Higher Egg Counts Research Articles

Immunodiagnosis of infection with Schistosoma mansoni: enzyme-linked immunosorbent assay for detection of antibody to circulating antigen.

A circulating antigen, a negatively charged polysaccharide from the trematode Schistosoma mansoni, was noncovalently bound to the surface of poly(L-lysine)-coated wells in polystyrene trays, which were then used in a micro-enzyme-linked immunosorbent assay (ELISA) test. The method provides an immunodiagnostic test for schistosomiasis of exceptional sensitivity with a high degree of specificity. Comparison of Bell egg counts and ELISA titers revealed a good correlation (r congruent to 0.80) in young individuals with low to moderate worm burdens, but this relationship was less marked in older individuals or those with high egg counts.

Schistosomiasis in Saudi Arabian recruits. A morbidity study based on quantitative egg excretion.

We surveyed stool and urine specimens from 245 Saudi Arabian trainees for parasites. Schistosoma mansoni eggs were found in the stool in 66 (26.9%) and S. haematobium eggs were recovered from the urine in 1 (0.4%). Additional parasites were recovered in 167 (68.2%) of the survey group and were not more common in those with schistosomiasis (P greater than .10). Schistosome egg counts ranged from 0--6,320 eggs/g feces (mean 447.9). When patients with high egg counts (over 400 eggs/g) were compared with uninfected controls, abdominal complaints and fatigue were found to be more frequent (P less than .05) in the infected group, as was eosinophilia (P less than .001). Other laboratory and physical examination findings were equally present in both groups. This study reaffirms the value of quantitative examination of stool specimens for schistosome eggs.

Morbidity from Schistosoma mansoni infections: an epidemiologic study based on quantitative analysis of egg excretion in Ethiopian children.

Abstract Morbidity from infection with Schistosoma mansoni was investigated in a population of school children, aged 7 to 16 years, from the town of Chwahit, located north of Lake Tana in Highland Ethiopia. Malaria was under control in the area, and S. haematobium was not endemic. Quantitative fecal egg counts were determined for 336 children (94% of those in the school) by the Kato thick-smear method; other intestinal parasites were determined by the Ritchie formol-ether concentration method. Morbidity was measured by a standardized medical examination of 272 of these children and was analyzed in four categories of egg count intensity: 0 (12%), 1–100 (19%), 101–500 (40%), and 501 + (29%) eggs per gram (epg). Prevalence was 88%, and the geometric mean egg count was 259 epg. The highest prevalence and intensity were found in 12-year-olds (95% and 300 epg, respectively). No schistosomiasis-associated symptoms were significantly related to the intensity of S. mansoni infection, although the complaint of blood in the stool was more frequent in groups with higher egg counts. There was a trend for hepatomegaly (especially of the left lobe) to increase in frequency with increasing egg count, but this trend was not significant. These children had no splenic enlargement. Anthropometric weight-for-height measurements, average school grade, and days absent from school were not related to the intensity of S. mansoni infections. Physical performance in a standardized 12-minute walk-run was better in uninfected boys, but there was no correlation with the intensity of infection. The minimal morbidity found in this population is compatible with the moderately low intensity of S. mansoni infection and with the findings of a previous population-based study in a neighboring village.

The intensity and effects of infection with Schistosoma mansoni in a rural community in northeast Brazil.

The intensity of infection with Schistosoma mansoni and its effects were investigated in a defined population living on three contiguous fazendas (subcounties) in a nonmalarious area of northeast Brazil near Salvador, Bahia. Quantitative stool egg counts (Bell technique) were performed on 363 of 417 individuals (90%) of all ages; physical examinations were done on 294 of 357 individuals (82%) 5 years of age and older. The maximum increase in prevalence was observed between the 1- to 4- and 5- to 9-year age groups, while the maximum increase in fecal egg count occurred between 5- to 9- and 10- to 14-year age groups. Highest egg counts were observed in the 10- to 14-year age group (geometric mean of 301 eggs per ml of stool) while the maximum prevalence (100%) was in the 20- to 24-year age group. In the fazenda with the lowest quantitative egg counts the age specific prevalence rates increased more slowly than in the fazendas with higher egg counts. In the study group nearly 50% of the total fecal egg output was accounted for by 22 individuals (6%) who had a mean age of 12.6 years. Egg counts for this selected group were all over 800 eggs per ml of stool with a mean of 1,514 eggs per ml of stool. In children under 15 years of age, the frequency of hepatomegaly and splenomegaly varied directly with the egg count; further, the degree of hepatomegaly was directly correlated with increasing egg counts. No splenic enlargement was noted in children not excreting eggs. In adults, on the other hand, neither splenomegaly nor hepatomegaly could be directly related to schistosomal infection per se. In children, neither the presence of infection with S. mansoni nor its intensity was reflected by altered anthropometric measurements. In the one fazenda tested the frequency of stools positive for occult blood correlated with increasing S. mansoni egg counts.

Observations on the faecal egg count of calves naturally infected with Ostertagia ostertagi

The faecal egg counts of seven groups of calves exposed to infection with O. ostertagi on pastures were found to follow a similar course to those of calves experimentally infected on one occasion or of calves infected daily. They declined from an early peak according to an apparently logarithmic curve. It was concluded that faecal egg counts were largely independent of worm numbers and tended to follow a stereotyped pattern. Acute clinical ostertagiasis was as liable to lead to high egg counts as was poor thriving due to the other causes. The relevance of these findings to the epidemiology of ostertagiasis and to the use of faecal egg counts in the diagnosis of parasitic gastro-enteritis are discussed.The author thanks Miss C. N. Herbert for the calculations and curve fitting in this paper.

Dicrocoelium dendriticum: The Life Cycle in Britain

The work has demonstrated that one of the more important areas of Scotland where Dicrocoelium dendriticum is endemic carried infected colonies of Helicella itala which live in association with the ant Formica fusca. Workers of the ant were shown to acquire typical metacercarial cysts after the ingestion of slime balls, and the cysts gave rise to mature lancet flukes in sheep and hamsters, eggs appearing in the faeces after 56 and 48 days respectively. Higher egg counts were obtained from hamsters to which more cysts were administered. This is the first occasion on which an ant intermediate host has been demonstrated for Dicrocoelium in Britain.

Análise morfológica e quantitativa dos ovos de Schistosoma mansoni em fezes humanas

Os autores, na primeira parte do trabalho, descrevem os principais tipos de ovos de S. mansoni observados em fezes de pacientes originários de zonas endêmicas da esquistossomose e nunca anteriormente submetidos a tratamento. Descrevem a presença de ovos viáveis maduros e imaturos, além de diversos tipos de ovos mortos, inclusive calcificados. Chamam a atenção para a raridade deste último achado, que entretanto, não deve ser desprezado no controle coproscópico após terapêutica antiparasitária. Apresentam fotografias e as dimensões médias dos ovos observados. Em uma segunda parte, fazem a contagem dos ovos de S. mansoni por cm3 de fezes. Encontram maior número de ovos, tanto viáveis como mortos, nos pacientes portadores da forma hepatoesplênica da doença, do que nos portadores da forma hepatointestinal. Verificaram, entretanto, que as percentagens dos diversos tipos de ovos não se afastam muito. Supõem que, ao lado de outros fatures, um maior número de vermes no hospedeiro deva exercer papel importante no desenvolvimento das formas graves da esquistossomose mansoni. Encontram também maior número de ovos, tanto viáveis como mortos, nos indivíduos menores de 20 anos do que nos maiores de 20 anos de idade. No entanto. a percentagem dos diversos tipos de ovos eliminados não sofre grandes modificações nos dois grupos de doentes. Acreditam que além de fatores imunitários, c envelhecimento dos vermes com o decorrer da parasitose possa ser responsável pela diminuição na oviposição. Os dados relativos à contagem global de ovos de S. mansoni em fezes de pacientes afastados de zonas endêmicas confirmam, de uma maneira geral, os resultados encontrados por outros autores em áreas endêmicas da esquistossomose mansoni, quando se referem ao maior ou menor número de ovos eliminados, em relação à forma clínica da parasitose e ao grupo etário dos pacientes.

The influence of infection intensity of Schistosoma mansoni on resistance against existing and subsequent infections in Macaca mulatta.

Summary The biology of light infections of Schistosoma mansoni and their immunogenic effects were studied in seven Macaca mulatta by means of routine egg counts, worm numbers and cellular reactions against schistosomula in the lungs. Two monkeys showed statistically significant increases in eggs when re-exposed at 250 days. One of these was strongly resistant to added infection at 500 days and the other relatively so. Three other animals re-exposed for the first time after 500 days were almost normally susceptible at that time. Thereafter, one of these failed to spontaneously terminate an infection with high egg counts, resulting from 20 light exposures, although its resistance to reinfection became strong. Two other monkeys, receiving only a single initial exposure of 50 cercariae, produced eggs uniformly for much longer periods than is characteristic of heavy infections. One of these two animals, when re-exposed at 800 days, showed a statistically significant increase in egg output, while the other was strongly resistant at 1100 days. Following terminal challenge at 1400 days, worm counts and cellular reactions against schistosomula in the lungs indicated strong resistance had been induced. This indicates that it required a longer time to induce a comparable resistance in the lightly infected animals than in those with heavy initial infections.

Splenomegaly in schistosomiasis mansoni.

SummaryEgg counts for Schistosoma mansoni in part of the population of a highly endemic town in Pernambuco, Brazil, showed that after reaching a maximum early in life, egg output decreased sharply. It is felt that acquired immunity may be involved.While splenomegaly in other parasitic or infectious diseases may start in infancy, spleen enlargement in schistosomiasis occurs suddenly after the tenth year of life. A connection between this process and the sudden decrease in egg output is strongly suspected. The incidence of splenomegaly is significantly higher in a population with high egg counts. Egg output is also higher in the members of families in which splenomegaly occurs.

Reactions of calves to infestation with the stomach worm, Haemonchus placei (Place, 1893) Ransom, 1911

Studies aimed a t determining the factors responsible for haemonchosis in cattle are reported. Observations on natural populations of Haemonchus placei confirmed the conclusions of Roberts, O'Sullivan, and Riek (1932) on the acquisition of resistance to this species and on the relationships of peak egg counts to the age of the animal and season of the year. Most of the 400 calves on which these observations were based developed a strong resistance and suffered no apparent ill effects; others only became resistant after suffering clinical haemonchosis; and about 8 per cent. either failed to develop resistance or lost it and died. Experiments with single doses, spaced doses, and continuous doses of larvae showed that H. placei has a comparatively short patent period. The trend assumed by the egg counts, irrespective of the method of infestation, was very similar, reaching its peak about the 6th to 10th week and thereafter rapidly declining to remain a t low levels. Calves on a 12 : 1 mixture of oaten and lucerne chaff gave much higher egg counts than calves on good quality lucerne alone, but the infestations did not vary in their persistence. A strong resistance was acquired, even from a single dose of larvae. This was shown by the failure of a test dose of larvae, administered after the egg count had been at low levels for some weeks, to cause any increase in the egg count; and by the presence, several weeks later a t autopsy, of relatively few adult worms, most of which were undersized with females containing few or no eggs. There were also numerous fourth stage larvae which had evidently persisted in this stage for many weeks. That so many immature worms occurred in resistant animals may signify that these young stages could be extremely important in the epidemiology of haemonchosis. "Selfcure", as defined by Gordon (1948) for H. contortus in sheep, could not be produced experimentally with H. placei in cattle, but egg count trends suggest that this type of reaction may sometimes occur among natural populations before resistance is finally acquired. Circulating antibodies could not be detected in experimentally infested animals. They were found, however, in animals with natural infestations of mixed species, and it is probable that in the latter case they were associated rather with Trichostrongylus than with Haemonchus. Data on egg counts in relation to the number of adult female worms present in experimentally infested calves strongly suggest that whilst the animal remains susceptible to infestation, egg counts are usually an accurate index of the degree of infestation, but that when resistance occurs the egg count is of little value for this purpose.

Some observations on the worm egg counts of Scottish hill lambs.

Worm egg counts have shown that after the end of June infestations of pathogenic significance occur in a considerable percentage of Scottish hill lambs. On the West Coast, however, heavy infestations do not occur until August, when the egg counts in other areas are rising again after falling for a few weeks in July.Identification of larvae from faeces cultures confirm that Ostertagia spp. are the first cause of high worm egg counts, followed in August by Trichostrongylus spp., then by H. contortus and C. ovina, and finally by B. trigonocephalum. Nematodirus spp. may be sufficiently numerous in a few districts to be of pathogenic importance in June and July.

Nematode parasite populations in sheep on lowland farms. 1. Worm egg counts in ewes.

1. Details are given of worm egg counts carried out on faeces from ewes during 1950–3.2. Two periods of high egg counts were recorded each year; one during spring and the other in late summer.3. The first increase appeared to correspond to the spring rise of other workers. It has been shown to be of short duration in each individual ewe, and the time of its occurrence directly related to the time of lambing.4. Details are given of the seasonal incidence of different species of nematodes.5. The spring rise is discussed and a theory is advanced to account for the phenomenon. It is emphasized that the fall in egg counts after the rise is as important as the increase.6. A suggestion that the summer rise is spurious and caused by a reduction in volume of faeces passed during the first week after weaning is accepted.