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Evaluation of ultrasonography for the detection of drug-induced changes in onchocercal nodules
K Darge1, J Troeger, C Engelke
1Department of Paediatric Radiology, Children's Hospital, Heidelberg University, Germany.
Abstract:
Clinical trials of macrofilaricidal drugs against Onchocerca volvulus are impeded due to the lack of means for assessing in vivo drug-induced changes in the onchocercomas. The application of ultrasonography in the sequential monitoring of morphologic alterations of onchocercal nodules after six weeks of suramin therapy was evaluated in 20 male patients from Ghana with a total of 64 nodule sites. After each follow-up session, a number of onchocercal nodules were extirpated so that by the end of one year, all nodules had been removed for histologic examination. The sonomorphologic changes observed and their time of appearance correlated well with the histologic findings of the onchocercomas. Eighty-three percent of the onchocercal nodules became hyperechogenic and 22% developed echo-free areas at the end of the follow-up period. Absence of the lateral acoustic shadow increased by more than 30% and the lack of differentiation of the worm center from the capsule and the nodule from its surrounding tissue increased by the end of one-year posttreatment to 100% and 91%, respectively. A mean reduction of nodule size of 27% was also documented. The histologic studies revealed that the proportion of the dead female worms increased from 17% at the end of the suramin therapy to 48% six months later and reached 61% at one year. It is concluded that ultrasonographic monitoring of onchocercomas can provide essential information on drug effects and facilitate clinical trials of macrofilaricidal drugs, limiting histologic evaluation to a few objectively selected onchocercomas.
Insights
Ultrasonography effectively monitors onchocercal nodules, revealing drug effects in clinical trials for Onchocerca volvulus. This imaging technique aids in assessing macrofilaricidal drug efficacy, reducing the need for extensive histologic analysis.
Area of Science:
- Medical Imaging
- Parasitology
- Clinical Pharmacology
Background:
- Clinical trials for Onchocerca volvulus macrofilaricidal drugs face challenges in assessing in vivo drug effects on onchocercomas.
- Novel methods are needed to monitor drug-induced changes within onchocercal nodules.
Purpose of the Study:
- To evaluate the utility of ultrasonography for monitoring morphologic changes in onchocercal nodules following suramin therapy.
- To correlate sonomorphologic alterations with histologic findings for assessing drug efficacy.
Main Methods:
- Sequential ultrasonographic monitoring of 64 onchocercal nodules in 20 Ghanaian patients over one year post-suramin therapy.
- Histologic examination of extirpated nodules to confirm sonomorphologic findings and worm viability.
Main Results:
- Ultrasonography showed significant changes, including increased hyperechogenicity (83%) and echo-free areas (22%).
- Absence of lateral acoustic shadow and loss of nodule differentiation increased significantly, correlating with histologic evidence of dead female worms (up to 61% at one year).
- A mean nodule size reduction of 27% was observed.
Conclusions:
- Ultrasonographic monitoring provides essential information on macrofilaricidal drug effects in onchocercomas.
- This imaging modality can facilitate clinical trials by reducing reliance on extensive histologic evaluations.