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As the story of Delta flight 3163 being quarantined after landing at Chicago's Midway International Airport broke Thursday afternoon, scant details of a passenger with a medical issue started to unfold — which got many people wondering, what could have happened?

Aviation officials in Chicago said the city's health department and fire department  responded to a flight that landed at Midway International Airport, but local police and fire officials told Fox News the Centers for Disease Control and Prevention (CDC) was handling it.

The agency later determined there was no threat and passengers were eventually allowed to exit the aircraft. But as this story was developing, I got several phone calls asking me what could be going on.

First, we need to realize that in today's world, any contagious disease can be brought to American soil -- at any minute -- via international travel. Not all countries have the same vaccinations and guidelines as we do, so diseases that are eradicated here, may still be very present in other parts of the world.

A contagious patient on a plane can easily jeopardize the safety of all other passengers and crew because of the nature of aircrafts' confined spaces and lack of air circulation.

The details of this particular case are still sparse, but WBBM Newsradio reported that the passenger may have been traveling from Ghana and may have had a sort of rash or contagious disease.

The good news is that most rashes are non-problematic. However, I think there must have been other issues that alerted the staff to notify health officials and emergency personnel on the ground, and ultimately, the CDC.

From the limited description of the problem aboard the flight, there are several diseases that health officials may have been concerned about.

Many times a simple rash is not a problem, but if it's associated with vomiting and acute fever, there is cause for concern. Rashes can be due to either viruses or bacteria.

Some of the diseases that come to mind that might cause this sort of emergency aboard an aircraft would be:

Chickenpox
A viral infection in which a person develops extremely itchy blisters all over the body. It used to be quite common in children, but has become much less common since the introduction of the chickenpox vaccine.

Scarlet fever
A disease caused by infection with the same bacteria that causes strep throat. The bacteria produce a toxin that causes a red rash that usually first appears on the neck and chest, then spreads over the body, and is rough in texture.

Parvovirus infection
Relatively common in kids and highly contagious. It's been called "slapped-cheek virus" because of the distinctive rash that develops. It is usually mild and easily treated but can be quite dangerous for pregnant women and those with compromised immune systems.

Coxsackie viruses
Part of the virus family which also includes polioviruses and hepatitis A virus that live in the digestive tract. In most cases, they cause mild flu-like symptoms and go away without treatment, and is sometimes referred to as "hand, foot and mouth disease" because of the painful blisters that form in those areas of the body.

Impitigo
A bacterial skin infection that causes oozing blisters.

Scabies
A skin condition caused by a very small species of mite. Scabies is easily spread and causes rashes and itching.

Remember, the CDC is also very concerned about the spread of influenza and SARS. But it seems that this time around, the severity of the quarantine has been minimized.

The CDC later released a statement saying that the woman had been in Africa and a family member was reportedly concerned that the rash might be monkeypox. In fact, a subsequent report indicates that the emergency may have been a false alarm over "bug bites," according to CBS news.

So let this serve as a reminder to us all that it's quite important for airline personnel, as well as passengers, to always be aware of their surroundings and be sure to speak up about any health concerns you may observe, because prevention is the key protecting the lives of the population.

The Associated Press and FOX Chicago News contributed to this report.