CASE REPORT: GNATHOSTOMIASIS IN TWO TRAVELERS TOZAMBIA DEVONC.HALE,LUCILLEBLUMBERG, AND JOHNFREAN Department of Medicine, Division of Infectious Diseases University of Utah, Salt Lake City, Utah; Department of Clinical Microbiology and Infectious Diseases, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg,SouthAfrica Abstract. Gnathostomiasis is a systemic infection caused by migrating nematode larvae of the genus Gnathostoma. Itisazoonosisinvolvingawidevarietyofanimalsasintermediateanddefinitivehosts,andconsumptionofrawfishis themainriskfactor.TheconditionismostcommonlyseeninsoutheasternAsia,buthasbeendescribedinanumberof other countries, all outside Africa. We report the infection in two travelers returning from southcentral Africa, who presented with non-specific symptoms and marked eosinophilia, and in whom schistosomiasis was initially suspected. Thetypicalmigratoryskinlesionsofgnathostomiasisappearedlater.Theinfectionsrespondedwelltoalbendazole.The patients acquired the infection in western Zambia; this region of Africa appears to be a newly identified risk area for gnathostomiasis in tourists who indulge in eating raw freshwater fish. CASE REPORT Gnathostoma species are tissue nematodes that should be considered in the differential diagnosis when a traveler from an endemic area presents with eosinophilia, especially when thereisanassociatedmigratoryskinrash.Muchofourknowl- edge regarding this organism has emerged from Southeast Asia, 1 butreportsfromMexico, 2 Equador, 1 andJapan 3 show that infection with this parasite is widespread. The medical literature has not previously considered Africa to be a risk region for gnathostomiasis, although a cluster of three cases was diagnosed in 1994 (Wolfe MD, unpublished data). Thisisareportofasingle-sourceinfectionoftwomenwho fishedontheZambeziRiverinwesternZambiafromAugust 4toAugust8,1998.Thepair,afatherandson,atefresh,raw breammarinatedinlemonjuice.Eachreturnedtohisrespec- tivehomewheresymptomsdevelopedabout12-14dayslater. Case 1. The father was a 70-year-old man who developed fever, chills, headache, myalgias, and arthralgias on August 19, 1998. The symptoms lasted several days, resolved, and thenrecurredonAugust25.HewasseenonAugust28atthe University of Utah/Salt Lake County International Travel Clinicandaskedifhemighthavemalaria.Theresultsofhis physical examination were normal and his malaria blood smearwasnegative,buthiswhitebloodcellcount(WBC)was 15,900×10 9 /Lwith25%eosinophils(normalranges:WBC  3-11.2×10 9 /L, eosinophils  0-6%).OnAugust31hewas treated presumptively with praziquantel for schistosomiasis. Serologic test results for schistosomiasis and strongyloidiasis were negative. He seemed to improve but returned on Sep- tember 15 with a rash on his entire right anterior chest wall extendingoverthedeltoidareaofhisshoulder.Therashwas erythematous, hot to the touch, indurated, and resembled a streptococcal cellulitis. The ampicillin/sulbactam that had been prescribed one day earlier by his primary care doctor wascontinued,butprednisone,whichhadbeenstartedatthe same time, was discontinued. His absolute eosinophil count remained elevated at 1,470 × 10 9 /L. Serologic test results for filariasis,toxocariasis,andtrichinosiswerenegative.Areturn visit on September 17 showed that the skin rash had almost completelyresolved,leavinga2×3mm,slightlyraised,firm noduleontheshoulder.Hewasseenonanemergencybasis intheeveningbecausethenodulehadmigrated4cmtoward his scapula, leaving a broad-based (1-2 cm) erythematous, indurated track (Figure 1). Gnathostomiasis was suspected and he was then treated with albendazole (400 mg twice a day).Twoseparatebiopsieswereperformedanddidnotde- tect any organism. A Western blot assay for gnathostomiasis done at the Mahidol University Applied and Technological Service Center in Bangkok, Thailand was reported on Octo- ber 1 as giving a positive result. The patient’s symptoms re- solved within four days of starting treatment with albenda- zole. Case 2. Thesonwasa45-year-oldmanlivinginSouthAf- ricawhowasassessedinitiallybyhisgeneralpractitionerand referredtotheSouthAfricanInstituteforMedicalResearch onSeptember5,1998.Hispresentingsymptomsweremuscle pain, intermittent low-grade fever, nausea, abdominal pain, sweating, chills, chest pain, shortness of breath, and fatigue. He had a WBC count of 19,970 × 10 9 /L with 55.5% eosino- phils. He was treated empirically with praziquantel for schis- tosomiasis. Results of tests for schistosomal-specific IgM, IgG, and IgA antibodies done on September 5 and 14 were subsequently reported as negative. His work up included three malaria smears, two Plasmodium falciparum histidine- richprotein2bloodantigenrapidtests,serologicanalysisfor amebiasis, abdominal ultrasound, and a chest radiograph, all of which were non-diagnostic. One week after initial presentation, he was seen with a 10-cmcutaneousswellingoftheleftbuttockthatwasslightly hot to the touch, erythematous, and slightly pruritic, with a white center. He was given amoxycillin-clavulanate and the rash resolved in eight hours. One week later, the original lesion reappeared accompanied by a similar lesion 20 cm down the posterior thigh. These lesions were indurated, ery- thematous, and non-fluctuant with poorly defined edges. No skin tracks were seen. OnSeptember18hisWBCwas15,600×10 9 /Lwith55.9% eosinophils. A serum specimen for antibodies to Gnathos- toma was reported as positive on October 1. He was then treatedwithalbendazole(400mgtwiceaday).Abiopsyofa migratory skin lesion of his left thigh done on October 7 showed eosinophilic vasculitis and folliculitis, but no larva. His symptoms and eosinophilia resolved with three weeks of treatment. DISCUSSION Gnathostomiasis was previously diagnosed clinically and serologicallyinagroupofthreeindividualswhoaterawcat- fish caught on the Rufiji River in southeastern Tanzania in Am. J. Trop. Med. Hyg., 68(6), 2003, pp. 707–709 Copyright © 2003 by The American Society of Tropical Medicine and Hygiene 707