8. HUMAN HEALTH AND
DISEASES
· Health is a state of complete physical, mental & social well-being. It is affected by genetic disorders, infections, change in life style (food, water, rest, exercise, habits etc).
·
Mind
influences immune system (through neural and endocrine systems) and thereby
health.
·
When
the functioning of organs or systems of the body is adversely affected, it is
called a disease.
·
Diseases
may be infectious (transmits from one person to another) or non-infectious
(do not transmit. E.g. cancer).
· Disease causing organisms are called Pathogens. Parasites are
pathogens as they harm the host.
Good humour hypothesis (by Hippocrates
& Indian Ayurveda system): It states that health is a state of body &
mind where there is a balance of certain humours. Persons with ‘black bile’
belong to hot personality and would have fevers.
William Harvey disproved this
hypothesis. He discovered blood circulation and demonstrated normal body
temperature in persons with black bile using thermometer.
COMMON INFECTIOUS DISEASES IN MAN
1. BACTERIAL DISEASES
a. Typhoid: Pathogen is Salmonella typhi.
· Mode of transmission: It
enters small intestine through food & water and migrates to other organs via
blood.
· Symptoms: Sustained
high fever (39o-40o C), headache, weakness, stomach pain,
constipation & loss of appetite. Intestinal perforation and death may
occur.
Widal test
is used for confirmation of the disease.
Mary Mallon (Typhoid Mary) was a professional
cook. She was a typhoid carrier who spread typhoid for several years through
the food she prepared.
b.
Pneumonia:
Pathogen is Streptococcus pneumoniae &
Haemophilus influenzae.
It
infects lung alveoli. The alveoli get filled with fluid leading to respiratory
problems.
· Mode of transmission: Inhaling
the droplets/aerosols released by an infected person. Sharing glasses and
utensils with an infected person.
· Symptoms: Respiratory
problems, fever, chills, cough, headache. In severe cases, lips and finger
nails turn grey to bluish colour.
Other bacterial diseases: Dysentery, plague, diphtheria, etc.
2. VIRAL
DISEASES
a. Common cold: Pathogen is
Rhinoviruses.
It
infects nose & respiratory passage but not lungs.
· Mode of transmission:
Inhaling droplets resulting from cough or sneezes. Through contaminated objects
(pens, books, cups, doorknobs, computer accessories) etc.
· Symptoms: Nasal
congestion & discharge, fever, headache, sore throat, cough, hoarseness,
tiredness etc.
Common cold lasts for 3-7 days.
3. PROTOZOAN
DISEASES
a. Malaria: Pathogen is
Plasmodium sp. (P. vivax, P. malariae & P. falciparum).
Most serious (malignant) malaria is caused by P. falciparum.
·
Mode
of transmission: By
female Anopheles
mosquito.
· Symptoms: Haemozoin (toxin released by Plasmodium)
causes chill and high fever recurring every 3-4 days.
Life cycle of Plasmodium
b. Amoebiasis (Amoebic
dysentery): Pathogen is Entamoeba histolytica.
·
Mode of transmission: Houseflies (mechanical carriers) transmit parasites from
faeces to food & water.
· Symptoms: Constipation,
abdominal pain and cramps, stools with excess mucus and blood clots.
4. HELMINTH
DISEASES
a. Ascariasis: Pathogen is
Ascaris (Intestinal parasite).
·
Mode of transmission: Soil, water, vegetables, fruits etc. contaminated with
faeces containing eggs of parasites.
· Symptoms: Internal
bleeding, muscular pain, fever, anaemia and blockage of intestinal passage.
b. Filariasis (Elephantiasis):
Pathogen is Filarial worms or Wuchereria (W. bancrofti & W. malayi).
·
Mode of transmission: Bite of female Culex
mosquito.
·
Symptoms: Filarial worms live in lymphatic vessels (usually of lower limbs). It
causes chronic inflammation of the organs in which they live for many years.
Limbs and genital organs may be deformed.
5. FUNGAL
DISEASES
a.
Ring worms: Pathogens are Microsporum,
Trichophyton & Epidermophyton.
They are seen in groin, b/w toes etc.
·
Mode of transmission: From soil or by using towels, cloths, comb etc. Heat and
moisture help fungi to grow.
·
Symptoms: Dry, scaly lesions on skin, nails, scalp etc. Intense itching.
PREVENTION
AND CONTROL OF DISEASES
Personal hygiene
Keep the body clean. Use clean
drinking water, food etc.
Public hygiene
a. Proper
disposal of wastes and excreta.
b. Periodic
cleaning and disinfection of water reservoirs, pools, cesspools and tanks.
c. Avoid
contact with infected persons or their belongings (to control air-borne
diseases).
d. Standard
practices of hygiene in public catering.
e. Control
and eliminate the vectors (e.g. mosquitoes).
-
Avoid stagnation of
water.
-
Regular cleaning of
household coolers.
-
Use of mosquito nets.
-
Introduce larvivorous
fishes like Gambusia in ponds.
-
Spraying insecticides in
ditches, drainage and swamps.
-
Provide doors and windows
with wire mesh.
These
precautions can avoid vector-borne diseases like Malaria, Filariasis, Dengue
& Chikun gunya.
Vaccines & immunisation helped to control diseases like smallpox, polio, diphtheria, pneumonia & tetanus. Drugs like antibiotics also helped to treat infectious diseases.