Pandemic diseases can be defined as a wide-spread outbreak of an infectious disease. It is an epidemic of an infectious disease that spreads over a region and affects large populations of the world. They are by nature uncontrollable diseases. Pandemic diseases are classified based on how they move from initial human infections to full-blown infectious diseases spread over countries and continents, and eventually even spread worldwide. The pandemic alert system scale ranges from phase one, being low risk, to phase six, being full-blown pandemic spread. With pandemic diseases the number of people who die depends on: the number of people infected, the severity of the disease, the vulnerability of large populations, and the effectiveness of preventative steps put forward.
Leprosy is a chronic disease that affects the skin, peripheral nerves, mucosa of upper respiratory tract, as well as the eyes. Symptoms sometimes only appear a year after the person has contracted the disease via droplets from the nose or mouth. If it remains untreated it can cause permanent serious damage. The treatment for leprosy is multidrug treatment (MDT).
Rift valley fever (RVFV) infects both humans and animals. The virus infects humans through inoculation, or through inhalation of aerosols produced during the slaughter of infected animals. Outbreaks are often associated with periods of heavy rainfall, after which the mosquito population flourishes. Ribavirin has shown some promise as an antiviral.
Smallpox is caused by the variola virus. It was mainly spread by direct and prolonged contact with a person who had already developed the characteristics of the disease, as well as through coughing and sneezing. The first symptoms of smallpox usually appear 12 to 14 days after the person becomes infected. Patients became contagious once the first sores appeared in their mouths and throats, and they remained contagious until their last smallpox scab fell off.
Swine flu is a disease caused by a strain of the influenza virus which is the same virus that infects the respiratory tracts of pigs. This respiratory disease is known as swine influenza, H1N1 virus or H3N2v virus. Swine flu is contagious and has similar symptoms to that of the usual seasonal flu virus, but frequently with greater repercussions. There are also symptoms which rarely occur in seasonal flu but are very commonly experienced in swine flu patients. The only way to be certain that you have swine flu is by going to have a laboratory test done.
A disease or condition is not a pandemic merely because it is wide-spread or kills many people; it must also be infectious. The examples given above suggest that the concept of a pandemic, as applied to important global events spanning many centuries, includes diseases of very different etiologies that exhibit a variety of epidemiologic features. There seems to be only one invariable common denominator: widespread geographic extension.