Differences in the Clinical and Laboratory Features of Imported Onchocerciasis in Endemic Individuals and Temporary Residents

Abstract

Many parasitic infections have different presenting features in endemic individuals (ENDs) and immunologically naive temporary residents (TRs). Temporary residents with loiasis often display acute symptoms and hypereosinophilia, in contrast to a parasite-induced subclinical state in chronically infected ENDs. Few studies have examined differences in ENDs and TRs infected with the related filarial parasite Onchocerca volvulus. We identified 40 TRs and 36 ENDs with imported onchocerciasis at the National Institutes of Health between 1976 and 2016. All study subjects received an extensive pretreatment medical history, physical examination, and laboratory investigations. We performed additional parasite-specific serologic testing on stored patient sera. Asymptomatic infection occurred in 12.5% of TRs and no ENDs (P = 0.06). Papular dermatitis was more common in TRs (47.5% versus 2.7%, P < 0.001), whereas more pigmentation changes occurred in ENDs (41.7% versus 15%, P = 0.01). Only endemic patients reported visual disturbance (13% versus 0%, P = 0.03). One TR (3.3%) had onchocercal eye disease, compared with 22.6% of ENDs (P = 0.053). Absolute eosinophil counts (AECs) were similar in ENDs and TRs (P = 0.5), and one-third of subjects had a normal AEC. Endemic individuals had higher filarial-specific IgG4 and were more likely to be positive for IgG4 antibodies to Ov-16. Temporary residents and ENDs with imported O. volvulus infection presented with different dermatologic manifestations; ocular involvement occurred almost exclusively in ENDs. Unlike Loa loa, clinical differences appear not to be eosinophilmediated and may reflect chronicity, intensity of infection, or the presence of Wolbachia in O. volvulus.

Identification of the complement 9‐binding protein in Setaria equina excretory‐secretory products

“…The molecular weight identified in electrophoresis and immunoblotting was 21 kDa which is also known for OV‐16. OV‐16 had been known as a diagnostic antigen for onchocerciasis in ELISA for the detection of reacting IgG4 . Although the protein appeared in 2D as two spots with the same molecular weight instead of one spot, peptide sequencing and immunoblotting indicated that these two spots represented one protein.…”