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A P- iii, Q - iv, R - ii, S - i
Any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms is called disease. Diseases can be caused by microorganisms (pathogens) also.
The table above depicts some of the common contagious diseases and the causative agents.
Cholera : It is a bacterial disease caused by the bacterium Vibrio cholerae. This disease is transmitted by contaminated foods and water. It is generally found in places where there is a lack of sanitation facilities. Some of the symptoms of Cholera are weight loss, nausea, vomiting, bloating in the belly, cramps in the muscles and blood or mucus in the stool.
Figure : Common symptoms of cholera
Filariasis or Elephantiasis : This disease is caused by helminthes like Wuchereria bancrofti and Wuchereria malayi. The filarial worm is transmitted from one person to another by Culex mosquitoes. These worms cause a slowly developing chronic inflammation of the organs in which they live for many years, usually the lymphatic vessels of the lower limbs and genital organs. This leads to accumulation of fluids between the tissues and deformity of the affected organs.
Figure : Common symptoms of elephantiasis
Tuberculosis : It is caused by Mycobacterium tuberculosis. TB bacteria starts multiplying once it enters the lungs. It can cause severe symptoms such as coughing up blood and mucus from the lungs that lasts for two weeks or longer, sweating at night, pain in the chest, chills and fever.
Figure : Common symptoms of tuberculosis
Typhoid : Salmonella typhi is a pathogenic bacterium which causes typhoid fever in human beings. It is spread by contaminated food and water. The common symptoms seen are continued high fever, headache, stomach pain, constipation, loss of appetite and perforations in the intestine in severe cases.
Figure : Common symptoms of typhoid