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203Introduction to Microbiology
vomiting, pain, and stiffness of the neck, sometimes convulsions
followed by paralysis of a limb. Death may occur in rare cases.
Causative organisms: It is caused by poliovirus, which has
three distinct serotypes, 1, 2, and 3. Type 1 is most predominant
during epidemics. The virus inhabits the alimentary canal and
throat of man.
Incubation period: 7 to 14 days.
Epidemiological determinants:
Agent factors:
1. Type 1 virus is most predominant during epidemics.
The source of infection is a case or carrier of cholera.
2. The human being is the only known reservoir of
cholera infection.
3. Feces and oropharyngeal secretions of a case are
infective.
4. The period of communicability is 7 to 10 days before
and after the onset of symptoms.
Host factors:
1. Age: Poliomyelitis affects children of all ages, especially
those below 5 years of age. Acute poliomyelitis or
infantile paralysis is one of the main crippling diseases
of childhood.
2. Gastric acidity: The vibrio is destroyed in an acidity of
pH 5 or lower.
3. Population mobility: The movement of people increa-
ses the risk of exposure to infection.
4. Economic status: The incidence of cholera tends to be
the highest in the lower socio-economic groups.
5. Immunity: Re-infection can occur since infection with
one type does not protect completely against the other
two types of viruses.
Environmental factors:
1. Polio is more likely to occur during the rainy season.
2. Contaminated water, food, and flies increase the
transmission of disease.
Mode of transmission: It is transmitted usually by the fecal-
oral route, through direct contact, and sometimes through milk.
204 Social Pharmacy
The virus multiplies in the throat and intestinal tract and then
is absorbed and spreads through the blood and lymph system.
The symptoms of the disease develop after 5–35 days (average
7–14 days) from the time of infection.
Prevention and control: The following measures are
recommended:
1. Notification and isolation of the patient.
2. Proper disposal of urine and feces. The feces remain
infective for 4 weeks.
3. All sources of water supply should be properly
protected and supply of safe and potable drinking
water must be ensured.
4. Overcrowding in schools, theatres, and other places
should be avoided.
5. Active immunization of all children with polio vaccine.
Two types of vaccines are used throughout the world:
i. Inactivated (Salk) polio vaccine (IPV).
ii. Oral (Sabin) polio vaccine (OPV).
Under the Expanded Program on Immunization
(EPI), routine administration of three doses of oral
polio vaccine is recommended for the age group of
3 to 9 months. A single booster dose is given at the
age of 18 months. Hot fluids should be given for half
an hour after the vaccine has been administered.
iii. Anti-fly measures should be intensified.
Treatment: Unfortunately there is no specific treatment. The
following measures are taken to control symptoms while the
infection runs its course:
1. Complete bed rest preferably in the hospital is essential.
2. The affected limb should be supported.
3. The limb should be provided passive movements to
prevent contractures.
4. Severe cases may need life-saving measures, especially
breathing help.
5. Symptoms are treated based on their severity.
6. Urinary tract infections are treated with antibiotics.
205Introduction to Microbiology
7. Urinary retention is treated with medicines like
bethanechol.
8. Moist heat (heating pads, warm towels) is used to
reduce muscle pain and spasms.
9. Physical therapy, braces, and corrective shoes should
be provided to prevent contractures and recover
muscle strength and function.
b. Viral Hepatitis
Hepatitis is a liver disease characterized by inflammation of
liver cells. There are different types of hepatitis, viz.:
i. Hepatitis A
ii. Hepatitis B
iii. Hepatitis C
iv. Hepatitis D
v. Hepatitis E
vi. Hepatitis G.
Causative organism: Hepatitis is caused by Hepatitis viruses
(Type A, B, C, D, E, G) of the Picornaviridae family.
Incubation period:
Hepatitis A: 10–50 days.
Hepatitis B: 30–180 days.
Hepatitis C: 2 weeks–6 months.
Epidemiology: It is an endemic disease common in children
and young adults all over the world. Epidemics also occur
frequently.
Epidemiological determinants:
Agent factors:
1. The source of infection is a case of hepatitis.
2. Feces, blood, serum, and other fluids are infectious.
3. The period of communicability is greatest from 2 weeks
before to 1 week after the onset of jaundice.
Host factors:
1. Age and sex: It occurs mostly in children of both sexes
than adults. However, people of all ages may be
infected, if susceptible.
206 Social Pharmacy
2. Immunity: The disease confers life-long immunity in
95% of cases.
Environmental factors: Hepatitis does not show a seasonal
trend but most infections occur in rainy seasons.
Mode of transmission:
1. Hepatitis spreads mainly by the fecal-oral route. The
virus is excreted in the stools of the patient.
2. Contamination of water and food may lead to explosive
outbreaks. The disease is also spread by direct contact.
3. As a sexually transmitted infection, hepatitis A may
occur mainly among homosexual men because of oral-
anal contact.
Clinical features: The onset is accompanied by anorexia
followed by progressive jaundice and hepatitis, which may
sometimes end in coma and death.
Prevention and control:
1. Improvement in sanitation.
2. Use of only boiled water for drinking during epidemics.
3. Intensification of anti-fly measures.
4. Active immunization against hepatitis.
Treatment: There is no specific treatment. The patient must
take complete bed rest for 2–3 weeks. A diet rich in fruit juices
and glucose is recommended. Fatty foods should be avoided.
c. Cholera
Cholera is an acute specific infection of the gastrointestinal tract.
Causative organism: Cholera is caused by Vibrio cholera,
which is a Gram-negative, actively motile, comma-shaped
bacteria.
Incubation period: 1 to 2 days.
Mode of transmission: Cholera is spread by fecal-oral route,
through ingestion of polluted water or contaminated food. It
can also spread through clothes and linen soaked with
discharges of infected persons. Flies also spread the infection.
Persons attending cholera patients must wash their hands
properly to avoid infecting the food, drink, or themselves.
207Introduction to Microbiology
Epidemiology: It occurs in people of all ages and both sexes
are affected. It occurs in summer and autumn. Cholera is
endemic in Maharashtra, Tamil Nadu, Madhya Pradesh, Assam
and Andhra Pradesh.
Epidemiological determinants:
Agent factors:
1. The source of infection is a case or carrier of cholera.
2. The human being is the only known reservoir of cholera
infection.
3. Stools and vomit of cases and carriers of cholera are
infective.
4. The period of communicability is 8 days to weeks/
months.
Host factors:
1. Age and sex: Cholera affects all ages and both sexes.
2. Gastric acidity: The vibrio is destroyed in an acidity of
pH 5 or lower.
3. Population mobility: The movement of people
increases the risk of exposure to infection.
4. Economic status: The incidence of cholera tends to be
the highest in the lower socio-economic groups.
5. Immunity: The disease does not confer lifelong
immunity.
Environmental factors:
1. Contaminated water and food increase the trans-
mission of disease.
2. Soil pollution, low standards of personal hygiene, lack
of education, and poor quality of life are responsible for
the transmission of disease.
Clinical features: Cholera is characterized by:
1. Sudden onset of severe watery diarrhea and vomiting
resulting in extreme dehydration.
2. Death, if dehydration is not corrected.
3. Low blood pressure and collapse.
Prevention and control:
1. Compulsory and prompt notification of cases and
isolation of patients.
208 Social Pharmacy
2. The sprinkling of lime water on the floor of the patient’s
room.
3. Anti-fly measures.
4. Disinfection of patient’s excreta and linen are the
preventive measures.
5. Prophylactic immunization with the cholera vaccine is
effective. Cholera vaccine contains killed bacteria and
is administered subcutaneously in 2 doses of 0.5 mL
each at an interval of 4 to 6 weeks.
Treatment: The treatment consists of oral rehydration
therapy and antibiotics. The objective of oral rehydration
treatment is to replace fluid and electrolytes lost through
diarrhea. Depending on the condition of the patient, fluids may
be given by mouth or intravenously. The World Health
Organization (WHO) has developed an oral rehydration
solution that is cheaper and easier to use than the typical
intravenous fluid. This solution of sugar and electrolytes is now
being used internationally.
Tetracycline and chloramphenicol in doses of 500 mg of
either drug 4 times a day is recommended for 3 days. Furalizine
and septran are also recommended as alternative drugs.
d. Acute Diarrhoeal Disease
It is a common illness in children under 5 years old. A
significant proportion of diarrheal disease can be prevented
through safe drinking water and adequate sanitation and
hygiene. Diarrhea is usually a symptom of an infection in the
intestinal tract, which can be caused by a variety of bacterial,
viral, and parasitic organisms.
Causative agents: It is caused by a variety of bacterial, viral,
and parasitic organisms such as Rotavirus and Escherichia coli,
Cryptosporidium, and Shigella species.
Epidemiology: Water contaminated with human feces, for
example, from sewage, septic tanks, and latrines, is of particular
concern. Animal feces also contain microorganisms that can
cause diarrhea. Diarrhoeal disease is a leading cause of child
mortality and morbidity in the world and mostly results from
209Introduction to Microbiology
contaminated food and water sources. Worldwide, 780 million
individuals lack access to improved drinking water, and 2.5
billion lack improved sanitation. Diarrhea due to infection is
widespread throughout developing countries.
Epidemiological determinants:
Agent factors:
1. The source of infection is a case or carrier of cholera.
2. Man is the only known reservoir of infection.
3. Stools and vomit of cases and carriers of cholera are
infective.
4. The period of communicability is 8 days to weeks/
months.
Host factors:
1. Age and sex: It affects children especially those
between 6 months and 2 years of both sexes.
2. Malnutrition: It is more common in persons with
malnutrition.
3. Population mobility: The movement of people
increases the risk of exposure to infection.
4. Economic status: The incidence tends to be the highest
in the lower socio-economic groups.
5. Immunity: The disease does not confer life-long
immunity.
Environmental factors:
1. Contaminated water and food increase the trans-
mission of disease.
2. Soil pollution, low standards of personal and domestic
hygiene, lack of education, and poor quality of life are
all contributory factors.
Mode of transmission: Diarrhoeal disease can also spread
from person to person, aggravated by poor personal hygiene.
Food is another major cause of diarrhea when it is prepared or
stored under unhygienic conditions. Unsafe domestic water
storage and handling is also an important risk factor. Fish
and seafood from polluted water may also contribute to the
disease.
210 Social Pharmacy
Clinical features:
1. Severe dehydration.
2. Lethargy/unconsciousness.
3. Sunken eyes.
4. Skin pinch goes back very slowly (>2 seconds).
5. Restlessness.
6. Irritability.
7. Sunken eyes.
Prevention and control:
1. Provision of safe drinking water.
2. Adequate sanitation and hygiene.
3. Exclusive breastfeeding for the first 6 months to
newborns.
5. Good personal and food hygiene.
Treatment:
1. Oral rehydration solution (ORS).
2. 20 mg zinc tablets.
3. Rehydration with intravenous fluids in case of severe
dehydration or shock.
e. Typhoid
Typhoid is an acute communicable disease.
Causative organism: Typhoid is caused by the bacillus
Salmonella typhi.
The incubation period: 10 to 14 days.
Epidemiology: Typhoid is usually endemic and occurs
throughout the year but higher numbers of cases are reported
during the rainy season. It is most common in the age group of
6 to 30 years.
Epidemiological determinants:
Agent factors:
1. The source of infection is a case or carrier.
2. A case (or carrier) is infectious as long as bacilli appear
in stools or urine.
3. Man is the only known reservoir of infection.
211Introduction to Microbiology
4. Stools and urine of cases and carriers of typhoid are
infective.
Host factors:
1. Age and sex: Typhoid affects people of all ages and
sexes. The highest incidence occurs in the 5–19 years of
age group.
2. Economic status: The incidence tends to be the highest
in the lower socio-economic groups.
3. Immunity: The disease does not confer life-long
immunity.
Environmental factors:
1. Enteric fever does not show a seasonal trend and the
peak incidence is reported during July–September.
2. Contaminated water and food increase the trans-
mission of disease.
3. Soil pollution, low standards of personal and domestic
hygiene, lack of education, and poor quality of life are
all contributory factors.
Mode of transmission: The disease spreads through the fecal-
oral route. The bacilli are excreted in the stools and urine.
Indiscriminate defecation and urination lead to the spread of
infection through soil, water, food, and flies. The disease
spreads chiefly by ingestion of contaminated food, water, milk,
and milk products and by consumption of unwashed, raw
vegetables. Typhoid can also spread through direct contact,
and in a small proportion of cases, through vomits, i.e. infected
bedclothes, towels, etc.
Clinical features:
1. Fever
2. Bradycardia
3. Pea soup diarrhea
4. Rose spots on the chest.
Prevention and control:
1. Prompt detection, isolation, and treatment of suffering
patients are very important in controlling outbreaks of
typhoid fever.
212 Social Pharmacy
2. Food should be protected from flies.
3. Raw vegetables and fruits should be taken only after
washing them in a weak solution of potassium
permanganate.
4. Drinking water and milk must be boiled.
5. Improvement of sanitation especially by ensuring safe
and potable water supply, proper excreta disposal, etc.
constitutes a very useful control measure.
6. TAB vaccine protects against typhoid. The vaccine is
given in 2 doses of 0.5 mL each subcutaneously at an
interval of 4 to 6 weeks. Under the expanded program
on immunization (EPI), all children are immunized
with the TAB vaccine at the time of school entry.
Treatment: The patient requires complete bed rest during
the period of fever and for at least 10 to 15 days after the fever
comes down; the patient must be given a soft diet as there is
ulceration in the small intestine.
In most cases typhoid fever is not fatal hence antibiotics are
used in its treatment.
1. Third-generation cephalosporins (ceftriaxone, cefo-
taxime, cefixime) are the treatment of choice. Fluoro-
quinolones such as ciprofloxacin and ofloxacin may be
used as first-choice drugs.
2. Ampicillin, chloramphenicol, trimethoprim-sulfa-
methoxazole, amoxicillin, and ciprofloxacin are also
used to treat typhoid.
f. Amoebiasis
Amoebiasis is an infection of the intestines and a cause of
diarrhea.
Causative agents: Entamoeba histolytica.
Incubation period: 1–3 weeks.
Epidemiology: Amoebiasis is common among people living
in poor sanitation and travelers to developing countries. It most
commonly affects young to middle-aged adults.