Types of Diseases: Book Source: Sciecnec and technology , Dr BRAOU

1. TYPES OF DISEASES

Source:  Sciecnec and technology , Dr BRAOU

Any departure from the state of a good health can be generally called as “disease”. Similarly, any undesirable change occurring in the normal structure or functioning of a tissue or an organ of human body is referred to as disease. The diseases are classified into many types by the doctors or researchers. These are Infectious diseases, Congenital diseases, Dreadful diseases and Epidemic diseases

Attribution:  "Science and Technology" by Dr. B. R. Ambedkar Open University is licensed under CC BY 4.0

 Unit: 05, Page No: 55 - 71

2. Infectious Diseases

Infectious Diseases are also called as communicative diseases. These are passed from one person to another in different ways and through different media such as water, air, food, clothes etc. These are caused by micro organisms and worms. Some of the common infectious diseases are cold, cough and diarrhoea etc. The infectious diseases are caused by microorganisms are as follows.

Bacteria- Cholera, Dysentery, Whooping cough, Leprosy, Plague, Syphilis, Gonorrhea, Tuberculosis (TB), Typhoid, Menangitis etc.

Viruses- Chiken Pox, Cold, Influenza, Measles, Mumps, Rabies etc.

Protozoa- Malaria, Amoebic dysentery, Sleeping sickness etc.

Fungi- Skin-diseases, Ring worm diseases etc.

Worms- Filaria, Cysticercosis

Tuberculosis (TB): Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, an obligate aerobe, first isolated by Robert Koch in 1887. Hence it is known as Koch’s bacillus. Mycobacterium bovis causes tuberculosis in cattle and can also cause bovine tuberculosis in humans. The organism is a small rod like and enters the respiratory tract and grows on the lung tissue. The symptoms are chronic cough, chest pains, high fever and a flow of thick expectorated matter called sputum. “Directly observed therapy under supervision (DOTS)” strategy is at present implemented by WHO to control and prevent tuberculosis

But all diseases are not infectious. Some diseases are not caused by external infections. So these cannot be spread from person to person. For example diabetes, anaemia, joint pains, cancer, asthma, scurvy, obesity, hysteria etc., are some of the non-infectious diseases.

Attribution: "Science and Technology" by Dr.B.R.Ambedkar Open University is licensed under CC BY 4.0

Unit : 05  ,    Page No: 55 - 71

3. Congenital Diseases

Congenital Diseases

A number of diseases of man are acquired at birth. Such diseases are passed on from one generation to another in some members (congenital defects). Sir Archibald Garrod was bold enough to say that such inherited disorders are due to defective metabolism. However we now know that not all inherited disorders are due to detective metabolism.

Table : Inherited diseases, their causes and effects

Attribution: "Science and Technology" by Dr.B.R.Ambedkar Open University 
Unit : 05  ,    Page No: 55 - 71

4. Dreadful Diseases

Dreadful Diseases

AIDS, Cancer and very recently SARS are considered as dreadful diseases. The diseases cancer and AIDS have been known for few decades while the disease SARS has been identified only recently i.e. about one decade back.

SARS (Severe acute respiratory syndrome): Severe acute respiratory syndrome (SARS) is a mysterious cold killer and it is a communicable viral disease caused by a new strain of corona virus. This SARS virus was officially declared the causative agent on 16 th April 2003 by WHO.

SARS mostly spread through close contact with an infected person (droplet transmission) when that person sneezes and cough droplets escape into air. The most common symptoms in patient progressing to SARS include fever, malaise, chills, headache, myalgia, dizziness, cough, sore throat and running nose etc. In some cases there is rapid deterioration with low oxygen saturation and acute respiratory distress requiring ventilator support. It is capable of causing death in as many as 10 per cent of cases.

CANCER: Cancer may be regarded as a group of diseases characterized by an (i) abnormal growth of cells (ii) ability to invade adjacent tissues and even distant organs, and (iii) the eventual death of the affected patient if the tumour has progressed beyond that stage when it can be successfully removed. Cancer can occur at any site or tissue of the body and may involve any type of cells. Environmental factors include tobacco, alcohol, dietary factors, occupational exposures, viruses, parasites, life styles (customs and habits), radiation, air and water pollutants, pesticides etc. They act as agents causing cancer.

Attribution: "Science and Technology" by Dr.B.R.Ambedkar Open University
Unit : 05  ,    Page No: 55 - 71

5. Epidemic Diseases

Epidemic means “upon or above” and occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience. Epidemics of infectious disease are generally caused by a change in the ecology of the host population (e.g. increased stress or increase in the density of the vector species), a genetic change in the parasite population or the introduction of a new parasite to a host population (by movement of parasites or hosts). An epidemic may be restricted to one location; however, if it spreads to other countries or continents and affects a substantial number of people, it may be termed a pandemic. The epidemic diseases are whooping-cough, measles, influenza, and recent epidemics like Dengue, Swine flu and Chikungunya.

DENGUE: Dengue fever is an infectious disease carried by mosquitoes and can be caused by any one of four types of dengue virus: DEN-1, DEN-2, DEN-3, and DEN-4.This disease used to be called “break -bone” fever because it sometimes causes severe joint and muscle pain that

feels like bones arc breaking.

Dengue fever symptoms of typical uncomplicated (classic) dengue usually start with fever within 4 to 7 days after you have been bitten by an infected mosquito. These symptoms include: high fever, up to 105°F, severe headache, retro-orbital (behind the eye) pain, severe joint and muscle pain, nausea and vomiting, and rash. The rash may appear over most of the body 3 to 4 days after the fever begins, and then subsides after 1 to 2 days. There may be a second rash a few days later.

SWINE FLU : Swine flu has been creating a terror effect all around the globe and has been declared an epidemic in most parts of the world. In India, day by day, the graph of infected persons has been claimed to go up so, it is important to take into consideration this disease, as it may prove to be a deadly one. Swine influenza, also called pig influenza, swine flu, hog flu, and pig flu, is an infection caused by any one of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is any strain of the influenza family of viruses that is endemic in pigs. As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1,H1N2, H2N1, H3N1, H3N2, and H2N3.

The main route of transmission is through direct contact between infected and uninfected animals. These close contacts are particularly common during animal transport. The direct transfer of the virus probably occurs either by pigs touching noses, or through dried mucus. Air- borne transmission through the aerosols produced by pigs, coughing or sneezing is also an important means of infection.

CHIKUNGUNYA : Chikungunya occurrence was first detected in human blood samples in 1952-53 from Tanzania, Africa. This disease was reported in India for the first time in Calcutta in 1963. Chikungunya virus is transmitted by two mosquitoes, Aedes albopictus and Aedes egypti from the infected to a normal person. The disease is also locally named as Joint Pain disorder. This mosquito is an oracious day time feeder and bites people only during day time and the mosquito Aedes albopictus is also termed as a tiger mosquito for it shows the characteristic presence of white stripes on the body and its large size than a normal mosquito.

Symptoms are expressed after an incubation period of 1-12 days after a mosquito bite, which include fever, headache, joint pain (or Arthralgia), Arthritis affecting multiple joints, swelling of joints, Rash (rare symptom), conjunctival infection, photophobia, chills, nausea, vomiting, and bleeding or hemorrhage (rare symptom).

Attribution: "Science and Technology" by Dr. B. R. Ambedkar Open University.
Unit: 05, Page No: 55 - 71