Effects of hypertonic solutions on two species of human intestinal parasites during fecal examination
Abstract
Aim: Ova and parasite examination by flotation requires hypertonic solutions, which can damage the egg and cyst membranes, leading to false negatives. The authors investigated the harmful effects of ZnSO4 and C12H22O11 solutions on the ova and parasite examination. Materials & methods: The authors processed samples using the Three Fecal Test technique. Aliquots were floated in different pH levels, temperatures and solution densities. Results: Densities above 1.12 g/ml led structures to collapse after 6–10 min. pH neutralization of the ZnSO4 solution did not prevent the parasites from changing. Conclusion: All structures were altered when standard methods were performed. To delay collapse, the parasite floating under 5 °C is highly desirable.
Plain language summary
Fecal exams require solutions that can damage the intestinal parasite's shape. This is bad for diagnosis. The authors investigated the harmful effects of these solutions on fecal exams. The authors processed samples using a technique called the Three Fecal Test. Fecal samples were floated in different conditions, including neutral and acidic solutions, high and low temperatures and varying densities of chemical solutions. Densities above 1.12 g/ml altered the structures of parasites. Neutral solutions did not prevent the structures from changing. The structures of all parasites were altered when the usual techniques were performed. Thus, the techniques for diagnosing intestinal parasites in feces must be improved. Temperatures under 5 °C are the best for preventing the destruction of parasite membranes.
Tweetable abstract
Hypertonic solutions in ova and parasite (O&P) exams can damage the membranes of intestinal parasites.
Papers of special note have been highlighted as: • of interest
References
- 1. WHO. Working to Overcome the Global Impact of Neglected Tropical Diseases: First WHO Report on Neglected Tropical Diseases. WHO, Geneva (2010).
- 2. . Parasitologia: parasitos e doenças parasitárias do homem nos Trópicos Ocidentais. Parasitol. Parasitos E Doenças Parasitárias Homem Nos Tróp. Ocidentais. Koogan, Rio de Janeiro, Brazil, 883–883 (2008).
- 3. TF-Test modified: new diagnostic tool for human enteroparasitosis. J. Clin. Lab. Anal. 30(4), 293–300 (2016).
- 4. TF-Test quantified: a new technique for diagnosis of Schistosoma mansoni eggs. Trop. Med. Int. Health 24(5), 586–595 (2019). • Discusses a new and helpful technique for diagnosing Schistosoma mansoni.
- 5. World Health Assembly 66. Neglected tropical diseases (2013). https://www.who.int/publications/i/item/WHA66.12
- 6. . Diagnostic Medical Parasitology (6th Edition). ASM Press, Washington, DC, USA (2016). • Discusses the diagnosis of parasites.
- 7. . A comparative study of the TF-Test®, Kato-Katz, Hoffman-Pons-Janer, Willis and Baermann-Moraes coprologic methods for the detection of human parasitosis. Mem. Inst. Oswaldo Cruz 107(1), 80–84 (2012). • Compares the efficiency of different parasitological techniques.
- 8. . High prevalence of Blastocystis spp. infection in children and staff members attending public urban schools in São Paulo State, Brazil. Rev. Inst. Med. Trop. Sao Paulo 58, 31 (2016).
- 9. Spatial distribution of intestinal parasitic infections in a Kaingáng indigenous village from southern Brazil. Int. J. Environ. Health Res. 26(5–6), 578–588 (2016).
- 10. Use of the aqueous biphasic system as an alternative for concentration of Ascaris lumbricoides eggs, with non-toxic separation of faecal residues and fats. Trop. Med. Int. Health 24(11), 1320–1329 (2019). • Discusses an original approach for preventing parasite membranes from collapsing.
- 11. . Evaluation of a novel kit (TF-Test) for the diagnosis of intestinal parasitic infections. J. Clin. Lab. Anal. 18(2), 132–138 (2004). • Discusses a new and more efficient fecal processing technique.
- 12. Advances in the canine coproparasitological examination. In: Dogs – Domestication History, Behavior and Common Health Problems (Volume 23, 45th Edition). Nova Science Publishers, Inc., NY, USA, 91–103 (2013).
- 13. A historical review of the techniques of recovery of parasites for their detection in human stools. Rev. Soc. Bras. Med. Trop. 53, e20190535 (2020). • Reviews conventional techniques and perspectives in parasitology.
- 14. Comparative study of five techniques for the diagnosis of canine gastrointestinal parasites. Rev. Bras. Parasitol. Vet. 24(2), 223–226 (2015).
- 15. A new laboratorial method for the diagnosis of gastrointestinal parasites in dogs. Rev. Bras. Parasitol. Vet. 22(1), 1–5 (2013).
- 16. Validation of a new technique to detect Cryptosporidium spp. oocysts in bovine feces. Prev. Vet. Med. 134, 1–5 (2016).
- 17. . A simple levitation method for the detection of hookworm ova. Med. J. Aust. 2(18), 375–376 (1921).
- 18. . The detection of intestinal protozoa and mange parasites by a floatation technique. J. Pathol. Ther. 36(Pt 4), 266–275 (1923).
- 19. A critical study of clinical laboratory technics for the diagnosis of protozoan cysts and helminth eggs in feces. I. Preliminary communication. Am. J. Trop. Med. 18(2), 169–183 (1938).
- 20. . Flotation technique for Opisthorchis and Clonorchis eggs. Trans. Royal Soc. Trop. Med. Hyg. 56(2), 174 (1962).
- 21. . Ethyl acetate as a substitute for diethyl ether in the formalin–ether sedimentation technique. J. Clin. Microbiol. 10(6), 852–853 (1979).
