Comparison of different techniques and stains for direct diagnosis of Trichinella spiralis

ABSTRACT

Background: The aim of Trichinella inspection is to reliably detect larvae in meat at levels which are capable of causing human trichinellosis. Trichinoscopy is a rapid, cost effective but is less sensitive in detection of low muscle larvae (ML)numbers. Artificial digestion is more convenient, and flexible, but may destroy immature larvae. Baermann technique may enhance the efficiency of diagnosis. Giemsa and Leishman stains provide identical contrasting coloration as Hematoxylin and Eosin (H-E) with the both advantages of that they can be used for staining non-histological sectionsand rapid preparation.The primary aim of the study was to compare the efficiency of digestion and Baermann techniques for detection of ML in muscles. Secondary aim was detection of ML by Geimsa and Leishman stain and their comparison with routinely used stain H-E. Methods: Muscles from 36 mice orally infected with Trichinella spiralis encysted larvae were examined. Larvae from 1 g samples of different muscles were recovered by digestion and Baermann techniques after different dose of infection. Muscle samples were prepared for staining with Giemsa, Leishman and H-E. Results: Number of larvae recovered by Baermann was higher recovered by digestion method (P ˃0.5). Leishman stain was the best stain for rapid detection of ML after 30 min followed in validity by Geimsa then H-E. Conclusion: Baermann concentration technique showed higher sensitivity than digestion method. Leishman stain is superior to Giemsa stain as it takes less time. Both stains are considered good alternative to H-E for rapid and easy diagnosis of trichinellosis in post-mortem animals