Methods
The case notes of patients in whom gnathostomiasis was diagnosed at the Hospital for Tropical Diseases were reviewed retrospectively for clinical symptoms and confirmatory serologic results for the period April 1, 2000, to March 31, 2001. Clinical and laboratory data gleaned from case notes are described in the following sections.
The definition of clinical Gnathostoma infection is: 1) a history of intermittent, migratory skin and subcutaneous swellings (localized or not localized) with or without peripheral blood eosinophilia (eosinophil count >0.4 x 109/L), or 2) otherwise undiagnosed eosinophilia with nonspecific symptoms. Plausible epidemiologic risk is defined as travel to an area in which gnathostomiasis had been reported previously (i.e., Southeast Asia and Central and South America). We did not impose a time limit on previous travel in our study. Positive Gnathostoma serologic results were defined as the presence on immunoblot of the specific 24-kDa band diagnostic of Gnathostoma infection.[5,6] All serologic testing for gnathostomiasis was performed in the Department of Helminthology of the Faculty of Tropical Medicine at Mahidol University in Bangkok, Thailand. For patients at risk of Loa loa infection (because of previous travel to regions in central or West Africa where the infection is endemic), day-blood tests (samples taken between 12:00-2:00 p.m.) were performed to check for microfilaria and a filaria enzyme-linked immunosorbent assay was performed to exclude this diagnosis (Calabar swellings, indicative of Loa loa infection, may mimic gnathostomiasis).
During the 12-month study period, we identified 16 patients who had clinical symptoms consistent with Gnathostoma infection, a plausible epidemiologic risk, and positive serologic results. Seven patients were referred by their general practitioner (primary care physician) and four by consultant physicians working elsewhere in London. Median time from onset of symptoms to diagnosis was 12 months (range 3 weeks-5 years). A dietary history was recorded for three patients who reported eating (among other things) raw fish and watercress (patient 1); mutton, fish, and chicken in Bangladesh (patient 3); and fish and a variety of crustacea from market stalls in Southeast Asia (patient 13). Eosinophilia was noted in seven patients and was usually modest, always declining after treatment. Median erythrocyte sedimentation rate (available for 12 patients, data not shown) was 10 (range 1-62). The countries visited most frequently by our 16 patients were India (n=4), Bangladesh (n=3), China (n=2), and Thailand (n=2). Standard treatment during the period of study was albendazole (400 mg twice a day for 21 days). Three patients required a second course for recurrence of symptoms and incomplete resolution of eosinophilia.
Detailed travel histories for these patients are described in the Table . The following sections include a case history for four patients; all of these patients had positive Gnathostoma serologic results and responded to albendazole therapy.
Case 1. A 26-year-old Asian woman, a resident of Hong Kong, was referred to our hospital by her primary care physician. She complained of the episodic appearance of 'irritating' lumps on her limbs. Nine months earlier, the first of these lumps appeared on her right hand; since then, she had had a similar lump on her left foot and left hand, each lasting a few days and resolving spontaneously with no visible or palpable sequelae. Nine years previously, she had noted a lump rising near her left knee, which was followed 4 days later by a similar lump on her right thigh; both lumps had resolved spontaneously. All of the lumps were subcutaneous and estimated at 3-6 cm in diameter. A positive rheumatoid factor and anti-nuclear antibody >1:1,280 were noted. Her diet frequently included raw fish.
Case 2. A 37-year-old woman from Bangladesh reported a 3-year history of intermittent swelling of the right forearm and upper arm to the midbiceps area associated with pruritus, myalgia, and arthralgia. The onset of her symptoms had occurred while she was visiting Bangladesh, where she had eaten mutton, fish, and chicken. An eosinophil count of 4.37 x 109/L had prompted referral from a rheumatology clinic to the Hospital for Tropical Diseases. After a 21-day course of albendazole, her eosinophil count decreased to 1.12 x 109/L; symptoms recurred several months later. After treatment with a second course of albendazole (400 mg twice a day for 21 days), her symptoms resolved and her eosinophil count returned to normal (0.25 x 109/L).
Case 3. A 49-year-old Caucasian woman complained of a 12-month history of abdominal pain and symptoms suggesting gastroesophageal reflux. She had traveled widely in Southeast Asia 18 months earlier but denied eating crustacea or non-kosher meat. Gastric biopsy at upper gastrointestinal endoscopy demonstrated eosinophilic gastritis (peripheral blood eosinophil count of 0.95 x 109/L), a finding that prompted serologic testing for Gnathostoma. Her symptoms resolved with albendazole treatment.
Case 4. Pain developed in the left thigh of a 30-year-old man while he was participating in the Eco-Challenge 2000 race in Borneo. A 4x3-cm lump in his thigh was initially attributed to a muscular tear; when this lump persisted for 12 months, he was referred to the Hospital for Tropical Diseases. Magnetic resonance imaging of the thigh (Figure 3) showed a lobulated lesion in the vastus lateralis muscle surrounded by edema. Serologic results were positive for Gnathostoma. Treatment with albendazole substantially reduced the size and firmness of the lesion but did not completely resolve it.
Magnetic resonance image of thigh with Gnathostoma larva (case 4).
Emerging Infectious Diseases. 2003;9(6) © 2003 Centers for Disease Control and Prevention (CDC)
Cite this: Gnathostomiasis: An Emerging Imported Disease - Medscape - Jun 01, 2003.
