MRSA is a staph infection that’s typically spread by direct contact with someone’s skin infection or their personal items, such as towels or razors. In health care settings, MRSA can cause severe and potentially life-threatening infections, such as bloodstream infections. However, in community settings, such as locker rooms, most MRSA infections are skin infections that manifest as swollen and painful red bumps on the skin.

A person infected with parvovirus B19 (fifth disease), an illness that causes a mild rash and commonly affects children, is contagious during the early part of the illness, before the rash appears. By the time a child has the characteristic "slapped cheek" rash of fifth disease, for example, he or she is probably no longer contagious and may return to school or child care center. 

This contagious period is different from that for many other rash illnesses, such as measles, for which the child is contagious while he or she has the rash.

Hives (red bumps on the skin) typically are caused by an allergic reaction to a drug or food. They also can be caused by infections or stress.

A contagious virus called herpes simplex type 1 causes cold sores; more than half the U.S. population is affected by type 1 herpes virus by their 20s. Some people have no symptoms of the infection, while others develop painful cold sores on the lips, chin, cheeks, or nostrils -- or less commonly on the gums or the roof of the mouth -- that can last a week or longer. 

The lesions can also appear on the genital area. Another herpes simplex virus known as herpes simplex type 2 spreads by sexual contact and typically affects the genital area.

The exact cause of acne is unknown, but it is thought to involve excess oil, clogged pores, inflammation, and bacterium called P. acnes , which is found on everyone’s skin.

Eczema, a general term for many types of skin inflammation, is not contagious. However, it is believed to be genetically connected, so it is not uncommon for members of the same family to be affected.

VZV causes chickenpox and shingles. Someone with chickenpox or shingles can pass VZV to someone who has never had chickenpox, but they cannot cause a person to develop shingles. You can’t “catch” shingles from someone else. Shingles can occur only when the VZV is reactivated, usually years after a person has had  chickenpox.

Poison ivy is contagious, but the rash caused by poison ivy is not contagious if the oil from the plant has been washed from skin, clothing, or tools that have been in contact with the plant or leaves.

A person with a cold is most contagious in the first two to three days and usually isn’t contagious at all by the seventh to 10th day. Symptoms usually begin within those first two or three days of “catching” a cold, but it can take as long as a week.

Meningitis is inflammation of the membranes that cover the brain and spinal cord. It can be caused by viral or bacterial infections that commonly cause routine illnesses. Most occur from infections that are contagious and spread via drops of fluid from the throat and nose of someone who is infected that become airborne when the person coughs, laughs, talks, or sneezes. 

Bacterial meningitis is usually more severe than viral meningitis and can have serious aftereffects, such as brain damage, hearing loss, limb amputation, or learning disabilities. Vaccines are available for several of the causes of bacterial meningitis.

Four types of bodily fluids can transmit HIV: blood, semen, breast milk, and vaginal secretions. HIV does not survive well outside the body, so the virus isn’t likely to be transmitted through the environment. There’s no documented instance of anyone being infected with HIV by contact with an environmental surface.

“Hepatitis” means inflammation of the liver, and it is also the name of a family of viral infections that affect the liver. The type of hepatitis is named for the virus that causes it, such as hepatitis A, hepatitis B, or hepatitis C. Drug or alcohol use also can lead to hepatitis, and some cases are caused by the body mistakenly attacking its own tissues, but those are not the most common causes. 

Hepatitis does not always occur with symptoms, but when it does they include loss of appetite, nausea and vomiting, diarrhea, stomach pain, and jaundice.

Malaria is spread by infected mosquitoes, not by direct contact with an infected person. It primarily is a concern in developing countries in warm climates. Symptoms of malaria are similar to those of the flu, including chills, fever, vomiting, and diarrhea.

Vaccines are the most effective method of preventing disease.