The
plague of man is a severe, systemic bacterial
infectious disease. Without antibacterial
therapy, the disease is associated with a high case fatality rate, ranging from 40% (
bubonic plague) to nearly 100% (septicemic and
pneumonic plague). The disease is caused by Yersinia pestis, a non-motile, gram-negative, facultative anaerobic bacterium belonging to the family of Enterobacteriaceae. In nature, Y. pestis has been found in several rodent species and some other small animals such as shrews. Within its reservoir host, Y. pestis circulates via flea
bites. Transmission of Y. pestis to humans occurs by the
bite of rat fleas, other flea vectors or by non vectorial routes, e. g., handling infected animals or consumption of contaminated food. Human-to-human transmission of the pathogen occurs primarily through
aerosol droplets. Compared to the days when
plague was a pandemic scourge, the disease is now relatively rare and limited to some rural areas of Africa. During the last ten years, however,
plague outbreaks have been registered repea- tedly in some African regions. For treatment of
plague,
streptomycin is still considered the
drug of choice.
Chloramphenicol,
doxycycline,
gentamicin and
ciprofloxacin are also promising drugs.
Recombinant vaccines against
plague are in clinical development.