Disease Causative Agents

Trachoma is a bacterial infection. It is caused by bacteria Chlamydia trachomatis. It is an eye infection. It causes itching and irritation of eyes. In severe condition, it may result in blindness.

Anthrax is a bacterial disease caused by the bacterium Bacillus anthracis. It can occur in four forms: skin, lungs, intestinal, and injection. It commonly affects grazing animals like sheep, pigs, cattle, horses, goats. However, it rarely affects humans as well. Tick fever is a disease spread by the bite of an infected tick. It is caused by spirochete species like Borelliahermsii, Borelliaparkerii. Symptoms include fever, headache, muscles pains, rash. Coccidiosis is a disease of the intestinal tract of animals caused by coccidian protozoa. Symptoms include droopiness, loss of appetite, pale combs and wattles, blood or mucus in the feces, diarrhea, dehydration. Rinderpest is a disease of cattle caused by a paramyxovirus. Symptoms include fever, dysentery, inflammation of the mucous membranes.

• House flies are not the neatest of insects. They visit such places as dumps, sewers, and garbage heaps. They feed on faecal matter, discharges from wounds and sores, sputum, and all sorts of moist decaying matter such as spoiled fish, eggs and meat. House flies are strongly suspected of transmitting at least 65 diseases to humans, including typhoid fever, dysentery, cholera, gangrene, poliomyelitis, yaws, anthrax, tularemia, leprosy and tuberculosis. Flies regurgitate and excrete wherever they come to rest and thereby mechanically transmit disease organisms.
• Pertussis, also known as whooping cough, is a highly contagious respiratory disease. It is caused by the bacterium Bordetella pertussis. Pertussis is known for uncontrollable, violent coughing which often makes it hard to breathe.
• Pertussis, also known as whooping cough, is a highly contagious respiratory disease. It is caused by the bacterium Bordetella pertussis. Pertussis is known for uncontrollable, violent coughing which often makes it hard to breathe.

The common cold is an infectious disease caused by rhinovirus. It causes inflammation of upper respiratory tract.

An airborne disease is any disease that is caused by pathogens and transmitted through the air. all respiratory droplets. The airborne transmission that occurs utilizes small particles or droplet nuclei that contains these infectious agents or pathogens. These particles and droplets are capable of remaining suspended in air for extended periods of time. Inhalation of these particles results in respiratory tract infection. Whooping cough (Bordetella pertussis), meningitis (Neisseria species), diphtheria (Corynebacterium diphtheriae), pneumonia (Mycoplasma pneumoniae, Streptococcus species) and tuberculosis (Mycobacterium tuberculosis) are some of the bacterial diseases that spread through air. 

Cholera is caused by a bacterium called Vibrio cholerae. A person gets cholera by drinking water or eating food infected with the bacterium. Once swallowed, it settles in the lining of the small bowel and releases a toxin (poison) that can cause the body to flush liquid into the small bowel, resulting in watery diarrhoea. Typhoid fever is an acute illness associated with fever caused by the Salmonella typhi bacteria. The bacteria spread through contaminated food or water and occasionally through direct contact with someone who is infected. 

City dwellers are facing the acute problems of water and vector borne diseases due to water logging and improper solid waste management and sanitation. The water logging and reprehensible drainage, contamination of water of upper layer from which major portion of the people get the polluted water through shallow bored hand pumps for drinking and other domestic purposes, are main cause of water borne diseases in the city. It is evident from studies that about 70.5 % population is suffering from the abdomen diseases cause by using polluted and contaminated water. Japanese encephalitis, jaundice, cholera, colitis, diarrhoea, dysentery, typhoid and skin diseases are common.

The diseases which are transmitted through contaminated air are known as airborne diseases. When the person lives in an overcrowded area which is poorly ventilated house, the person may suffer from breathing and airborne related diseases. The person may suffer from respiratory infections and disorders.

The disease can be transmitted directly or indirectly depending on the surrounding factors like example air , water and soil. Therefore, (b) is the correct answer.

Direct transmission is communicable and contagious disease. It is spread from one infected person to the host. It can be transferred due to direct sexual contact, through air in the form of sneezing or coughing, through contaminated food and water due fecal matter etc. Therefore, (d) is the correct answer.

Infections can also be transmitted through contaminated air, soil, water, surroundings etc. Food not prepared in hygienic conditions can also cause infection. Therefore, (c) is the correct answer.

Indirect Transmission is the spread of disease from host to host by means of a vector. Therefore, (b) is the correct answer.