Diseases are abnormalities in our body causing discomfort as a result of organs or organ systems being affected. Diagnosis of disease is aided by signs which our body exhibits. These signs are called symptoms. Symptoms help in the accurate diagnosis of the disease under the careful supervision of an experienced physician.
Most of the diseases are contagious, they spread from one person to another through various modes such as air, water and contaminated food, or through vectors. Microbial agents move from an infected person to a non-infected person through different media. They are called communicable diseases since they can be communicated.
Microbes which can potentially cause a disease to spread through the air. This can be in the form of a cough and sneezes ejected from the mouth of an infected person in the form of tiny, almost invisible droplets. The ambient air is now infected, any person inhaling this air falls sick which harbours microbes with the capability to cause a new infection. Some common diseases that are spread through the air are – Pneumonia, Tuberculosis, Common cold. Airborne diseases are more likely to spread in a crowded ecosystem.
Also Read: Diseases Communicable Non Communicable
Another mode by which diseases spread is water. This occurs when excreta of an infected person gets mixed with potable water in a community, for example, the excreta can be from a person diagnosed with cholera. Microbes are responsible for causing cholera to enter into the system of a non-infected person once the water is consumed causing cholera to spread. Proper treatment of drinking water can be helpful to keep a check on water-borne diseases.
Diseases can also spread through sexual contact with an infected person. It is one of the closest physical contacts two people can have with each other. Examples for sexually transmitted diseases are – AIDS, Syphilis, Gonorrhea. These diseases are not spread through casual contact with an infected person such as hugs, handshakes, eating in their vicinity, playing sports or any other way in which we interact with them socially.
Viruses causing AIDS is the HIV which can spread through sexual contact or blood-to-blood contact from an infected person. It can also spread from an infected mother to her baby during her gestation period or breastfeeding.
Animals can act as hosts as they have the potential to carry pathogens and cause diseases to other animals and humans too, which usually occurs through direct contact. These animals are called vectors as they act as intermediaries carrying the infected agents. Mosquitoes are one of the most common vectors. Female mosquitoes require nutrition rich food to produce mature eggs. They usually obtain required nutrition by feeding on human blood, hence transmitting diseases.
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Further reading: Infectious Diseases