The great monument, the Charminar of Hyderabad, AP, India was constructed between 1591 to 1593 by Mohd. Quli Qutbshah to commemorate the ceasation of a natural outbreak of plague in man.
Plague is an acute, febrile disease of rodents and other animals caused by infection with Yersinia pestis. It is normally present among wild rodents and is accidentally transmitted to human beings by flea-bite, or inhalation.
Plague occurs in 2 different epidemic forms.
Plague as a biological weapon
Plague was also used as a potential bio-terrorist agent in wars against China, Soviet Union.
Intentional dessimination of plague bacillus by an aerosol route was used as a biological weapon. Releasing plague infested fleas in populated areas also caused outbreakes of plague. Aeriolisation of plague bacillus was also attempted. The size of outbreak depends on the characters of the strain, quantity of the biological agent used, environmental conditions and methods of aereolisation. Symptoms begin 1-6 days after the exposure and people die quickly following onset of symptoms. Bubonic menifestations may be absent.
Yersinia pestis is a gram-negative, small, non-motile cocco- bacillus measuring about 1.5 X 0.7 um. It is capsulated and shows bipolar staining resembling a safety pin.
Rat flea - Xenopsylla cheopis, X austia, X brasilliensis and Pulex irritants ingest blood containing plague bacilli from the diseased rat. The bacilli multiply in the gut of the flea. When the rat dies the fleas leave the body of the rat and attack another rat, and the cycle continues.
The flea may bite human beings. The person who is bitten by the infective flea may develop plague.
Plague bacillus enters the body by the bite of infected flea they multiply rapidly and cause lymphadinitis with subsequent symptoms.
(1)Patients develop symptoms of bubonic plague 2-8 days after the bite of a flea. There is sudden onset of fever, chills and weakness. The glands are swollen and painful. The buboes most typically develop in groin, axella or cervical region. Bubos are about 1 - 10 cm in diametre and the skin is red in color. They are extremely tender, non-fluctuent and hot with considerable surrounding odema. Death of digits and nose may occur in advanced cases and derived the name black death.
It usually arises secondary to Bubonic plague. Septicaemic plague may lead to dessiminated intravascular coagulation, necrosis of small vessels and blood tinged skin lesions.
It is caused due to inhalation of the organisms in the aerosols. It involves the lungs and is chracterised by temperature, malaise and respiratory symptoms. This can occur as a consequence of Bubonic or septicaemic plague or can be aquired through air-borne route during close contact with Pnuemonic plague patients. As a consequence of biological weaponisation or handling the culture in the laboratory pneumonic plague can also occur
Sudden appearance of large number of patients with fever cough, shortness of breath, chest pain and fulminent course leading to death suggest the possibility of pneumonic plague. Bubo formation occurs in natural transmissions. Haemoptisis (blood coming from lungs through mouth) strongly suggest plague.
Bubo aspirates, blood and sputum should be collected and sent for laboratory diagnosis. Microscopically on wayson's rapid staining, the bipolar stained bacteria are diagnostic of plague. Fluorescent antibody testing also gives positive reaction.
Y pestis can be cultured on blood agar, macconkys-agar and can be identified by appropriate laboratory methods.
Control in human beings
A patient with plague must be kept in isolation for 72 hours after antibiotic treatment is started. When there are lot of dead rats(ratfalls) plague should be suspected.
Control of Fleas
Control of fleas with disinfectents like 10% DDT or 3% BHC or 0.5% malathyon.
Control of rats
Mass destruction of rats by anti-rodent drugs like zincphosphate, veraphrin and improving general sanitation.
Control by vaccination
Halfkins vaccine will give protection against bubonic plague and not against pneumonic plague. Two doses given at an interval of 7-14 days will give protection for about 6 months commencing from the 7th day after the second injection. Boosters are recommended every 6 months.
Doctors , nurses, microbiologists and all other health workers actively conneccted with plague work should take tetracyclin 500mg every 6 hrs for 5 days.
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