Adaptation of Ritchie's Method for Parasites Diagnosing with Minimization of Chemical Products

Latin America, Africa, and Asia present wide dissemination and high prevalence rates of waterborne parasitic diseases, which is a strong indicative of the fragility of public sanitation systems. In this context, parasitological analyses represent extremely relevant instruments. Several parasite diagnosis methods exist, among which Ritchie’s method (1948) stands out. This method uses formaldehyde and ether, two reagents of toxicological importance that can cause damages to environmental and occupational health. The present study aimed to compare Ritchie’s method modified by Régis Anécimo, without use of solvents, with the traditional Ritchie’s method, routinely used for helminth and protozoa diagnosing in Brazil. Some changes were introduced in the modified method, such as controlled increase of water temperature used after stool dilution and substitution of formaldehyde and ether by a neutral detergent before material centrifugation for observation of parasites. In examined samples by both methods, multiple infections were commonly observed; the modified method presented a similar sensitivity to identify the parasites. The development of analytic diagnosis methods that minimize the use of chemical products like ether and formaldehyde represents an important tool to prevent occupational diseases among exposed professionals, as well as to preserve environmental quality through the use of clean techniques. 1. Introduction In many regions, intestinal parasites represent a very important medical-sanitary problem, due to their large-scale dissemination and high prevalence. This situation is typical of developing countries, where interrelations between etiological agent and host are favored, considering the precarious basic sanitation conditions, predisposing environmental factors, and the unfavorable socioeconomic conditions of an important part of the population [1]. In developing countries, the most frequent helminthiases are those caused by intestinal infection with soil-transmitted helminths such as Ascaris lumbricoides and Trichuris trichiura, and hookworms (Necator americanus and Ancylostoma duodenale) [2]. According to Centers for Disease Control and Prevention (CDC) [3], around 1.5 billion individuals are infected with Ascaris lumbricoides, 1.1 billion with Trichuris trichiura and 1.3 billion with hookworms, and that, the main clinical manifestations are intestinal obstruction, malnutrition, and anemia due to iron deficiency. It is also estimated that 200 and 400 million people, respectively, host protozoa such as Giardia duodenalis and Entamoeba