A qPCR to quantify Wolbachia from few Onchocerca volvulus microfilariae as a surrogate for adult worm histology in clinical trials of antiwolbachial drugs

The filarial nematode Onchocerca volvulus causes onchocerciasis (river blindness), a neglected tropical disease affecting 21 million people, mostly in Sub-Saharan Africa. Targeting the endosymbiont Wolbachia with antibiotics leads to permanent sterilization and killing of adult worms. The gold standard to assess Wolbachia depletion is the histological examination of adult worms in nodules beginning at 6 months post-treatment. However, nodules can only be used once, limiting the time points to monitor Wolbachia depletion. A diagnostic to longitudinally monitor Wolbachia depletion from microfilariae (MF) at more frequent intervals < 6 months post-treatment would accelerate clinical trials of antiwolbachials. We developed a TaqMan qPCR amplifying the single-copy gene wOvftsZ to quantify Wolbachia from as few as one MF that had migrated from skin biopsies and compared quantification using circular and linearized plasmids or synthetic dsDNA (gBlock®). qPCR for MF from the rodent nematode Litomosoides sigmodontis was used to support the reproducibility and validate the principle. The qPCR using as few as 2 MF from O. volvulus and L. sigmodontis reproducibly quantified Wolbachia. Use of a linearized plasmid standard or synthesized dsDNA resulted in numbers of Wolbachia/MF congruent with biologically plausible estimates in O. volvulus and L. sigmodontis MF. The qPCR assay yielded a median of 48.8 (range 1.5–280.5) Wolbachia/O. volvulus MF. The qPCR is a sensitive tool for quantifying Wolbachia in a few MF from skin biopsies and allows for establishing the qPCR as a surrogate parameter for monitoring Wolbachia depletion in adult worms of new antiwolbachial candidates.

Multimodal biomarker discovery for active Onchocerca volvulus infection

The neglected tropical disease onchocerciasis, or river blindness, is caused by infection with the filarial nematode Onchocerca volvulus. Current estimates indicate that 17 million people are infected worldwide, the majority of them living in Africa. Today there are no non-invasive tests available that can detect ongoing infection, and that can be used for effective monitoring of elimination programs. In addition, to enable pharmacodynamic studies with novel macrofilaricide drug candidates, surrogate endpoints and efficacy biomarkers are needed but are non-existent. We describe the use of a multimodal untargeted mass spectrometry-based approach (metabolomics and lipidomics) to identify onchocerciasis-associated metabolites in urine and plasma, and of specific lipid features in plasma of infected individuals (O. volvulus infected cases: 68 individuals with palpable nodules; lymphatic filariasis cases: 8 individuals; non-endemic controls: 20 individuals). This work resulted in the identification of elevated concentrations of the plasma metabolites inosine and hypoxanthine as biomarkers for filarial infection, and of the urine metabolite cis-cinnamoylglycine (CCG) as biomarker for O. volvulus. During the targeted validation study, metabolite-specific cutoffs were determined (inosine: 34.2 ng/ml; hypoxanthine: 1380 ng/ml; CCG: 29.7 ng/ml) and sensitivity and specificity profiles were established. Subsequent evaluation of these biomarkers in a non-endemic population from a different geographical region invalidated the urine metabolite CCG as biomarker for O. volvulus. The plasma metabolites inosine and hypoxanthine were confirmed as biomarkers for filarial infection. With the availability of targeted LC-MS procedures, the full potential of these 2 biomarkers in macrofilaricide clinical trials, MDA efficacy surveys, and epidemiological transmission studies can be investigated.

Dermatology

Infections of the skin?, Skin infestations?, Ulcers?, Rashes?, Dermatitis eczema?, Psoriasis?, Pityriasis rosea?, Lichen planus?, Drug eruptions?, Vasculitis?, Erythema nodosum?, Urticaria?, Erythema multiforme?, Blistering disorders?, Connective tissue diseases?, Disorders of pigmentation?, Skin cancers?, Common cutaneous viral infections?, Varicella zoster virus?, Poxvirus infections?, Cutaneous leishmaniasis?, Lymphoedema elephantiasis?, Lymphatic filariasis?, Onchocerciasis 'river blindness'?, Loiasis Loa loa?, Dracunculiasis Guinea worm?, Other parasites that invade the skin?, Cutaneous larva migrans?, Larva currens?, Podoconiosis?, The non-venereal treponematoses?

CDC Warns of Increased Ivermectin Overdoses

No abstract available. Article truncated after 150 words. The US Centers for Disease Control and Prevention (CDC) is warning of an increase in cases of ivermectin overdose due to people self-prescribing the drug in an effort to prevent or treat COVID-19 (1). Ivermectin is used to treat river blindness and intestinal roundworm infection in humans and to de-worm pets and livestock. A study published earlier this year showed that ivermectin killed SARS-CoV-2 in cells in vitro. The authors proposed that the medication be investigated as a cheap and easily available treatment for COVID-19. However, subsequent studies have failed to find any benefit in humans (3). In a new communication to its Health Alert Network, the CDC says cases of overdose and misuse are rising (1). More than 88,000 prescriptions were written for the drug ivermectin in the week ending August 13, an increase of 2400% over the weekly average prior to the COVID-19 pandemic (Figure 1). Unfortunately, the …

The burden of skin disease and eye disease due to onchocerciasis in countries formerly under the African Programme for Onchocerciasis Control mandate for 1990, 2020, and 2030

Background Onchocerciasis (“river blindness”) can cause severe morbidity, including vision loss and various skin manifestations, and is targeted for elimination using ivermectin mass drug administration (MDA). We calculated the number of people with Onchocerca volvulus infection and onchocercal skin and eye disease as well as disability-adjusted life years (DALYs) lost from 1990 through to 2030 in areas formerly covered by the African Programme for Onchocerciasis Control. Methods Per MDA implementation unit, we collated data on the pre-control distribution of microfilariae (mf) prevalence and the history of control. Next, we predicted trends in infection and morbidity over time using the ONCHOSIM simulation model. DALY estimates were calculated using disability weights from the Global Burden of Disease Study. Results In 1990, prior to MDA implementation, the total population at risk was 79.8 million with 26.0 million (32.5%) mf-positive individuals, of whom 17.5 million (21.9%) had some form of onchocercal skin or eye disease (2.5 million DALYs lost). By 2030, the total population was predicted to increase to 236.1 million, while the number of mf-positive cases (about 6.8 million, 2.9%), people with skin or eye morbidity (4.2 million, 1.8%), and DALYs lost (0.7 million) were predicted to decline. Conclusions MDA has had a remarkable impact on the onchocerciasis burden in countries previously under the APOC mandate. In the few countries where we predict continued transmission between now and 2030, intensified MDA could be combined with local vector control efforts, or the introduction of new drugs for mopping up residual cases of infection and morbidity.

Comparative Analysis of the Diagnostic Methods Used in Detecting River Blindness in Selected Endemic Areas of Imo State, Nigeria

Onchocerciasis also known as river blindness is a chronic parasitic disease caused by the filarial worm Onchocerca volvulus. This study was a cross sectional experimental study carried out to compare the diagnostic methods used in detecting river blindness in selected endemic areas of Imo state, Nigeria. The multistage sampling technique was adopted to select samples for the study. All subjects used for this study gave an informed consent to be part of the study. Bloodless skin snips were collected from the center of the nodule or other parts of the body with the assistance of a laboratory scientist and taken to the laboratory for analysis. A total of four hundred inhabitants of the studied communities (Umulolo, Amuro, Umuna, Umunumo, Onicha, Nzerem, Umuneke and Umulewe) were examined. Out of these, the number infected by onchocerca volvulus based on Skin-Snip Microscopy, Polymerase Chain Reaction (PCR), Mazzotti test, Dietylcarbamazine (DEC) patch test and Enzyme linked Immunosorbent Assay (ELISA) test were 59, 197, 50, 107, 201 respectively. SPSS analysis using the one way ANOVA showed a significance difference (P< 0.05) in the sensitivity of the PCR, Skin Snip Microscopy, Mazzotti, DEC Patch test and ELISA used for detecting Onchocerca volvulus in all the study areas. In conclusion, the diagnostic screening efficiency of ELISA and PCR were observed to be higher than that of the other diagnostic methods analyzed. It was recommended that further evidence-based, comparative research studies on current and conventional diagnostic methods should be done to ascertain reliability, reproducibility, sensitivity and accuracy of methods used for detecting River Blindness. Keywords: River Blindness, Onchocerciasis, Skin-Snip Microscopy, Polymerase Chain Reaction (PCR), ELISA test.

Emodepside targets SLO-1 channels of Onchocerca ochengi and induces broad anthelmintic effects in a bovine model of onchocerciasis

Onchocerciasis (river blindness), caused by the filarial worm Onchocerca volvulus, is a neglected tropical disease mostly affecting sub-Saharan Africa and is responsible for >1.3 million years lived with disability. Current control relies almost entirely on ivermectin, which suppresses symptoms caused by the first-stage larvae (microfilariae) but does not kill the long-lived adults. Here, we evaluated emodepside, a semi-synthetic cyclooctadepsipeptide registered for deworming applications in companion animals, for activity against adult filariae (i.e., as a macrofilaricide). We demonstrate the equivalence of emodepside activity on SLO-1 potassium channels in Onchocerca volvulus and Onchocerca ochengi, its sister species from cattle. Evaluation of emodepside in cattle as single or 7-day treatments at two doses (0.15 and 0.75 mg/kg) revealed rapid activity against microfilariae, prolonged suppression of female worm fecundity, and macrofilaricidal effects by 18 months post treatment. The drug was well tolerated, causing only transiently increased blood glucose. Female adult worms were mostly paralyzed; however, some retained metabolic activity even in the multiple high-dose group. These data support ongoing clinical development of emodepside to treat river blindness.