Abstract:

Objective To analyze the clinical features and diagnosis of an imported loiasis patient in Shanghai. Methods Epidemiological data were collected and patient’s clinical signs and symptoms were studied. Blood and bone marrow sample smears were prepared and stained with Wright’s solution for parasitological analysis under a light microscope. The internal transcribed spacer 1(ITS-1) region of the parasite was sequenced after PCR amplification and were analyzed using basic local alignment search tool (BLAST) program of GenBank. The patient was treated with properly. Result The patient worked in Congo from May to November 2015 and developed with swellings and darkening of the skin in distal left upper extremity after he returned to China in January 2016. He went to a local hospital and in Zhejiang Province the examination results showed elevated number of eosinophiles as well as inflammation in the left upper limb as revealed by magnetic resonance, then was diagonsed as eosinophilic fasciitis. The symptoms were not improved after over 1 year treatment with oral medrol. The patient then went to the dermatology department of Shanghai Ruijin Hospital for further treatment on Febuary 27, 2018. Physical examination concluded dark skin, no swellings, no lumps, no lymphadenopathy or other abnormalities. Eosinophils count was 8.2 × 10⁹/L. Microfilariae were found in blood and marrow smears. More microfilariae were found in blood smear of 8 ml peripheral blood after centrifugation. PCR amplification resulted in a band of ~457 bp, sequence of which had 100% homology to that of Loa loa (GenBank Accession No: DQ995497). The microfilariae were identified as Loa loa microfilariae by morphological observation and gene sequencing. The patient was diagnosed as loiasis and treated with single oral ivermectin at 150 μg/（kg·d）. After 2 weeks of treatment, no microfilaria was found in the peripheral blood, and only 12 microfilariae were found in concentrated blood smear of 8 ml peripheral blood. The number of eosinophils was 6.39 × 10⁹/L. These results suggested the effectiveness of ivermection. Conclusion This is an imported loasis case diagnosed by parasitological examination and molecular detection.

Key words: Loa loa, Imported, Diagnosis, Internal transcribed spacer 1