Travel Update: Recent Clinical Investigations From the CDC
Travel Update: Recent Clinical Investigations From the CDC
Conference Coverage
By Lin Chen, MD
At the 50th annual meeting of the American Society of Tropical Medicine and Hygiene in Atlanta, Ga, November 11-15, 2001, several clinical investigations from the Centers for Disease Control and Prevention (CDC) were presented. These investigations included an outbreak of histoplasmosis in travelers returning from Nicaragua (Michelle Weinberg, Surveillance and Epidemiology Branch, Division of Global Migration and Quarantine), endemic mycoses in travelers (Rana Hajjeh, Mycotics Diseases Branch), and African trypanosomiasis in US travelers (Anne Moore, Parasitic Diseases Branch).
Outbreak of Febrile Illness Among Travelers Returning From Nicaragua
Five patients presented to urgent care facilities with fevers of 102-104°F within 3 days of return from Nicaragua. They had been on a 12-day geology-biology field trip. Of the 15 travelers, 12 developed symptoms including fevers, dry cough, myalgia, and fatigue. Physical examinations were notable for mild-to-moderate respiratory distress. Laboratory results in 4 patients showed slight elevations in liver function tests, and chest radiographs were abnormal in 12.
The trip occurred from May 19-30, 2001. Among the activities described were visits to a cave (old silver mine) for less than 10 minutes, where bats were present. This was felt to be the site of exposure to histoplasmosis. Symptoms began on May 31-June 2, 2001. The only person who did not enter the mine showed no symptoms. Patients were treated with itraconazole for 6-12 weeks with or without steroids.
Histoplasmosis can lead to serious morbidity. Travel health consultants should provide pretravel counseling regarding the risks of infection and avoidance of exposure. Information regarding the use of masks for protection can be found at www.cdc.gov/niosh/97-146.html.
Endemic Mycosis
Additional outbreaks of coccidioidomycosis and histoplasmosis associated with travel were reviewed. Besides the outbreak of histoplasmosis in travelers returning from Nicaragua in 2001, other outbreaks of histoplasmosis have occurred as a result of travel to Acapulco (Calinda Beach Hotel) 2001,1,2 and travel to Cavernas de Castenado in Costa Rica 1998. Recent outbreaks of coccidioidomycosis occurred in Washington State residents who had traveled to Tecate, Mexico, in 1996,3 and in Pennsylvania residents who had traveled to Hermosillo, Mexico, in 2000.4
Endemic mycoses occur as a result of inhalation of spores in the soil, and follow soil disturbances. Incubation commonly lasts 1-2 weeks. Clinical spectrum is wide, ranging from asymptomatic infection to invasive disease among high-risk patients. Common features of the highlighted outbreaks include flu-like symptoms, prominent fatigue, rash in coccidioidomycosis, and high attack rates. Diagnosis can be made by serology, culture, and histopathology. Skin tests can be helpful. The patients with severe symptoms of coccidioidomycosis can be treated with fluconazole, itraconazole, or amphotericin B. The patients with symptomatic histoplasmosis can be treated with itraconazole and steroids.
Coccidioidomycosis at Dinosaur National Monument5
Another outbreak recounted in the CDC Clinical Investigations presentations was a cluster of coccidioidomycosis that occurred in 10 workers at an archeologic site in Dinosaur National Monument, Utah, in June and July 2001. The workers affected included 2 National Park Service archeologists and an 8-member team of student volunteers and leaders, who had sifted dirt for artifacts. The incubation period appeared to be 10-14 days. The most common presentations were fever, difficulty breathing, cough, fatigue, shortness of breath, myalgia, and generalized skin rash. All 10 persons had diffuse pulmonary infiltrates on chest radiographs. Initial serologic tests were negative for antibodies to Coccidioides immitis, but further testing using immunodiffusion tube precipitin detected IgM antibodies in 9 of the 10 persons.
This outbreak in northeastern Utah suggests that C immitis is endemic further north than previously recognized. Infectious disease and travel medicine consultants should be aware of the extended area of endemicity, and consider coccidioidomycosis in febrile respiratory illnesses in persons who have traveled to these areas and who may have had dust exposure.
African Trypanosomiasis in US Travelers
A sharp increase in the cases of African trypanosomiasis was noted in 2001. Moreover, a change in geographic distribution has emerged: most of the recent cases were acquired in Tanzania or in parts of Kenya contiguous with Tanzania. Short-term travelers have been affected, with a mean duration of visit being 13 days.
The number of African trypanosomiasis in Tanzania nationals reported to the Ministry of Health has increased from 1996 to 2000. At the same time, there has been a 67% increase in the number of US travelers to Tanzania from 1996 to 2000. It is not yet clear whether the rise in African trypanosomiasis among US travelers is associated with an increase in the risk in Tanzania or an increase in travel to risky areas.
Between 1967 and 2001, 31 US travelers were diagnosed with African trypanosomiasis. 70% were male, mean age 48.9 years. A total of 55% had been on a photosafari, and 35% had gone hunting. Incubation period was 5-16 days, with a mean of 8.6 days. Symptoms included fever (100%), thrombocytopenia (74%), chancre (52%), liver function elevations (48%), renal insufficiency (42%), headache (32%), leukopenia (26%), cardiac dysfunction (23%), rash (23%), mental status changes (23%), disseminated intravascular coagulation (16%), anemia (16%), and lymphadenopathy (5%).
Interval between onset of symptoms and diagnosis was nearly 1 week. For stage 1 (hemolymphatic) disease, the intervals between onset and diagnosis ranged from 1 to 16 days (median 5 days). Patients were treated with suramin. For stage 2 (central nervous system) disease, the intervals ranged from 5 to 42 days (median 11 days). Patients were treated with suramin and melarsoprol. Outcome of the 31 US patients at 2 years showed 30 cures, 1 relapse requiring retreatment, and no deaths.
Travel medicine specialists should discuss the risk of African trypanosomiasis and vector exposure with travelers whose itinerary includes the Serengeti (or other game parks near the Serengeti). Drugs for African trypanosomiasis were difficult to obtain a year ago. They are now available and are donated by the pharmaceutical companies. To obtain suramin, melarsoprol, or nifurtimox, contact CDC Drug Service at (404) 639-3670. For assistance with diagnosis or management, contact the CDC Parasitic Branch at (770) 488-7760.
African Trypanosomiasis in European Travelers8
TropNetEurope had reported an increase of African trypanosomiasis (T brucei rhodesiense) in February and March 2001, acquired during travel to the Serengeti (see TMA Update July/August 2001). Ten patients from multiple European countries have been diagnosed to date. The European patients presented commonly with chancres (90%), lymphadenopathy, and fevers. Based on an estimate of 120,000 visitors to the Serengeti, an annual incidence is estimated to be 7.5/100,000 visitors to Serengiti National Park.
References
1. CDC. Outbreak of acute respiratory febrile illness among college students—Acapulco, Mexico, March 2001. MMWR Morb Mortal Wkly Rep. 2001;50(14):261-262.
2. CDC. Update: Outbreak of acute febrile respiratory illness among college students—Acapulco, Mexico, March 2001. MMWR Morb Mortal Wkly Rep. 2001;50(18):359-360.
3. Cairns L, et al. Outbreak of coccidioidomycosis in Washington State residents returning from Mexico. Clin Infect Dis. 2000;30:61-64.
4. CDC. Coccidioidomycosis in travelers returning from Mexico—Pennsylvania, 2000. MMWR Morb Mortal Wkly Rep. 2000;49(44):1004-1006.
5. CDC. Coccidioidomycosis in workers at an archeologic site—Dinosaur National Monument, Utah, June-July 2001. MMWR Morb Mortal Wkly Rep. 2001;50(45): 1005-1008.
6. Nasta P, et al. Acute histoplasmosis in spelunkers returning from Mato Grosso, Peru. J Travel Med. 1997;4:176-8.
7. Valdez H, Salata RA. Bat-associated histoplasmosis in returning travelers: Case presentation and description of a cluster. J Travel Med. 1999;6(4):258-260.
8. Jelinek T, et al. Increased activity of African trypanosomiasis among travellers to the Serengeti National Park in Tanzania: Data from Tropneteurop. Am J Trop Med Hyg. 2001;65(suppl):50. Abstract 48.
Dr. Chen, Clinical Instructor, Harvard Medical School and Travel/Tropical Medicine Clinic, Lahey Clinic Medical Center, is Associate Editor of Travel Medicine Alert.
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