This document discusses various diseases caused by pathogens like bacteria, viruses, protozoa, and fungi. It provides details on the causative agents, target organs, modes of transmission, symptoms, and prevention for diseases like typhoid, pneumonia, common cold, malaria, amoebiasis, ascariasis, elephantiasis, and ringworm. It emphasizes the importance of personal and public hygiene for prevention of diseases through measures like proper disposal of waste, use of clean water and food, cleaning of water sources, and mosquito control.

2.  Any condition which
interferes with the
normal functioning of
the body is called a
disease.
 Disease may be defined
as a disorder in the
physical, physiological,
psychological or social
state of a person
caused due to
nutritional deficiency,
physiological disorder,

3. Pathogens
Bacteria
Viruses
Fungi
Protozoans
Helminths

4.  Pathogen : Salmonella typhi (Bacteria)
 Target organ - Small intestine
 Mode of transmission :
 Through contaminated food and water
 Confirmation Test - Widal test
 Symptoms :
 High fever (39° to 40°C)
 weakness
 stomach pain
 constipation
 headache and loss of appetite
 In severe cases intestinal perforation and death may
occur.

5.  Pathogen :
 Streptococcus pneumoniae and Haemophilus
influenzae (Bacteria)
 Target organ - Alveoli of the lungs
 Mode of transmission :
 By inhaling the droplets/aerosols released by an
infected person
 By sharing glasses and utensils with an infected
person
 Symptoms :
 Fever, chills, cough and headache
 In severe cases, the lips and finger nails may turn
gray to bluish in colour.

6.  Pathogen :
 Rhino viruses (Virus)
 Target organ - Nose and respiratory passage but
not the lungs.
 Mode of transmission :
 Through droplets from cough or sneezes of an
infected person
 Through contaminated objects such as pens, books,
cups, doorknobs, computer keyboard or mouse, etc.
 Symptoms :
 Nasal congestion and discharge
 Sore throat, hoarseness, cough, headache &

7.  Pathogen :
 Plasmodium vivax, P. malaria, P.falciparum
 Mode of transmission :
 By bite of female Anopheles mosquitoes
 Incubation period :
 Approximately 12 days
 Symptoms
 Headache, nausea and muscular pain.
 Feeling of chilliness and shivering followed by fever
which becomes normal along with sweating after some
time.
 The patient becomes weak and anaemic.
 If not treated properly secondary complications may lead
to death.

8. Prevention and cure:-
 Fitting of double door and windows (with wire
mesh) in the house to prevent entry of
mosquitoes.
 Use of mosquito net and mosquito repellents.
 No water should be allowed to collect in ditches
or other open spaces to prevent mosquito
breeding.
 Sprinkling of kerosene oil in ditches or other open
spaces where water gets collected.
 Antimalarial drugs to be taken.

10.  Pathogen :
 Entamoeba histolytica (Protozoan)
 Target organ - Large intestine of human
 Mode of transmission :
 Houseflies transmit the parasite from faeces of
infected person to food, food products and water.
 Symptoms :
i. Constipation
ii. Abdominal pain and cramps
iii. Stools with excess mucous and blood clots

11.  Pathogen : Ascaris
 Target organ – intestine
 Mode of transmission :
 The eggs of the parasite are
excreted along with the
faeces of infected persons
which contaminate soil,
water, plants, etc.
 contaminated water,
vegetables, fruits, etc.
 Symptoms :
 Internal bleeding
 Muscular pain
 Fever
 Anemia
 Blockage of the intestinal
passage

12.  Pathogen : Wuchereria (W. bancrofti
and W. malayi)
 Target organ –
 Lymphatic vessels of lower limbs
 Mode of transmission :
 bite by female Culex mosquito
 Symptoms :
 Blocked lymph ducts
 Enlarged groin lymph nodes
 Fever
 Thickened skin tissue
 Impaired lymphatic drainage
Elephantiasis

13.  Ringworm is a fungal infection
of the skin.
 The name “ringworm” is a
misnomer, since the infection
is caused by a fungus, not a
worm.
 Pathogens :
 Microsporum
 Trichophyton
 Epidermophyton

14.  Symptoms :
 Appearance of dry, scaly lesions on various parts of
the body such as skin, nails and scalp are the main
symptoms of the disease.
 These lesions are accompanied by intense itching.
 Heat and moisture help these fungi to grow, which
makes them thrive in skin folds such as those in the
groin or between the toes.
 Mode of transmission :
 They acquired from soil or by using towels, clothes
or even the comb of infected individuals.

15.  Maintenance of personal and public hygiene
 Keeping the body clean
 Consumption of clean drinking water, food,
vegetables, fruits, etc.
 Proper disposal of waste and excreta;
 Periodic cleaning and disinfection of water
reservoirs, pools, cesspools and tanks
 Vaccination and immunisation

16. MOSQUITO
MALARIA
DENGUE
FEVER
FILARIASIS
JAPANESE
ENCEPLALITIS
YELLOW
FEVER
CHIKUNGUNYA

17.  To avoid stagnation of water
in and around residential
areas
 Regular cleaning of
household coolers,
 Use of mosquito nets,
 Introducing fishes like
Gambusia in ponds that feed
on mosquito larvae,
 Spraying of insecticides in
ditches, drainage areas and
swamps, etc.
 Doors and windows should be
Gambusia