WILLIS METHOD MODIFICATION WITH A VIEW TO IMPROVING ROUTINE COPROPARASITOLOGICAL DIAGNOSIS

Autores

  • Matheus Diniz Gonçalves Coêlho Faculdade de Pindamonhangaba - FAPI
  • Aryadne Gonçalves de Faria
  • Lucas Tobias Rodrigues Maciel
  • Francine Alves da Silva-Coêlho

DOI:

https://doi.org/10.5216/rpt.v48i1.55402

Resumo

Intestinal parasites still cause high morbidity and mortality, due to poor hygiene and sanitary
conditions, and therefore indiscriminate treatment has been routine practice advocated by the
Public Health staff. Although there is a consensus regarding the need to diagnose such diseases,
this is not performed with the necessary care, due to great demand and the lack of a wide ranged
and highly sensitive technique. In this sense, most clinical laboratories use routine methods for
fecal examination such as the Lutz sedimentation or modified Ritchie methods, which are complete
and easy to execute, but do not have adequate sensitivity to detect low density eggs and protozoan
cysts, especially when there is a predominance of low parasite burdens. In contrast, there are
methods that are based on the flotation of low density developmental forms, namely, the Willis
method (NaCl flotation d=1.120), which is rapid, easy to perform and allows high density egg
flotation but with low sensitivity for protozoan cysts; and the Faust method, which is based on
centrifugal flotation of developmental forms in a 33% ZnSO4 (d=1.200) solution, but with the
disadvantage of being lengthy and requiring a centrifuge. In this study, we verified the applicability
of introducing an alteration in the Willis method, which consisted in the substitution of NaCl by
ZnSO4 in order to combine the advantages of this method with the Faust method. 208 samples were
assessed by the Willis and Ritchie methods and by the proposed method (modified Willis). The
latter proved superior to the other two (? <0,0001 – X2) regarding the detection of protozoan cysts,
but similar to the Ritchie method in regard to other diagnosed parasites, therefore demonstrating
the high potential for the introduction of this modified method in the routine of fecal diagnosis.

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Biografia do Autor

Matheus Diniz Gonçalves Coêlho, Faculdade de Pindamonhangaba - FAPI

Professor de Parasitologia da Faculdade de Pindamonhangaba, Mestre em Análises Clínicas e Doutor em Ciências na área de biotecnologia.

Aryadne Gonçalves de Faria

Fundação Universitária Vida Cristã (FUNVIC), Faculdade de Pindamonhangaba, Laboratório de Parasitologia e Malacologia, Pindamonhangaba, São Paulo, Brazil.

Lucas Tobias Rodrigues Maciel

Fundação Universitária Vida Cristã (FUNVIC), Faculdade de Pindamonhangaba, Laboratório de Parasitologia e Malacologia, Pindamonhangaba, São Paulo, Brazil.

Francine Alves da Silva-Coêlho

Universidade de Taubaté (UNITAU), Instituto Básico de Biociência (IBB), Laboratório de Parasitologia, Taubaté, São Paulo, Brazil.

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Publicado

12-04-2019

Como Citar

Coêlho, M. D. G., Gonçalves de Faria, A., Tobias Rodrigues Maciel, L., & Alves da Silva-Coêlho, F. (2019). WILLIS METHOD MODIFICATION WITH A VIEW TO IMPROVING ROUTINE COPROPARASITOLOGICAL DIAGNOSIS. Revista De Patologia Tropical / Journal of Tropical Pathology, 48(1), 25–34. https://doi.org/10.5216/rpt.v48i1.55402

Edição

Seção

ARTIGOS ORIGINAIS / ORIGINAL ARTICLES