Infections and Diseases

Infection and disease

Disease is a condition that interferes with the normal functioning of the body. It can affect the whole body or only part of it.

When disease is caused by microorganisms they are known as infectious disease or communicable disease.

Communicable disease is disease which can be spread from one person to another. They are caused by pathogens such as viruses, bacteria, protozoa and fungi. Examples of communicable diseases are AIDS, Malaria, Cholera, Tuberculosis, Typhoid, Ring worms. Vectors are organisms which carry pathogens e.g. fleas, mosquitoes, bees, tsetse fly. Communicable diseases are classified according to their occurrence.

1. Epidemic diseases These are outbreaks of communicable disease which affect a large number of people in a short period of time, e.g. Cholera, Typhoid, Meningitis and plague.

2. Pandemic diseases These are communicable diseases which affect a whole country, continent or the whole world e.g. HIV/AIDS

3. Endemic diseases These are communicable diseases which regularly occur in a particular area and are difficult to get rid of e.g. Malaria, gonorrhea, syphilis, bilharzia.

Disease can be grouped also depending on the cause e.g.

SN	Cause	Disease e.g.
1	Bacterial disease	Typhoid, Cholera, TB, Gonorrhea
2	Viral diseases	AIDS, Polio, measles, smallpox, chickenpox
3	Protozoan diseases	Amoebic dysentery, Trypanosomiasis (sleeping sickness), malaria
4	Fungal diseases	Ring worms, candidiasis, athlete's foot
5	Genetic disease (inherited diseases)	Haemophilia, sickle cell, anaemia, down syndrome, albinism
6	Worm diseases	Elephantiasis, bilharzia (schistosomiasis)
7	Hormonal diseases	Diabetes mellitus, diabetes insipidus
8	Malnutrition diseases	Kwashiorkor, obesity, marasmus, Goitre, Anaemia, Rickets

Diseases also can be grouped according to mode of transmission e.g.

Mode of Transmission	Disease Examples
Airborne diseases	Tuberculosis, common cold, influenza, whooping cough
Water-borne diseases	Cholera, Typhoid fever, Schistosomiasis
Contaminated blood	HIV/AIDS, Malaria
Physical contact (contagious diseases)	Ring worms, Scabies

Routes through which disease causing agents enter our bodies are mouth, nose, penis, vagina, anus, skin, open wounds.

Non-infectious (non-communicable) diseases are diseases which can't be transmitted from one person to another e.g. sickle cell, anaemia, albinism, kwashiorkor, arthritis, skin cancer, diabetes. Diseases can be broadly divided into two categories:

1. Communicable diseases (infectious diseases)
2. Non-communicable diseases (non-infectious diseases)

Common infectious diseases

SN	Disease	Causal Agent	Clinical Features	Mode of Transmission	Methods of Prevention and Control
1	Measles	Virus	Inflammation of respiratory tract, fever, contact rash	Inhalation and contact	Vaccination
2	Cholera	Bacteria (Vibrio cholerae)	Diarrhea, vomiting, weight loss, muscle cramps, wrinkled skin	Contaminated food and water	Wash hands after toilet and before meals, boil drinking water, wash fruits before eating, vaccination, medical treatment
3	Meningitis	Bacteria and Virus	Fever, headache, vomiting	Droplets from coughing or sneezing	Isolation of patient, vaccination, medical treatment
4	Tuberculosis	Bacteria (Mycobacterium tuberculosis)	Prolonged cough, blood-stained sputum, fever, poor appetite, weight loss, night sweats	Droplets when coughing or sneezing	Vaccination, cover nose and mouth while coughing or sneezing, medical treatment
5	Plague	Bacteria (Yersinia pestis)	Inflammation of lymph nodes, fever, internal bleeding, body aches, coughing	Spread by fleas found on rats	Vaccination, elimination of rats, medical treatment
6	Bilharzia (Schistosomiasis)	Blood flukes (Schistosoma)	Blood-stained feces/urine, abdominal pain, diarrhea, fever, enlarged liver/spleen	Water with snail larvae	Kill snails, proper sewage disposal, wear protective shoes in water-logged areas, drain stagnant water, medical treatment
7	Malaria	Protozoa (Plasmodium)	Chills, fever, sweating, vomiting, pain in joints, headache, abdominal pain	Transmitted by female Anopheles mosquito	Use mosquito nets, drain stagnant water, cut bushes, use mosquito sprays, anti-malaria drugs
8	Scabies	Microscopic mites	Intense itching, rashes, and burning sensation	Skin-to-skin contact, sharing personal items	Good hygiene, wash clothes in hot water, avoid sharing personal items, medical treatment
9	Rabies	Virus	Fever, difficulty swallowing, restlessness, loss of feeling, vomiting, hydrophobia	Bites/saliva from infected animals	Vaccination, eliminate infected animals, seek medical treatment
10	Diabetes	Insulin disorder, genetic factors	Fatigue, weight loss, excessive hunger, poor wound healing	N/A	Control weight, exercise regularly, avoid alcohol, stop smoking, diet control, insulin injection
11	Cancer	Mutations, carcinogens (e.g., smoking)	Tumours, bleeding, pain, weight loss, poor appetite	N/A	Avoid carcinogens, surgery, chemotherapy, radiation therapy, immunotherapy, hormonal therapy
12	Tetanus	Bacteria (Clostridium tetani)	Painful muscle spasms, lockjaw	Contact with soil, rusted objects	Vaccination, avoid rusted equipment, cover wounds when in contact with soil
13	Typhoid	Bacteria (Salmonella typhi)	Vomiting, diarrhea, high fever	Contaminated food and water	Improve sanitation, boil drinking water, proper toilet use, vaccination
14	Dysentery	Bacteria (Shigella) or Protozoa (Entamoeba histolytica)	Severe diarrhea, abdominal pain, profuse bleeding	Contaminated food and water	Improve sanitation, boil drinking water, rehydration therapy, antibiotics