Comparação dos Métodos de Lutz, Willis e Kato-Katz no diagnóstico de helmintos intestinais (Uberlândia, MG)

Abstract

Intestinal helminths are one of the main worldwide public health problems. Although, great advances in the development of immunologic techniques to diagnose intestinal parasites has occurred, parasitological fecal methods remain the most utilized due to thcir low cost and easy execution. In the present study, the prevalence of intestinal helminths was determined in a urban-rural community in the city of Uberlândia-MG. Lutz, Willis and Kato- Katz parastitological methods were used. To methods results were analyzed comparing the following parameters: prevalence, efficiency, concordance, specificity and sensibility. One hundred seventy-two (172) stool samples were obtained. Slides of the specimens were prepared in triplicate for each of the tested methods. General helminth prevalence rate was 26.16% Prevalence rate in males was 27.40% and 25.25% in females. Age group that presented the highest prevalence coefficient was the group 0 to 10 years (42.22%). No significant statistical differences were found between males and females or between the age groups, except between the groups 0-10 and 40-50 years. The majority of cases (89%) were infested witli only one parasite. Of the total of infested individuais (45 cases), 77.77% were detected by Lutz method, 46.66% by Willis method and 44.44% by Kato-Katz method. Statistical difference was found among methods using the Q Cochran Test (x2=5.99; Q=74.82 e a=74.82), which demonstrates that Lutz method was the best in tenns of diagnosis. Ancylostomatides (9.88%), Hymenolepis nana (6.98%) and Enterobius vermicularis (5,23%) were the most frequently found helminths. Lutz method was more efficient than the other two methods analyzed. This method diagnosed 70.59% of the 17 cases of ancylostomatides, 83.33% of the 12 cases de II. nana 55.55% of the 9 cases de E. vermicularis. All 5 cases of Strongyloides stercoralis (x2 = 5.99, Q=10.00) were diagnosed only by Lutz method. Significant statistical difference was found between S. stercoralis cases and ILnana (%2 = 5.99, Q=9.60) cases. Lutz method was the best method for diagnosis in both parasites. The sensibility of Willis and Kato-Katz methods was 60% and 61%, respectively and specificity was 95% and 96%, respectively. Predictive positive and ncgative values were 56% and 96% for Willis method and 64% and 96% for Kato-Katz method. Prevalence of intestinal helminths in the studied area was low and considering the rural characteristics of the study population, results were not very different lrom other results obtained in the region. Comparison among the methods indicates that the isolated utilization of any of the methods produces an underestimation of intestinal helminth prevalence, but also shows that Lutz method presents the best results in diagnosing these helminth diseases in the studied community.