Health came to be regarded as a state of complete physical, mental and social well-being. However, when our body is infected with a disease we are no longer healthy. Diseases can be of two types: infectious and non-infectious. As the name suggests, infectious diseases are those that can be transmitted from one person to another.
Diseases can be caused by a variety of organisms such as bacteria or fungi. All disease-causing organisms are called pathogens. Pathogens enter our body through various means, adapt to the environment inside the body and multiply inside. They then interfere with normal bodily functions, causing either morphological or functional damage. The bacteria Salmonella Typhi causes typhoid fever in humans. Typhoid fever can be confirmed by a Widal Test. In extreme cases, typhoid can cause intestinal perforation and death. Pneumonia, dysentery, plague and diphtheria are other diseases caused by bacteria.
Viruses are not behind when it comes to causing infectious diseases. Rhino viruses are responsible for causing the common cold. Nasal congestion and discharge, a sore throat, headache and hoarseness are symptoms of the common cold, which lasts for about three to seven days.
Helminths like Ascaris and Wuchereria are also responsible for causing pathogenic diseases in human beings. Ascaris, the common round worm, is an intestinal parasite that causes Ascariasis. It is characterised by internal bleeding, muscular pain, fever, anaemia and blockage of the intestinal passage. Wucheria Bancrofti, is a filarial worm that causes a disease called filariasis. It is characterised by chronic inflammation of the organs. The worm occupies the lymphatic system, where they continue to live for years. The genital organs are often affected, resulting in gross deformities. Filariasis can be transmitted to healthy people by female mosquito vectors.
Other pathogens such as fungi like Microsporum, Trichophyton and Epidermophyton cause ringworms that appear as dry, scaly lesions on various parts of the body such as the skin, nails and scalp. These lesions also cause intense itching. Ringworms can be transmitted to healthy individuals by sharing towels, combs and clothes of an infected person. Therefore, pathogens like bacteria, fungi, viruses and helminths are responsible for causing some common yet extremely infectious diseases.