Bubonic plague as bio terrorism:
Abstract :
It is very fortunate to discover wide range of antibiotics.Every year there are sporadic cases all over the world especially in Chinese sub continent.
History
The black death was devastating pandemic that first hit Europe in the middle of 14th century 1347 to 1351 {Medivalise} killing 40 to 60% of European population.
Bubonic plague : The best known variant of deadly infectious disease plague caused by Yersinia pestis {Enterobactreiaceae}.
Deaths - 80 million
Sequence of pandemics:
300 B.C Libia Syria Egypt
1st pandemic { Antique} :
532 A.D Egypt
541 A.D Turkey Constantipole
543 A.D Italy
2nd pandemic{ Medivalis} :
In 1334 an epidemic occurred.After a decade it spread to European countries through trade route.
* Giovani Boccaccio described palgue as black death.
Trade route of spread:
Katta{Mangolia} - Bhagdad, Constantipole, Alexandria and then to European countries
3rd pandemic {Orientalis} :
Started in 1855.
In the period from 1894 to 1903 India wa affected and the deaths were 12 million
And in 2002 and 2003 re emergence of infection occurred.
In 2009, an outbreak occurred in Tibetian plateau.In 2014, Chinese city new cases were registered. In 2010 -2015,3248 cases all over the world reported.
CDC{Centre for Disease Control} categorised palgue into Category A bio terrorism{bio war}.
Course of disease:
Types : Bubonic plague ,Pnuemonic plague ,Severe septicemic plague
Flea : Xenopsiella cheopis
When an infected flea bites a rodent then it gets infected. Hereafter humans get infected either by feeding on infected rodents or bitten by infected by rat fleas. Most pandemics are due to human to human transmission via trade route.
Bubonic plague:
Actually blood route results in bubonic plague. Extracellular multiplication occurs rapidly at 37 degree Celsius temperature of host's body and then several virulence factors causes inflammatory response spreading infection to regional lymph nodes {bubo} by lymphatics.
V antigen - 11 surface and secreted proteins Yersinia outer membrane proteins{YOP} like YOP H, YOP E and YOP M causes anti phagocytic , cytotoxic effects and binds thrombin respectively. Finally leads to peripheral vascular collapse and disseminated intra vascular coagulation.
Primary septicemic plague leads to septicemia and death.
Details of Yersinia pestis:
Incubation period is 2 to 6 days.
Microscopic details : Non motile, gram negative bacillus , safety appearence.
Culture : At 28 degree Celsius in blood agar and Mc conkey agar.
Clinical features : malaise, shaking chills, fever, lymphadenopathy{1 -10 cms lymph nodes}.
Pnuemonic plague:
Fulminant variant with 100% mortality rate associated with lobar pnuemonia and respiratory distress syndrome. Cough, productive sputum, chest pain, dyspnea, hemoptysis associated with nausea, vomiting and abdominal pain.
Treatment:
Must be given within 18 -24 hours.
Drug of choice is Streptomycin i.m {FDA approved} but is costly.
Gentamycin is preferred.
Oral drug of choice is Doxycycline.
What's new ?
Recent studies show that the pathogen is very sensitive to heat and sunlight and cannot survive outside the body of the host. It may survive in wet soil and humid conditions and decaying animal carcass. So anti plague aerosols are prefered to avoid the spread of pneumonic plague. Antibiotic therapy is recommended till clinical improvement and the patient must be isolated for first 48 hours during treatment. N95 masks with air filters and negative pressurised rooms are prefered to avoid transmission of disease.