3. introduction
Some diseases are caused by bacteria and some , such
as AIDS and the common cold, are caused by viruses.
Normally, our immune system protects us against
diseases. But sometimes our body – because of too little
sleep or a lot of stress- becomes so weak that the immune
system does not work properly and we succumb to
diseases.
4. Types Of Diseases
Infectious Disease : Diseases where microbes are the
immediate cause.
Contagious diseases : A subset of infectious diseases.
Communicable diseases : Diseases which spread through
an infected person to a healthy person through air, water,
contaminated food and pathogens .
Airborne diseases : A disease that spread from air .
Non-communicable diseases :It is a medical condition
or disease which by definition is non-infectious and non-
transmissible between persons.
5. Infectious agent Disease
Virus Common cold, influenza,
dengue fever, AIDS
Bacteria Typhoid fever, cholera,
tuberculosis, anthrax
Fungi Many common
infectious disease
Protozoan Malaria, amoebiasis
Worms worm infections,
elephantiasis
6. Modes of transmission of
diseases
Infectious disease(bacteria,fungi,etc.)
Parasites
Contaminated food or water
Blood transmission
Vectors/animals
Direct physical contact
7. Means of spread of infectious disease
1. Air born diseases Common cold,
pneumonia, tuberculosis
2. Water born
diseases
Cholera, amoeboisis
3. Through vectors Anopheles mosquitoes –
vector of malaria
8. Congenital disease – Are present since birth.
Caused due to genetic abnormalities / due to
metabolic disorder / malfunctioning of organ.
Permanent, generally not easily curable & may be
inherited to children
9. Acquired diseases – Which develop after
birth
Infectious disease – Communicated from diseased
person to healthy person. Caused by some
biological agents / pathogens like – Viruses,
bacteria, protozoan, nematodes, fungi
Non-infectious disease – Restricted only to those
persons who are suffering. Diseases that are not
caused by infectious agents.
10. How can we prevent Diseases?
There are two ways, one general and one specific to each diseases .
The general ways of preventing infections mostly relate to preventing
exposure.
How can we prevent exposure to
infectious microbes?
For airborne microbes , we can prevent exposure by providing living
conditions that are not overcrowded .
For waterborne microbes, we can prevent exposure by providing safe
drinking water . This can be done by treating the water to kill any
microbial contamination .
For vector-borne infections , we can provide clean environments .
This would not , for example, allow mosquito breeding . In other words ,
public hygiene is one basic key to the prevention of infectious
diseases .
11. Bacterial diseases include any type of illness
caused by bacteria. Bacteria are a type of
microorganism, which are tiny forms of life that
can only be seen with a microscope. Other types
of microorganisms include viruses, some fungi,
and some parasites.
Millions of bacteria normally live on the skin, in
the intestines, and on the genitalia. The vast
majority of bacteria do not cause disease, and
many bacteria are actually helpful and even
necessary for good health. These bacteria are
sometimes referred to as “good bacteria” or
“healthy bacteria.”
What Are Bacterial Diseases?
12. Symptoms of bacterial diseases vary
depending on the type of bacterial infection, the
area of the body that is infected, and other
factors, such as the patient’s age and health
history. The symptoms of bacterial diseases
can also resemble symptoms of other
diseases, such as colitis, influenza, and viral
infections. The classic symptom of a bacterial
infection is a Fever.
What are the
symptoms of
bacterial diseases?
13. INFECTIOUS DISEASES
I. Infection Agents
Organisms that can cause diseases are classified in wide
range of categories. Some of them are viruses, some
are bacteria, some are fungi and some are unicellular
animals, the protozoans.Some diseases are also
caused by multicellular organisms such as worms.
Common example of diseases caused by viruses are the
common cold,influenza,dengue,fever and AIDS and
common skin infection caused by different kinds of
fungi.Protozoans cause many familiar diseases such as
malaria and kala azar.Worms tend to cause a variety of
intestinal infections and elephtiasis
14. Caused to Infection By
Microorganisms1.Malaria
Malaria is a fatal disease for human beings. Approximately 300 million people
around the world get infected with malaria every year.Malaria is caused by a
protozoan parasite Plasmodium.This disease spreads through the bite of an
insect vector-the female Anopheles mosquito which feeds on the human blood.
Symptoms-1.Cold stage,feeling of extreme cold and shivers ;2.hot stage,high
fever, faster respiration and heart beat; and 3.sweating stage,due to the
profuse sweating,temperature of the body goes down to norrmal.Even after
cured of malaria, the patient feels weak and anaemic.
Prevention-1.Insect-repellents should be used to prevent mosquito bites.
2.One should keep under mosquito nets.
3.Wire-gauze should be used on doors and windows of
houses to prevent entry of mosquitoes.
4.Mosqito larvae can be killed by sprinkling kerosene oil on
large-sized water bodies.
5.The breeding grounds should be should be
destroyed.Thus,the ditchess,puddles or swamps around human
dwellings should be drained or filled.
Control-A drug named quinine, which is extracted from the bark of the
Cinchona tree,is used to treat a person suffering from malaria.
15. Rabies(Hydrphobia)
The bite of a rabid dog(mad dog) and some other such as
monkeys,cats or rabbits may cause rabies,which is fatal viral
disease cause by rabies virus or lyssa virus which is present in
the saliva of infected animals.The viruses are injected into human
blood by the bite of rabid animal.
Symptoms-Rabies is characterised by serve,headache,high
fever,painful contraction of muscles of throat and chest.The patient
feels restless,does excessive salivation, has a choking feeling and
finds difficulty in take of even liquid.
Prevention-1.Cleaning the wound with carbolic soap and clear water
immediately after the dog bite is an important preventive measure.
2.Any antiseptic medicine should be applied the wound
caused by a dog bite.
3.A rabid animal shows excessive salivation and
tries to seek isolation after bite. Such mad animals should be
killed.
Control-Rabies can be treated with Pasteur’s treatment,in
which a course of 14 vaccines was given.Currently 5 anti-
rabies vaccines are prescribed at an interval of 0-3-7-14-30 day
of dog bite.
16. Diseases caused by Bacteria
Cholera
Cholera is an actuely infectious, fatal disease.Sometimes cholera
occurs in epidemic form and spread over large population.Cholera
is caused by the bacterium, Vibrio cholerae.It is transmitted by
flies,contaminated food and water.When the bacteria f cholera is
ingested,they multiply in the small intestine and invade its
epithelial cells.When the bacteria die,they release toxins which
irritate the intestinal lining and lead to the secretion of large
amounts of water and salts.
Symptoms-1.Watery diarrhea which is generally painless.
2.Efforts vomiting without nausea.
3.Loss of several liters of liquid from the patient’s
body takes place within hours.
Prevention-1.Person should be immunised by standard cholera
vaccine
2.Careful personal hygiene and good sanitation in the
community are the only certain protection against cholera.
3.In cholera-prone areas, boiled water and cooked
should be taken
17. TyphoidTyphoid is the most common communicable disease in India. It is
common in humans of the 1 to 15 years age group. Typhoid is cause
by a rod-shaped and motile bacterium, called Salmonella typhi which
is found in the intestine of intestine of human beings.Infection takes
place by the oral route through ingestion of food,milk or water
contaminated by contact with faecal mattar of the typhoid patient.The
bacteria spread through faecal mattar by house flies.
Symptoms-1.Headache and typhoid fever which rises maximum in
the afternoon. The temperature increases each day in the first week.
2.High fever in the second week.Fever gradually declines
during 3rd
and 4th
day.
3.In nutshell symptoms of typhoid include continuous
fever often with delirium, slow pulse, tender and distended
abdomen,diarrhoea with water-green stools.
Prevention-1.Proper sanitation and disposal of faecal mattar
prevents infection
2.TAB-vaccination provides immunity for 3 days.
3.Typhoral oral vaccine also prevents typhoid.
Control-There are standard drugs e.g., Chloromycetin which cure
typhoid.
