Biology In Human Welfare Human Health And Disease 1

Health#

Health does not simply mean ‘absence of disease’ or ‘physical fitness’. It could be defined as a state of complete physical, mental and social well-being. When people are healthy, they are more efficient at work. This increases productivity and brings economic prosperity. Health also increases longevity of people and reduces infant and maternal mortality.

Health is affected by

(i) genetic disorders – deficiencies with which a child is born and deficiencies/defects which the child inherits from parents from birth; (ii) infections and (iii) life style including food and water we take, rest and exercise we give to our bodies, habits that we have or lack etc.

Disease: When one or more organs or systems malfunction, resulting in signs and symptoms, we consider this a disease.

Disease Categories: Diseases are broadly classified into infectious and non-infectious.

Infectious Diseases: These are easily transmitted between individuals. They are very common, and everyone experiences them at some point in their lives. Some infectious diseases, such as AIDS, are fatal.

Non-Infectious Diseases: Among these, cancer is a leading cause of death.

Other Factors Affecting Health: Drug and alcohol abuse also negatively impact health.

Bacterial Diseases:#

Typhoid Fever: Caused by Salmonella typhi Enters through contaminated food/water, migrates to other organs via the bloodstream. Symptoms include high fever (39-40°C), weakness, stomach pain, constipation, headache, and loss of appetite. Severe cases can lead to intestinal perforation and death. Diagnosed by the Widal test. Example: Typhoid Mary, a cook who unknowingly spread the disease for years.

Pneumonia: Caused by bacteria like Streptococcus pneumoniae and Haemophilus influenzae. Infects the alveoli (lung air sacs), filling them with fluid and impairing respiration. Symptoms include fever, chills, cough, and headache. Severe cases may cause gray/bluish discoloration of lips and fingernails. Spread through droplets from coughs/sneezes or shared utensils/glasses.

Other Bacterial Diseases: Dysentery, plague, diphtheria.

Viral Diseases:#

Common Cold: Caused by rhinoviruses. Infects the nose and respiratory passage (not the lungs). Symptoms include nasal congestion, discharge, sore throat, hoarseness, cough, headache, and tiredness (lasting 3-7 days). Spread through droplets from coughs/sneezes or contaminated objects.

Protozoan Diseases:

Malaria: Caused by Plasmodium species (P. vivax, P. malariae, P. falciparum). P. falciparum causes the most serious form (malignant malaria). The parasite’s life cycle involves two hosts: humans (where it multiplies in liver cells and red blood cells, releasing the toxic haemozoin) and female.

Anopheles mosquitoes (the vector). Symptoms include recurring chills and high fever.

Amoebiasis (Amoebic Dysentery): Caused by Entamoeba histolytica, a parasite in the large intestine. Symptoms include constipation, abdominal pain, cramps, and bloody stools. Spread through fecal contamination of food and water; houseflies act as mechanical carriers.

Helminthic Diseases:#

Ascariasis: Caused by Ascaris (roundworm), an intestinal parasite. Symptoms include internal bleeding, muscle pain, fever, anemia, and intestinal blockage. Spread through contaminated water, vegetables, and fruits (eggs are excreted in feces).

Elephantiasis (Filariasis): Caused by Wuchereria (W. bancrofti and W. malayi) (filarial worms), causing chronic inflammation of lymphatic vessels (often lower limbs and genitals). Spread through the bite of female mosquito vectors.

Fungal Diseases:#

Ringworm: Caused by fungi from the genera Microsporum, Trichophyton, and Epidermophyton. Symptoms include dry, scaly lesions with itching on skin, nails, and scalp. Spread through contact with infected individuals or soil. Heat and moisture promote fungal growth.