Sodium azide preservation of faecal specimens for Kato analysis

The modified Kato technique has the advantages of reproducibility, simplicity and economy: the disadvantage is that it cannot be used in conjunction with traditional faecal preservatives. Sodium azide has been evaluated as a preservative for human faeces for subsequent Kato analysis. More than 400 faecal samples (from normal and malnourished children, and from mixed-age participants in a field survey of the Turks and Caicos Islands) were each mixed with 2-5mg of sodium azide powder and stored in 2 or 4ml autoanalyser cups at ambient tropical temperature. At intervals up to 30 weeks, aliquots were prepared for Kato analysis. Trichuria trichiura, Ascaris lumbricoides and Necator americanus eggs were well preserved without degenerative or developmental changes in morphology. Quantitative analyses of 18 samples indicated that the mean egg count/sample did not change significantly after storage for 1, 2, 4, 8, 12 and 16 weeks in preservative. The use of aside preservative extends the applications of the Kato technique to field and clinical studies in which delays may occur between specimen collection and examination. The direct costs of azide preservation are substantially lower than for traditional methods and the preserved specimens are more compact and resistant to leakage. (Summary)

The relative public morbidity caused by whipworm and roundworm - abstract

The whipworm's eggs are encountered more commonly than those of any other geohelminth in the stools of West Indian children. Eighty per cent (260) of the children aged 6 months to 6 years in the village of Anse-la-Rays, St. Lucia, were examined. A detailed history was taken by questionnaire, anthropometry, physical examination performed and stools collected. The physical examination and stool collection were repeated after two to three months. Of 9 children (3.4 percent) with reported rectal prolapse, seven had faecal egg counts indicative of heavy trichuris burdens, one other stool was positive at 1,440 eggs per gram (epg). 84 percent of all children (260) had trichuris; 62 percent, ascaris; 14 percent were ó 80 percent weight for age (WA); 7 percent 90 percent height for age (HA); 52 percent ó 15cm mid upper arm circumference (MUAC). 27 children with "Heavy Trichuris" i.e. egp > 25,000 and/or rectal prolapse, were significantly different from the rest of the population being between 2 and 4 years of age, 28 percent were ó 80 percent WA and ó 90 percent HA although MUAC was not different. Stool frequently and pica were positively associated with blood mucous and sand in the stool. Thirty-six children with "Heavy Ascaris" i.e. epg > 25000, were not significantly different to the total population. Our conclusion is that whipworm may cause more objective morbidity than roundworm to children, especially those over two years old. In a hyperendemic village massive trichuriasis is one of the most common factors associated with chronic diarrhoea (AU)

Spironoura tikasinghi sp. n. (nematoda: kathlanidae) from a turtle in Trinidad, W.I

Spironura tikasinghi sp. n. from the cecum and small intestine of a turtle, Geoemyda punctularia, from Trinidad, is characterized by having spicules 530 to 570 um, and a gubernaculum 310 to 340 um long. It is compared with other species from South and Central America, and with those reported from turtles. (AU)

Laboratory and field studies on the Jamaican strain of human Strongyloides

Laboratory and field studies were done on the Jamaican strain of human Strongyloides. In the laboratory, optimal conditions for propagations of the free-living cycle were investigated. The mongrel puppy was employed as a model for the exploration of various aspects of host-strongyloid relationships. The histological reaction to normal skin to penetrating larvae, and of sensitised skin to larvae, excretory-secretory ("ES") and somatic ("S") antigen, was determined. Enzymatic activities of falariform larvae were assayed in vitro. Several factors predisposing to autoinfection were examined. The anthelmintic activity of levamisole and thiabendazole was compared. In the field, a follow-up study was done and pilot surveys for prevalence were conducted throughout Jamaica in areas contrasting in climatic and physiographic features. The results indicated that optimal conditions for propagation of the heterogonic cycle existed at a temperature range of 26§C to 30§C, a pH range of 7.5 to 8.0, and a stool consistency equal to that of a very thick paste. The reaction of normal skin to invading larvae was essentially a non-specific, acute inflammatory response; with sensitised skin, there was significant degranulation of mast cells in the presence of larvae, "ES" and "S" antigen. Collagenase, galatinase, fibrinase, lipase and hyaluronidase activity of falariform larvae were demonstrated. Autoinfection was experimentally induced by constipation, by vincristine therapy, by ileal ligation and by simulation of ileal volvulus. A general hypothesis was advanced to explain the etiology of autoinfection. Levamisole possessed statistically significantly greater anthelmintic activity than thiabendazole against Strongyloides in vitro, but not in vivo in puppies. It was unable to eradicate the parasite completely from the stools of five out of six infected patients. Preliminary data suggest that the chronicity of strongyloidiasis in Jamaican patients is due to internal autoinfection rather than external reinfection. The low prevalence of the infection in the general population is very low (30 out of 1,555 persons positive, or 1.9 percent)(AU)