Health : according
to WHO 1948 state of compete physical , mental, social, well being and not
merely an absence of disease or infirmity
Disease : Any variation in the normal
structure and function of tissue or an organ of body is called disease.
Common Human Diseases:
Disease is defined as condition of disturbed or
deranged functioning of one or more organs or organ systems of the body, caused
due to infections, defective diet or heredity.
All human diseases can be broadly classified into
A. congenital diseases B. acquired diseases.
A. Congenital
diseases –
They are present from birth; may be caused by
genetic abnormality or metabolic disorder.
They may be
permanent and were practically incurable. However, modem research has helped to
cure some inborn diseases through gene therapy, enzyme replacement therapy,
etc.
B. Acquired
diseases –
They develop after the birth and can be subdivided
into-
(a) Communicable or infectious diseases
(b) Non- Communicable or Non-infectious diseases
Communicable or
Infectious diseases –
The diseases which are transmitted from infected
person to another healthy person either directly or indirectly, are known as
Communicable or Infectious diseases. E.g. Malaria and other diseases.
Non- Communicable or
Non –
Infectious diseases -The diseases that cannot be
transmitted from infected person to another healthy one either directly or
indirectly are known as Non- Communicable or Non Infectious diseases. Cancer
and deficiency diseases.
Communicable diseases are caused by pathogens like
viruses, bacteria, fungi, helminth worms, etc.
All the disease-causing organisms are called 'Pathogens'.
Many pathogens use another organism, the 'Vector' to
reach us.
These vectors are actually parasites.
Parasite is an organism that lives in or on the body
of another organism and derives its nutrition from that of host organism.
Parasites are two
types-:
Ectoparasite E.g. bedbug
Endoparasite. E.g. Plasmodium is a protozoan
endoparasite of the mosquito (vector) and human beings.
Malaria:
l.It is a vector (mosquito) borne infectious disease
caused by protist - P asmodium.
2.There are four species of Plasmodium-
Plasmodium vivax , Plasmodium ovale,
Plasmodium malariae Plasmodium falcip m.
3 .Only Plasmodium falciparum causes serious illnes hile others are rarely fatal. Based on the species, there are
4 - types
of malaria
Signs and symptoms of
malaria: -
Symptoms of malaria begin to appear about 'J 0 15
days after the bite of infective mosquito.
Initial symptom are fever, headache, d ~ills, may be
difficult to recognize as malaria.
Classical symptoms of malaria are c c ic occurrence
of high fever followed by sweating and sudden shivering.
Such entire episode lasts for fou to six hours and
recurs every two days or three days.
Vomiting and convulsions.
Arthralgia (joint pain), anae ia due to rupturing
ofRBCs.
Haemoglobinuria, hepatomegaly (liver enlargement).
Retinal damage ( eye).
Cerebral malaria (brain infection).
Stages in the life
cycle of Plasmodium in mosquito and human
Mode of transmission:
I.Plasmodium is
transmitted from one person to othe through an insect vector- female Anopheles
mosquito.
2.When infected female Anopheles sucks the hum n b
ood, it may transfer sporozoites to human circulation.
3. Sporozoites reproduce asexually through fission
schizogony) in the liver cells or erythrocytes.
4.The cells formed are now called merozoites.
5.The cells formed within erythrocytes function as
gametocytes (gamogony).
6.Gametocytes if taken up by female Anopheles,
fertilization occurs in its gut.
7.Diploid
zygote is formed which transforms into oocyst.
8.S.Oocyst forms large number of aploid sporozoites
through meiosis (sporogony). 9.Sporozoites migrate to sali ary glands and are
ready to infect new human host.
Diagnosis and
Treatment:
1.Malaria can diagnose microscopic study of blood
smear.
2.Besides, other rapid diagnostic tests based on
nucleic acid amplification techniques are also used.
3. Treatment
of malaria includes Artemisinin based combination therapies (ACTs).
4.WHO has recommended 5 different ACTs which
includes various combinations of artesunate, sulfadoxine, pyrimethamine, etc.
5. In addition, quinine is also used.
Prevention and Control:
I.Prevention of mosquito bite by using mosquito nets
and insect repellents.
2.Spraying insecticides and draining stagnant water
where mosquito lays eggs.
3.Mosquito
larvae can be controlled by using Gambusia fresh water fish
(biocontrol).
Amoebiasis:
Amoebiasis is
also known as Amoebic dysentery. It's a common infection of human
gastro-intestinal tract, which affects 15 % population of India.
Amoebiasis is
caused by a protist parasite-Entamoeba histolytica.
Signs and symptoms:
Diarrhoea, flatulence,
stool with mucus and abdominal pains (cramps) are common.Passing of blood with
stool is common in severe cases.
Hepatomegaly occurs if parasite
enters the liver. Liver develops amoebic liver abscess accompanied with fever
and pain in right abdomen.
Mode of transmission :
Faeco-oral route.
Eating with dirty hands.
Contaminated food and
water
Diagnosis and
Treatment :
Diagnosis of amoebiasis is made through microscopic examination of the stool sample.Amoebiasis is treated by the use of Metronidazole and Tinidazole which can destroy the E. histolytica in the digestive tract as well as other tissues.
Prevention and Control
:
Wash hands with hot water
and soap after using toilets and changingbaby’s diaper
Drink boiled
water. Otherwise, water must be chlorinated and filtered.
Avoid eating unhygenic food.
Vegetables must be
properly
washed and cooked. Proper
sanitary facilities including sewage
disposal help in prevention
Ascariasis :
It is
an infectious disease
of human intestinal tract,
caused by roundworm- Ascaris
lumbricoides.Ascaris lumbricoides is an endoparasitic round worm or nematode.
Signs and symptoms :
Gastro-intestinal
discomfort accompanied with vomiting and
fever.
Presence of live worms in
feacal matter.
Pulmonary disorders occur
in some patients.
Pneumonitis (inflammation
in alveolar wall).
Loss of apetite and weight
loss.
Eosinophilia (number of eosinophils is increased.
Mode of transmission:
Food and
drinks contaminated with the
eggs of these
worm is the main
mode of transmission.
Eggs
hatch inside the intestine of the new host.
The larvae pass through various organs and
settle as adults in the digestive system.
Diagnosis and Treatment:
Diagnosis can be
done by microscopic examination of the stool.
Anti-helminthic drugs
like Piperazine,
Mebendazole, Levamisole, Pyrantel are effective against Ascaris
lumbricoides
Prevention and Control
:
1.Avoiding defaecation in open space, prevents
the spread of Ascaris.
2.Personal
hygienic habits like
washing hand with water
and soap after
using toilet are also important.
3.Washing vegetables
throughly before cooking
4.avoiding raw vegetables is important for prevention of ascariasis
Typhoid :
Typhoid is an acute
infection of intestine.
It is caused by Salmonella
typhi.
It is Gram -ve bacteria
found in intestinal lumen of infected preson.
Pathogenicity is due to “O”- antigen, a lipopolysaccharide (LPS), present on surface coat. Flagella contains “H”- antigen.
Signs and Symptoms :
Prolonged fever as high as
1040F.
General nausea, fatigue,
headache.
Abdominal pain,
constipation or diarrhoea.
Rose-coloured rash on
skin.
White coat on tongue,
cough.
Anorexia (loss of
apetite).
If not treated-
breathlessness, irregular heartbeats, haemorrhage
Mode of transmission :
It is a food and water
borne disease.
Insects like housefly and
cockroaches feeding on fecal matter, may transfer the bacteria to food
material.
Poor hygiene habits and
poor sanitation conditions are responsible for the spread of typhoid
Diagnosis and Treatment :-
Widal test is used for diagnosis of typhoid. Treatment
of typhoid involves surgical
removal of gall
bladder in severe cases.
Antibiotics like Chloromycetin is helpful treatment.
For prevention of typhoid WHO recommendes two vaccines as oral
(Ty21a vaccine) and
injectable (Typhoid
polysaccharide vaccine) sold as- typhim vi and typherix
Pneumonia :
Pneumonia is an inflammatory condition of lungs or
alveoli of lungs.
It is caused by a variety of pathogens which
may be viruses like influenza virus,
adenovirus, para influenza and Respiratory
Syncytial Virus (RSV)
or bacteria like Streptococcus pneumoniae
or
fungal
pathogens e.g. Pneumocystis jirovecii and Pneumocystis carinii. Pneumonia can
also be caused by chemical burns or physical injury to lungs.
Signs and Symptoms :-
Cough produces yellow or
greenish sputum or phlegm.
High fever.
Shortness of breath (Dyspnea).
Chest pain during deep
breath or coughing.
Loss of appetite, fatigue,
headaches, vomiting, joint pains and muscle aches
Pneumonia -Infectious
agents
Mode of
transmission :
Pneumonia mostly spreads by
direct person to person
contact.
It can
also spread via
droplets released by infected person or even by using shared
clothes and utensils.
Diagnosis and
Treatment : Course of treatment depends
upon pathogen leading to
the disease. For
bacterial pneumonia, antibiotics like
Benzyl penicillin, Ampicillin and Chloramphenicol are effective.
Prevention and Control
:-
Vaccination is important
prevention in both children and adults.
Vaccines against Haemophilus
influenzae and Streptococcus pneumoniae in first year of life, help
greatly to reduce the chances of causing Pneumonia