Biology Today — May 2017

Bacterial Diseases

Typhoid

• Typhoid is a common bacterial disease caused by a rod-like bacterium, Salmonella typhi, which is commonly found in the
intestine of man.

Mode of transmission

• Typhoid spreads via faecal oral route, i.e., through food and water contaminated with faeces of the patient. House flies may
carry the pathogens from the faeces to the food, milk and water.

• Incubation period varies from 1-3 weeks (average 2 weeks).

Symptoms

• This disease is characterised by the inflammation of ileum and colon, enlargement of liver and spleen, abdominal pain, pea-soup
diarrhoea which may become haemorrhagic, constant fever, extreme weakness, vomiting, rash causing rose spots on the upper
abdomen and sore throat.

• Typhoid is diagnosed by Widal test.

Prevention and Treatment

Isolation and

hygienic disposal

of faeces

Purification

of water

supplies

Reduction in contamination

of food by personal

hygiene and control of flies

Giving TAB vaccine

which provide immunity

for about   3    years

Antibiotics like

ciprofloxacin and

chloramphenicol

Proper

sewage

treatment

Anthrax

• Anthrax is an acute infectious disease caused by air-borne, spore-forming, rod-like, non-motile bacterium, Bacillus anthracis.

• Anthrax spores can be produced in a dry form which can be stored as particles that can be used in biological warfare.

Mode of transmission

• Infected animals shed a large number of bacilli (bacteria) in the discharges from the mouth, nose and rectum which sporulate in
the soil. These spores act as source of infection.

• It requires thousands of spores to cause human infection. Anthrax does not spread from human to human.

Symptoms

• Initial symptoms resemble those of common cold. Later there is difficulty in breathing, cough, fever, fast pulse and cardiovascular
collapse.

• If left untreated, anthrax in all forms can lead to septicemia and death.

Prevention and treatment

• The only known effective prevention against anthrax is the anthrax vaccine, which was developed from an attenuated strain
of B. anthracis.

• A suitable antibiotic like ciprofloxacin is quite effective, particularly if used in the initial stages of disease. But in cattle, ciprofloxacin
may be effective only in chronic condition.
Table: Other bacterial diseases
Disease Pathogen Mode of
transmission/
Incubation period

Symptoms Control measures/

Treatment

1. Cholera Vibrio cholerae Contaminated food and
   drinks / 2 - 3 days

Vomiting, dehydration,

muscular cramps

Proper sanitation/ORS,

tetracycline

2. Diarrhoeal
   diseases

E.coli, Shigella,

Campylobacter, Salmonella,

Clostridium

Contaminated food and

drinks/variable period

Frequent stools with

blood, dehydration, low

blood pressure

Proper sanitation /ORS