Modes of transmission and measures for the prevention and control for communicable and non communicable disease

1. Modes of transmission and measures for the
prevention and control for communicable and
non communicable disease
CM 7.2
Dept. of Community Medicine
ESIC MCH, Hyderabad

2. Communicable diseases are illnesses that can be
transmitted from one person or organism to another,
often through various modes of transmission.
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3. Modes of Transmission
1. Direct Transmission:
a) Person-to-Person: skin to skin, sexual contact
b) Droplet spread:> 5 micron, travel 1 m Eg Influenza,
Meningococcus
c) Inoculation in skin/mucosa: Rabies, Hb B, C
d) Contact with soil: Tetanus, Hookworm
e) Trans-placental: TORCH, Varicella, Syphilis
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4. Indirect Transmission
a) Airborne Transmission:
Droplet nuclei; Microscopic droplets ( size < 5 micron) containing
pathogens are released into the air when an infected person
coughs, sneezes, talks, or breathes. These droplets can be inhaled
by others, causing diseases like tuberculosis or COVID-19.
b) Waterborne Transmission:
- contaminated water sources, either by ingestion or contact
with contaminated water. Examples include cholera and
dysentery.
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5. Indirect Transmission
c) Foodborne Transmission:
- Improper food handling and storage can lead to outbreaks of
illnesses like salmonella or E. coli infections.
d) Vector-Borne: Bite of infected vectors such as mosquitoes (e.g.,
malaria, Zika virus) or ticks (e.g., Lyme disease).
e) Fomite Transmission: contaminated objects, surfaces, or hands
Eg flu, COVID 19
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6. Approach to Prevention & Control
1. Reservoir of infection
2. Route of infection/ Interruption of Tranmission
3. Susceptible host
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7. Controlling Reservoir of Infection
• Early diagnosis & Prompt Treatment
• Notification
• Always notifiable- Small pox, H Influenza, SARS
• Potentially notifiable- Plague, Cholera, Yellow fever, Hemorraghic fevers
• PHEIC- H1N1, Polio, Ebola, Zika, COVID-19
• Isolation: Separation of infected persons/animals from others
for the period of communicability ( IP)
• Quarantine : Restriction of movement of persons who are
well but have potential to develop disease due to contact
with infected case
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8. Interruption of Transmission( Route)
• Disinfection
• Concurrent –done as soon as possible after discharge of inf material from the body
of infected person
• Terminal-removed by death, after discharge, or transfer
• Pre current ( prophylactic) –disinfection of water by Cl, Pasteurization of milk,
handwashing
• Sterilization: destroy all microbial forms including spore, mycobacteria,
non enveloped virus and fungi
• Antiseptic-Arrest growth or action of microorganism
• Sanitizer-reduces number of bacterial contaminants
• Detergent-surface cleaning agent
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9. Protecting Susceptible host
• Active Immunization
• Live-BCG, OPV, MMR, Rota, Varicella, Yellow Fever
• Killed-IPV, Rabies, H Influenza A, Hep A
• Toxoid-D, T
• Subunit ( purified Ag)-Hb B, Pneumococcal, HPV, Meningococcal
• Passive immunization
• S. Ig and targeted Ig : Eg Rabies, Tetanus, Heb B , RSV, Botulism antitoxin, etc
• Herd Immunity
• Also known as 'population immunity', is the indirect protection from an infectious disease
that happens when a population is immune either through vaccination or immunity
developed through previous infection.
• Ro, Vaccine effectiveness, Population heterogeneity waning immunity
• Chemoprophylaxis:
• Eg fluoridated water -dental caries; trimethoprim-sulfamethoxazole - Pneumocystis
pneumonia prophylaxis in AIDS patients; CHQ - Malaria
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