Bacterial Diseases

Common Bacterial diseases include Diarrhoea, Dysentery, Typhoid, Whooping Cough, TB, Diphtheria, Cholera etc.


Diarrhea can be caused by all sorts of parasites including viruses, Bacteria and protozoa.  Most common virus causing Diarrhoea in adults is Norovirus.  Most common virus causing Diarrhoea in children below 5 years is rotavirus. A rotavirus vaccine Rotavac has been recently launched in India.

Most common bacteria causing Diarrhoea is campylobacter; others are salmonellae, shigellae and some strains of Escherichia coli (E.coli).


Dysentery is usually caused by a bacterial or protozoan infection or infestation of parasitic worms, but can also be caused by a chemical irritant or also viral infection. The most common cause of the disease in developed countries is infection with a bacillus of the Shigella group (causing bacillary dysentery). Infection with the amoeba Entamoeba histolytica can cause amoebic dysentery


Typhoid is transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella enterica enterica. The bacteria perforate through the intestinal wall and are phagocytosed by macrophages. It is a G- short bacillus that is motile due to its peritrichous flagella.

Whooping Cough

Pertussis or Whooping cough is a highly contagious bacterial disease caused by Bordetella Pertussis.


Tuberculosis is caused by various strains of Mycobacterium, usually Mycobacterium tuberculosis. It usually attacks the lungs but can also affect other parts of the body. It is spread through the air when people who have active infection cough, sneeze, or spit. In most cases the disease is asymptomatic, latent infection, and about 10% latent infections eventually progresses to active disease. If untreated, it killed 50% of its victims.


TB that is resistant at least to isoniazid  and rifampicin  the two most powerful first-line anti-TB drugs is called the Multi-drug-resistant tuberculosis (MDR-TB). It develops because the when the course of antibiotics is interrupted and the levels of drug in the body are insufficient to kill 100% of bacteria. This means that even if the patient forgets to take medicine, there are chances of developing MDR-TB. MDR-TB is treated with secondline of antituberculosis drugs such as a combination of several medicines called SHREZ (Streptomycin+isonicotinyl Hydrazine+Rifampicin+Ethambutol+pyraZinamide)+MXF+cycloserine.


When the rate of multidrug resistance in a particular area becomes very high, the control of tuberculosis becomes very difficult. This gives rise to a more serious problem of extensively drug-resistant tuberculosis (XDR-TB). XDR-TB is caused by strains of the disease resistant to both first- and second-line antibiotics. This confirms the urgent need to strengthen TB control.

Extent of TB

One third of the world’s population is thought to be infected with M. tuberculosis, and every second a new infection occurs. About 80% of the population in many Asian and African countries test positive in tuberculin tests.  The highest number of deaths from TB is in Africa Region.

HIV and TB

HIV and TB form a lethal combination, each speeding the other’s progress. TB is a leading cause of death among people who are HIV-positive. In Africa, HIV is the single most important factor contributing to the increase in the incidence of TB since 1990. Tuberculosis was declared a global emergency by the WHO in 1993.


BCG (Bacillus Calmette-Guérin) was the first vaccine for TB that discovered in 1905 by Albert Calmette and Camille Guérin. Once WHO declared TB a global emergency, BCG vaccine along with DOTS was used in more than 192 countries as a preventive therapy. However, there was a controversial side of BCG vaccination that it showed variable efficacy, that depended on geography. It was concluded that BCG efficiency goes down as one gets closer to equator. There were several explanations to this phenomenon. One such theory said that in areas where there are high levels of background exposure to tuberculosis, every susceptible individual is already exposed to TB prior to BCG, which is why the natural immunizing effect of background tuberculosis duplicates any benefit of BCG. This means that BCG is less effective in the area where the Mycobacteria are less prevalent. Another theory says that Variable efficacy is because of the Genetic variation in BCG strains.


DOTS, is an acronym for Directly Observed Treatment, Short course. The DOTS strategy represents the most important public health breakthrough of the decade, in terms of lives which will be saved. It is based largely on research done in India in the field of TB over the past 35 years.


Leprosy or Hansen’s disease is caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Leprosy has a high degree of stigma attached to it because of the fact that there was no cure for the disease till the eighties and also due to disfigurement caused by the disease.

Some drugs such as rifampicin, clofazimine, and dapsone are used to treat Leprosy.


Diphtheria is caused by Corynebacterium diphtheriae, an anaerobic Gram-positive bacterium. It is an acute respiratory disease caused by bacteria, which leads to a thick coating in the nose, throat or airway. Diphtheria takes its name from Greek word ‘dipthera’ referring to the leathery membrane or coating that grows on the tonsils, throat and in the nose.

Diphtheria is a purely vaccine-preventable disease and effective vaccine is available.


Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting.

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