This document defines communicable diseases and describes various disease-causing microorganisms. It discusses how communicable diseases spread from person to person or between humans and animals. Common routes of transmission include respiratory droplets, contaminated food or water, vectors, and direct or indirect contact. The document also provides descriptions and examples of bacteria, viruses, fungi, protozoa, rickettsiae, and parasitic worms that can cause infectious diseases.

1. JOHNY WILBERT, M.Sc[N]
LECTURER,
APOLLO INSTITUTE OF HOSPITAL
MANAGEMENT AND ALLIED SCIENCE

2. Definition of Communicable
diseases
A communicable disease is an illness due to a
specific infectious (biological) agent or its
toxic products capable of being directly or
indirectly transmitted from man to man, from
animal to man, from animal to animal, or from
the environment (through air, water, food,
etc..) to man

3. Communicable disease: a disease that can
be spread to a person from another person,
an animal or object. Ex: common cold,
influenza, tuberculosis, etc.
Non-communicable disease: a disease that
can NOT be spread from person to person. Ex:
cancer, heart disease, cirrhosis, etc.

4. Virus: smallest simplest life form. Not alive, and cause upper
respiratory infections and many other types of diseases.
Bacteria: simple one-celled organisms. They are everywhere.
Not all bacteria is bad.
Fungi: more complex than bacteria, but cannot make their
own food. Thrive in warm, moist environments.
Protozoa: one celled, animal like organisms.

5. Description
Single-celled
microorganisms
Most are beneficial but
close to a hundred types
are known to cause
disease
Some release poisonous
substances
Diseases
Tuberculosis, strep
throat, diphtheria,
whooping cough,
meningococcemia,
cholera, meningitis,
syphilis

6. Description
Smallest known
pathogen infecting cells
of biological organisms
Unable to reproduce
on their own, it
replicates through
infecting host cells
Diseases
Common cold, measles,
rabies, polio, mumps,
influenza, SARS,
hepatitis, chicken pox,
HIV

7. Description
Single celled or
multi-celled parasitic
organisms which can
live on skin, mucous
membranes and
lungs
Obtain food from
organic materials
such as plant,
animals or human
tissue.
Diseases
Athlete’s foot,
ringworm and tinea
flava .

8. Description
 Grows inside living
cells and resembles
bacteria
 Carried as parasites
such as ticks, fleas
and lice
Diseases
Spotted fever
RICKETTSIAE

9. Description
Tiny, single-
celled organisms
producing toxins
Reproduce fast
through sexual
and asexual
ways
Diseases
Malaria
PROTOZOA

10. Description
Helminths
Largest pathogen
that can enter the
body
Diseases
Tapeworm,
hookworm, pinworm,
roundworm
Wormlike orgs.
Living and
feeding in living
hosts while
disrupting the
nutrients
absorption of
their hosts,
causing weakness
and disease
PARASITICWORMS

11.  Direct
 Blood-borne or sexual – HIV, Hepatitis B,C
 Inhalation – Tuberculosis, influenza, anthrax
 Food-borne – E.coli, Salmonella,
 Contaminated water- Cholera, rotavirus, Hepatitis A
 Indirect
 Vector-borne- malaria, trypanosomiasis
 Fomites
 Zoonotic diseases – animal handling and feeding
practices (Mad cow disease, Avian Influenza)

12.  The poor hygiene behaviors promote the
transmission of infectious diseases
 The fecal-oral and respiratory routes are the
most common sources of transmission
 Young children and adults may not wash their
hands after using toilets and before
eating/preparing food.

13. Causative Agent
Reservoir
Portal of exit
Mode of transmission
Portal of entry
Susceptible host

14. It is a microbial organism with the
ability to cause disease.
Example: Bacteria, Virus, Fungi and
Parasites.

15. It is a place where microorganisms can
thrive and reproduce.
Microorganisms can thrive in human
beings, animals and inanimate objects
such as water, table tops and door
knobs.

16. It is a place of exit providing a way
for a microorganism to leave the
reservoir.
Principal portals of exit are: Digestive
system, urinary system, respiratory
system, reproductive system and the
blood.

17. It is a method of transfer by which the
microorganism moves or is carried
from one place to another or from
reservoir to a susceptible host.

18. It may be any opening allowing
the microorganism to enter the
host.
It is within the same system of
portals of exit.

19. It is an individual who cannot
resist a microorganism invading
the body, multiplying and
resulting infection.
HOST- a person susceptible to
disease, lacking physical resistance
to overcome the invasion of the
pathogenic organism.

20. Common Communicable
Diseases

21.  The common cold is a respiratory infection caused
by over 200 different viruses. Symptoms include
congestion, sore throat and cough. It can be spread
through direct and indirect contact. Treatment
includes rest, liquids and over the counter
medications. Prevention techniques include
handwashing and avoiding contact with infected
persons.

22. Influenza, more commonly called “flu”, is a
respiratory infection caused by several groups of
viruses. Symptoms include high fever, fatigue,
muscle and joint aches. It is spread through direct
contact with infected people and water droplets in
the air from coughs and sneezes.
Treatment includes rest, liquids, and over the
counter medications. Prevention includes avoiding
contact with infected persons and vaccines

23. - infection in the lung
parenchyma by viruses,
bacteria and other pathogens
due to various factors.

24.  2 billion people infected with microbes that cause TB.
 Not everyone develops active disease
 A person is infected every second globally
 22 countries account for 80% of TB cases.
 >50% cases in Asia, 28% in Africa (which also has
the highest per capita prevalence)
 In 2005, there were 8.8 million new TB cases; 1.6
million deaths from TB (about 4400 a day)
 Highly stigmatizing disease

25.  Every year, 500 million people become severely ill
with malaria
 causes 30% of Low birth weight in newborns Globally.
 Caused by plasmodium species.
 >1 million people die of malaria every year. One child
dies from it every 30 seconds
 40% of the world’s population is at risk of malaria.
Most cases and deaths occur in SSA.
 Malaria is the 9th leading cause of death.
 11% of childhood deaths worldwide attributable to malaria
 children account for 82% of malaria deaths worldwide

26. Small red spots that become
blisters/ scabs
13- 17 days
Early stage of rupture of blisters
Caused by Varicella Zoster
virus.