Clinical Features of Imported Loiasis: A Case Series from the Hospital for Tropical Diseases, London.

We retrospectively analyzed the background, clinical features, and treatment response of 50 cases of imported loiasis who presented between 2000 and 2014 to the Hospital for Tropical Diseases (HTD), London, United Kingdom. Of them, 29 were migrants from, and 21 were visitors to, countries where the disease is endemic. Clinical features differed between these groups. Migrants experienced fewer Calabar swellings (odds ratio [OR] = 0.12), more eye worm (OR = 3.4), more microfilaremia (OR = 3.5), lower filarial antibody levels, and lower eosinophil counts (P < 0.05 for all tests). Among 46 patients who were started on treatment at HTD, 33 (72%) received diethylcarbamazine (DEC) monotherapy as first-line treatment, and among 26 patients who were followed up after treatment, seven (27%) needed a second course of treatment. There were 46 courses of treatment with DEC, and 20 (43%) of them had reactions. All patients with microfilaremia > 3,000 microfilariae/mL and all those with an elevated C-reactive protein (CRP) (≥ 5 mg/L) before treatment had reactions (P = 0.10 and P = 0.01, respectively). These data suggest that monotherapy with DEC may not be the optimal treatment for patients with loiasis, particularly for those with a high microfilarial load.