Estudo estatístico de contagens de ovos de nematódeos, realizadas na câmara Mcmaster e pelo sistema lamínula-lâmina no método centrífugo-flotação

Abstract

Nematode egg-counts in ovine faeces were analysed statistically, using the McMaster slide and the centrifugation microscope slide - coverslip technique. The following parameters were considered: mean value of the OPG, the infection level of the animal and the dilution of the sample, in each case using faeces from sheep parasitized with gastrointestinal nematodes. It was seen that, when using counts from the McMaster slide, the level of the infection of the animal is closely related to the statistical distribution followed by counts at different dilutions, and that these tend to deviate from the Poisson distribution and approach the Normal as the OPG count increases. Egg-counts in the two cells of the McMaster slide are statistically independent. It was shown that both for the McMaster slide and the slide-coverslip system, a significantly greater part of the counts consisted of random values. x v i i i It was judged that, for both types of counts, there was a very close relationship between the level of the OPG and the dilution or quantity of faeces used. The comparative efficiency of the McMaster and the centrifugation slide-coverslip techniques depends on the level of the infection of the animal also.