Morphometric variability of <i>Schistosoma intercalatum</i> eggs: a diagnostic dilemma

Almeda, J.; Ascaso, Carlos; Marçal, G. A.; Corachán, M; Southgate, V. R.; Rollinson, David

doi:10.1017/s0022149x00015224

Cited by 10 publications

(9 citation statements)

References 17 publications

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“…The length and width of F. hepatica eggs shed by different hosts were different: the eggs were larger in the most usual hosts (cattle and sheep) than in nutria, rats, or rabbits. This has previously been recorded in another trematode: the eggs of Schistosoma intercalatum are larger when shed by the usual human host than by mice (Almeda et al, 1996). Morphological variations of a strigeoid trematode were also host-related (Palmieri, 1977;Perez Ponce de Leon, 1995).…”

Section: Discussionsupporting

confidence: 61%

Morphological variability inFasciola hepaticaeggs in ruminants, rodents and lagomorphs

Abrous¹,

Comes

Gasnier

et al. 1998

J. Helminthol.

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The length and width of 1297 Fasciola hepatica eggs shed in cattle hosts, 337 in sheep and 199 in nutria, were measured from several parts of France. The data were compared with those obtained from other studies in Spain, France (where rats were also investigated), Germany and the Netherlands. One way analysis of variance and discriminant analysis were used to assess differences between host origins. The distribution of length and width of eggs were analysed using skewness and kurtosis Fisher coefficients. The eggs recovered from sheep, cattle, rodents and lagomorphs were different in size: the eggs found in rodents (length L × width W in μm: 8592) and lagomorphs (L × W in μm: 9100) were smaller than those found in sheep and cattle (L×W in μm: 10,000). These morphological differences in F. hepatica eggs were host-induced in rats (L×W in μm: 9709 in cattle to 8949 in rats) and rabbits (L×W in μm: 9709 in cattle to 8432 in rabbits). These differences in size of eggs might correspond to their being less able to develop into miracidia in less frequent hosts such as rodents and rabbits.

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Section: Discussionsupporting

confidence: 61%

Morphological variability inFasciola hepaticaeggs in ruminants, rodents and lagomorphs

Abrous¹,

Comes

Gasnier

et al. 1998

J. Helminthol.

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“…Indeed, if the evidence of S. haematobium is widely reported in Lambaréné, 12,27 only scarce data reveal the presence of S. intercalatum 10 or S. guineensis 16 in the area. Because S. haematobium eggs can be found in stool, 28 and confusion between S. intercalatum and S. haematobium eggs is possible when the differentiation is carried out based only on their shape and size using a microscopic method, 29 as we did, it will be relevant to use a molecular method to reconfirm the presence of S. intercalatum and/or S. guineensis in the area.…”

Section: Discussionmentioning

confidence: 96%

Epidemiology of Schistosomiasis and Soil-Transmitted Helminth Coinfections among Schoolchildren Living in Lambaréné, Gabon

Dejon-Agobé

Honkpéhèdji

Zinsou

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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Schistosomiasis is a parasitic infection highly prevalent in Central Africa where it is co-endemic with many other parasitic infections, including soil-transmitted helminths (STHs). For its optimal control, there is a need of descriptive epidemiological data for each endemic region. The objective of the present study was to determine the epidemiological situation around schistosomiasis in Lambaréné, Gabon. A cross-sectional study was conducted among schoolchildren. One urine sample per day was collected on three consecutive days for the diagnosis of schistosomiasis using a urine filtration technique. One stool sample was collected for the detection of Schistosoma spp. and STH spp. eggs using the Kato-Katz technique, and for larvae, using the coproculture technique. A total of 614 schoolchildren were included in the analysis. The overall prevalence of schistosomiasis and STH infections was 26% (159/614) and 15% (70/473), respectively. Human-freshwater contact was the main risk factor for schistosomiasis in the area (relative risk (RR) = 2.96 [2.20-4.00], P < 0.001). Hematuria .10], P < 0.001) and proteinuria (RR = 2.12 [1.63-2.75], P < 0.001) as well as infection with Trichuris trichiura (RR = 1.86 [1.33-2.61], P = 0.002) and Ascaris lumbricoides (RR = 1.96 [1.19-3.21], P = 0.039) were associated with an increased risk of schistosomiasis. Trichuris trichiura was the highest prevalent STH species in the area. Our study reports a moderate prevalence for schistosomiasis with human-water contact as the main risk factor, whereas the prevalence of STH infections appears to be low. Our results stress the need for the implementation of WHO recommendations for schistosomiasis control.

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“…Besides, egg size and shape (length/width ratio) were highly variable; about 70% of this variation was present within a single patient. Intraspecific variability is known to impede species identification (Almeda et al 1996) and therefore complicates the differentiation between pure and hybrid species. Finally, it should be noted that none of the studies mentioned above used molecular methods to verify species status.…”

Section: Discussionmentioning

confidence: 99%

“…Different schistosome species or strains have typically different mean egg sizes or different maxima when plotting density curves (Pitchford, 1965; Almeda et al 1996). The unimodal distribution of egg-measurements in this study and the absence of morphological differences between HH eggs and HB eggs suggest that both genetic classes of eggs belong to one random mating schistosome population, without mating restrictions in the next generation.…”

Section: Discussionmentioning

confidence: 99%

Detecting hybridization in African schistosome species: does egg morphology complement molecular species identification?

et al. 2017

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Hybrid parasites may have an increased transmission potential and higher virulence compared to their parental species. Consequently, hybrid detection is critical for disease control. Previous crossing experiments showed that hybrid schistosome eggs have distinct morphotypes. We therefore compared the performance of egg morphology with molecular markers with regard to detecting hybridization in schistosomes. We studied the morphology of 303 terminal-spined eggs, originating from 19 individuals inhabiting a hybrid zone with natural crosses between the human parasite Schistosoma haematobium and the livestock parasite Schistosoma bovis in Senegal. The egg sizes showed a high variability and ranged between 92·4 and 176·4 µm in length and between 35·7 and 93·0 µm in width. No distinct morphotypes were found and all eggs resembled, to varying extent, the typical S. haematobium egg type. However, molecular analyses on the same eggs clearly showed the presence of two distinct partial mitochondrial cox1 profiles, namely S. bovis and S. haematobium, and only a single nuclear ITS rDNA profile (S. haematobium). Therefore, in these particular crosses, egg morphology appears not a good indicator of hybrid ancestry. We conclude by discussing strengths and limitations of molecular methods to detect hybrids in the context of high-throughput screening of field samples.

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Morphometric variability of Schistosoma intercalatum eggs: a diagnostic dilemma

Cited by 10 publications

References 17 publications

Morphological variability inFasciola hepaticaeggs in ruminants, rodents and lagomorphs

Morphological variability inFasciola hepaticaeggs in ruminants, rodents and lagomorphs

Epidemiology of Schistosomiasis and Soil-Transmitted Helminth Coinfections among Schoolchildren Living in Lambaréné, Gabon

Detecting hybridization in African schistosome species: does egg morphology complement molecular species identification?

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