Question

How does an infectious disease become a pandemic disease? Include using key terms reservoir, mode/ vehicle of transmission, vectors, disease development, and virulence factors youre description.

Answer 1

Hi Answer:

The infectious diseases are the disorders mostly caused by the bacteria, the ruses, fungi, and parasites. As we known that our body is the host of several microorganisms, they live in or on the body but most of them are harmless to our body or certain are even helpful to us. It is observed that some of this microorganism become the cause of certain infections under some specific conditions and may cause mild to serious disease. Some infections are speeded from persons to persons and some are from the bites of insects and animals. The sign and symptoms of every infection depending on the casual organism but a most common symptom of almost all infectious diseases are fever and tiredness. Some infections such as measles and chickenpox can be prevented by the vaccines. In certain cases when the infections are not controlled and it spread rapidly to the large area and become a severe disease is known a Pandemic. The recent example of a pandemic is the rapid global spread of H1N1 influenza virus in early 2009.   

How infectious disease become pandemic disease:

The conversion of normal infectious disease into a pandemic disease is a multistep process. This conversion didn’t take place overnight it took some time. The details that how the infection spread from its reservoirs to the susceptible host is described in the diagram below:

Whenever an infectious organism come in the contact of some person then it causes the disease only to those whose immune system is weak. During a normal bacterial, the viral infection took place we just consult the doctor and get proper treatment and this disease is cured with the treatment physician advice us to complete the treatment course for the complete removal of the infection. But its human nature or some time we become careless (when infection get cured no symptom of infection left) and stop the treatment and didn’t take medicines. At this time our infection gets cured but the casual organism is not fully eliminated from the body. It is still there in a weak form which is unable to cause infection. This condition when a person has no symptom of infection and he didn’t complete the treatment course, he become the reservoir of that particular infectious organism. Now the cured person is an active reservoir and it provides the shelter or environment to divide the pathogen. Next step is the transmission of the pathogen it took place by the direct contact or via the vector or carrier. Indirect method when reservoir person comes in the direct contact to the susceptible host by direct droplets i.e. Respiratory transmission. The second mode is the carrier or vector mode in this method an insect contact Whenever a vector, carrier (insect or animal) bite the host it carries the pathogen with it and when next time it bites the susceptible host it transfers this pathogen to the that. This is the carrier or vector mode of infection transmission. In this process, the carrier or vector has no effect of infection.    

As the pathogen reaches to the next host it starts its multiplication and causes the infection to the host. This chain of infection is continuously going on and infecting a large number of hosts. The infectious disease which strong virulence factor causes severe infection with fatal results. The infectious disease which has fast infection cycle and strong virulence factor spread very fast and affect a large population of the big area becomes a pandemic disease.