What were those tiny red spots?

Her great-grandmother had lived long into old age, enjoying the role of matriarch of a large family whose members now spanned thousands of miles from the Caribbean to the northeastern United States.

It was in her first week of soccer camp after her seventh-grade year that the family received news of bisabuela's death in San Juan. Her parents decided the whole clan should go to Puerto Rico for the funeral to celebrate her great-grandmother's rich life.

Beyond the funeral, it had been an exciting trip, playing with cousins and friends, enjoying fireworks in Old San Juan, taking a relaxing visit into the country, and looking up at the stars from the back of a pickup truck.

But just a few days after her trip - while getting back into the swing of camp in the hot New Jersey summer - the middle schooler didn't feel well, and her mother had to pick her up early.

Initially, there was a constellation of symptoms that are considered "nonspecific," meaning they could accompany many illnesses: fever, achiness, headache, and back pain.

Then a rash developed.

The child's pediatrician examined her and sent off for some basic blood work. The only abnormality was that her platelet count - the cells in the blood responsible for clotting - was a bit low.

The doctor was well-versed in the many infections, from common childhood viruses to tick- and mosquito-transmitted illnesses, that could trigger a "summertime flu" in the New Jersey suburbs.

But that intervening trip to Puerto Rico threw a bit of a curve.

The patient's mother called an old friend, an infectious-diseases doctor, and sent him photos of her daughter's rash.

Hearing about the family trip, he thought immediately of one disease. But he didn't want to jump too quickly to a diagnosis. When a patient has traveled, illnesses acquired at home before or after the journey - or even in the airport - must be considered.

In the heat of summer - and with the patient's symptoms and this rash with tiny dark red dots, called a petechial rash - Rocky Mountain spotted fever had to be considered.

Despite the name, the disease, transmitted by tick bites, is seen in all 48 continental states and is most common in the Carolinas.

If Rocky Mountain spotted fever was a possibility, antibiotics would have to be started immediately. The disease could be fatal if not treated.

Then a phone call came from Puerto Rico that cemented the infectious-diseases doctor's initial suspicion.

The patient's uncle had become ill at the same time as his niece - even more severely, with fevers and some bleeding - and he landed in the hospital in San Juan.

"This means your daughter has dengue fever, too," the physician told the patient's mother.

Dengue fever is known on various Caribbean islands as "break-bone fever" for the severe aches and prostration that characterize the illness.

The disease is seen at high levels, even in cities, so urban travelers are at risk.

It is transmitted by a virus in the saliva of mosquitoes, in particular the Aedes aegypti variety.

The uncle's illness sounded like severe dengue fever, indicating the patient had been in an area where she was likely exposed, as well.

Dengue fever has been seen in travelers to the Florida Keys in the last few years, and mosquitoes that carry it can be found much farther inland. So there is a theoretical risk the disease could spread further within the United States.

Though many mosquitoes take their blood meals at dawn and dusk, the dengue-carrying gang nibble all day long, making bites harder to avoid.

To avoid infection, people should apply DEET on skin and clothes, use permethrin on clothes and bed nets (but not on skin), screen all windows, and use air-conditioning when possible. Vaccines are being developed, but nothing is available yet.

There is no direct treatment for the dengue virus, and care is "supportive."

Severe disease, known as dengue hemorrhagic fever, usually occurs during a second infection with a different dengue strain, and is largely due to the body's strong immune reaction to the virus.

In that case, supportive care tends to be very aggressive in the hospital intensive care unit.

But in the mild case of the future eighth grader, supportive care was delivered by her mother's tender arms on the couch.

In a little more than a week, the patient was back to soccer camp and kicking up a storm.