Disease Causative Agents

It is a diarrheal infection of the small intestine caused by Giardia lamblia. It is caused by the ingestion of infective cysts.

Chlamydia is a bacterial infection disease transmitted when people have sexual relations.

Crohn's disease, also known as regional enteritis, is an inflammatory disease of the intestines.

This is the correct option. Hepatitis C is not a waterborne disease. Hepatitis C is commonly spread via direct contact with the blood of a person who has the disease.

This is the correct option. Polio is not a bacterial disease. It is a viral disease.

Most of the skin infections are caused by fungi. For example, ringworms. Bacteria and viruses cause internal infections like TB, influenza, etc. Mosquitoes can cause rashes on skin (it is not a disease) and may also transmit other diseases (not related to skin). Thus, (1), (2) and (3) are not suitable. So, only (4) is correct.

Common cold, pneumonia and tuberculosis are airborne diseases, i.e. they spread through air because their causative agents, i.e. virus and bacteria, are present in the air. On the contrary, malaria is not airborne because it is caused by Plasmodium, which spreads through the bite of female anopheles mosquitoes and is not present in the air. Thus, (4) is the correct answer.

Bacterial diseases are those diseases that are caused and transmitted by different bacteria. Typhoid, cholera and tuberculosis are caused by bacteria namely Salmonella typhii, Vibrio cholera and Bacillus calmettie, respectively. Dengue fever is caused by a virus, which is transmitted by the vector Aedes mosquito. Hence, option (3) is the correct answer.

Common cold (usually caused by viruses) is an infection of the upper respiratory tract. Signs and symptoms include coughing, sore throat, runny nose, sneezing and fever which usually resolve in seven to ten days, with some symptoms lasting up to three weeks. 

Headache, diarrhoea and common cold last for some time and affect us severely for that short period. But they do not leave any of the effects like weakness. Thus, these are acute diseases. On the contrary, tuberculosis is chronic because it affects us for a long time and also makes the body weak, even after the infection is cured. It is caused due to bacteria and in this disease, the lungs and the respiratory system are affected. In this, mucus begins to collect in lungs, gradually leading to inefficient gaseous exchange, frequent cough and even bleeding in the throat at later stages. Hence, option (4) is the correct answer.

Diarrhoea is an infection of stomach (gastro) and intestine in which the person suffers from water loss and loose stools. Hence, it is a gastrointestinal disorder (as is clear from its name).

Minamata disease was first discovered in Minamata city in Kumamoto prefecture, Japan, in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation's chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea, which when eaten by the local populace resulted in mercury poisoning.

Treponema is the causative agent of syphilis.

Correct answer :- (1) Polio

Yes, this is the correct answer, as all the above diseases are water borne.