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Infectious diseases
As if toxic pollution isn’t enough, every breath you take fills your lungs with a
multitude of dangerous germs. The sneeze of the person next to you, or the gases
from animal housing nearby propels bacteria, viruses and fungi into the atmosphere.
Natural or man-
Bacteria are the dominant life form on earth and adapt to almost all habitats. In the air they like to attach to other substances, thus increasing their chances of survival. Bacteria are present high in the atmosphere and drift long distances in the prevailing wind.
Food and water are also likely carriers of bacteria. Most bacteria are harmless but others cause diseases such as cholera, pneumonia, leprosy, diphtheria, scarlet fever and tetanus.
Viruses don’t feel as comfortable in the air as bacteria do. They require a host to multiply and most don’t defend well against climatic variations and UV radiation. There are always exceptions, of course, such as the polio virus, which can live long enough to travel several kilometres Some animal viral diseases can cause outbreaks from some distance away. Nevertheless, close contact is still the major means of spreading viral diseases such as chickenpox, influenza, measles and the common cold.
A major fungal disease dispersed by the air is histoplasmosis, also known as ‘bird fever.’ The fungus grows in bird and bat droppings. Dry droppings readily release the fungus into the air when they are disturbed, and then an unsuspecting person downwind inhales the microscopic organism and gets infected. While the lungs are the primary targets, the fungus can also invade other parts of the body. A mild attack has symptoms that are almost indistinguishable from those of the common cold, while a more serious form infects the liver and the eye.
The skin and the linings of nose, throat and airways are the first line of defence against any dangerous organism. An impaired immune system or dry mucus layer, allows the invaders to break through the barrier and infect the tissue or enter the bloodstream. A bodily reaction to the invasion can occur at the point of entry or at a distant organ.