The infection can be transmitted through contact with an infected person or contaminated food and drink.
The bacteria is spread in tiny droplets when an infected person coughs or sneezes.
You get it by drinking water or eating food that's been contaminated by an infected person.
Hepatitis A spreads by mouth via traces of fecal matter from an infected person, the health department said.
Antibiotics can be effective anthrax-killers in an infected person, especially if someone contracts cutaneous anthrax and gets prompt treatment.
Ebola is passed on by contact with the fluids of an infected person.
Health officials said the move was a "precaution" for people who may have come into contact with the infected person at the Bristol Brunel Academy.
The disease, which is contagious and spreads through the air when an infected person coughs, spits or sneezes, strikes everywhere, but predominantly affects the poor.
Shots of seemingly innocent objects a bus pole, an empty glass, both recently touched by an infected person are held for just an instant longer than usual.
Norovirus can be spread through contact with contaminated surfaces or objects, by contact with an infected person, or by the consumption of contaminated food or water.
It can be spread by putting something in the mouth that had been contaminated with traces of faecal matter from an infected person, even if it appeared clean.
Although transmission of rhinovirus infection by way of surfaces is not as likely as transmission by direct contact with an infected person, it is important, say the researchers.
Markel, along with most analysts, says that in prior pandemics, the so-called R-naught number -- the number of new infections caused by each infected person -- has been approximately 2.0.
So it's unlikely that you can get the infection directly from an infected person, such as a restaurant worker who doesn't wash his or her hands adequately after using the toilet.
But even if such recommendations were universally followed, they would not halt the spread of the disease, she said, noting that an infected person can spread the virus prior to getting flu symptoms.
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In most cases, people are infected after being exposed to saliva from an infected person, usually while traveling to parts of the world, such as Africa and Asia, where the disease is more prevalent.
Norovirus spreads easily via contaminated food or drinking water, but a more insidious route is from a person touching a surface contaminated with the residue of stool or vomit from an infected person and then touching his or her mouth before hand-washing.
Once infected, a person is immune from further infection for life.
According to the World Health Organization it can take a person infected with HIV 10 to 15 years to develop AIDS. Effective treatment with antiretroviral drug, however, is delaying the development of AIDS and allowing people to live longer, healthier lives.
When infected bugs bite a person, they leave behind T. cruzi parasites on the skin.
When a person gets infected with a virus, the body typically mounts an immune response to it.
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Although a person is infected, they may not develop any of the classic symptoms, such as a chronic cough.
Symptoms usually begin between 12 to 48 hours after a person becomes infected with most healthy people making a recovery within one to three days.
In about 80% of cases, a person who is infected will not be aware and will have no symptoms.
Saturday, China reported a 7-year-old Beijing girl is the latest person to become infected with the H7N9 flu strain, bringing the total to 44.
"The length of time a person has been infected before treatment, whether the patient has been given sufficient treatment, and whether there are co-infections present, can all have a big impact on a patient's recovery, " it says.
Another key number is the incubation period--how long it takes one person to become sick after being infected.
So far, every person who died from H5N1 was infected from birds directly.
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Typically one person in the United States is infected with swine flu every one to two years, although there have been 12 cases in the three-year period between December 2005 and January 2009.
Transmission to humans is extremely rare, but possible if a person is in close contact with an infected animal, the Food Standards Agency said.
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