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193Introduction to Microbiology
be chronic nasal or throat carriers. The nasal carriers are
more dangerous than the throat carriers.
3. The nasopharyngeal secretion of the case is infective.
4. The period of infectivity is 14 to 28 days.
Host factors:
1. Age: Diphtheria particularly affects children of age 1 to
5 years of both sexes.
2. Immunity: Infants born of immune mothers are
relatively immune during the first few weeks or
months of life.
Environmental factors: Cases of diphtheria occur in all
seasons, although winter months favor its spread.
Mode of transmission: Diphtheria is spread mainly by
droplet infection, contaminated objects, or food. It may also
spread to susceptible persons directly from infected cutaneous
lesions. The bacteria most commonly infect the nose and throat.
In some cases, diphtheria may first infect the skin, producing
skin lesions.
Clinical features: Diphtheria can infect the respiratory tract
and skin. Symptoms of diphtheria depend on the body part
that is affected. It can lead to difficulty breathing, heart failure,
paralysis, open sores, or ulcers.
Prevention and control:
1. Artificial active immunization with alum-precipitated
diphtheria toxoid is effective. The commonly used
vaccine is the diphtheria, tetanus, and pertussis vaccine
(adsorbed), which protects against three common
diseases of childhood diphtheria, pertussis, and
tetanus.
2. Prompt notification and isolation of the patient at home
or in the hospital is needed.
3. Anyone who has come into contact with the infected
person should receive an immunization or booster
shots against diphtheria. Protective immunity lasts
only 10 years from the time of vaccination, so adults
need to get a booster of tetanus-diphtheria (Td) vaccine
194 Social Pharmacy
every 10 years. Those who carry diphtheria without
symptoms should be treated with antibiotics.
Treatment: Treatment should be started immediately.
1. Anti-diphtheria serum and antibiotics (penicillin, and
or erythromycin) for relief of symptoms.
2. Acute cases are promptly treated with diphtheria
antitoxin in doses of 20,000 to 50,000 IU units. The
household and other contacts may be given a
prophylactic dose of 500 to 1000 units.
3. One-lack unit of penicillin in normal saline can be
injected every 3 hours, for 2–3 days.
4. Administration of fluids by IV.
5. Bed rest.
6. Heart monitoring.
7. Insertion of a breathing tube.
8. Correction of airway blockages.
l. Whooping Cough (Pertussis)
Whooping cough is an acute respiratory infection involving
the trachea, bronchi, and bronchioles. It is a very common
childhood disease occurring in children under 5 years.
Causative organism: Bordetella pertussis or Haemophillus
pertussis or Bordetella parapertussis bacteria.
Incubation period: 7–14 days.
Epidemiological determinants:
Agent factors:
1. Source of infection: B. pertussis infects only men. The
source of infection is a case of pertussis
2. Infective material: The bacilli are present in the
nasopharyngeal and bronchial secretions, which are
infective. Objects freshly contaminated by such
discharges are also infective.
3. Period of communicability: A week after exposure
to about 3 weeks after the onset of the paroxysmal
stage.
195Introduction to Microbiology
Host factors:
1. Age: It is very common in children under 5 years.
2. Sex: Incidence and fatality are observed to be more
prevalent among female than male children.
3. Socio-economic conditions: The risk of exposure is
greater in the lower social classes living in overcrowded
conditions than in well-to-do groups.
Environmental factors: Cases of pertussis occur in all seasons,
although winter and spring months favor its spread.
Mode of transmission: Whooping cough is spread mainly
by droplet infection, contaminated fomites, and direct contact.
The main source of infection is nasopharyngeal, laryngeal, and
bronchial discharges. The germs are present in the nose and
throat of the patient and each time an infected person coughs,
sneezes or talks, these germs are spread in the air. Most children
contract the infection from playmates.
Clinical features: The disease develops slowly with fever,
cold, and an irritating cough. The child then becomes more ill
and suffers from the typical cough with the characteristic
‘whoop’ (loud crowing inspiration). During the coughing phase
the child often vomits, the eyes may bulge and breathing is
difficult.
Prevention and control:
1. The best preventive measure is the active immunization
of all infants with DPT (diphtheria, pertussis, and
tetanus) vaccine starting at 1–2 months of age.
2. The general principles of isolation, treatment, and
disinfection of discharges from the nose and throat are
applied for prevention and control.
3. It is important to protect very young and weak children
from exposure. The affected children should be kept
away from the school for 6 weeks.
Treatment:
1. Antibiotics such as erythromycin may help in
alleviating the symptoms quickly if treatment is started
early enough.
196 Social Pharmacy
2. Unfortunately, in most of the cases, whooping cough is
diagnosed too late when antibiotics are not very
effective. However, the medicines may help in reducing
the patient’s ability to spread the disease to others.
3. Infants younger than 18 months need constant super-
vision because their breathing may temporarily stop
during coughing spells.
4. Infants with severe cases should be hospitalized.
5. An oxygen tent with high humidity may be used.
6. Fluids may be given through a vein if coughing spells
are severe enough to prevent the person from drinking
enough fluids.
7. Sedatives may be prescribed for young children.
8. Cough mixtures, expectorants, and suppressants are
usually not helpful and should not be used.
m. Meningococcal meningitis
Meningococcal meningitis is a form of meningitis
(inflammation of the membranes around the brain or spinal
cord).
Causative agents: Neisseria meningitidis.
Incubation period: 1–10 days.
Epidemiology: Although meningitis affects all ages, young
children are most at risk. Higher risk is seen in people living at
mass gatherings, living in refugee camps, and overcrowded
households.
Mode of transmission: It spreads from person to person by
respiratory droplets or throat secretions.
Clinical features: Sore throat, fever, headache, stiff neck,
aching muscles, nausea, dehydration, vomiting, skin rashes,
cerebral edema, chills, sweating, weakness, loss of appetite,
photophobia, shock.
Prevention and control:
1. Vaccination.
2. Take plenty of rest.
3. Avoid close contact with sick people.
197Introduction to Microbiology
Treatment: Intravenous administration of antibiotic drugs,
like cephalosporin plus dexamethasone is generally used to
treat meningococcal meningitis.
n. Acute Respiratory Infections
Acute respiratory infections (ARI) indicate infections of any
part of the respiratory tract (upper/lower respiratory tract)
and otitis media that interfere with normal breathing. Acute
respiratory infection prevents the body from getting oxygen.
ARI is the most common cause of illness and death in infants,
children, old aged, cigarette smokers, and people with impaired
respiratory tract reserves. Anyone whose immune system
might be weakened by another disease is at risk. People with
heart diseases or other lung problems are more likely to contract
an acute respiratory infection.
Causative agent: ARI may be caused by a variety of microbial
agents including bacteria and viruses (Table 4.4).
Table 4.4: Pathogens causing acute respiratory infections
Viruses Bacteria Others
Adenovirus Streptococcus pyogenes Plasmodium
Rhinovirus Bordetella pertussis Chlamydia type B
Coronavirus Corynebacterium diphtheria
Influenza virus Haemophi/us influenzae
Enterovirus Klebsiel/a pneumoniae Legionel
Respiratory Streptococcus aureus
syncytial virus
Measles Mycobacterium tuberculosis
Many viruses and bacteria infect the respiratory tract but
do not always produce ARI. A large number of risk factors
including environment (e.g. air-pollution, passive smoking),
family circumstances (poverty, poor access to medical care),
and medical (malnutrition, prematurity, measles, chronic lung
disease, HIV/AIDS, diarrhea, malaria) increase the possibility
of developing acute respiratory infection.
Incubation period: 2–20 days.
198 Social Pharmacy
Epidemiology: ARI is the most common cause of death in
both developed and developing countries. The prevalence of
ARI is high in children under 5 years.
Mode of transmission: Acute respiratory infections causing
pathogens can spread from person to person by the airborne
route. Pathogens may also be transmitted by direct contact with
an infected person or with objects having pathogens on them.
Clinical Features: The early symptoms of acute respiratory
infection usually appear in the nose and upper lungs. Main
symptoms include: (i) congestion, (ii) running nose, (iii) cough,
(iv) sore throat, (v) body aches, (vi) fatigue, (vii) high fever
and chills, (viii) difficulty in breathing, (xi) dizziness, (x) low
blood oxygen level, (xii) loss of consciousness, and (xiii) ear
problems.
Prevention and Control:
1. Frequently wash hands.
2. Always sneeze on a tissue.
3. Avoid smoking.
4. Take a nutritious and vitamin-rich diet.
5. Immunization with MMR (measles, mumps, and
rubella) pertussis vaccine and conjugate vaccines
against Haemophilus influenzae type B, lowers the risk of
acute respiratory infection.
Treatment:
1. Appropriate use of antibiotics and bronchodilators.
2. Prompt referral of severe cases of infections and
providing pre-referral treatment.
3. Use of oxygen to treat hypoxia.
o. Tuberculosis
Tuberculosis (TB) is a specific communicable disease occurring
in acute or chronic form. It primarily affects the lungs
(pulmonary TB). It can also affect the intestine, meninges, bones
and joints, lymph nodes, skin, and other tissues of the body.
The disease also affects animals (bovine tuberculosis).
Causative organism: Tuberculosis is a contagious disease
caused by Mycobacterium tuberculosis, which attacks both
pulmonary as well as non-pulmonary tissues.
199Introduction to Microbiology
Incubation period: 4 to 6 weeks for primary lesions to 1 year
for the disease to develop.
Epidemiology: TB continues to be a major health problem in
India. There are about 10 million patients with TB and nearly
half a million die of TB every year. Symptoms of the disease
usually develop gradually.
Mode of transmission: Human sources spread infection
through droplets formed when a patient coughs, sneezes, or
talks. Bovine sources are the milk from infected animals,
especially cows. Overcrowding, poor ventilation, and lighting
favor the spread of TB. Flies may act as mechanical carriers.
Clinical features: Cough is the earliest symptom, and fever
continues for a long time. Pain in the chest, feeling of weakness,
and loss of weight are associated symptoms. Blood in sputum
appears in later stages. In an advanced stage of the disease,
the patient develops feeling out of breath on exertion. In
children, there may only be swelling of the lymph nodes.
Prevention and control:
1. Decent and sanitary dwellings.
2. Reduction of overcrowding.
3. Improvement of sanitary conditions both in residential
and occupational sites.
4. Good nutritional status.
5. Health education of the people.
6. Early detection of cases through sputum examination
and chest X-ray investigation.
7. Channels of transmission should be blocked by
advising the patient to cover his mouth with a piece of
cloth while coughing, talking or sneezing,
8. Sputum should be collected in a wide-mouthed contai-
ner with a lid and disposed of by burning, or collected
in a container with phenol and buried.
9. The patient should sleep in a separate room having
good ventilation and direct sunlight. Children should
be kept away from the patient. Separate utensils,
towels, handkerchiefs, etc. should be used by the
patient. All family members should be examined and
investigated by X-ray and sputum examination.
200 Social Pharmacy
10. To raise the immunity of non-infected persons.
11. Immunizing all newborns with BCG vaccine is an
important method of TB control. In India, BCG
vaccination is given to all newborn babies as part of the
expanded program on immunization (EPI).
Treatment: The first choice drugs used in treatment of
tuberculosis are:
1. Isoniazid.
2. Rifampicin.
3. Pyrazinamide.
4. Ethambutol.
The second choice drugs used in the treatment of
tuberculosis are:
1. Amikacin.
2. Moxifloxacin.
3. Streptomycin
4. Para-amino salicylic acid.
5. Ethionamide.
The anti-tubercular drugs should be taken according to the
prescribed schedule.
p. Ebola Virus Disease
Ebola virus disease (EVD) (formerly known as Ebola
hemorrhagic fever) is a serious disease with a 50% average
fatality rate. Recovery from EVD depends on good supportive
clinical care and the patient’s immune response. Survivors of
Ebola virus infection have antibodies that can be detected in
the blood up to 10 years after recovery.
Causative agent: EVD is caused by a group of viruses of the
genus Ebolavirus (Filoviridae family) including Ebola virus
species Zaire ebolavirus (EBOV), Sudan virus (SUDV), Taï Forest
virus (TAFV), Bundibugyo virus (BDBV).
Incubation period: 2–21 days.
Epidemiology: Ebola appeared for the first time in Zaire and
Sudan in 1976. The Ebola outbreak in West Africa in 2014–2016
was a major one. The 2018–2019 outbreak in the eastern
201Introduction to Microbiology
Democratic Republic of the Congo (DRC) was very complex,
adversely affecting public health response activities. EVD is
most common in human beings and non-human primates
(monkeys, gorillas, and chimpanzees). The bats carrying the
virus can transmit it to other animals.
Epidemiological determinants:
Agent factors:
1. Bats of the Pteropodidae family are the natural Ebola
virus host.
2. The bats carrying the virus can transmit it to other
animals.
Host factors: The case fatality rate is 60–70%.
Mode of transmission: Persons infected with Ebola can
spread the disease to others only after they develop symptoms
of illness. The Ebola virus spreads through close contact with
the:
1. Blood or body fluids (urine, saliva, sweat, feces, vomit,
breast milk, and semen) of an infected person.
2. Objects (such as needles and syringes) that have been
contaminated with body fluids (like blood, feces, vomit)
from a person sick with Ebola.
3. Semen from a man recovered from EVD. Semen of a
person may carry the virus for several weeks to months
after recovery from EVD.
During an Ebola outbreak, healthcare workers have a chance
of getting infected if precautions are not strictly practiced. They
should wear masks, and PPE kits, and must use disposable
needles and syringes, and properly sterilized equipment. Burial
ceremonies that involve direct contact with the body of the
deceased can also contribute to the transmission of Ebola.
Clinical features: Symptoms of EVD can be sudden and
include: (i) Fever, (ii) fatigue, (iii) muscle pain, (iv) severe
headache, (v) sore throat, (vi) weakness, (vii) vomiting,
(viii) diarrhoea, (ix) rash, (x) abdominal (stomach) pain,
(xi) septicemia, (xii) renal failure, (xiii) liver failure, and (xiv)
unexplained hemorrhage (bleeding or bruising).
202 Social Pharmacy
Prevention and control:
1. Avoid close contact with the blood and body fluids
(such as urine, feces, saliva, sweat, vomit, breast milk,
semen, and vaginal fluids) of an infected person.
2. Avoid direct or close contact with items that may have
come in contact with an infected person’s blood or body
fluids.
3. Wear gloves and appropriate personal protective
equipment (PPE) while taking care of ill patients.
4. Wash hands regularly after visiting patients in the
hospital, as well as after taking care of patients at home.
5. Ensure the safe and dignified burial of the body of
someone who died from EVD.
6. Avoid contact with bats and non-human primates or
blood, fluids, and raw meat prepared from these
animals (bush meat) or meat from an unknown source.
7. Handle animals with gloves and other appropriate
protective clothing.
8. Consume thoroughly cooked animal products (blood
and meat).
Treatment: There is no licensed vaccine against Ebola virus
disease and the treatment is only symptomatic. Following basic
interventions can significantly improve the chances of survival
if given timely manner.
1. Provide fluids and electrolytes (body salts) intra-
venously or orally.
2. Offer oxygen therapy to maintain oxygen status.
3. Use medication to support blood pressure, reduce
vomiting and diarrhea and to manage fever and pain.
4. Treat other infections, if they occur.
B. Intestinal Infections
a. Poliomyelitis
Poliomyelitis is an acute, viral, infectious disease, affecting the
central nervous system and resulting in paralysis of voluntary
muscles of the lower extremities. The legs are more affected
than the arms. The attack begins with fever, headache,