Presence Of Parasitic Infections Research Articles

Gut microbiota of an Amazonian fish in a heterogeneous riverscape: integrating genotype, environment, and parasitic infections.

A number of key factors can structure the gut microbiota of fish such as environment, diet, health state, and genotype. Mesonauta festivus, an Amazonian cichlid, is a relevant model organism to study the relative contribution of these factors on the community structure of fish gut microbiota. M. festivus has well-studied genetic populations and thrives in rivers with drastically divergent physicochemical characteristics. Here, we collected 167 fish from 12 study sites and used 16S and 18S rRNA metabarcoding approaches to characterize the gut microbiome structure of M. festivus. These data sets were analyzed in light of the host fish genotypes (genotyping-by-sequencing) and an extensive characterization of environmental physico-chemical parameters. We explored the relative contribution of environmental dissimilarity, the presence of parasitic taxa, and phylogenetic relatedness on structuring the gut microbiota. We documented occurrences of Nyctotherus sp. infecting a fish and linked its presence to a dysbiosis of the host gut microbiota. Moreover, we detected the presence of helminths which had a minor impact on the gut microbiota of their host. In addition, our results support a higher impact of the phylogenetic relatedness between fish rather than environmental similarity between sites of study on structuring the gut microbiota for this Amazonian cichlid. Our study in a heterogeneous riverscape integrates a wide range of factors known to structure fish gut microbiomes. It significantly improves understanding of the complex relationship between fish, their parasites, their microbiota, and the environment. IMPORTANCE The gut microbiota is known to play important roles in its host immunity, metabolism, and comportment. Its taxonomic composition is modulated by a complex interplay of factors that are hard to study simultaneously in natural systems. Mesonauta festivus, an Amazonian cichlid, is an interesting model to simultaneously study the influence of multiple variables on the gut microbiota. In this study, we explored the relative contribution of the environmental conditions, the presence of parasitic infections, and the genotype of the host on structuring the gut microbiota of M. festivus in Amazonia. Our results highlighted infections by a parasitic ciliate that caused a disruption of the gut microbiota and by parasitic worms that had a low impact on the microbiota. Finally, our results support a higher impact of the genotype than the environment on structuring the microbiota for this fish. These findings significantly improve understanding of the complex relationship among fish, their parasites, their microbiota, and the environment.

Micronutrients and socio-demographic factors were major predictors of anaemia among the Ethiopian population.

Anaemia is characterised by low hemoglobin (Hb) concentration. Despite being a public health concern in Ethiopia, the role of micronutrients and non-nutritional factors as a determinant of Hb concentrations has been inadequately explored. This study focused on the assessment of serum micronutrient and Hb concentrations and a range of non-nutritional factors, to evaluate their associations with the risk of anaemia among the Ethiopian population (n 2046). It also explored the mediation effect of Zn on the relation between se and Hb. Bivariate and multivariate regression analyses were performed to identify the relationship between serum micronutrients concentration, inflammation biomarkers, nutritional status, presence of parasitic infection and socio-demographic factors with Hb concentration (n 2046). Sobel-Goodman test was applied to investigate the mediation of Zn on relations between serum se and Hb. In total, 18·6 % of participants were anaemic, 5·8 % had iron deficiency (ID), 2·6 % had ID anaemia and 0·6 % had tissue ID. Younger age, household head illiteracy and low serum concentrations of ferritin, Co, Cu and folate were associated with anaemia. Serum se had an indirect effect that was mediated by Zn, with a significant effect of se on Zn (P < 0·001) and Zn on Hb (P < 0·001). The findings of this study suggest the need for designing a multi-sectorial intervention to address anaemia based on demographic group.

From Parasitized to Healthy-Looking Ants (Hymenoptera: Formicidae): Morphological Reconstruction Using Algorithmic Processing.

Background: Parasites cause predictable alternative phenotypes of host individuals. Investigating these parasitogenic phenotypes may be essential in cases where parasitism is common or taxa is described based on a parasitized individual. Ignoring them could lead to erroneous conclusions in biodiversity-focused research, taxonomy, evolution, and ecology. However, to date, integrating alternative phenotypes into a set of wild-type individuals in morphometric analysis poses extraordinary challenges to experts. This paper presents an approach for reconstructing the putative healthy morphology of parasitized ants using algorithmic processing. Our concept enables the integration of alternative parasitogenic phenotypes in morphometric analyses. Methods: We tested the applicability of our strategy in a large pool of Cestoda-infected and healthy individuals of three Temnothorax ant species (T. nylanderi, T. sordidulus, and T. unifasciatus). We assessed the stability and convergence of morphological changes caused by parasitism across species. We used an artificial neural network-based multiclass classifier model to predict species based on morphological trait values and the presence of parasite infection. Results: Infection causes predictable morphological changes in each species, although these changes proved to be species-specific. Therefore, integrating alternative parasitogenic phenotypes in morphometric analyses can be achieved at the species level, and a prior species hypothesis is required. Conclusion: Despite the above limitation, the concept is appropriate. Beyond parasitogenic phenotypes, our approach can also integrate morphometric data of an array of alternative phenotypes (subcastes in social insects, alternative morphs in polyphenic species, and alternative sexes in sexually dimorphic species) whose integrability had not been resolved before.

Intestinal Parasitic infestations in children visiting Pravara Rural Hospital, Loni (Maharashtra-India)

: Intestinal parasitic infections represent major health problem particularly in tropical countries. Intestinal parasitic infections are closely related to poor sanitation and socioeconomic status. In rural populations these infections are common as most of population belong to low socioeconomic group and also lack proper hygiene. These infestations has implications for child health in terms of physical growth retardation and development.: This two years prospective study was carried out in Dept. of Microbiology, Rural medical college, (PIMS-DU) Loni. All stool specimens from children (0 -14 years) received in Dept. of Microbiology were included in the study. All stool specimens were subjected to macroscopic and microscopic examination. Both saline wet mount and iodine wet mount were prepared and examined for microscopic features.: A total of 460 stool specimens were received during the study period. Males (56.5%) outnumbered females (43.5%) in the present study. Maximum children belonged to age group 1 - 5yrs. A total of seven stool specimen showed parasites giving the positivity 1.52%. Commonest intestinal parasite was found to be E. histolytica in our study. We found one case of H. dimunita which is quite uncommon parasite. Intestinal parasitic infestations like amoebiasis, hookworm, ascariasis exertdiverse clinical manifestation such as malnutrition, iron deficiency anemia, intestinal obstruction. Presence of parasitic infections is expected to be high in agricultural rural population. But we found the quite low positivity in our area may be owing to better sanitation awareness and compliance to Government deworming health program.

Fatal outcome in a patient under immunosuppressant therapy infected with human T-lymphotropic virus type 1 (HTLV-1), cytomegalovirus (CMV) and Strongyloides stercoralis: a case report

BackgroundStrongyloidiasis is a gastrointestinal parasitic infection caused by percutaneous infection with Strongyloides stercoralis. Digestive symptoms such as diarrhea and abdominal pain are the main manifestation, but serious infections such as septicemia, purulent meningitis, and bacterial pneumonia may occur in individuals harboring human T-lymphotropic virus type 1 (HTLV-1) or who are immunocompromised. Although coinfection with Strongyloides stercoralis and HTLV-1 can lead to chronic strongyloidiasis and a disseminated form of the disease, there is a high rate of response to the anthelmintic ivermectin.Case presentationWe report a case of strongyloidiasis infection syndrome that was difficult to differentiate from immune reconstitution inflammatory syndrome (IRIS) for various reasons. The patient had been treated with the corticosteroids tacrolimus (Tac) and mycophenolate mofetil (MMF) for systemic lupus erythematosus (SLE) with lupus nephritis and pancytopenia. When the steroid was reduced, she developed cytomegalovirus (CMV) enteritis, and her respiratory status rapidly deteriorated immediately after the withdrawal of Tac and MMF. It was difficult to distinguish immune reconstitution inflammatory syndrome from strongyloidiasis infection syndrome because stool cultures were negative and eosinophils were not increased. Bronchoscopy revealed viable Strongyloides, leading to a diagnosis of strongyloidiasis infection syndrome, but the patient died despite treatment.ConclusionsBoth corticosteroid therapy and HTLV-1 infection can be associated with a decrease of eosinophils, despite the presence of parasitic infection. In conclusion, even if multiple culture tests are negative, the risk of parasitic infection should be assessed in patients receiving immunosuppressants and steroids even in non-endemic areas.

Negative immunomodulation by parasitic infections in the human response to vaccines.

Parasitic infections are an important cause of global morbidity and mortality and are highly prevalent in "underdeveloped" countries. The presence of parasitic infections is associated with modulation of the immune system and changes in the response to bacterial and viral vaccines. The objective of this review was to compile, summarize and analyze information about immunomodulation by parasitic infections and its effects on the immune response to vaccines. We also identified the parasites most associated with immunomodulation of vaccine responses and those vaccines most affected. In addition, articles evaluating the effect of chemoprophylaxis for malaria on the immune response against vaccines were considered. The most affected vaccines are Bacillus Calmette-Guérin and bacterial polysaccharide vaccines. Malaria is the infection most associated with decreased response to vaccines; however, there are discordant results. Chemoprophylaxis for malaria did not change the immune response to vaccination. While parasitic infections can alter the immune response to vaccination, it is important to clarify the discrepancies and establish the mechanisms.

Effects of anthropogenic stress on the presence of parasites in a threatened population of black howler monkeys (Alouatta pigra)

Habitat disturbance disrupts the ecological interactions of mammals, leading to negative consequences for biodiversity. In particular, it is suggested that parasite-host interactions are affected in tropical ecosystems, with parasite diversity reduced as environmental perturbations take place. In this study, we examined whether the disruption of tropical forests affects the presence of parasites in a population of endangered black howler monkeys (Alouatta pigra) that inhabits a highly fragmented landscape in Balancan, Tabasco, Mexico. Our working hypothesis was that increased forest perturbation would negatively affect the incidence of parasitic infections (parasite presence and richness) in black howler monkeys. We conducted a parasitological study and collected stool samples from 65 adult individuals living in 30 forest fragments across a disturbance gradient. We recovered parasite eggs from stool samples using flotation and sedimentation techniques. We selected fragment size and distance from each forest fragment to the nearest village as measures of forest perturbation. We analyzed the effects of forest perturbation on parasite presence and richness using generalized linear models. Other driving factors such as seasonality, host density, and sex were also considered in the models. Gastrointestinal parasite infection was positively related to distance between forest fragments and the nearest human settlement (β = 0.55 ± SE 0.28, z = 2.0, P = 0.05). No effects of fragment size or any other variable considered in the model on the presence of parasite infection were observed. Parasite richness was not affected by any of the measures of forest perturbation, nor by any other variables considered in the analysis. Our findings suggest that an increase in forest perturbation may negatively affect the probability of parasite infection in black howler monkeys, as individuals living in close proximity to human settlements showed a lower presence of parasites. We proposed that the low parasite infection rates recorded in this monkey population reflect synergistic effects associated with both the alteration of the parasite-primate network, as well as the low resilience of parasites to thrive in a disrupted ecosystem.

Morphological description of Cosmocerca sp. (Nematoda: Cosmocerdidae) from the Mascarene grass frog Ptychadena cf. mascareniensis (Amphibia: Ptychadenidae). A light and scanning electron microscopic studies

The Mascarene grass frog Ptychadena cf. mascareniensis is a species of frog with a vast area of distribution in Africa. A total of 300 frog specimens were collected from different localities at El-Giza province, Egypt; then dissected and examined for the presence of parasitic infection. Only eighty six (28.66%) specimens were found to be naturally infected with nematode parasite. Seasonally, the prevalence of infection was reached its maximum value of 74.66% during summer and minimum values of 26.66% (20/75), 13.33% (10/75) during spring and autumn, respectively; while no records were observed during winter season. The morphology of the recovered parasite was studied by using light and scanning electron microscopy. The adult worm characterized by anterior extremity with small mouth opening being surrounded by three lips provided with four sub-median cephalic papillae and one pair of lateral amphids. Body measurements showed that male worms were smaller than females measuring 1.22-2.43 (2.21 ± 0.1) mm in length and 0.21-0.34 (0.29 ± 0.01) mm in width. Females measured 1.9-3.7 (2.8 ± 0.1) mm in length and 0.24-0.42 (0.38 ± 0.01) mm in width. Comparing the present parasite with other species of the same genus described previously, several similarities were observed. However, peculiar new characteristics such as the arrangement of plectanes and somatic papillae, the presence of gubernaculum, the position of nerve ring, excretory pore, and vulval opening make it reasonable belongs to the family Cosmocercidae and identified as Cosmocerca sp. In addition, the present study was the first report for occurrence of cosmocercid species from the Mascarene grass frog in Egypt.

Reproductive effects of endocrine disrupting chemicals, bisphenol-A and 17β-oestradiol, on Cerastoderma edule from south-west England: field study and laboratory exposure

Endocrine disruption has rarely been reported in field populations of the edible cockle and the context with the general health of the shellfish is unclear. This study examined the reproductive state of two Cerastoderma edule populations over a 6-month period to assess their reproductive condition, the incidence of intersex and presence of parasitic infection. A further seven native sites from south-west England were examined during the peak reproductive season to identify the presence of intersex within the region. Laboratory exposures of organisms collected from field populations showed a significantly female-biased sex ratio compared with controls when exposed to the endocrine disrupting chemicals, bisphenol-A (nominal concentration: 0.1 µg L−1) and 17β-oestradiol (nominal concentration: 0.1 µg L−1), but none of the chemical exposures induced intersex. Intersex was revealed in seven out of the nine native populations of C. edule sampled at peak reproductive season. The highest incidence and most severe case of intersex were reported at Lower Anderton on the River Tamer which also had a significantly female-biased sex ratio. Additionally, the dominant trematode family was the Bucephalaidae. Parasitic infection influences the maturity of C. edule by lowering both mean gonad index and condition index. These results suggest that endocrine disrupting chemicals could be contributing factors towards the development of intersex in C. edule.

Infection with Strongyloides papillosus in sheep: Effect of parasitic infection and treatment with albendazole on basic haematological parameters

The aim of this study was to determine and evaluate the basic haematological parameters in conditions of natural infection of sheep with Strongyloides papillosus, as well as after the administration of antihelminthic albendazole (ABZ). Based on the intensity of infection with S. papillosus the sheep were divided into three groups: mild, moderate and high, and after that the sheep received a single dose of ABZ of 5mg/kg per body weight, per orally. Sampling of faeces and blood for parasitological and haematological assaying respectively, was performed on the 0 and the 21st day after the treatment with ABZ. The presence of parasitic infection with S. papillosus leads to a decrease of erythrocyte count, while the lowest values were established in the group with the highest intensity of parasitic infection (p &lt; 0.001). After treatment with ABZ the decrease of erythrocyte count was more prominent, which was, based on comparison with control groups C1 and C2, unequivocally established to be the consequence of treatment with ABZ. Detected values of haematocrit and erythrocyte indices indicated the presence of parasitic infection: the lowest values were established in the group with the highest intensity of parasitic infection. After treatment with ABZ haematocrit levels in control group C2 were statistically significantly lower compared to the control group C1 (p &lt; 0.001). In the presence of parasitic infection, the neutrophil and eosinophil counts increased almost linearly up to the value of 44.24?2.50% and 13.29?0.61% respectively, in the group of sheep with the highest intensity of parasitic infection (p &lt; 0.001; compared to control group C1). After treatment with ABZ the decrease of the number of these white blood cells is statistically significant (p &lt; 0.001). Bearing in mind our previous research and the connection of disbalanced redox equilibrium after the treatment with ABZ with changes, it is necessary to include antioxidative substances in the anti-parasitic treatment protocols.

Measuring the Change in Zinc Ion Concentration in Eye Tear Fluid between Healthy and Parasite Infected Individuals: Relationship between Zinc Ions in Tear Fluid and Parasitic Infection by Soil-Transmitted Helminths

Infection by soil-transmitted helminths has been correlated with lowered concentration of zinc ions in serum. This study investigated the relationship between changes in zinc ion concentration in tear fluid for healthy versus parasitic infected individuals. The study used a serodiagnosis method to determine the presence of parasite infection. Our results conclude that converse to lowered zinc levels in serum, there is a significant increase in the concentration of zinc ions in eye tear fluids for parasite-infected individuals. These results support our continuing efforts to develop a low-cost, point-of-care diagnostic test specific to helminth infection. This will support the ongoing global anti-worm treatment efforts.

INCIDENTAL PARASITIC INFECTIONS IN SURGICALLY REMOVED APPENDICES: A RETROSPECTIVE ANALYSIS.

Numerous parasitic infections can cause inflammation of the appendix and can mimic appendicitis clinically. The diagnosis is generally achieved only after surgery. However early diagnosis through stool examination may prevent life-threatening complications. This study investigated the presence of parasitic infections in surgically removed appendices as an etiology of acute appendicitis. A retrospective study included patients who had undergone surgery for acute appendicitis over a period of three years from Jan 2012 to Dec 2014. Demographic data, laboratory investigations, operative data and pathological findings, presence and type of parasites were retrieved. The results showed that out of 1536 patients with appendectomy done, 938 (61.1%) were males and 598 (38.9%) were females. Parasitic infection was demonstrated only in 0.4% (6 patients). Mean average age of these patients was 12 years. Enterobius vennicularis was present in 4 patients (66% of the parasitic affection) and Schistosoma mansoni in 2 patients (34% of the parasitic affection). Other etiologies were acute suppurative appendicitis (94.1%), chronic appendicitis (3.1%), tumors (0.3%), tuberculosis (0.2%) and actinomycosis (0.1%). Appendix was found normal in 2% of patients underwent appendectomy.

A Cross-Sectional Study on Intestinal Parasitic Infections in Rural Communities, Northeast Thailand

Despite the existence of effective anthelmintics, parasitic infections remain a major public health problem in Southeast Asia, including Thailand. In rural communities, continuing infection is often reinforced by dietary habits that have a strong cultural basis and by poor personal hygiene and sanitation. This study presents a survey of the prevalence of intestinal parasitic infections among the people in rural Thailand. The community-based cross-sectional study was conducted in villages in Khon Kaen Province, northeastern Thailand, from March to August 2013. A total of 253 stool samples from 102 males and 140 females, aged 2-80 years, were prepared using formalin-ethyl acetate concentration methods and examined using light microscopy. Ninety-four individuals (37.2%) were infected with 1 or more parasite species. Presence of parasitic infection was significantly correlated with gender (P=0.001); nearly half of males in this survey (49.0%) were infected. Older people had a higher prevalence than younger members of the population. The most common parasite found was Opisthorchis viverrini (26.9%), followed by Strongyloides stercoralis (9.5%), Taenia spp. (1.6%), echinostomes (0.4%), and hookworms (0.4%). The prevalence of intestinal protozoa was Blastocystis hominis 1.6%, Entamoeba histolytica 0.8%, Entamoeba coli 0.8%, Balantidium coli 0.4%, Iodamoeba bütschlii 0.4%, and Sarcocystis hominis 0.4%. Co-infections of various helminths and protozoa were present in 15.9% of the people. The present results show that the prevalence of parasitic infections in this region is still high. Proactive education about dietary habits, personal hygiene, and sanitation should be provided to the people in this community to reduce the prevalence of intestinal parasite infections. Moreover, development of policies and programs to control parasites is needed.

Nutritional status, intestinal parasite infection and allergy among school children in northwest Ethiopia.

BackgroundParasitic infections have been shown to have deleterious effects on host nutritional status. In addition, although helmintic infection can modulate the host inflammatory response directed against the parasite, a causal association between helminths and allergy remains uncertain. The present study was therefore designed to evaluate the relationship between nutritional status, parasite infection and prevalence of allergy among school children.MethodsA cross sectional study was performed involving school children in two elementary schools in Gondar, Ethiopia. Nutritional status of these children was determined using anthropometric parameters (weight-for-age, height-for-age and BMI-for-age). Epi-Info software was used to calculate z-scores. Stool samples were examined using standard parasitological procedures. The serum IgE levels were quantified by total IgE ELISA kit following the manufacturer’s instruction.ResultA total of 405 children (with mean age of 12.09.1 ± 2.54 years) completed a self-administered allergy questionnaire and provided stool samples for analysis. Overall prevalence of underweight, stunting and thinness/wasting was 15.1%, 25.2%, 8.9%, respectively. Of the total, 22.7% were found to be positive for intestinal parasites. The most prevalent intestinal parasite detected was Ascaris lumbricoides (31/405, 7.6%). There was no statistically significant association between prevalence of malnutrition and the prevalence of parasitic infections. Median total serum IgE level was 344 IU/ml (IQR 117–2076, n = 80) and 610 IU/ml (143–1833, n = 20), respectively, in children without and with intestinal parasite infection (Z = −0.198, P > 0.8). The prevalence of self reported allergy among the subset was 8%. IgE concentration was not associated either with the presence of parasitic infection or history of allergy.ConclusionThe prevalence of malnutrition, intestinal parasitism and allergy was not negligible in this population. In addition, there was no significant association between the prevalence of allergy and their nutritional status, and parasite infection. Further research prospective observational and intervention studies are required to address the question of causality between nutritional factors, parasites, and allergy.

Anthropometric Status, Anemia and Intestinal Parasitic Infections among Primary School Children in Alexandria, Egypt

BACKGROUND: In developing countries, malnutrition is a major health problem with prevalence ranges of 4-46%. Early childhood malnutrition is irreversible and intergenerational, with adverse consequences on adult health. OBJECTIVES: This study aimed to determine the current prevalence and some associated risk factors of anemia, anthropometric indices and intestinal parasitic infection among primary school children in Alexandria, Egypt. METHODS: A cross sectional study was carried out on 330 school children aged 6-12 years, attending governmental primary schools, in Alexandria. The sample was selected using a multistage random cluster sampling technique. Nutritional status of these children was determined using age and the anthropometric parameters of weight and height. z-scores of height-for-age, weight-for-age and weight-for-height were computed. Epi Info 2000 software was used to evaluate the anthropometric results of each individual. Cyanmethaemoglobin method and two Kato thick smear technique were employed to identify blood hemoglobin and parasites respectively. Data were analyzed using appropriate descriptive, univariate and multivariate logistic regression methods. RESULTS: Underweight, stunting, wasting, anemia and intestinal parasitoses were 4.2%, 3%, 3.7%, 84.5% and 33.6 % respectively. Parasites encountered during the study were Ascaris lumbricoides (24.6%), Trichuiris trichiura (19.6 %), and Enterobius vermicularis (3%) respectively. Based on multiple logistic regression analyses, the main risk factor for stunting was the presence of parasitic infection (OR = 4.85; 95%CI=1.23-19.12). The risk factors for anemia were age ≥10 years (OR = 8.79; 95% CI = 2.01- 38.35), and presence of parasitic infection (OR= 2.26; 95% CI = 1.07- 4.82), while the risk factors for parasitic infection were age 8 -10 years (OR = 1.94; 95% CI = 1.13 - 3.34; P = 0.02),and age ≥10 years (OR = 1.99; 95% CI = 1.05 - 3.79; P = 0.035), anemia (OR= 2.1; 95% CI = 0.99- 4.44; P = 0.054) and stunting (OR = 4.33; 95% CI = 1.05 - 17.83; P = 0.042). CONCLUSION: Findings from this study are strongly suggestive that intestinal parasitic infections and malnutrition exist in school children residing in Alexandria and constitute a major health problem that needs to be addressed immediately to reduce morbidity and mortality . Key words: Malnutrition, anemia, parasitic infections, primary school children, and stunting.

Global analysis of a simple parasite-host model with homoclinic orbits

In this paper, a simple parasite-host model proposed by Ebert et al.(2000) is reconsidered. The basic epidemiological reproduction number of parasite infection (R0) and the basic demographic reproduction number of infected hosts (R1) are given. The global dynamics of the model is completely investigated, and the existence of heteroclinic and homoclinic orbits is theoretically proved, which implies that the outbreak of parasite infection may happen. The thresholds determining the host extinction in the presence of parasite infection and variation in the equilibrium level of the infected hosts with R0 are found. The effects of R0 and R1 on dynamics of the model are considered and we show that the equilibrium level of the infected host may not be monotone with respect to R0. In particular, it is found that full loss of fecundity of infected hosts may lead to appearance of the singular case.

Infections with gastrointestinal nematodes, Fasciola and Paramphistomum in cattle in Cambodia and their association with morbidity parameters

Prevalence and seasonal variations of helminth infections and their association with morbidity parameters were studied in traditionally reared Cambodian cattle. Four villages in two provinces of West Cambodia were visited on monthly intervals over a period of 11 months, during which 2391 animals were faecal and blood sampled for parasitological and haematological examinations. The body condition score (BCS), faecal consistency (diarrhoea score, DS), colour of the ocular conjunctivae (FAMACHA©) and packed cell volume were determined for each individual animal. The overall proportion of samples that was positive for gastrointestinal nematodes was 52%, 44% and 37% in calves (from 1 to 6 months), young animals (6 to 24 months) and adults (over 24 months), respectively, while geometric mean faecal egg counts (FECs) for each of these age categories were 125, 66 and 15 eggs per gram, respectively. Six genera of strongyles were found in the faecal cultures, i.e. in descending order of occurrence, Cooperia, Oesophagostomum, Haemonchus, Trichostrongylus, Mecistocirrus and Bunostomum. The prevalences of Fasciola and Paramphistomum, estimated by coprological examination, varied between 5–20% and 45–95%, respectively. Logistic mixed models were used to investigate associations of morbidity markers with the presence of parasite infection. A low BCS was associated with gastrointestinal nematode and liver fluke infections, and soft faecal consistency with Paramphistomum infections. However, other factors such as nutritional deficiencies and intercurrent diseases are likely to enhance the effects of parasites and should therefore be considered when using these morbidity parameters as indicators of parasitism.

Stable isotopes indicate individual level trophic diversity in the freshwater gastropod Lymnaea stagnalis

In lacustrine ecosystems, benthic grazers are generally thought to feed on sediment detritus and microalgae, although there is a paucity of information on food resource use within populations. In this study, we investigated individual level trophic signatures for grazing snails, Lymnaea stagnalis, along with primary consumers and producers in the same habitat, using carbon and nitrogen stableisotope analyses. In addition, we tested whether ontogeny and parasite presence influence food resource use. The large variation in d 13 C and d 15 N isotopic signatures indicated that individuals within a population feed on different food sources. Snails appear to have much greater individual variance in trophic behaviour than the other lacustrine species sampled (larval chironomid Chironomus plumosus, amphipods, Gammarus lacustris, zooplankton Ceriodaphnia sp. and Simocephalus vetulus). Moreover, variation among snails was not explained by shell length or the presence of parasitic infections. Habitat heterogeneity and resource availability at the microhabitat level may be the primary factors determining individual food sources.

Nutritional status in two Mbyá-Guaraní communities from Misiones (Argentina)

Growth and nutritional status of children and adults in two Mbyá-Guaraní communities from Argentina, was assessed. Height, weight, sitting height, upper arm circumference, triceps and subscapular skinfold were measured on 120 individuals aged from 2 to 60 between March and May, 2001. Data were transformed to z-scores using United States references (NHANES I and NHANES II). A z-score of less than -2 was used as the cut-off point to determine the prevalence of stunting and wasting respectively. Mean z-scores for weight, height, and upper arm circumference lie below the reference (0 > Z > -3), while in sitting height ratio and muscular area for females they were above the US standard (0 < Z < 2). Skinfold thicknesses and muscular area for males were similar to the reference (2 > Z > -1). Our findings are in agreement with others South American Indian research that the prevalence of stunting (36.7%) is significantly higher than wasting (1.8%). The presence of parasitic infections and nutritional environment previously described in this population could be related to the short stature.

The Combined Effect of Isolation and Fasciola hepatica Infection on the Life History Traits of Fossaria cubensis

Life history traits of Fossaria cubensis were compared between isolated and paired snails after infection with three miracidia of Fasciola hepatica. Four experimental groups were tested: isolated–unexposed, paired–unexposed, isolated–infected, and paired–infected. A repeated-measures ANOVA showed statistically significant interactions among isolation, infection, and age effects for shell size, number of egg masses per snail, number of eggs per snail, and number of viable eggs per snail. Isolated–unexposed snails exhibited the higher values of these variables and those of survival and finite and intrinsic rates of natural increase. Infection stimulated shell growth during the prepatent period, but differences were present only in paired snails since isolation causes a similar effect. Reproduction, in terms of the number of egg masses per snail and the number of eggs per mass per snail, decreases in the presence of parasitic infection, whereas isolation stimulates it. These effects were observed from early stages of infection.