Comparison between Two Methods for Diagnosis of Trichinellosis: Trichinoscopy and Artificial Digestion

Abstract

(Larrieu 1981, Nader et al. 1986, Brusolini & Gore 1992. Most of the cases were associated with the consumption of pork meat subproducts.In Argentina two methods of diagnosis are used: trichinoscopy and artificial digestion; both methods allowing a direct observation of the larvae encysted in the skeletal muscles. Trichinoscopy is the primary method, even though, it is considered less sensitive than artificial digestion. Fifteen or more larvae per gramme of muscle, are considered necessary for detection using trichinoscopy, whereas, artificial digestion only requires four larvae per gramme (Ruitenberg & Kampelmacher 1970, Van Knappen et al. 1980, Köhler & Pfeiffer 1983, Acha & Szyfres 1989. In this study, we compare the trichinoscopy method to artificial digestion in order to establish if there are significant differences in sensibility of one method with respect to the other; we also analize the distribution of larvae in the chosen muscles. MATERIALS AND METHODSFive months old wistar rats SPF (n=17) were infected per os with 500 Trichinella spiralis encysted larvae from a strain maintained in rats since + Corresponding author. Fax: +54-21-253276 Received 2 January 1997 Accepted 16 May 1997 1960. Forty days after infection, the rats were euthanized using sulphuric ether vapours.Trichinoscopy -From each animal, a 1 g sample was taken from the following muscles: diaphragm, tongue, masseters, intercostals, a triceps brachialis and a cuadriceps femoralis (opposite members of triceps). Samples were reduced to subsamples of 5 mm x 1 mm thickness; they were pressed between two sheets of glass and observed microscopically with 4x. Afterwards, encysted larvae were totaled. All the samples were recovered for processing by artificial digestion.Artificial digestion -It was performed at 39ºC for 3 hr in a solution of 1% pepsin (0.7 Fip µ/mg) and 1% HCl (37%) in distilled water, in a proportion of 15 ml/g of sample. The mixture was shaken. The larvae, were then filtered and those concentrated by sedimentation were washed and counted. The double-blind system was used in order to register the data obtained from both methods.Statistical analysis -Analysis of variance was used: a Fisher test was applied in order to compare quantitative data; and a Chi square test for the qualitative results (Lison 1976). The obtained data were transformed for the analysis of variance and linear correlation, with the following relationships: number of larvae (x) equals the square root of (x), divided by the sample weight (Sokal & Rohlf 1984, Kirby 1993). Table I shows that the averages of larvae per gramme of T. spiralis detected by trichinoscopy (t) are significantly smaller in intercostals, triceps RESULTS

A review of testing and assurance methods for Trichinella surveillance programs

“…This method results in 0.5–1.0 g of muscles cut in small pieces about the size of a grain of rice ( Boireau et al, 2007 ). Then samples are compressed between two thick glass slides and examined via an optical microscope at 4×-40× zoom ( Beck et al, 2005 ; Boireau et al, 2007 ; Vignau et al, 1997 ). As with artificial digestion techniques, it relies on the operator's familiarity with the organism to be effective, but even experienced operators generally attain worse sensitivity than can be achieved through artificial digestion.…”

The Role of Ducks (Muscovy) and Catfish (Clarias Lazera) Meat in Transmitting Trichinella Spiralis Infection

“…Trichinella spiralis larvae were determined after the trichinoscopic examination of naturally infected diaphragmatic muscles of freshly slaughtered pigs in Cairo abattoir, Egypt, according to the method described by Vignau et al (1997) where one gram of these muscles adjacent to the tendinous part of the diaphragm was sub-cut into small pieces then compressed between two glass plates of the trichinoscope and examined under 40× magnification of a binocular light microscope (LABOMED, Labo America, Inc. U.S.A). An amount of 50 g from these muscles was dissected into very small pieces.…”

Present status of trichinellosis - a neglected zoonosis in India

“…Experts opine that trichinoscopy can detect the infection only when there are three to five larvae per gram of muscles (Webster et al 2006). Others say that number of larvae per gram of meat should be 15 or more for trichinoscopic detection (Vignau et al 1997). Outbreaks involving several hundred cases had been reported in past following consumption of pork and pork products that had even passed the trichinoscopic examinations procedures in Sweden (1961) andGermany (1967).…”