Quantitative Changes In Antibodies Against Onchocercal Native Antigens Two Months Postivermectin Treatment Of Onchocerciasis Patients

Serum antibodies to Onchocerca volvulus native sodium duodecylsulphate slat extracted antigens and epitopes recognized by three monoclonal antibodies designated Cam8, Cam22, and Cam28 were measured using indirect (sandwich) and competitive enzyme-linked immunosorbent assay (ELISA). Paired serum samples (n=32) were obtained before and two months post-ivermectin treatment. Those with increases of ten percent and above (≥10%) were 16 (50%) for IgG, 13 (40.7%) for both IgG1 and IgG4. Nine (28.2%) for IgM, eight (25%) for IgG3, IgA with four (12.5%) was the least, while IgG2 was not assayed due to cross-reaction. The higher increases in IgG, IgG1 and IgG4 antibodies in females (n=16) than males (n=16) were significant by T-test of unpaired data (

Relationship between oral declaration on adherence to ivermectin treatment and parasitological indicators of onchocerciasis in an area of persistent transmission despite a decade of mass drug administration in Cameroon

BACKGROUND: Onchocerciasis control for years has been based on mass drug administration (MDA) with ivermectin (IVM). Adherence to IVM repeated treatment has recently been shown to be a confounding factor for onchocerciasis elimination precisely in rain forest areas where transmission continues and Loa loa co-exists with Onchocerca volvulus. In this study, participants’ oral declarations were used as proxy to determine the relationship between adherence to IVM treatment and parasitological indicators of onchocerciasis in the rain forest area of Cameroon with more than a decade of MDA. METHODS: Participants were recruited based on their IVM intake profile with the aid of a semi-structured questionnaire. Parasitological examinations (skin sniping and nodule palpation) were done on eligible candidates. Parasitological indicators were calculated and correlated to IVM intake profile. RESULTS: Of 2,364 people examined, 15.5 % had never taken IVM. The majority (40.4 %) had taken the drug 1–3 times while only 18 % had taken ≥ 7 times. Mf and nodule prevalence rates were still high at 47 %, 95 % CI [44.9–49.0 %] and 36.4 %, 95 % CI [34.4–38.3 %] respectively. There was a treatment-dependent reduction in microfilaria prevalence (r(s) =−0.986, P = 0.01) and intensity (r(s) =−0.96, P = 0.01). The highest mf prevalence (59.7 %) was found in the zero treatment group and the lowest (33.9 %) in the ≥ 7 times treatment group (OR = 2.8; 95 % CI [2.09–3.74]; P < 0.001). Adults with ≥ 7 times IVM intake were 2.99 times more likely to have individuals with no microfilaria compared to the zero treatment group (OR = 2.99; 95 % CI [2.19–4.08], P < 0.0001). There was no clear correlation between treatment and nodule prevalence and intensity. CONCLUSION: Adherence to ivermectin treatment is not adequate in this rain forest area where L. loa co-exists with O. volvulus. The prevalence and intensity of onchocerciasis remained high in individuals with zero IVM intake after more than a decade of MDA. Our findings show that using parasitological indicators, reduction in prevalence is IVM intake-dependent and that participants’ oral declaration of treatment adherence could be relied upon for impact studies. The findings are discussed in the context of challenges for the elimination of onchocerciasis in this rain forest area

Onchocerca volvulus: Characterization of the clinical status of onchocerciasis patients using antibodies reactivity in enzyme-linked immunosorbent assays

Serum anti-bodies, IgA, IgG class and subclasses (excluding IgG2) and IgM responses to crude sodium-duodecyl sulphate (SDS) extract of Onchocerca volvulus female adult worms, were tested with indirect enzyme-linked immunosorbent assay (ELISA). Antigenic epitopes defined by monoclonal anti-bodies (mAbs) designated CAM8, CAM22 and CAM28 were measured using inhibition (competitive) ELISA. Generally, cases (n=95) with proven parasitological and or clinical evidences had the highest mean optical density (OD) values for IgG, IgG1, IgG3 and IgG4 anti-bodies compared to the endemic normal (n=19) and non-endemic control (n=7) groups. Reactivity varied with infection status and was more in those having skin microfilariae than those without skin mf. Individuals with chronic skin diseases (n-20) had higher anti-body levels than those with optic nerve disease (OND, n=12). Serum inhibition of Cam22 was higher, while Cam28 was lower in those with, than without skin microfilariae. Those manifesting chronic skin diseases showed a remarkable increase in percentage inhibition of both mAbs in sharp contrast to the OND group. There were very few Cam8 responders which did not show any apparent clinical trend. It is not known whether this is an indication of selective tolerance or immunosupression. The study showed that anti-body responses to the parasite antigens had strong positive association (