A Colorado woman who contracted Marburg fever while in Uganda should serve as a reminder to health-care workers that diseases that were once just exotic names in medical textbooks can show up in emergency departments in North American hospitals, experts say.
The speed of global travel and the popularity of adventure tourism combine to increase the risk that bad bugs can travel from their homes to ours, they warned Sunday.
"Most of the time when you hear hoof beats in the infectious disease world, it really is likely a neighbourhood horse," said Dr. Michael Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota.
"But there are those rare and ever-growing chances that it could be a zebra. And unless we stay vigilant to that point, if it is a zebra, one day you could be in a big amount of trouble."
Fortunately, the unusual year-old Marburg case - which came to light on the weekend - did not end tragically. The woman, who is the first reported case of the fever in North America, survived.
She is thought to have been infected in December 2007, while touring an attraction known as the python cave in the Maramagambo forest of Queen Elizabeth Park in western Uganda. The cave is home to thousands of bats; some species of bats are thought to be the reservoir of the Marburg virus.
She became ill about two weeks later, after returning to Colorado. (The incubation period for the disease ranges from two to 21 days.) But it wasn't until a year later, in January 2009, that it was confirmed the women had suffered from Marburg.
Diagnosing the disease isn't always straightforward. While the tell-tale sign seen in the worst cases - blood gushing from multiple orifices - would immediately bring hemorrhagic fevers to mind, only about half of cases develop that symptom, said Dr. Eileen Farnon, chief of epidemiology in the special pathogens branch of the U.S. Centers for Disease Control.
In fact, early symptoms can be more vague and can be confused with other diseases one might encounter while travelling - malaria and dengue fever among others. Those symptoms can include severe headache, muscle aches, malaise, high fever, diarrhea and nausea. A rash on the trunk of the body is also common.
Even though the cause of illness was not identified while the Colorado woman was sick, she appears not to have infected any of her caregivers, either at home when she first developed symptoms or after she was admitted to hospital.
In the African countries where Marburg and its cousin, the Ebola virus, are found, health-care workers in under-equipped hospitals often make up a tragic second wave of infections, contracting the viruses from their patients.
But the precautions hospitals in developed countries instituted to protect health-care workers from HIV likely also dramatically lower the risk that an undiagnosed patient with a hemorrhagic fever would spread the illness to caregivers.
Farnon said test results are still pending on a household contact who travelled with the woman to Uganda and cared for her once she became ill. The tests are looking to see whether the person caught the virus last year and recovered; there is no thought anyone is currently ill as a result of the woman's case.
Her doctors did suspect a hemorrhagic fever and testing was done while she was in hospital. But Farnon said the tests were run late in her illness, at a time when her body was starting to fight off the virus. Two types of tests were done looking for virus and virus particles; the results of both were negative.
In July, the woman read a newspaper article about a Dutch tourist who died of Marburg after visiting the same cave in Uganda. Convinced she too had contracted the disease, she demanded to be retested.
The tests were not rushed. Farnon said it was felt, based on the earlier negative testing, that the woman had not had Marburg. When the tests were analyzed and the positive result found, additional tests were taken to confirm the finding.
When the results became available in January, it became apparent that the woman's immune system had beaten off one of nature's worst killers and a hospital in Colorado had dodged a big bullet.
Farnon said authorities hope the Colorado case will raise awareness among the medical professionals of the possibility they might see patients with hemorrhagic fevers.
"She certainly did receive good care here but more people need to be aware of the need to consider hemorrhagic fever and then to test quickly and to institute appropriate precautions quickly," Farnon said.
Travellers need to understand the risks of contact with bats and other animals that might transmit diseases, she said.
As for the Colorado woman, she was gravely ill and has had a long convalescence. While she still suffers from fatigue, she's definitely on the mend, Farnon suggested.
"She simply isn't quite back to 100 per cent but she's almost there. And she's certainly functional and exercising and working."
