Notes-Class 8-General Science-Chapter-2-Health and Diseases-Maharashtra Board

Infectious Diseases: Diseases spread through contaminated air, water, food or vectors (insects and other animals) are called as infectious diseases.

1) Tuberculosis. :

Pathogen :  Mycobacterium tuberculae.

Mode of infection : Spitting by patient, through air, prolonged contact with and sharing of materials of patient.

Symptoms : Chronic cough, bloody spitting, emaciation, difficult breathing.

Prevention and treatment : BCG vaccine, isolation of patient, regular medication like DOT. [/responsivevoice]

 2) Hepatitis (Jaundice). :

Pathogen : Hepatitis virus- A, B, C, D, E.

Mode of infection :  Contaminated water, sharing of needles, blood transfusion.

Symptoms : Anorexia, yellow urine, general weakness, nausea, vomiting, grey stool.

Prevention and treatment : Drinking boiled water, proper cleaning of hands.

 3) Dysentery. :

Pathogen :  Bacteria, virus,Shigella, bacilli,Entamoeba histolytica.

Mode of infection : Contaminated food and water.

Symptoms : Watery stool, pains in abdomen.

Prevention and treatment : Drinking of boiled water, proper storage of food, ORS consumption.

4) Cholera. :

Pathogen :  Vibrio cholera (bacterium).

Mode of infection : Contaminated food and water.

Symptoms : Vomiting, severe diarrhea, cramps in legs.

Prevention and treatment : Following hygienic practices, avoiding open place food, drinking boiled water, vaccination against cholera.

5) Typhoid :

 Pathogen :  Salmonella typhi (bacterium).

 Mode of infection : Contaminated food and water.

 Symptoms : Anorexia, headache, rash on abdomen, dysentery, fever up to 104⁰ F.

 Prevention and treatment : Drinking clean water, vaccination, proper disposal of sewage. 

6) AIDS (Acquired ImmunoDeficiency Syndrome.)

Pathogen :This disease is caused by a deadly virus known as HIV (Human Immunodeficiency Virus).

Symptoms : In this disease, the patient suffers from various types of diseases due to weakening of his/her natural immunity of the body. AIDS cannot be diagnosed or confirmed without proper tests in medical laboratories. ELISA test is basically used for its proper diagnosis. Although the symptoms of AIDS may differ from person to person.

Prevention : Preventive measures for AIDS are:

• Avoid sexual contact / intercourse with unknown people.
• Check blood thoroughly before transfusion.
• Avoid sharing or using the same needles or syringes. 

7) Dengue :

Pathogen  This disease is caused by DEN-1 - 4 virus belonging to the type- flavivirus.

This is a disease which is transmitted by Aedes mosquito which lays eggs in water-logged places, which multiply over time.

 Symptoms

1. Acute fever and headache, vomiting.
2. Pains in eye socket is very prominent symptom.
3. Decrease in platelet count that may lead to internal hemorrhage.

 Prevention  : Mosquitoes breeding can be prevented by adopting the following measures:

• Larvae-eating fishes should be introduced and left in pond water.
• Water storage and collection should always be done in closed vessels.
• There should be proper drainage of potted plants to avoid accumulation of water in the pots.
• Use of pesticides against mosquitoes as and when necessary. 

8) Malaria  : Malaria is spread by female Anopheles Anopheles and Aedes grow in clean water.

Malaria is mainly caused and spread in human beings when a female Anopheles mosquito bites which usually breed in stagnant water.

9) Swine Flu:

Pathogen : Swine flu is caused by the virus influenza A (H1N1).

 Reasons of infection :

• Infection for swine flu occurs through pigs and humans.
• Viruses of swine flu are spread through secretions of nose, throat and saliva.

 Diagnosis of Swine Flu: For diagnosis of swine flu, liquid from throat of patient is sent in laboratory.

Diagnostic facilities are available in National Institute of Virology (NIV), Pune and National Institute of Communicable Diseases (NICD), Delhi.

 Symptoms :

• Difficulty in breathing.
• Sore throat, body pains. 

10) Elephantiasis : Elephantiasis is caused by the bite of a female Culex mosquito which breeds in dirty and sewage water. 

Infections through Animals : It occurs due to the bite of the infected animals.

 Rabies: This is a viral disease. It occurs due to the bite of the infected dog, rabbit, monkey, cat etc. Virus enters the brain via neurons. Rabies is fatal disease

 Symptoms :

1. Fever for 2 – 12 weeks
2. Exaggerations in behaviour.
3. Hydrophobia..

 Prevention : However, fatality can be prevented by timely vaccination before onset of symptoms. Symptoms start to appear within 90 –175 days of dog bite. 

Non-infectious diseases : Diseases which do not occur through infections and body contacts are called as non-infectious diseases. Such diseases arise in human body itself due to certain reasons.

Examples :  1.Cancer, 2. Diabetes, 3. Hypertension, 4. Heart Diseases. 

1.Cancer : Uncontrolled and abnormal cell growth is called as cancer.

Group or lump of cancerous cells is called as malignant tumor.

Cancer can occur in various organs like lungs, mouth, tongue, stomach, breast, uterus, skin and tissues like blood.

 Reasons : Consumption of tobacco, gutkha, smoking, alcoholism, lack of fiber content

(fruits and leafy vegetables) in food, excessive consumption of junk food (pizza, burger etc) are some of the many possible reasons. Heredity may also be a reason.

 Symptoms :

2. Chronic cough, hoarse voice, difficulty in swallowing.
3. Incurable scar and inflammation.
4. Lumps in breast.
5. Unexplained weight-loss. 

2. Diabetes: The hormone- insulin produced in pancreas controls the level of sugarglucose

in blood. If insulin is secreted in low quantity, glucose level cannot be controlled; this disorder is called as diabetes.

 Reasons for diabetes : • Heredity • Obesity • Lack of physical exercise • Mental stress

 Symptoms -

1. Unexplained weight loss
2. Increased obesity
3. Frequent urination at night
4. Feeling thirsty often
5. Weakness due to giddiness

Preventive measures:

Following the proper diet, medicines and exercise under the supervision of doctor helps to keep the diabetes under control.

3. Heart Diseases : Efficiency of the heart decreases due to decreased blood supply and thereby oxygen and nutrient supply to the heart muscles. Due to this, heart has to perform more work that leads to stress on it. This may cause heart attack.

If someone has heart attack, immediate consultation of doctor and treatment is necessary.

 Reasons : Smoking, alcoholism, diabetes, hypertension, obesity, lack of physical exercise, heredity, mental stress, anger, anxiety.

Symptoms :

Severe chest pains, pains in shoulder, neck and arms, cramps in hand, uneasiness, tremors.

Treatments : Heart diseases can be managed to an extent by following the below listed medical procedures:

1. Angioplasty
2. By-Pass surgery
3. Open heart surgery
4. Heart transplant
5. Installation of stents
6. Installation of pacemaker.

Generic medicines : Generic medicines are also known as general medicines. These are

manufactured and distributed without any patent.

These medicines are at par in quality with branded medicines. Production cost of these

medicines is very low due to fewer expenses on research as their formula is readily available.

Poor people do not afford the costly medicines. Generic medicines is the alternative for this.

Misuse of Medicines : Sometimes, some people take the medicines without prescription of

doctor. Overdose of medicines may affect our body. Ex. Overdose of pain killers may damage nervous system, excretory system, liver. Overdose of antibiotics may lead to nausea, stomach ache, dysentery, rash, white patches on tongue etc.

Vaccination: Vaccination is important to prevent the infectious diseases. 

Lifestyle and diseases : Lifestyle includes the daily routine and the type of food.

Nowadays, habits like staying in bed till late morning and going to bed late in night, frequent changes in meal timings, lack of physical exercise, consumption of junk food, etc. have been increased. Due to this, such people are getting sick frequently.

If frequency of becoming sick is to be lowered, people should follow right lifestyle. It must include sufficient sleep, right food, yogasanas, pranayam and physical exercise. Physical exercise should also be as per one’s own capacity.

Pranayam and yogasanas should be performed under the expert supervision.