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223Introduction to Microbiology
system. Heavily infected areas exist in Uttar Pradesh, Bihar,
Andhra Pradesh, Odisha, Tamil Nadu, Kerala and Gujarat.
People of all ages and both sexes are susceptible.
Epidemiological determinants:
a) Agent factors:
1. Microfilariae (Mf) of W. bancrofti and B. malayi display a
nocturnal periodicity, i.e., they appear in large numbers
at night.
2. The source of infection is a person with circulating Mf
in peripheral blood.
Host factors:
1. Age: It affects all ages.
2. Sex: Males are more frequently exposed to the risk of
acquiring disease than females.
3. Immunity: Man may develop resistance to infection
only after many years of exposure.
4. Housing: Poor sanitation provides ideal resting places
for mosquitoes.
Environmental factors: Bad drainage, inadequate sewage
disposal, and lack of town planning aggravate the problem of
filariasis.
Mode of transmission: The disease is transmitted from an
infected person to a new host through the bite of a mosquito.
The main vectors are Culex fatigans and Mansonides mosquitoes.
Clinical features:
1. Fever.
a. Lymphedema.
b. Testicular pain.
c. Skin exfoliation.
d. Limbor genital swelling.
e. Hardening and thickening of the skin of the legs,
arms, scrotum, vulva, and breasts.
f. Dry nocturnal cough, shortness of breath, and
wheezing.
g. Ocular lesions.
h. Loss of visual acuity.
224 Social Pharmacy
Prevention and control:
1. Protection from mosquito bites.
2. Adult mosquito control (vector control) can be
achieved by insecticidal spray, larvicidal measures,
removal of aquatic plants, and improvement of
environmental sanitation.
3. Health education of the people is most important in
dealing with the problem of filariasis.
Treatment:
1. Albendazole (a broad-spectrum anthelmintic) combi-
ned with Ivermectin is the treatment of choice.
2. A combination of diethylcarbamazine (DEC) and
albendazole is also effective.
3. All of these treatments are microfilaricides; they do not
affect the adult worms.
d. Chickunguna
Chikungunya is a mosquito-borne viral disease. The person
affected with chikungunya walks in a stooped posture because
of joint pain.
Causative agent: Chikungunya is caused by the chikun-
gunya virus (CHIKV), an arthropod-borne RNA virus (genus
Alphavirus; family Togaviridae).
Incubation period: 2–12 days.
Epidemiology: The virus occurs widely in sub-Saharan
Africa, India, and in many areas in Asia. The disease occurs
mostly in the rainy season. There was a large outbreak of
Chikungunya in India in 2006. The affected states were Andhra
Pradesh, Kerala, Tamil Nadu, Karnataka, Maharashtra,
Gujarat, Madhya Pradesh, Delhi, Rajasthan, Goa, Odisha, Uttar
Pradesh, Pondicherry, West Bengal, Andaman and Nicobar
Islands.
Mode of transmission: Most commonly, the mosquitoes
involved are Aedes aegypti and Aedes albopictus. These two
species can also transmit other mosquito-borne viruses,
including dengue. The mosquitoes breed in stagnant water.
The mosquitoes bite during the day and at night with peak
225Introduction to Microbiology
activity in the early morning and late afternoon. There is no
direct person-to-person transmission. Chikungunya virus is
transmitted rarely from mother to newborn around the time
of birth and through breastfeeding.
Clinical features:
1. Abrupt onset of high fever (40°C/104°F).
2. Chills, anorexia.
3. Joint pain (lower back, ankle, knees, wrists or phalan-
ges) that is often debilitating and varies in duration.
4. Joint swelling and stiffness.
5. Conjunctivitis.
6. Rashes.
7. Headache.
8. Muscle pain.
9. Nausea and vomiting.
10. Fatigue.
11. Leucopenia.
D. Surface Infections
a. Trachoma
Trachoma is also known as granular conjunctivitis. It is an
infectious disease of the eyes characterized by inflammation
of the conjunctiva and cornea. It is one of the main causes of
blindness in India.
Causative organism: Trachoma is caused by Chlamydia
trachomatis, which invades mucous membranes covering the
surface of the eyeball and lining of the lids.
Epidemiology: It is especially prevalent in the states of
Punjab, Rajasthan, and Uttar Pradesh.
Epidemiological determinants:
Agent factors:
1. Children with active disease, chronically infected older
children, and adults are the main reservoirs.
2. Ocular discharges of infected persons and fomites are
infective.
226 Social Pharmacy
3. The period of communicability is as long as active
lesions are present in the conjunctiva.
Host factors:
1. Age: It occurs mostly in preschool-aged children
between the ages of 2 years and 5 years. Infection is less
frequent and shorter in duration in adults.
2. Sex: Prevalence is equal in both sexes in younger age
groups. In older age groups, females are affected more
than males.
Environmental factors:
1. Most incidence of active trachoma in India occurs in
April–May and again during July–September.
2. The custom of applying kajal or surma to the eyes is a
positive risk factor.
3. Low standards of personal hygiene, lack of education,
and poor quality of life are responsible for the trans-
mission of disease.
Incubation period: 5 to 12 days.
Mode of transmission:
1. Eye-to-eye transmission is the rule.
2. It spreads by direct or indirect contact with eye and
nose discharges of infected, e.g. infected fingers, towels,
kajal or Surma, and handkerchiefs.
3. Flies carrying eye discharges from the infected person
can transmit the infection to a healthy person.
4. The spread of trachoma is favored by malnutrition,
overcrowding, and inadequate personal cleanliness.
Clinical features: Irritation of the eyes with tearing, pain,
light sensitivity, eyelid swelling, and vision loss.
Prevention and control:
1. Contributory factors like personal hygiene, socio-
economic conditions, and overall living conditions
must be improved.
2. Health education of the people about the mode of
transmission of the disease and its prevention are other
preventive measures.
227Introduction to Microbiology
3. The National Trachoma Control Program was started
in 1963 and is now integrated with the National
Program in Prevention and Control of Visual Impair-
ments and Blindness.
Treatment:
1. Sulphacetamide eye drops (10–20%) and tetracycline
eye ointments (1%) are used in the treatment of
trachoma.
2. Erythromycin and rifamycin have also been used in the
treatment of trachoma.
3. Antibiotics (doxycycline and erythromycin) can pre-
vent long-term complications if used in the initial stage.
4. In certain cases, eyelid surgery may be needed to
prevent long-term scarring, which can lead to
blindness, if not corrected.
b. Tetanus
Tetanus is an acute infectious disease that affects the body’s
muscles and nerves.
Causative agent: Tetanus is caused by the endotoxin of
Clostridium tetani.
Epidemiology: It is an important endemic infection in India.
It is also an important cause of infant mortality. It can also
affect older children and adults. The disease is very widely
distributed in rural areas.
Epidemiological determinants:
Agent factors: Reservoir of infection: The natural habitat of
the organism is soil and dust.
Period of communicability: None.
Host factors:
1. Age: Commonly, tetanus is a disease of the active age
(5 to 40 years). Tetanus occurring in the newborn is
known as “neonatal tetanus”. Infants typically contract
the disease at birth, when delivered in non-aseptic
conditions.
2. Sex: Although a higher incidence is found in males,
females are more exposed to the risk of tetanus,
especially during delivery.
228 Social Pharmacy
3. Occupation: Agricultural workers are at special risk
because of their contact with soil.
4. Rural-urban differences: The incidence of tetanus is
much lower in urban than in rural areas.
5. Immunity: No age is immune unless protected by
previous immunization.
Incubation period: 3 to 21 days.
Clinical features: Painful spasms and twitching of the jaw
muscles cause difficulty in opening the mouth and in masti-
cation (lock jaws).
1. Rigidity of the neck due to contraction of the muscles
of the neck.
2. Arched body likes a bow.
3. Difficulty in swallowing.
4. Fever.
5. Sweating.
6. Headache.
7. High blood pressure.
8. Rapid heart rate.
Mode of transmission: The tetanus bacilli are found in the
intestinal tract of horses and cattle. Spread is always through
injury, lacerations, burns, and invasion through which the
contaminated matter with tetanus spores makes its entry.
Tetanus is not directly transmitted from person to person.
Prevention and control:
1. All wounds should be thoroughly cleaned and a 3%
iodine solution should be applied.
2. The general hygienic conditions of the people must be
improved.
3. Active immunization with tetanus toxoid vaccine is
highly recommended to prevent tetanus. Children
under 5 years of age are routinely protected with a
triple vaccine (diphtheria, pertussis, and tetanus).
4. Passive immunization is carried out with anti-tetanus
serum (ATS) or human tetanus immunoglobulin in
non-immune cases.
229Introduction to Microbiology
5. Penicillin and tetracycline are also given to the injured
persons as these antibiotics kill the tetanus bacilli.
c. Leprosy
Leprosy (Hansen’s disease) is a chronic infectious disease
characterized by lesions of the skin. There are two types of
leprosy:
i. Non-lepromatous type in which there is good resistance of
the body and hence lesions are localized.
ii. Lepromatous type in which there is poor resistance of the
body with the result that the lepra bacilli multiply and the
lesions are generalized.
Causative organism: Leprosy is caused by Mycobacterium
leprae.
Incubation period: 3 to 5 years.
Epidemiology: It is a major public health problem and is
widespread in most parts of the country. The states of Tamil
Nadu and Andhra Pradesh are particularly severely affected.
Epidemiological determinants:
Agent factors: The most important source of infection in the
community is multibacillary cases (lepromatous and borderline
lepromatous cases).
Host factors:
1. All ages are prone to infection although it mainly
affects children and young adults.
2. The incidence and prevalence of leprosy appear to be
higher in males than in females.
Mode of transmission:
1. It is mainly transmitted by continuous, prolonged
contact with an infected person. Droplet infection and
fomites do not play an important role.
2. The role of insects in the transmission of the infection is
suspected but not established.
3. Bacilli may also be transmitted via breast milk from
lepromatous mothers or tattooing needles.
230 Social Pharmacy
Clinical features:
1. Skin lesions
2. Muscle weakness
3. Paralysis
4. Trophic changes in the skin, muscles, and small bones
of hands and feet.
5. Deformities such as claw hands, claw fingers, wrist
drop, foot drop, facial paralysis, disfigurement of ears
and shortening of fingers and toes, etc.
Prevention and Control: The main principles of leprosy
control are early diagnosis and complete treatment to render
the patient non-infectious. Early recognition of the disease and
its notification and isolation of infectious cases are general
preventive measures. Lepers (leprosy patients) can be kept in
leprosariums, hospitals, or leper homes.
Leprosy is not a hereditary disease and is curable.
Treatment: Chemotherapy is of vital importance in the
control of leprosy. Following antibiotics are used in the
treatment of leprosy:
1. Dapsone (DDS)
2. Rifampicin
3. Clofazimine
4. Fluoroquinolones
5. Macrolides
6. Minocycline.
Generally, antibiotics are given in combination. Penicillin
and streptomycin are of particular value for the control of
secondary infections. Aspirin (NSAID) and prednisone
(corticosteroid) are used to control inflammation.
E. Sexually Transmitted Diseases
a. Acquired Immune Deficiency Syndrome (AIDS)
Acquired immune deficiency syndrome (AIDS) is a chronic
infection that destroys the immune system in the body and the
body becomes unable to fight infection.
231Introduction to Microbiology
Causative agent: It is caused by a virus called HIV (human
immunodeficiency virus).
Epidemiology: AIDS was first detected in the USA amongst
homosexuals in 1979. According to WHO, more than 25 million
people have died of AIDS around the world since its detection
and more than 33 million people are living with AIDS
worldwide. The disease is common in the 15 to 50 years age
group. 60% of infected persons die within one year and 80 to
90% within two years.
Symptoms: People infected with HIV may take 10 years or
more to develop symptoms. This period is known as
asymptomatic HIV infection, which is followed by early
symptomatic HIV infection and later advanced to AIDS in
which CD4 T-cell count falls to 200 cells/mm
3
. Because of a
damaged immune system, people infected with AIDS are
susceptible to a variety of life-threatening infections and
cancers. Some common symptoms of AIDS are: Chills, fever,
fatigue, sweats (particularly at night), swollen lymph glands,
aching muscles, weakness, and weight loss.
Mode of transmission: The virus is transmitted via blood
and other body fluids. In an HIV-infected person, blood and
sexual fluids, i.e. semen or vaginal fluids; contain the virus.
HIV is therefore transmitted through unprotected sexual
intercourse with an HIV-infected person. Anal intercourse is
the commonest cause. Habitual IV drug abusers as well as
infected prostitutes can also spread disease to others. Pregnant
females suffering from the disease can pass it on to unborn
children. The use of HIV blood-contaminated needles or
syringes can also transmit HIV from one person to another.
HIV infection is not transmitted through casual everyday
contact like shaking hands, touching, hugging, kissing,
coughing, sneezing, using the same telephone instrument,
swimming pool or toilet seat, sharing eating utensils or foods,
bites of mosquitoes, and other insects. Donating blood is safe.
Incubation period: It varies from 6 months to 10 years.
Prevention and control:
1. Safe sex is the most important preventive measure.
Always a pre-lubricated condom should be used
232 Social Pharmacy
throughout sexual intercourse. A condom should be
properly disposed of and never be re-used.
2. The blood should be tested for HIV before transfusion.
Safe blood is certified and stamped on the label as
follows: HIV, HBS antigen, VDRL negative.
3. Sterilized disposable needles and syringes should be
used in blood transfusion.
4. A woman who is a carrier of HIV should avoid
pregnancy.
Pharmacists can play a vital role in educating the general
public about AIDS and its prevention.
Treatment: Presently, there is no treatment, that can provide
the cure for AIDS, but quality of life can be improved in patients
by antiretroviral therapy which suppresses virus replication.
There are currently more than 20 approved antiretroviral drugs
in the US and Europe (including combined formulations) and
many more in the expanded access programs and trials.
REVISION QUESTIONS
Long Answer Questions (10 Marks)
1. Write causative agent, clinical features, mode of trans-
mission, clinical features, diagnosis, treatment, prevention
and control of cholera.
2. What is SARS? Write causative agent, mode of trans-
mission, clinical features, diagnosis, treatment, prevention,
and control of SARS.
3. Write causative agent, mode of transmission, clinical
features, diagnosis, treatment, prevention, and control of
Ebola virus disease.
4. Write causative agent, mode of transmission, clinical
features, diagnosis, treatment, prevention, and control of
influenza.
5. Write causative agent, clinical features, mode of trans-
mission, diagnosis, treatment, prevention, and control of
Covid 19.