Causes of the diseases

Diseases not caused by organisms – Non communicable diseases

                       Diabetes mellitus is a state of expulsion of excess unused glucose in theurine due to less production of insulin

 Similarly, Diabetes Insipidus, Coronary heart diseases, Renal failure,Hypertension, Obesity, AIzheimer’s disease ,stroke affecting the functions of the brain, etc, all are caused due to metabolic disorders.

Hereditary diseases orGenetical disorders:    

• Albinism is an inheriteddisorder of melanin metabolism, characterized by the absence of melanin in the skin,hairs and eyes
• Haemophilia, Sickle cell anemia,Thalassemia, Down’s syndrome,Bubble boy syndrome , etc are a few other genetical disorders.

Nutritional Deficiency diseases:  Protein deficiency causes Marasmusand Kwashiorkor.

Diseases caused by Organisms: Robert Koch and Louis Pasteur werethe first toestablish the Germ theory of diseases.

Some Important Vitamin Deficiency Diseases are Tabulated Below:

Parasitic Micro -organism: They are viruses, bacteria, fungi andprotozoans,

Viruses and viral diseases in man:

• The Viral body consists of a nucleicacid, DNA or RNA and a protein cover.
• Deadly diseases such as Polio, rabies, hepatitis, encephalitis (brain fever), etc.
• and visible under Compound Mi ~\ 1 »‘ yy _

Bacteria and Bacterial Diseases: Bacteria are unicellular prokaryotes and visible under compound Microscope

• Some bacterial diseases in man are Tuberculosis, Leprosy, Cholera, Typhoid, Diphtheria, Tetanus,Plague, Pneumonia, Syphilis, Gonorrhoea, etc.
• Fungi and Fungal Diseases: Fungi are non green saprophytic or parasitic living on dead and decaying organic matter or livingorganisms.
• fungi are parasitic on man and cause Ringworm attacking thekeratinizedlayer of skin.
• Dandruff, Athletes foot are some other fungal diseases in man.
• Protozoan and Protozoan Diseases: Protozoans are unicellularanimalcules, some parasitize man and cause diseases such as malaria,amoebic dysentery, sleeping sickness, etc.
• Parasitic macro – organisms: Infestations of the body with tapeworm,liver fluke, round worm, filarial worm, etc,.causediseases in man likeTaeniasis, Ascariasis, Filariasis, etc,.

Diseases Caused by Microbes and Prevention

• Viral diseases
• Common Cold

In lowers the resistance of the body, leading to a number of secondaryinfections like pneumonia bronchitis, etc,

Transmission

• Droplets discharged from the nose
• Close inanimate objects like handkerchief, bedding, clothes, utensils, toilet articles, etc,. (called fomites)
• Control and prevention: There are no effective measures to control common cold. However, a good nourishing food, avoiding contact with patients and wearing suitable clothing  aresuggested, to keepaway from common cold.

Influenza

• Causative agent: A(N₁N₁)Virus is spherical in shape and highlycontagious causing influenza

Transmission

• nasal and mouth droplets of patients It also spreads through fomites.

Bacterial diseases

• Bacteria are prokarotic organisms. Some of the bacteria are parasitic inman, causing diseases like TB, Cholera, Typhoid, dysentry etc,.

Tuerculosis

• It is an airborne disease affecting the lungs and also parts f our bodysuch as bones, joints, lymph glands, alimentary tract, liver, kidney, etc.
• 0Mycobacterium tuberculosis, a rod shaped bacterium causestuberculosis (TB).

Symptoms

• The affected parts develop lesions in the form of small nodules calledtubercles
• Persistant cough
• loss of body weight

Transmission

• Through air. Large number of bacteria leave the patients through thedroplets of sputum expelled by the patients(while eating, sneezing)

Prevention

• Keeping one self healthy and avoiding in sanitary conditions,overcrowding and poor ventilation
• Sunlight and fresh air
• Isolation of the patients
• Incineration (burning) of the droplets, the sputum from the patients to prevent its occurrence in the air.
• Immunization with BCG vaccine is an effective measure to prevent this disease.

Typhoid

• Flagela – Salmonella typhi causes typhoid.

Symptoms

• Continuous fever.
• Inflammation and ulceration of intestine.
• Enlargement of spleen and a characteristic red spot eruption on theabdomen.

Transmission

• Through food and water contaminated with the germ, the personalcontact with patients and carriers.
• Flies are also important transmitting agents of this disease.
• Prevention and control: Artificial immunization with typhoid vaccine isadvised.
• A recovery from typhoid usually confers a permanent immunity.

Protozoan diseases:

• Some of the unicellular protozoans are parasitic pathogens and causediseases in man.

Malaria

• Causativ e agent:Plasmodium is responsible for causing malaria. Four different species of Plasmodium namely,P.Vivax,P.malariae,P,falciparum and P.ovale in India causing malaria
• Plasmodium falciparum is the most serious one.

Transmission

                       Vector – the female Anopheles mosquito.

Symptoms

• Chilliness and rise in temperature. This is followed by perspiration andlowered body temperatures.
• Successive attacks of malaria result in the distension of spleen anddestruction of liver tissues.

Prevention and control:

• Sanitary measures include ground fogging with disinfectants.
• Closure of stagnant pools of water

Life cycle of malarial parasite – Plasmodium:

• The sexual stage ofPlasmodium takes place in female Anopheles mosquito
• Vegetative stage occurs in man. When a female Anopheles mosquitobites an infected person, these parasites enter the mosquito andundergo further development in the mosquitoes body
• The parasites multiply within the body of the mosquito to formsporozoites that are stored in the salivary glands of mosquito.
• When these mosquitoes bite a person,the sporozoties (the infectious stage) are introduced into his body
• They multiply within the liver cells first and enter the RBC of man, resulting in the rupture of RBC
• This result in the release of toxic substance called haemozoin which is responsible for the chill and high fever ,recurring three to four days

Sir.Ronald Ross

• Ronald Ross 91857 – 1932), a British Indian physician.
• He discovered the presence of malarial parasites in the femaleAnopheles mosquito
• In 1902, he was awarded the Nobel prize for his work on malaria.

Amoebic dysentry (Amoebiasis)

• Causative agent: Entamoeba histolytica – a protozoan parasite in thelarge intestine of man causes Amoebiasis.

Symptoms

• Fever
• Constipation and abdominal pain and cramps.
• Stools with excess mucous and blood clot.

Transmission

• It is a water and food borne disease. House flies act as mechanical carrier

Fungal diseases in man

Ringworm

Symptoms

• Superficial infections in skin hair ,nail etc; and form patches and itching

Transmission

By direct contact or through fomites such as towels, combs, etc,.

Modes of Transmission

Of Infectious Germs

• Direct Transmission: By direct transfer of germs from the patient to normal healthy person through close contact, the diseases like diphtheria, pneumonia, cholera, typhoid, measles, mumps, etc,. are transmitted.
• During sneezing, coughing and talking, the droplets from the patientsare discharged from the mouth and the nose and enter the air.
• Through the umbilical cord, the germs are transferred from the infected mother to the child

Indirect transmission through fomites: Clothing, bedding,handkerchief, toilet articles, utensils, drinking cups and glasses

Such contaminated objects are called fomites.

• Transmission by animals: ticks, mites, birds, insects and mammalstransmit diseases like cholera, malaria, rabies, etc;

Immunization

Immunity:      

• Immunity is part of a complex system of defence reaction inthe body. It means the defence against or specific resistance exhibitedtowards the infectious organisms and their products
• The infectious organisms that invade the bodyand the toxins producedby them and any foreign protein entering the body are called antigens
• The immune system which includes blood plasma, lymph and lymphocytesanalyze the chemical nature of the antigens and produce the suitable proteinaceous substances called antibodies to detoxify the antigens

Artificial Active Acquired Immunity: E.g The polio drops and triple antigen injected into the child in the immunization programme                                           

Types of immunity

                                                            Immunity

Natural or Innate naturally                                            Acquired or specific developed in the

Available right from birth                                             body after birth

   Active                                                                                                                                              Passive

    Antibodies arePre-formed                                                                                          Produced by forth immunity

                                                                                                                                  Bring                                                                           

                        Antigenic stimulus     

                                                                                                                     Natural                         Artificial

Artificial                                                          Natural

Immunization Schedule

Immunization schedule followed in India

Immunization:

Administering vaccines to prevent the disease is called immunization.

• BCG Tuberculosis Vaccine
• DPT Diphtheria, Pertussis,
• Tetanus Vaccine (Triple antigen)
• MMR Mumps, Measles, Rubella
• DT Diphtheria, Tetanus (Dual antigen)
• TT Tetanus toxoid

HIV and Prevention

• Transmitted through sexual contact or through blood and blood products. Robert Gallo at National Institute of Health, USA and Luc Montagnier at Pasteur Institute ,Paris isolated the virus, Human Immune Deficiency Virus(HIV)which causes AIDS
• HIV is a retro virus with protein envelope and the genetic materialRNA.
• HIV causes profound Immune suppression in humans.
• It is due to the depletion of one type of WBC, which is involved in theformation of antibodies called CD4 plus T-helper cells (lymphocytes).
• Symptoms: Significant weight loss, chronic diarrhoea, prolonged fever,opportunistic infections such as tuberculosis, candidiasis and recurrent herpes zoster (viral) infection.

Test for Virus:

• Enzyme Linked Immuno Sorbent Assay (ELISA)
• Western Blot – a confirmatory test.

Prevention:

• Protected sexual behaviour.
• Safe sex practices.
• Screening the blood for HIV before blood transfusion
• Usage of disposable syringes in the hospitals
• Not sharing the razors / blades in the saloon
• Avoid tattooing using common needle