The Emergence of Zoonotic Onchocerca lupi Infection in the United States--A Case-Series.

This case-series describes the 6 human infections with Onchocerca lupi, a parasite known to infect cats and dogs, that have been identified in the United States since 2013. Unlike cases reported outside the country, the American patients have not had subconjunctival nodules but have manifested more invasive disease (eg, spinal, orbital, and subdermal nodules). Diagnosis remains challenging in the absence of a serologic test. Treatment should be guided by what is done for Onchocerca volvulus as there are no data for O. lupi. Available evidence suggests that there may be transmission in southwestern United States, but the risk of transmission to humans is not known. Research is needed to better define the burden of disease in the United States and develop appropriately-targeted prevention strategies.

The onchocerciasis chronicle: from the beginning to the end?

The year 2012 marks the 25th anniversary of the donation of ivermectin to fight onchocerciasis and the projected date for elimination of transmission of the disease in the Americas. This review looks at the history of onchocerciasis, from its discovery through to 2025, by which time it is projected that the disease will have been eliminated as a public health problem, except in a handful of sub-Saharan countries, where it should be well on the way towards elimination.

Use of an ophthalmologic ultrasoundscanner in human onchocercal skin nodules for non-invasive sequential assessment during a macrofilaricidal trial with amocarzine in Guatemala. The first experiences.

Ultrasonography of onchocercal skin nodules was performed with an ophthalmologic real time linear scanner with a B probe of 10 MHz. A clinical trial in Guatemala with amocarzine (CGP 6140)--a new oral macrofilaricidal compound--investigated three repeat dose regimens and one placebo control group, each group consisting of six patients. Onchocercal nodules were scanned before treatment and on day 10, 30 and 60 after start of amocarzine. A total of 28 treated and 8 additional untreated nodules were analysed and compared with the histologic findings following nodulectomy at day 60. Of the 28 treated nodules, 21 were of onchocercal origin and seven were lymph nodes. The correlation between ultrasonography and histology was good in 25 patients, but did not match in three. In 20 out of 21 treated nodules a progressive ultrasonographic change over two months was seen. Of the eight additional untreated nodules, five were of onchocercal origin, one was a lymph node, one an epidermoid cyst and in one only fibrous tissue was detected. The ultrasonography correlated well to histology in seven nodules but not in one. In five onchocercal nodules no change was observed over two months. For initial control purposes six nodules were excised around day 10, four were of onchocercal origin and two were lymph nodes. The correlation was good in four. The present results indicate that an ophthalmologic real time linear scanner can be used in the bidimensional mode as a non-invasive method to assess sequentially the events in superficial onchocercal nodules following chemotherapy with amocarzine. This is the first objective non-invasive method permitting sequential assessment of the content of onchocercal nodules and it is far superior than subjective sequential manual palpation.

In vitro assessment of the activity of anthelmintic compounds on adults of Onchocerca volvulus.

The viability of adult Onchocerca volvulus and the effect of 12 known anthelmintic compounds on the parasites have been evaluated in an in vitro culture system. Three different parameters, a colorimetric assay, using NADH-dependent reduction of a tetrazolium salt to dark blue formazan by living adult worms, motility indices of male worms and lactate excretion of female worms were used to determine worm viability. The experiments showed that over a short term period of six days the viability of the worms did not decline significantly. The use of males isolated by dissection of whole nodules for the evaluation of drug effects in vitro is preferable to collagenase isolated worms. Mel W, milbemycin a and d, ivermectin, levamisole, CGP 6140 and, to a lesser extent, suramin immobilized male worms or significantly reduced the motility indices at a concentration of 10 microM. The tetrazolium reduction by male worms was not affected by levamisole, whereas the other active compounds demonstrated significant inhibitory effects. Diethylcarbamazine, mebendazole, flubendazole, metrifonate and CGP 20376 had no significant effect on male viability. Comparable activity was seen with the intact female worms isolated by collagenase digestion. Mel W, the milbemycins and ivermectin significantly inhibited tetrazolium reduction, whereas suramin and the other compounds had only slight or no inhibitory effects on female O. volvulus. Although one still has to aim at an improvement of the culture conditions, the in vitro test system using adult O. volvulus provides a basis for further research on potential antifilarial compounds.

Quantitative assessment of microfilariae and adults of Onchocerca volvulus in ethanol-fixed biopsies and nodules.

Ethanol-fixed Onchocerca nodules and skin snips were successfully digested with collagenase to assess the parasite load. The importance of this technique for investigations in the field is discussed.

An evaluation of skin snip techniques used in the quantitative assessment of microfilarial densities of Onchocerca volvulus.

A study was undertaken to determine whether significant variations occur in the quantitative assessment of onchocercal microfilarial densities when different methods of treating skin snips are used. The results show that teasing of the snip should be avoided because it reduces the sensitivity of the method.