Criteria for identification of Schistosoma mansoni eggs in faecal sediments prepared with the Helmintex method and stained by ninhydrin

Helmintex is a sensitive method used for detecting Schistosoma mansoni eggs. Here, we describe the observed frequency of six proposed criteria associated with the identification of S. mansoni eggs prepared with the Helmintex method and stained with ninhydrin. The efficacy of these criteria in classifying S. mansoni eggs when applied in various combinations was also examined. Nine observers registered the presence or absence of 6 different criteria in 100 eggs using a microscope at 100x magnification. Ninhydrin purple, which was frequently observed, was the criterion associated with the lowest inter-observer variability. At least three criteria were associated with a significantly better performance in egg identification. In conclusion, ninhydrin staining and a combination of criteria are recommended for microscope examination of faecal sediments.

Parámetros poblacionales de tres parasitoides (Hymenoptera: Scelionidae, Encytidae) utilizando al depredador Podisus nigrispinus (Heteroptera: Pentatomidae) como hospedero / Polpulation parameters of three parasitoids (Hymenoptera: Scelionidae, Encytidae) hosted by the predator Podisus nigrispinus (Heteroptera: Pentatomidae)

The reproductive parameters of Telenomus podisi, Trissolcus brochymenae (Hymenoptera: Scelionidae) and Ooencyrtus sp. (Hymenoptera: Encyrtidae) were studied for three generations on their natural host Podisus nigrispinus (Dallas, 1851) (Hemiptera: Pentatomidae). A parasitism rate of 10 eggs/day/species was used under laboratory conditions of 27 +/- 1 degrees C, 60 +/- 10 percent RH and 14 h of photophase. No significant differences were detected between generations in terms of net reproductive rate (Ro), intrinsic rate of natural increase (rm), generation time (T) and the effect of doubling time on population increase (DT). However, T. podisi and T. brochymenae had significantly higher Ro and rm values, and lower T and DT values, with rm 1.59 and 1.50 times higher than Ooencyrtus sp., respectively. In addition the former species also had shorter egg-adult period, greater longevity of females and reproduction period than the other species. These results confirm the greater reproductive potential of T. podisi and T. brochymenae, which are commonly found parasitizing P. nigrispinus

Control de calidad externo en el diagnóstico parasitológico de cryptosporidium parvum / External quality control in the parasitological diagnoses of cryptosporidium parvum

Between 1991 and 1994, 8 external quality assessments of Cryptosporidium parvum infection diagnosis were performed. Stool specimens were sent to 74 laboratories, to be stained and examined. In 40 laboratories (54.1 percent), the diagnosis was correct in all evaluations, whereas in 34 (46 percent), the diagnosis disagreed with the parasitology reference laboratory in one ocassion or more. The mean correlation of diagnoses with the reference laboratory was 88 percent (range 79-96 percent). Ninty-three percent of negative samples and 87 percent of positive samples were correctly diagnosed. These figures are similar to those obtained abroad. These results lead to the development of a quality control network for the diagnosis of Cryptosporidium parvum infections along the country aiming to improve its reliability