Comparison of different staining methods for the nematode Strongyloides papillosus isolated from rabbits

Abstract

Strongyloidiasis in rabbits is a disease caused by Strongyloides papillosus helminths, manifested by skin inflammation, diarrhea, weight loss, and stunting of animals in growth and development. Confirmation of invasion is carried out mainly by required methods of helminthoovoscopy and helmintholarvoscopy. The most well-known methods of helmintholarvoscopic diagnosis of feces for strongyloidiasis are the method of D. Baermann (1917) and its modifications according to V. I. Shilnikov (1983), the method using the “asterisk” device (according to V. F. Nikitin and T. Pavlasek, 1988), the method of coprohelmintho-larvoscopic rings (according to S. I. Ponomar, N. M. Soroka, 2007), the method of T. I. Popova, standardized by S. I. Ponomar (2003). There are no laboratory methods with 100 % reliability at the present stage. Therefore, our studies on improving the lifelong helminthocoprological diagnosis of strongyloidiasis in rabbits are relevant. Our work aimed to compare different methods of staining the pathogen S. papillosus. Laboratory studies were carried out in the laboratories of the Department of Parasitology and Veterinary Sanitary Expertise of the Dnipro State Agrarian and Economic University. For staining S. papillosus, 20 dyes were used: 1 % alizarin red, 1 % brilliant blue, Turk's solution, 1 % brilliant green, 1 % methylene blue, 1 % amido black 10B, 1 % eosin, Ziehl's solution, Lugol's solution, 1 % сarbolic gentian violet, Romanowsky-type, 1 % Sudan, 1 % bromophenol blue, 1 % orange G, 1 % bromocresol green, 1 % safranin, Zadorozhny-Dozmorov's-type, Mikhin's-type, Muromtsev's-type. We have proposed 20 dyes for staining the internal organs of larvae and free-living males and females pathogens of Strongyloides without or with temperature fixation. Live pathogens S. papillosus, without temperature fixation, pass only Lugol's and safranin's solutions. All other dyes showed the highest staining, but only when the preparation was heated for 2–3 seconds to 60 °C. However, the dyes showed different degrees of coloration. Bromocresol green stained the walls of the internal organs of the helminth. Namely, the nematodes acquired a green color, and the membranes of a part of the esophagus and intestines became dark green. During microscopy, this allowed accurate identification and differentiation into larvae and free-living males and females of S. papillosus and simplified their counting.