If a patient comes to your hospital with a fever and history of travel to West Africa, there's no question what you'll be most worried about—Ebola.
But there are a number of other diseases that should be considered in differential diagnosis, even as you take precautions against the possibility of Ebola, because they will present with similar symptoms and are endemic to the same area.
“These diseases are so similar,” said Steven S. Krotzer, MD, a travel medicine specialist and assistant professor of medicine at Mayo Clinic in Scottsdale, Ariz. “There might be little nuances that you bring up in a lecture as a teaching point, but the bottom line is they all look the same. Basically, they're fever, headache, and muscle aches, and the person is obviously sick . . . often [gastrointestinal] symptoms, often cough.”
Hospitalists faced with such a patient should focus on ruling out the most immediately deadly possibilities and then use testing and detailed history-taking to narrow down the diagnosis, experts said, while taking all the necessary precautions.
“If they've been to West African countries where Ebola transmission is occurring, very, very quickly get that patient isolated so that we can keep everybody safe,” said Michael Edmond, MD, FACP, chief quality officer at the University of Iowa Hospitals and Clinics in Iowa City.
The biggest killers
On the list of potential deadly diseases other than Ebola, “Number 1 and number 2 and number 3 are malaria,” said Dr. Krotzer. Malaria is the infectious disease responsible for the most travel-related mortality by far, he added.
“For people who've gone to West Africa, in addition to Ebola, the most important to think about would be malaria, because particularly with falciparum malaria, if not diagnosed, they could get very ill and even die,” agreed Dr. Edmond.
Looking for malaria is urgent and not difficult, the experts said. “It's very treatable and it's diagnosable without sending [polymerase chain reaction] tests off to CDC,” said Dr. Krotzer.
Another killer that requires specific testing is meningococcal meningitis. “This part of the world is called the meningitis belt—not technically at the coast, but you go just a bit into the interior of these countries, including Sierra Leone, Liberia, Guinea,” said Dr. Krotzer. Winter in North America is meningitis season in Africa, with the disease being so common in certain areas that as many as 1 in 10 people on the street may be carrying meningococci.
If meningitis is diagnosed, the patient should remain in isolation, because “it's an immediately life-threatening disease,” Dr. Krotzer said.
Other viral illnesses also necessitate continued isolation. “Ebola is not the only hemorrhagic fever out there. There are other ones—Marburg and Lassa,” said Dr. Krotzer.
Lassa fever has overlapped with Ebola, but has the advantage that there is an antiviral available to treat it, according to Lin Chen, MD, FACP, director of the Travel Medicine Center at Mount Auburn Hospital in Cambridge, Mass. “There were some cases of Lassa fever in Nigeria recently, coinciding with this Ebola virus outbreak . . .;That's a good illustration that we can't forget about other hemorrhagic fevers,” she said.
Less deadly options
Treatment is less specific for many of the other possible viral causes of illness, including dengue, chikungunya, and West Nile virus. “The average doc doesn't have to be thinking of all the lists of arboviruses, because they're all basically treated the same way, in a supportive manner, and they usually don't have profound implications from an infectious disease standpoint, with transmission to other patients or hospital staff,” said Dr. Krotzer.
Of course, before you assume the disease is viral, hunt for a bacterial cause. “Virtually all of these patients are going to be pan-cultured,” said Dr. Krotzer. “They're going to have blood cultures, and a urine culture, and a stool culture if they have any diarrhea.”
Typhoid, and enteric fever generally, is a possible result in a patient who's been in Africa. “Typhoid has got to be on the list, but actually the doc doesn't have to be thinking about that so much, because it's going to show up in the culture,” said Dr. Krotzer.
If the patient has cough and weight loss, consider tuberculosis, advised Dr. Edmond. If the symptoms are more gastrointestinal, other bacterial possibilities include shigellosis and campylobacteriosis. “Assuming they're quite symptomatic, they need to be tested and treated,” said Dr. Chen.
Leptospirosis is best identified as a possible cause of illness through the patient's history. “The key risk factor is submersion in the water—a whitewater rafter or just swimming,” said Dr. Krotzer. “It has liver function abnormalities and kidney abnormalities, and sometimes real severe conjunctivitis, which is actually sometimes seen in some of the hemorrhagic fevers, too.”
This type of water-borne bacteria is an example of the importance of history-taking in this diagnostic situation. “The key thing is to ask the patient about specific exposures—mosquitoes, ticks, contaminated food and water, illness in contacts, going into lakes and rivers, blood and body fluids,” said Dr. Chen.
Don't forget, however, that even patients with exotic histories can have common illnesses. “In Africa . . . it's always flu season. It'll look like plain old influenza and, in fact, it is,” said Dr. Krotzer.
Recent travel may also turn out to be a red herring. “Any person who presents who's been traveling, you have to think about what disease they might have acquired abroad, but then also what diseases they might have acquired here,” said Dr. Edmond.
And more than one diagnosis can be another possibility. “The other thing we see in travelers returning from developing countries is that they can have multiple diagnoses. Somebody can have campylobacteriosis and then also [have] chikungunya or something else,” said Dr. Chen. To pin down such a tricky diagnosis, “think broadly and consider all the potential exposures,” she advised.
Then, don't hesitate to summon expert assistance, even if an infectious disease physician is not readily available on site.
“There's somebody you could call,” said Dr. Krotzer, pointing out that the CDC, for example, maintains a malaria hotline. Some online diagnostic tools are also available, he noted, but they are not generally as helpful as a live, human expert.
“The travel history and the incubation period are really key, but [you] can determine those and then talk to somebody over the phone,” he said.