powers or, by heavenly disturbance.
Innocent groups of people were blamed for spreading plague and were persecuted by the panicked masses. Numerous references in art, literature and monuments attest to the horrors and devastation of past plague epidemics. So imprinted in our minds is the fear of plague that, even now, entering into the 21st century, a suspected plague outbreak can incite mass panic and bring much of the world's economy to a temporary standstill. The number of human plague infections is low when compared to diseases caused by other agents, yet plague invokes an intense, irrational fear, disproportionate to its transmission potential in the post-antibiotic/vaccination era.
In Maharashtra State, Plague surveillance unit is established in the year 1953. Since establishment, regular Plague survey is carried out in Plague prone areas. But till 1987, no confirmed case of plague was detected and hence the plague unit was abolished from 1th December 1987.
During August and September 1994, there was suspected outbreak of Plague in village Mamla of District Beed. Total 634 serologically positive cases from all over State were reported. Therefor, Plague Surveillance Unit is reestablished from 3rd October 1994 and is functioning under Joint Director Of Health Services, (M&F), Pune till to date. Infrastructure of State and staffing pattern of Plague Surveillance Unit is given in Annexure I & II respectively.