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Boston medical mysteries: A mini-epidemic

Solve a diagnostic puzzle: This is the case of a real patient treated at a Boston-area hospital

On Dec. 5, Mr. G and his wife left the cold and snowcaked city of Worcester to celebrate their wedding anniversary in balmy Puerto Rico. After landing in San Juan, they met their host family. The cordial hosts — D and M — had offered Mr. and Mrs. G a spare room at the far end of the house. The accommodations were comfortable and secure.

However, Mr. G soon noted that one of the hosts, the man, appeared ill. “When we first arrived, [M] looked pale and leaned heavily on the wall for just a few moments, not saying much,” he said. The man’s wife, D, seemed unaffected.

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The next day, Mr. and Mrs. G stepped out into the city. They strolled down the Plaza del Mercado de Rio Piedra, a busy marketplace that bustled with natives and tourists. On Dec. 7, the couple traveled to the slopes of the Sierra de Luquillo mountains, descending into the tropical rain forest called El Yunque. “The weather was gorgeous,” Mr. G recalled.

By noon, the couple had descended deep into the rain forest, where they broke for lunch. During that hour, he remembered, something bit him, four or five times. He guessed it was a mosquito. “I thought the bites pretty weird at the time. It wasn’t very buggy around there.” On the trip, they hadn’t seen many bugs or animals at all — just clouds of gnats, little lizards that scampered underfoot, and the birds in the trees.

Just as M, the host, seemed to recover from his illness, on Dec. 10, Mr. G awoke in the middle of the night in a profuse sweat. Although he had no thermometer, it was evident that he had broken out in a fever. As the night pressed on, strange and recurring dreams occupied his mind. The delusions and fevers were persistent. He developed a wincing headache that came and went nearly every minute. Mr. and Mrs. G left the host family in a rush and flew home, growing concerned about Mr. G’s sickness.

Back in the cold of Worcester, the couple’s troubles did not end. On Dec. 16, Mr. G awoke with a rash that covered his legs and arms, his feet nearly purple. “The capillaries on my feet broke and everything started to swell,” he reported. “I was purply up through the ankles. The rash looked fissured — like a fishnet.”

When he went to see Dr. Jeremy Golding, a family practitioner in Worcester, the doctor was most impressed by the rash. By Dec. 20, Mr. G received an e-mail from the hosts in Puerto Rico and found, to his surprise, that both he and M shared the same diagnosis.

The diagnosis

“I took one look at his legs and saw a brilliant erythema,” Dr. Golding says. Erythema — a deep, red color of the skin — stood out among Mr. G’s symptoms. Woven through the dark red was the lighter-colored “fishnet” that Mr. G described. One of Dr. Golding’s colleagues, who was from the Philippines, remembered hearing about a tropical rash that presented as “isles of white in a sea of red,” a pattern suggestive of dengue hemorrhagic fever.

Dr. Golding thought this was possible, especially since Mr. G had fevers and a headache, typical of the disease. He sent Mr. G’s blood to a lab to get him checked for dengue. A few days later, the test returned positive.

Dengue hemorrhagic fever has a scary name. But hemorrhage — or bleeding — is rare. Most often, people develop high fevers, headaches, and bone and muscle pain. Because of these symptoms, some people call dengue “breakbone fever.” Eventually, the virus is tackled by the immune system and the host gets better. In a small number of cases, people fall very ill and can even die. The disease is caused by a flavivirus — a family of pathogens that cause similar illnesses including yellow fever, West Nile, and Japanese encephalitis. Most of these viruses are spread by mosquitoes. But dengue is not spread by the kind of fat, muckwater mosquitoes we are used to in Boston.

The dengue mosquito is tiny, and is often found singly, rather than hovering in clusters like the mosquitoes of New England, said Dr. Sharone Green, an expert in flaviviruses who works at UMass Memorial Medical Center. “Most people don’t know if they’ve gotten bit.”

The dengue mosquitoes also feed all day long. Perhaps most disturbingly, the Aedes aegypti loves to live indoors. The moment it bites a person who has dengue, the mosquito remains infected for life. Consequently, a single insect may infect an entire household. “Dengue transmission is very focal,” she says. “When cases occur in Puerto Rico, they are often found in little clusters of homes and neighborhoods.”

So Dr. Green isn’t surprised to hear that Mr. G lived in the same house as someone who might have had similar symptoms. A few days after Mr. G had received his diagnosis, he received an e-mail from D — the woman whose husband had fallen ill in Puerto Rico. In her e-mail, she described the disease that had afflicted M:

“Hi, yes, he [M] had it as you left. After you left the numbers of people with the dengue skyrocketed. . . . We have always had a [dengue] season but not this long.”

During his trip to Puerto Rico, Mr. G had walked intoamini-epidemic that had risen around him. Clusters of people in San Juan soon became infected. According to the CDC, reports of dengue in Puerto Rico in December 2012 were above traditional epidemic levels. What happened throughout the region, had occurred on a smaller scale within the house where Mr. and Mrs. G had stayed. “It’s possible the same infected mosquito had bitten [the host] and the patient,” Dr. Green postulates.

Do you have your own medical mystery? Dr. Sushrut Jangi can be reached at sushrut.jangi@gmail.com.

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