Is imported onchocerciasis a truly rare entity? Case report and review of the literature

Abstract

Background: Onchocerciasis is endemic in a number of tropical countries in Africa and South America, and it is occasionally diagnosed as an imported disease in non-endemic areas.

Methods: We describe the case of an African migrant with long-lasting pruritus and a cutaneous nodule who was diagnosed with onchocerciasis after nodulectomy, and review the medical literature regarding imported cases of onchocerciasis in the period 1994-2014.

Results: Twenty-nine cases of onchocerciasis diagnosed in migrants from endemic countries, and in expatriates and travellers from non-endemic areas were retrieved. They were predominantly males (73.3%), had a median age of 37 years (two were aged <15 years), and acquired the diseases in sub-Saharan Africa, most frequently in Cameroon (43.3%). Diagnosis of onchocercosis was proven in 73.3% of patients. The most frequent clinical manifestations in these and our own patient were pruritus (23/30, 76.7%), unilateral leg or forearm swelling (13/30, 43.3%) and rash (12/30, 40.0%), whereas only two (6.9%) complained of eye symptoms. Eosinophilia was observed in almost all of the patients (92.0%), with median counts of 2915/μL among migrants and 1960/μL among travellers/expatriates. Eighteen patients underwent a skin snip biopsy, which was positive in 10 cases (55.5%); in the other 13 patients the parasite was directly demonstrated by means of a skin or nodule biopsy (n = 5), nodulectomy (n = 5) or slit lamp examination (n = 3). Eighteen received ivermectin, alone, and seven ivermectin combined with diethylcarbamazine or doxycycline. Outcome details were available for only 14 patients, all of whom were asymptomatic after a median follow-up of 10 months (range 1-48).

Conclusions: Onchocerciasis is a neglected tropical disease whose subtle and non-specific features may lead to under-diagnosis or underreporting in non-endemic areas. Physicians should consider this tropical disease when caring for migrants and travellers/expatriates with pruritus, skin lesions and eosinophilia.

Keywords: Immigrants; Imported infections; Onchocerciasis; Pruritus; River blindness; Travellers.