scholarly journals Correction to: Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Raphael Awah Abong ◽  
Glory N. Amambo ◽  
Patrick W. Chounna Ndongmo ◽  
Abdel Jelil Njouendou ◽  
Manuel Ritter ◽  
...  
Keyword(s):  
Drug Administration ◽  
Mass Drug Administration ◽  
Differential Susceptibility ◽  
Molecular Techniques ◽  
Onchocerca Volvulus ◽  
History Of

An amendment to this paper has been published and can be accessed via the original article.

scholarly journals Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: Relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

2020 ◽  
Author(s):  
Raphael Awah Abong ◽  
Glory N. Amambo ◽  
Patrick W. Chounna Ndongmo ◽  
Abdel Jelil Njouendou ◽  
Ritter Manuel ◽  
...  
Keyword(s):  
Real Time ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Real Time Pcr ◽  
Differential Susceptibility ◽  
Lamp Assay ◽  
Molecular Techniques ◽  
Onchocerca Volvulus ◽  
History Of ◽  
Higher Sensitivity

Abstract Background Ivermectin is an excellent microfilaricide against Onchocerca volvulus. However, in some regions, long term use of ivermectin has resulted in sub-optimal responses to the treatment. More data to properly document the phenomenon in various contexts of ivermectin mass drug administration (IVM-MDA) is needed. Also, there is a need to accurately monitor a possible repopulation of skin by microfilariae following treatment. Microscopy is known to have low sensitivity to detect skin microfilariae, when their density is low following treatment. This study was designed with two complementary objectives: (i) to assess the susceptibility of O. volvulus microfilariae to ivermectin in situations of contrasting history of treatments, and (ii) to document the repopulation of skin by the O. volvulus microfilariae following treatment, comparing the performances of 3 independent diagnostic techniques. Method Identified microfilaridermic individuals were treated with ivermectin and re-examined after 1, 3, and 6 months using microscopy, real-time PCR and LAMP assays. Susceptibility to ivermectin and trends in detecting reappearance of skin microfilariae were reported for the three techniques. Microscopy was used as an imperfect gold standard to determine the performance characteristics of real-time PCR and LAMP assay. Results In Bafia with over 20 years of IVM-MDA, 11/51 (21.6%) treated microfilaridemic participants where still positive for skin microfilariae after 1 month. In Melong, with 10 years of IVM-MDA, 2/29 (6.9%) treated participants were still positive. The microfilarial density reduction per skin biopsy within one month following treatment was significantly lower in participants from Bafia, but the pattern in the two sites was similar. In both study sites, the molecular techniques detected higher proportions of infected individuals than microscopy at all monitoring time points. LAMP assay showed lower specificity compared to real-time PCR and microscopy, but had comparable sensitivity to real-time PCR and significantly higher sensitivity than microscopy. Conclusion Patterns in skin mirofilarial clearance and repopulation were established. O . volvulus worms from Bafia with higher number of annual MDA were less susceptible to ivermectin. Molecular assays displayed higher sensitivity in monitoring O. volvulus microfilaridemia within six months following treatment.

scholarly journals Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: Relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

2020 ◽  
Author(s):  
Raphael Awah Abong ◽  
Glory N. Amambo ◽  
Patrick W. Chounna Ndongmo ◽  
Abdel Jelil Njouendou ◽  
Ritter Manuel ◽  
...  
Keyword(s):  
Real Time ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Real Time Pcr ◽  
Differential Susceptibility ◽  
Diagnostic Techniques ◽  
Molecular Techniques ◽  
Onchocerca Volvulus ◽  
Density Reduction ◽  
Low Sensitivity

Abstract Background. Ivermectin is an excellent microfilaricide against Onchocerca volvulus. However, in some regions, long term use of ivermectin has resulted in sub-optimal responses to the treatment. More data to properly document the phenomenon in various contexts of ivermectin mass drug administration (IVM-MDA) is needed. Also, there is a need to accurately monitor a possible repopulation of skin by microfilariae following treatment. Skin snip microscopy is known to have a low sensitivity in individuals with light infections, which can be the case following treatment. This study was designed with two complementary objectives: (i) to assess the susceptibility of O. volvulus microfilariae to ivermectin in two areas undergoing IVM-MDA for different lengths of time, and (ii) to document the repopulation of skin by the O. volvulus microfilariae following treatment, using 3 independent diagnostic techniques. Method. Identified microfilaridermic individuals were treated with ivermectin and re-examined after 1, 3, and 6 months using microscopy, actin real-time PCR (actinqPCR) and O-150 LAMP assays. Susceptibility to ivermectin and trends in detecting reappearance of skin microfilariae were determined using three techniques. Microscopy was used as an imperfect gold standard to determine the performance of actin-qPCR and LAMP. Results. In Bafia with over 20 years of IVM-MDA, 11/51 (21.6%) direct observe treated microfilaridemic participants were still positive for skin microfilariae after 1 month. In Melong, with 10 years of IVM-MDA, 2/29 (6.9%) treated participants were still positive. The microfilarial density reduction per skin biopsy within one month following treatment was significantly lower in participants from Bafia. In both study sites, the molecular techniques detected higher proportions of infected individuals than microscopy at all monitoring time points. LAMP demonstrated the highest levels of sensitivity and real-time PCR was found to have the highest specificity. Conclusion. Patterns in skin mirofilariae clearance and repopulation were established. O. volvulus worms from Bafia with higher number of annual MDA displayed a lower clearance and higher repopulation rate after treatment with ivermectin. Molecular assays displayed higher sensitivity in monitoring O. volvulus microfilaridemia within six months following treatment.

scholarly journals Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: Relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

2020 ◽  
Author(s):  
Raphael Awah Abong ◽  
Glory N. Amambo ◽  
Patrick W. Chounna Ndongmo ◽  
Abdel Jelil Njouendou ◽  
Ritter Manuel ◽  
...  
Keyword(s):  
Real Time ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Real Time Pcr ◽  
Differential Susceptibility ◽  
Diagnostic Techniques ◽  
Molecular Techniques ◽  
Onchocerca Volvulus ◽  
Density Reduction ◽  
Low Sensitivity

Abstract Background. Ivermectin is an excellent microfilaricide against Onchocerca volvulus. However, in some regions, long term use of ivermectin has resulted in sub-optimal responses to the treatment. More data to properly document the phenomenon in various contexts of ivermectin mass drug administration (IVM-MDA) is needed. Also, there is a need to accurately monitor a possible repopulation of skin by microfilariae following treatment. Skin snip microscopy is known to have a low sensitivity in individuals with light infections, which can be the case following treatment. This study was designed with two complementary objectives: (i) to assess the susceptibility of O. volvulus microfilariae to ivermectin in two areas undergoing IVM-MDA for different lengths of time, and (ii) to document the repopulation of skin by the O. volvulus microfilariae following treatment, using 3 independent diagnostic techniques.Method. Identified microfilaridermic individuals were treated with ivermectin and re-examined after 1, 3, and 6 months using microscopy, real-time PCR and LAMP assays. Susceptibility to ivermectin and trends in detecting reappearance of skin microfilariae were determined using three techniques. Microscopy was used as an imperfect gold standard to determine the performance of real-time PCR and LAMP.Results. In Bafia with over 20 years of IVM-MDA, 11/51 (21.6%) treated microfilaridemic participants where still positive for skin microfilariae after 1 month. In Melong, with 10 years of IVM-MDA, 2/29 (6.9%) treated participants were still positive. The microfilarial density reduction per skin biopsy within one month following treatment was significantly lower in participants from Bafia.In both study sites, the molecular techniques detected higher proportions of infected individuals than microscopy at all monitoring time points. LAMP demonstrated the highest levels of sensitivity and real-time PCR was found to have the highest specificity.Conclusion. Patterns in skin mirofilarial clearance and repopulation were established. O. volvulus worms from Bafia with higher number of annual MDA were less susceptible to ivermectin. Molecular assays displayed higher sensitivity in monitoring O. volvulus microfilaridemia within six months following treatment.

scholarly journals Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Raphael Awah Abong ◽  
Glory N. Amambo ◽  
Patrick W. Chounna Ndongmo ◽  
Abdel Jelil Njouendou ◽  
Ritter Manuel ◽  
...  
Keyword(s):  
Real Time ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Real Time Pcr ◽  
Differential Susceptibility ◽  
Diagnostic Techniques ◽  
Molecular Techniques ◽  
Onchocerca Volvulus ◽  
Density Reduction ◽  
Low Sensitivity

Abstract Background Ivermectin is an excellent microfilaricide against Onchocerca volvulus. However, in some regions, long term use of ivermectin has resulted in sub-optimal responses to the treatment. More data to properly document the phenomenon in various contexts of ivermectin mass drug administration (IVM-MDA) is needed. Also, there is a need to accurately monitor a possible repopulation of skin by microfilariae following treatment. Skin snip microscopy is known to have a low sensitivity in individuals with light infections, which can be the case following treatment. This study was designed with two complementary objectives: (i) to assess the susceptibility of O. volvulus microfilariae to ivermectin in two areas undergoing IVM-MDA for different lengths of time, and (ii) to document the repopulation of skin by the O. volvulus microfilariae following treatment, using 3 independent diagnostic techniques. Method Identified microfilaridermic individuals were treated with ivermectin and re-examined after 1, 3, and 6 months using microscopy, actin real-time PCR (actin-qPCR) and O-150 LAMP assays. Susceptibility to ivermectin and trends in detecting reappearance of skin microfilariae were determined using three techniques. Microscopy was used as an imperfect gold standard to determine the performance of actin-qPCR and LAMP. Results In Bafia with over 20 years of IVM-MDA, 11/51 (21.6%) direct observe treated microfilaridemic participants were still positive for skin microfilariae after 1 month. In Melong, with 10 years of IVM-MDA, 2/29 (6.9%) treated participants were still positive. The microfilarial density reduction per skin biopsy within one month following treatment was significantly lower in participants from Bafia. In both study sites, the molecular techniques detected higher proportions of infected individuals than microscopy at all monitoring time points. LAMP demonstrated the highest levels of sensitivity and real-time PCR was found to have the highest specificity. Conclusion Patterns in skin mirofilariae clearance and repopulation were established. O. volvulus worms from Bafia with higher number of annual MDA displayed a lower clearance and higher repopulation rate after treatment with ivermectin. Molecular assays displayed higher sensitivity in monitoring O. volvulus microfilaridemia within six months following treatment.

scholarly journals Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: Relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

2020 ◽  
Author(s):  
Raphael Awah Abong ◽  
Glory Ngongeh Amambo ◽  
Patrick Chounna Ndongmo ◽  
Abdel Jelil Njouendou ◽  
Ritter Manuel ◽  
...  
Keyword(s):  
Real Time ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Real Time Pcr ◽  
Differential Susceptibility ◽  
Diagnostic Techniques ◽  
Molecular Techniques ◽  
Onchocerca Volvulus ◽  
Density Reduction ◽  
Low Sensitivity

Abstract Background. Ivermectin is an excellent microfilaricide against Onchocerca volvulus. However, in some regions, long term use of ivermectin has resulted in sub-optimal responses to the treatment. More data to properly document the phenomenon in various contexts of ivermectin mass drug administration (IVM-MDA) is needed. Also, there is a need to accurately monitor a possible repopulation of skin by microfilariae following treatment. Skin snip microscopy is known to have a low sensitivity in individuals with light infections, which can be the case following treatment. This study was designed with two complementary objectives: (i) to assess the susceptibility of O. volvulus microfilariae to ivermectin in two areas undergoing IVM-MDA for different lengths of time, and (ii) to document the repopulation of skin by the O. volvulus microfilariae following treatment, using 3 independent diagnostic techniques.Method. Identified microfilaridermic individuals were treated with ivermectin and re-examined after 1, 3, and 6 months using microscopy, actin real-time PCR (actin-qPCR) and O-150 LAMP assays. Susceptibility to ivermectin and trends in detecting reappearance of skin microfilariae were determined using three techniques. Microscopy was used as an imperfect gold standard to determine the performance of actin-qPCR and LAMP.Results. In Bafia with over 20 years of IVM-MDA, 11/51 (21.6%) direct observe treated microfilaridemic participants were still positive for skin microfilariae after 1 month. In Melong, with 10 years of IVM-MDA, 2/29 (6.9%) treated participants were still positive. The microfilarial density reduction per skin biopsy within one month following treatment was significantly lower in participants from Bafia.In both study sites, the molecular techniques detected higher proportions of infected individuals than microscopy at all monitoring time points. LAMP demonstrated the highest levels of sensitivity and real-time PCR was found to have the highest specificity.Conclusion. Patterns in skin mirofilariae clearance and repopulation were established. O. volvulus worms from Bafia with higher number of annual MDA displayed a lower clearance and higher repopulation rate after treatment with ivermectin. Molecular assays displayed higher sensitivity in monitoring O. volvulus microfilaridemia within six months following treatment.

scholarly journals Rapid Point-of-Contact Tool for Mapping and Integrated Surveillance of Wuchereria bancrofti and Onchocerca volvulus Infection

2015 ◽  
Vol 22 (8) ◽  
pp. 896-901 ◽  
Author(s):  
Cathy Steel ◽  
Allison Golden ◽  
Eric Stevens ◽  
Lindsay Yokobe ◽  
Gonzalo J. Domingo ◽  
...  
Keyword(s):  
Drug Administration ◽  
Mass Drug Administration ◽  
Wuchereria Bancrofti ◽  
Lateral Flow ◽  
Onchocerca Volvulus ◽  
Buffer Strips ◽  
Predictive Values ◽  
Content Type ◽  
Single Antigen ◽  
Lateral Flow Strips

ABSTRACTElimination programs forWuchereria bancroftiandOnchocerca volvulusare in critical need of sensitive, specific, and point-of-contact (POC) tools that can be used for surveillance years beyond cessation of mass drug administration when infection intensities are low. Previously, Wb123 and Ov16 were identified individually as potential filarial antigens for an antibody-based POC test. The present study compares single-antigen Wb123- and Ov16-based POC tests with an integrated configuration to detect antibodies to Wb123 and Ov16 simultaneously. Wb123 and Ov16 isolates were striped onto lateral flow strips containing anti-IgG4. Sera fromW. bancrofti-,O. volvulus-, and other helminth-infected or -uninfected individuals were added to the strips with buffer. Strips were read for the appearance of a positive or negative test line for both antigens at 20 min and following drying. Sensitivity, specificity, and predictive values were calculated for the single-antigen and biplex strips. Single and biplex lateral flow strips showed nearly identical results, with >90% sensitivity for Ov16 and >92% sensitivity for Wb123. Overall specificities for the single and biplex tests were 98% and 96% for Ov16 and Wb123, respectively. Biplex tests performed as well as the single-antigen tests regardless of the intensity of patient IgG4 response. The high sensitivity and specificity make these new biplex tests extremely useful for POC long-term surveillance following mass drug administration in Africa that should reduce time and cost in areas where bancroftian filariasis and onchocerciasis are coendemic.

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