Question

Which of the following are infectious and non-infectious diseases respectively?
a. Typhoid and AIDS
b. AIDS and cancer
c. Pneumonia and malaria
d. Cancer and arthritis

Answer 1

Hint: An infectious disease is a disease caused by infection of microbial agents such as viruses, bacteria, fungi, protozoa, and helminths. Non-infectious diseases are not caused by pathogens but because of lifestyle factors, immunological disorders and genetic mutations.

Complete Answer:
Infectious diseases are caused by pathogens. In the given question, typhoid, AIDS, pneumonia and malaria are infectious diseases caused by bacteria and viruses. While cancer and arthritis are not caused by pathogens rather they are non-infectious diseases. These are caused by various factors like hereditary, mutations, immunological disorders etc.

Typhoid is the waterborne disease. Typhoid fever is caused by Salmonella typhi and is acquired by ingestion of food or water contaminated by faeces of infected humans or person-to-person contact. The bacteria colonize the small intestine, penetrate the epithelium, and spread to the lymphoid tissue, blood, liver, and gallbladder.

AIDS is Acquired Immunodeficiency Syndrome. It is an infectious disease syndrome caused by the human immunodeficiency virus and is characterized by the loss of a normal immune response, followed by increased susceptibility to opportunistic infections.

Pneumonia is an infection of the respiratory tract and involves one or both lungs. Potential pathogens are Staphylococcus aureus and Streptococcus pneumonia. Malaria is a vector borne infection and spreads through mosquito bite. Sporozoite is the motile, infective stage of Plasmodium, the causative agent of malaria. Thus Typhoid, AIDS, Pneumonia and Malaria are infectious diseases.

Cancer is unregulated growth of cells. A tumor is an overgrowth or lump of tissue resulting from neoplasia. The abnormal new cell growth and reproduction is because of loss of regulation in cell cycle. Tumor cells have different shapes and altered plasma membranes that may contain distinctive tumor antigens. The unregulated cell growth and loss of differentiation of such cells result in invasive growth that forms unorganized cell masses as tumors. The cancers are related to environmental, lifestyle, or behavioural exposures.

Arthritis is an autoimmune disease. In rheumatoid arthritis, autoantibodies against self IgG antibodies are formed by B cells, which form complexes deposited in joint tissue, causing inflammation and cartilage destruction. This results in the inflammation of joints, causing pain and stiffness that can worsen with age. It may be due to severe injury to joints, antibody-antigen complexes at joints, obesity. Thus Cancer and Arthritis are non-infectious diseases.

The correct choice is B, as AIDS is an infectious disease and cancer in non-infectious disease respectively.

Note: AIDS is an infectious disease caused by HIV. It results in decrease in immunity in individuals because HIV acts on B cells of human beings, while cancer is a non-infectious disease. It is the unregulated growth of cells because of various factors like genetic factors, mutation etc.