Update from OrlandoHighlights from the ASTMH Annual Meeting
CONFERENCE COVERAGE
The setting was almost idyllic. Christmas music with a southwestern twang was piped in along lakeside walkways. With the Disney-esque facade as a backdrop, more than 1000 people gathered for a real-world discussion of tropical illnesses at the 46th annual meeting of the American Society of Tropical Medicine and Hygiene in Orlando, Florida, during the second week of December 1997. While family members enjoyed the Magic Kingdom’s delights, conference participants talked about miserable killer diseases of importance to travel medicine practitioners. (The abstract book is available by calling 847-480-9592.)
Bartonella
Americans mostly think of Bartonella as the cause of cat scratch disease and might not be aware that B. bacilliformis causes an acute febrile anemia associated with a warty rash. A team of American military and Peruvian investigators presented results of their population-based, long-term epidemiologic study of Bartonella in an Andean village north of Lima. More than one-third of individuals surveyed reported having had an illness consistent with bartonellosis. Wondering if a reservoir or vectors were in the area, researchers found that only two of 319 studied patients had positive blood cultures but that approximately 20% of sandflies and 20% of household rodents were PCR-positive for Bartonella. (Abstract 67.) Travelers with close household contacts in small Peruvian villages could be at risk for bartonellosis.
In the United States, a CDC team compared clinical characteristics between seropositive and seronegative patients whose serum was submitted for Bartonella testing. Samples were more likely to be positive when submitted from September to January, when coming from younger individuals, and when taken from individuals with feline contact, adenopathy, and a history of a blister or papule. Bacillary angiomatosis and encephalopathy were more common in seropositive individuals. (Abstract 68.)
Don’t Forget
In a case report, a Swiss-American team told of a European nurse who became febrile after returning from a service project in Burundi. With tests for malaria and typhoid negative and despite therapy with ciprofloxacin and ceftriaxone, her condition deteriorated, and she developed thrombocytopenia, hypotension, and adult respiratory distress syndrome. Following her death, special tests for hemorrhagic fever viruses were negative, but histology and serology identified Rickettsia prowazekii as the cause of the fatal illness. Even though our thoughts focus on new and emerging pathogens when we see febrile patients returning from the tropics, we must not forget historically familiar illnesses such as typhus, which might not be effectively treated by commonly used, broad-spectrum antibiotics. (Abstract 69.)
Hurricanes, Civil War, and Pathogens
Ed Sanders reported a link between hurricane-induced flooding and leptospirosis in Puerto Rico. Following floods in September 1996, the incidence of leptospirosis, as tested with a rapid IgM dipstick assay on surveillance blood samples submitted to a dengue fever laboratory, was remarkably increased. Serum was more than three times as likely to be leptospirosis antibody positive following the floods as prior to the floods. Males were more frequently affected than females. While clinically similar to dengue fever, leptospirosis may, unlike dengue, respond to antibiotic therapy. Physicians should think of leptospirosis when evaluating returnees from the Caribbean who present with fever. (Abstract 70.)
Lassa fever, caused by an arenavirus, is endemic in Sierra Leone, Liberia, and Nigeria. With civil unrest limiting health care services in Sierra Leone, retrospective testing showed that clinical suspicion (based on fever, headache, and sore throat unresponsive to good antimalarial and antibiotic therapy in an endemic area coupled with facial or pharyngeal edema, bleeding, miscarriage, or respiratory distress) would have accurately predicted Lassa fever diagnosis 60% of the time. In such cases, ribavirin is indicated. While conservative, supportive care is effective in many patients, ribavirin seems to be helpful for severe cases. (Abstract 71.)
Helping at Home
Yale University reviewed 15 years of experience with an international health program for internal medicine residents. Via a questionnaire survey of former residents, it was learned that international health program participants were more likely to be in non-procedure oriented fields, to be involved with teaching and research, and to volunteer some of their professional services to medically underserved people. Some participants reported that the international experience had positively affected subsequent changes in career plans. (Abstract 73.) Travel medicine practitioners might be able to share some of their own international awareness and experiences in helpful ways by involving themselves with nearby medical students and residents.
Hello, Good-bye, and Look Out!
Kuwaiti researchers have noted a doubling of malaria cases in their non-endemic country since the end of the Gulf War. Most of Kuwait’s 2 million residents are from other countries, and international travel is common. Ninety percent of returning travelers with falciparum malaria presented within one month of their trip, but P. vivax-infected individuals often presented a longer time after returning to Kuwait. (Abstract 75.) Conference-goers were reminded that, in one North American city, patients with malaria waited an average of 6.5 days after initiating contact with a physician before their diagnosis was made. Greeting febrile patients? It is prudent to ask about travel, even if not recent, to a malarial area.
While onchocerciasis is not common in travelers, Portuguese physicians presented the first report of this filarial infection in their country. A man developed pruritic swelling of the hands, arms, and neck several months after returning from Gabon. Skin biopsies revealed Onchocerca volvulus, and the patient responded well to ivernectin. (Abstract 79.) With increasing travel, tropical illnesses are more and more often presenting in temperate countries.
Goodbye, dracunculiasis. A WHO-CDC team reminded clinicians that Guinea Worm infection is declining. With 3.5 million cases reported in 1986, there are fewer than 100,000 annual cases now. Eradication efforts (filtering and/or treating water, killing the vector in the water, and keeping infected individuals out of water) have been successful in many countries. (Abstract 74.) A scourge is disappearing from the tropical areas to which our patients travel.
Reminding listeners of recent news media concern about germ warfare, pathologist Jerry Smith reviewed findings from 41 autopsies of victims of a "military accident" in Eastern Europe. Pathologic features of anthrax seemed to have followed the diffusion of Bacillus anthracis toxin into surrounding tissues. Histology showed vasculitis, hemorrhage, and fibrin-rich edema surrounding the gram-positive, spore-forming rods. (Abstract 78.)
A Huge Epidemic
The seasonal occurrence of Neisseria meningitidis infection is well known across the "meningitis belt" spanning Africa. Nigeria, however, was particularly hard hit during the early months of 1996 with a N. meningitidis serogroup A epidemic that accounted for approximately 100,000 cases and 10,000 deaths. Children were particularly involved, as more than 1% of the country fell ill with this disease. A reported 16.5 million vaccine doses were given, and the epidemic waned even before the beginning of the rainy season. (Abstract 80.)
The introduction of a meningococcal vaccine into the childhood immunization schedule was tested in Niger. A conjugate vaccine given at 6, 10, and 14 weeks of age stimulated good antibody production; levels decreased by 1 year of age but rose with a 12-month "booster" dose of polysaccharide vaccine. (Abstract 81.) While further study is needed to evaluate the best dosing and timing of meningococcal vaccination of infants, it certainly behooves older travelers to the "meningitis belt" of Africa to be vaccinated for meningococcal disease.
Late-Breaking News Flashes
Some of the best presentations of the Orlando conference were made in a "late breakers" clinical session. A multicenter Canadian group studied the side effects of a "loading dose" of mefloquine (250 mg daily for 3 days, then weekly for 3 weeks) in more than 500 adults who had no history of seizure, psychosis, or previous mefloquine use. More than 90% of subjects had no side effects. Two percent of patients dropped out of the study (most with mild-to-moderate reaction such as headache and dizziness, 1 with an anxiety attack). The Canadian team concluded that "loading dose" mefloquine was well-tolerated and helped identify the occasional intolerances early.
A CDC team found that rubella outbreaks occur among foreign-born crew members on Caribbean cruises. Travelers, even on luxury cruises, should be current on "routine" immunizations such as the MMR.
Brad Connor reported preliminary data on "mixing" brands of hepatitis A vaccine. Individuals who had received an initial dose of Havrix were randomized in a blinded, multicenter trial to receive either Vaqta or Havrix for the second dose. No adverse reactions were noted, and all subjects responded with seemingly protective antibody production.
An ad for Disney vacations at the conference resort proclaimed, "If you believe in magic, you belong." There is certainly no magic available to ensure that we provide good care to travelers, but staying abreast of the latest research findings can certainly help our vacationing patients most safely and comfortably share the world they live in with a changing array of germs and diseases.
Bartonella has been associated with:
a. dog bites in temperate climates.
b. fever and anemia in South America.
c. mosquitoes in Africa.
d. chronic macular rashes.
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