Frequency and molecular characterisation of Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, and Entamoeba hartmanni in the context of water scarcity in northeastern Brazil

Prevalence of Human Intestinal Entamoeba spp. in the Americas: A Systematic Review and Meta-Analysis, 1990–2022

Among the seven species of Entamoeba known to infect humans, E. histolytica is widely recognized as a pathogen. It is reported that Entamoeba infections are common in the developing world, but rare in developed countries. The best way to diagnose these protozoan parasites is to detect antigens or DNA in the stool. This study aimed to review the prevalence, distribution, and diagnosis methods of Entamoeba spp. infecting humans in the Americas between 1990 and 2022. A systematic review and meta-analysis were performed, including 227 studies on Entamoeba infections from 30 out of 35 American countries. The pooled prevalence of each species of Entamoeba was calculated using the random-effects model. The assignment of Entamoeba species was mainly performed by microscopy. The most widely distributed and prevalent species was E. coli (21.0%). Of the studies, 49% could not differentiate the species of the Entamoeba complex. The pathogenic species E. Histolytica was distributed among 22 out of 30 American countries studied, with a pooled prevalence of 9%. Molecular data on Entamoeba species are still scarce. This is the first study that reviewed and summarized data on the prevalence of this protozoan genera among American countries.

Intestinal polyparasitism and levels of mucosal anthelmintic SIgA in children from endemic areas in Northeastern Brazil

Interactions between parasites during co-infections are often complex and can impact immunization and treatment programmes, as well as disease outcomes and morbidity. However, little is known about these interactions and the mechanisms involved. In this study, a coproparasitological survey was carried out in school-age children living in endemic areas of parasitic infection in the state of Sergipe, Northeastern Brazil. Anti-helminth-specific and total secretory immunoglobulin-A (SIgA) levels were measured in stool and saliva samples and were compared in children presenting monoparasitism, polyparasitism (helminths and/or intestinal protozoa) and no infections. The survey showed that protozoa were more prevalent than helminths, and that there was a high frequency of polyparasitism in the studied population, mainly from combinations of protozoan species. Although less frequent, combinations between species of protozoa and helminths were also observed. The levels of salivary SIgA in these co-infected individuals were lower than the average observed in infections with helminths alone. Although the children participating in this survey were asymptomatic, and it was, therefore, not possible to evaluate the impact of salivary SIgA reduction on the diseases, and the study highlights the need for further investigations of co-infections by intestinal parasites and the effects on immune response induced by the interactions between different parasites.

South American Entamoeba dispar strains produce amoebic liver abscesses with different pathogenicities and evolutionary kinetics

Amoebiasis is a protozoan disease caused by Entamoeba histolytica, and presents a geographic distribution of worldwide amplitude, high incidence, sometimes accompanied by severe clinical manifestations such as amoebic colitis and Amoebic Liver Abscess (ALA), remaining as a public health problem in developing countries. Entamoeba dispar is another species of amoeba that infects approximately 12% of the world's population, and it has previously been classified as noninvasive. However, E. dispar has already been isolated from patients with symptomatic non-dysenteric colitis, as well as its DNA sequences were detected and genotyped in samples from patients with dysenteric colitis, and patients with ALA, suggesting that this species could also be involved in the development of lesions in the large intestine and liver of human beings. In this context, this study aims to evaluate the ability of isolated strains of Entamoeba dispar in South America to cause liver damage, and to better characterize histopathological findings in 3, 8, 12 and 16 days after infection (DAI). Firstly, we assessed whether trophozoites from MCR, ACFN, ICS, ADO and VEJ E. dispar strains, and EGG Entamoeba histolytica strain differed in their in vitro phagocytosis ability, being related to greater ability to phagocyte with greater virulence. Then, we investigate and characterize histopathological changes present in the liver of mice induced by different strains of E. dispar. Our results demonstrated that trophozoites from E. dispar strains are capable of phagocyting human erythrocytes, but in lower amounts than Entamoeba histolytica. In addition, we described and characterized the lesions in different periods after infection by different E. dispar strains, and identified ACFN as the most pathogenic strain, followed by MCR. The large areas of necrosis produced by the ACFN strain as the eighth DAI, which also show high parasitism, led to 100% mortality. On the other hand, the ICS, ADO and VEJ strains did not produce mortality, and this was correlated with the presence of well-developed chronic granulomatous inflammation, necrosis absorption throughout the infection, and regeneration of the liver parenchyma. The greater pathogenicity of the ACFN strain strongly suggests that this strain could be producing higher levels of virulence factors. As the experimental infection, the heterogeneity of biological behavior of different Entamoeba dispar strains could be involved in the development of undiagnosed human clinical conditions.

A community-based, cross-sectional study to assess interactions between income, nutritional status and enteric parasitism in two Brazilian cities: are we moving positively towards 2030?

BACKGROUND

This study assessed the interactions between income, nutritional status and intestinal parasitism in children in Brazil.

METHODS

A cross-sectional study (n = 421 children aged 1 to 14 years living in the states of Piauí (rural communities in the city of Teresina) and Rio de Janeiro (rural and periurban communities in the city of Cachoeiras de Macacu) was performed in order to obtain income and anthropometric data, as well as fecal samples for parasitological analyses through the Ritchie technique.

RESULTS

Children infected with Ascaris lumbricoides had significantly lower means of height-for-age z scores (- 1.36 ± 0.75 vs. - 0.11 ± 1.02; p < 0.001), weight-for-age z scores (- 1.23 ± 0.74 vs. 0.09 ± 1.15; p = 0.001), and weight-for-height z scores (- 0.68 ± 0.44 vs. 0.23 ± 1.25; p = 0.006) when compared with uninfected children. Infection with hookworm was also associated with lower means of height-for-age z scores (- 1.08 ± 1.17 vs. - 0.12 ± 1.02; p = 0.015) and weight-for-age z scores (- 1.03 ± 1.13 vs. 0.08 ± 1.15; p = 0.012). Children infected with Entamoeba coli presented significantly lower means of height-for-age z scores (- 0.54 ± 1.02 vs. - 0.09 ± 1.02; p = 0.005) and weight-for-age z scores (- 0.44 ± 1.15 vs. 0.12 ± 1.15; p = 0.002). The multivariate multiple linear regression analysis showed that height-for-age z scores are independently influenced by monthly per capita family income (β = 0.145; p = 0.003), female gender (β = 0.117; p = 0.015), and infections with A. lumbricoides (β = - 0.141; p = 0.006) and Entamoeba coli (β = - 0.100; p = 0.043). Weight-for-age z scores are influenced by monthly per capita family income (β = 0.175; p < 0.001), female gender (β = 0.123; p = 0.010), and infections with A. lumbricoides (β = - 0.127; p = 0.012), and Entamoeba coli (β = - 0.101; p = 0.039). Monthly per capita family income (β = 0.102; p = 0.039) and female gender (β = 0.134; p = 0.007) positively influences mid upper arm circumpherence.

CONCLUSIONS

Intestinal parasitism and low family income negatively influence the physical development of children in low-income communities in different Brazilian regions.

Molecular identification of Entamoeba histolytica, E. dispar, and E. moshkovskii in children with diarrhea from Maracaibo, Venezuela

Introducción.

Las amebas no patógenas Entamoeba dispar, Entamoeba moshkovskii y Entamoeba bangladeshi son morfológicamente idénticas a Entamoeba histolytica, parásito responsable de la amebiasis, por lo cual se necesitan técnicas moleculares para diferenciarlas.

Objetivo.

Determinar la frecuencia de las diferentes especies de Entamoeba mediante reacción en cadena de la polimerasa (Polymerase Chain Reaction, PCR) en muestras fecales de niños menores de cinco años con diarrea, provenientes de Maracaibo (Venezuela).

Materiales y métodos.

Se recolectó una muestra fecal por individuo en 75 niños con diarrea (grupo de casos) y en 25 niños sin diarrea (grupo control). Las heces se evaluaron mediante examen microscópico, método de concentración de formól-éter y PCR múltiple anidada en una sola ronda para identificar E. histolytica, E. dispar y E. moshkovskii. Además, se hizo una encuesta en la que se recopilaron los datos demográficos, signos, manifestaciones clínicas y estrato socioeconómico de los niños.

Resultados.

El 48 % de los participantes (38 del grupo de casos y 10 del grupo de control) tenían enteroparásitos. Solo en las muestras de cuatro de los niños, se encontraron quistes del complejo Entamoeba (tres en el grupo de casos y uno en el de control). Mediante PCR se amplificaron nueve muestras (9 %) para la detección de las amebas estudiadas. En el grupo de casos se registraron tres (28,13 %) de E. histolytica, cuatro (30,50 %) de E. dispar y una (9,37 %) de E. moshkovskii, en tanto que solo una (25 %) muestra amplificó para E. dispar en el grupo de control.

Conclusión.

En general, predominó E. dispar; sin embargo, todos los infectados con E. histolytica se detectaron en el grupo de niños con diarrea y se detectó el primer caso de E. moshkovskii en la región.

Diversity, geographical distribution, and prevalence of Entamoeba spp. in Brazil: a systematic review and meta-analysis

The genus Entamoeba includes a variety of widely distributed species adapted to live in the digestive tracts of humans and a large variety of animals of different classes. The objective of this study was to investigate the prevalence, distribution, and molecular epidemiology of Entamoeba spp. in different classes of hosts in Brazil. Studies that analyzed hosts from several classes, including humans and domestic, wild, or captive animals, were considered. The pooled prevalence of Entamoeba spp. was calculated using the random-effects model. A total of 166 studies on humans and 16 on animals were included. The prevalence of Entamoeba spp. in the Brazilian population was 22% (95% CI: 21–24). The state with the highest prevalence was Paraiba with 72%, followed by Federal District with 53%, and Rondonia with 50%. In immunocompromized patients, the prevalence was 18%, and cancer (36%) was the most prevalent cause of immunosuppression. The prevalence of Entamoeba spp. in animal hosts was 12% (95% CI: 7–17). Captive wild animals and domestic farm animals showed the highest prevalence, with 16% and 15%, respectively. The species found more often were E. coli (86.5%), E. dispar (7.9%), and E. histolytica (3.1%). In conclusion, a high prevalence (22%) of Entamoeba spp. was found in the Brazilian population, with a prevalence of up to 50% mainly in the northern, northeastern, and central-western regions. The pathogenic species E. histolytica is distributed in most Brazilian regions, with significant prevalence percentages. Among animals, unidentified Entamoeba species were most prevalent in mammals.

Epidemiology, species composition and genetic diversity of tetra- and octonucleated Entamoeba spp. in different Brazilian biomes

Background

Entamoeba species harbored by humans have different degrees of pathogenicity. The present study explores the intra- and interspecific diversity, phylogenetic relationships, prevalence and distribution of tetra- and octonucleated cyst-producing Entamoeba in different Brazilian regions.

Methods

Cross-sectional studies were performed to collect fecal samples (n = 1728) and sociodemographic data in communities located in four Brazilian biomes: Atlantic Forest, Caatinga, Cerrado, and Amazon. Fecal samples were subjected to molecular analysis by partial small subunit ribosomal DNA sequencing (SSU rDNA) and phylogenetic analysis.

Results

Light microscopy analysis revealed that tetranucleated cysts were found in all the studied biomes. The highest positivity rates were observed in the age group 6–10 years (23.21%). For octonucleated cysts, positivity rates ranged from 1 to 55.1%. Sixty SSU rDNA Entamoeba sequences were obtained, and four different species were identified: the octonucleated E. coli, and the tetranucleated E. histolytica, E. dispar, and E. hartmanni. Novel haplotypes (n = 32) were characterized; however, new ribosomal lineages were not identified. The Entamoeba coli ST1 subtype predominated in Atlantic Forest and Caatinga, and the ST2 subtype was predominant in the Amazon biome. E. histolytica was detected only in the Amazon biome. In phylogenetic trees, sequences were grouped in two groups, the first containing uni- and tetranucleated and the second containing uni- and octonucleated cyst-producing Entamoeba species. Molecular diversity indexes revealed a high interspecific diversity for tetra- and octonucleated Entamoeba spp. (H ± SD = 0.9625 ± 0.0126). The intraspecific diversity varied according to species or subtype: E. dispar and E. histolytica showed lower diversity than E. coli subtypes ST1 and ST2 and E. hartmanni.

Conclusions

Tetra- and octonucleated cyst-producing Entamoeba are endemic in the studied communities; E. histolytica was found in a low proportion and only in the Amazon biome. With regard to E. coli, subtype ST2 was predominant in the Amazon biome. The molecular epidemiology of Entamoeba spp. is a field to be further explored and provides information with important implications for public health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04672-y.

Prevalence and Molecular Differentiation of Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, and Entamoeba hartmanni in Egypt

INTRODUCTION

Entamoeba histolytica-caused amoebiasis is a major cause of mortality worldwide. E. histolytica is morphologically indistinguishable from nonpathogenic species like E. dispar, E. moshkovskii, and E. hartmanni. Polymerase chain reaction (PCR) is the approved method by World Health Organization for diagnosis and differentiation of amoebiasis. This study aims to molecularly differentiate the four Entamoeba spp. using conventional PCR and correlate their prevalence with the patients' sociodemographic data.

METHODS

We collected fecal samples of 175 patients with gastrointestinal diseases at Damanhour General Hospital (El-Behira, Egypt). All microscopically positive samples were subjected to conventional PCR.

RESULTS

The overall prevalence of Entamoeba infection was 65.7% (115/175). The differentiation by PCR was successfully attained in 102 samples. The species distribution was as follows: E. histolytica (14.7%), E. dispar (61.8%), E. moshkovskii (11.8%); besides, 11.8% of samples revealed mixed infection. Of note, the infection rate was higher in men, patients from rural areas and patients who did not have sanitation facilities for sewage disposal.

CONCLUSION

This study demonstrates a high prevalence of infections caused by the nonpathogenic Entamoeba spp. E. dispar, E. moshkovskii, and E. hartmanni along with the pathogenic E. histolytica. Hence, we recommend PCR assay as an accurate, rapid, and effective diagnostic method for the detection and differentiation of the four morphologically indistinguishable Entamoeba spp. in both routine diagnosis of amoebiasis and epidemiological surveys.

The association between the lack of safe drinking water and sanitation facilities with intestinal Entamoeba spp infection risk: A systematic review and meta-analysis

Intestinal protozoa infections are responsible for considerable morbidity and mortality, especially where the exposed population suffers from a lack of drinking water and sanitation facilities. In this study, the association between the lack of safe drinking water and sanitation (toilet) facilities with intestinal Entamoeba spp infection in the children (5-11 years), adult (18-55 years), and all age (5-55 years) were assessed. For this purpose, some of the international databases such as Scopus, PubMed, Web of Science, and Embase were screened to up to 7 June 2019 in order to retrieve the related citations. Also, the pooled odds ratios (ORs) following 95% confidence intervals (CIs) were calculated using a random-effects model. Twenty-nine articles with 36 studies were included while the OR extracted or calculated by using 2 × 2 contingency tables. However, the ingestion of contaminated water insignificantly can increase the odds ratio (OR) of Entamoeba spp infection (OR 1.01, (95% confidence interval [CI] 0.58 to 1.43), no access to sanitation (toilet) facilities significantly can increase odds of Entamoeba spp infection (OR 1.18, 95% CI 1.05 to 1.32). The meta-regression analysis showed that over time, odds of intestinal Entamoeba spp infection increased in both lack of safe drinking water (Coefficient: 3.24, P-value < 0.01) and sanitation (toilet) facilities (Coefficient: 2.36, P-value < 0.05) subgroups. Considering the findings, lack of safe drinking water resulted in a further increase in intestinal Entamoeba spp infection among adult (OR: 2.76), children (OR = 0.57) and all age groups (OR: 1.50), and also lack of sanitation (toilet) facilities resulted in further increase intestinal Entamoeba spp infection in children (OR: 1.06), adult (OR: 1.26) and all age (OR: 1.16). In this context, the lack of safe drinking water and sanitation facilities (toilet) was associated with a high risk of intestinal Entamoeba spp infection. Further attempts to providing public health facilities can control the prevalence of intestinal Entamoeba spp.

Infections with Giardia duodenalis and Entamoeba histolytica/Entamoeba dispar as Hidden and Prevalent Conditions in Periurban Communities in the State of Rio de Janeiro, Brazil

This study aims to assess the prevalence, distribution, and etiological profile of intestinal parasitism in children living in periurban areas in Cachoeiras de Macacu, Rio de Janeiro, Brazil. A community-based cross-sectional survey (n = 479) was carried out. Prevalence of infection with G. duodenalis and E. histolytica/E. dispar was 8.6% (n = 41) and 13.4% (n = 64), respectively. Infection with G. duodenalis was significantly more frequent among children living in poor families (24/187 (12.8%) vs. 16/272 (5.9%); prevalence ratio (PR) = 2.18; 95% confidence interval (CI) = 1.19–3.99; p=0.011). This difference was also significant for infection with any pathogenic parasite (43/187 (23%) vs. 40/272 (14/7%); PR = 1.56; 95% CI = 1.06–2.30; p=0.026). In addition, people residing in houses with more than four inhabitants showed significantly higher positivity for infections with G. duodenalis and with E. histolytica/E. dispar (22/138 (15.9%) vs. 16/311 (5.1%); PR = 3.09; 95% CI = 1.68–5.71; p < 0.001 for G. duodenalis and 32/138 (23.2%) vs. 30/311 (9.6%); PR = 2.40; 95% CI = 1.52–3.79; p < 0.001 for E. histolytica/E. dispar). Laboratory diagnosis of protozoan enteric infections and effective drugs for their treatment are unmet goals in the primary health care system. Therefore, giardiasis and amebiasis are neglected conditions.

A Cross-Sectional Study of Entamoeba histolytica/dispar/moshkovskii Complex in Salvador, Bahia, Brazil

Epidemiological studies on species-specific Entamoeba infections are scarce due to the morphological similarity of pathogenic Entamoeba histolytica and nonpathogenic E. dispar and E. moshkovskii. The diagnosis of E. histolytica is frequently based on coproantigen (E. histolytica-Gal/GalNAc lectin specific) detection by immunoassays. However, specific E. histolytica-lectin is not expressed in cysts, which are eliminated by asymptomatic individuals leading to false-negative results and an underestimation of amebiasis prevalence. Molecular techniques based on the amplification of parasite DNA have been shown to be a highly sensitive and specific method that allows the detection of different Entamoeba species. This study aimed to assess the frequency of the species from E. histolytica/dispar/moshkovskii complex by molecular and immunological techniques in individuals attended at a public health system in Salvador-Bahia, Brazil. A cross-sectional study involving 55,218 individuals was carried out. The diagnosis was based on microscopy revealing E. histolytica/dispar/moshkovskii complex. The species differentiation was performed by E. histolytica-specific antigen, serological evaluation and by molecular technique. The overall prevalence of E. histolytica/dispar/moshkovskii complex determined by microscopy was approximately 0.49% (273/55,218). E. histolytica-specific antigen detection and molecular characterization returned 100% negativity for E. histolytica. However, serological evaluation returned an 8.9% positivity (8/90). In the stool samples analysed by PCR, it was not possible to identify E. histolytica and E. moshkovskii, although circulating IgG anti-E. histolytica has been detected.

Use of shotgun metagenomics for the identification of protozoa in the gut microbiota of healthy individuals from worldwide populations with various industrialization levels

Protozoa have long been considered undesirable residents of the human gut, but recent findings suggest that some of them may positively affect the gut ecosystem. To better understand the role and ecological dynamics of these commensal and potentially beneficial protozoan symbionts, we need efficient methods to detect them, as well as accurate estimates of their prevalence across human populations. Metagenomics provides such an opportunity, allowing simultaneous detection of multiple symbionts in a single analytical procedure. In this study, we collected fecal samples of 68 individuals from three Cameroonian populations with different subsistence modes and compared metagenomics-based and targeted methods of detection for two common protozoan genera: Blastocystis and Entamoeba. In addition, we analyzed our data along with publicly available fecal metagenomes from various worldwide populations to explore the prevalence and association patterns of ten protozoan genera. Regarding the detection method, microscopy was much less sensitive than metagenomics for Entamoeba, whereas qPCR was at least as sensitive as metagenomics for Blastocystis sp. However, metagenomics was more likely to detect co-colonizations by multiple subtypes. Out of the ten examined genera in 127 individuals from Cameroon, Tanzania, Peru, Italy or USA, only three (Blastocystis, Entamoeba and Enteromonas) had an overall prevalence exceeding 10%. All three genera were more common in less industrialized populations and their prevalence differed between continents and subsistence modes, albeit not in a straightforward manner. The majority (72.5%) of colonized individuals carried at least two protozoan species, indicating that mixed-species colonizations are common. In addition, we detected only positive and no negative association patterns between different protozoa. Despite the pitfalls of the metagenomic approach, ranging from the availability of good-quality sequencing data to the lack of standard analytical procedures, we demonstrated its utility in simultaneous detection of multiple protozoan genera, and especially its ability to efficiently detect mixed-species colonizations. Our study corroborates and expands prevalence results previously obtained for Blastocystis sp. and provides novel data for Entamoeba spp. and several other protozoan genera. Furthermore, it indicates that multiple protozoa are common residents of the healthy human gut worldwide.

Assessing the Influence of Water Management and Rainfall Seasonality on Water Quality and Intestinal Parasitism in Rural Northeastern Brazil

Introduction

The drought in the Brazilian semiarid region has affected the quality of water. This study assessed the relationships between enteric parasitoses, water management, and water quality, correlating them with pluviometric seasonality.

Methods

Cross-sectional surveys were carried out in four rural communities at the beginning of the dry season (n=151), at the end of the dry season (n=184), and in the rainy season (n=199), in order to collect sociodemographic data, human fecal samples, and samples of the water used for human consumption for physicochemical and microbiological analyses. In 2015, water filters were provided to 30 households under study.

Results

There was an increasing trend in detection rates of commensal protozoa and the Entamoeba histolytica/Entamoeba dispar complex at the beginning of the rainy season, with detection rates of 6% in 2014 and 21.6% in 2016. Giardia intestinalis and Ascaris lumbricoides presented distinct temporal distributions, which peaked in 2015: 20.1% and 30%, respectively. The proportion of inhabitants drinking inadequate water was 55% at the beginning of the dry season and 28.8% at the end of the dry season, reaching 70.9% at the beginning of the rainy season. The presence of filters reduced this proportion among those who received the hollow ceramic candle filter.

Conclusions

Data suggest that the strategies to increase water supply in the Brazilian semiarid region can be ameliorated in order to improve the quality of drinking water.

Prevalence of Entamoeba histolytica and other enteral parasitic diseases in the metropolitan region of Belo Horizonte, Brazil. A cross-sectional study

BACKGROUND

Enteral parasitic diseases are a public health problem in nations with low economic development and in settings with poor sanitation. Amebiasis is the second most frequent form of parasitosis, with a high burden of disease. Knowledge of the prevalence of enteroparasitoses in a given region is useful for planning clinical decision-making. Thus, the aim of this study was to estimate the prevalence of enteral parasitic diseases, especially amebiasis, through analysis on stool samples from public and private laboratories in a metropolitan area in southeastern Brazil.

DESIGN AND SETTING

Cross-sectional study conducted in the metropolitan region of Belo Horizonte, Brazil.

METHODS

We evaluated 6,289 fecal samples from one private and one public laboratory. The samples were concentrated by means of spontaneous sedimentation, and those that were positive for Entamoeba histolytica or Entamoeba dispar in optical microscopy analyses were processed to obtain deoxyribonucleic acid, with subsequent identification through the polymerase chain reaction.

RESULTS

Among the stool samples, 942 (15.0%) had parasitic infections; 73 (1.2%) of these were helminthic infections and 847 (13.5%) were protozoan infections, caused mainly by Escherichia coli (6.0%), Endolimax nana (5.2%) and Giardia lamblia (1.2%). Infections due to Entamoeba histolytica or Entamoeba dispar occurred in 36 samples (0.6%) and the polymerase chain reaction revealed five (13.9%) as Entamoeba histolytica.

CONCLUSION

The prevalence of enteral parasitic diseases is high in the metropolitan region of Belo Horizonte, although amebiasis may not be a problem.

Paediatric Strongyloidiasis in Central Australia

Few published studies are available describing the prevalence of paediatric strongyloidiasis in endemic areas within Australia. This literature review and exploratory clinical audit presents the first seroprevalence data for paediatric patients in Central Australia. A total of 16.1% (30/186) of paediatric inpatients tested for Strongyloides stercoralis in 2016 were seropositive (95% CI: 11.5% to 22.1%). Eosinophilia of unknown aetiology was the most common indication for testing (91.9%). Seropositive patients were significantly more likely to reside in communities outside of Alice Springs (p = 0.02). Seropositive patients were noted to have higher mean eosinophil counts with a mean difference of 0.86 × 10⁸/L (95% CI: 0.56 to 1.16, p < 0.0001), although the limited utility of eosinophilia as a surrogate marker of strongyloidiasis has been described previously. All seropositive patients were Indigenous. There was no significant difference in ages between groups. There was a male predominance in the seropositive group, although this was not significant (p = 0.12). Twelve patients had known human T-lymphotropic virus 1 (HTLV-1) status and all were seronegative. Further research describing the epidemiology of strongyloidiasis in Central Australia is required.

Prevalence and temporal trend (2005-2015) of anaemia among children in Northeast Brazil

OBJECTIVE

Anaemia is the main nutritional deficiency in Brazil, and a prevention and control programme (National Program for Iron Supplementation) has been developed since 2005. Studies on the temporal evolution of anaemia prevalence contribute to assessment of the effectiveness of the actions undertaken. The present study aimed to identify the prevalence and temporal trend of anaemia in children.

DESIGN

Study based on two cross-sectional household surveys carried out in 2005 and 2015. Anaemia was defined as Hb<11 g/dl (HemoCue®). Trend analysis was performed using the prevalence ratio (PR), calculated by Poisson regression with a robust adjustment of the variance. Differences were significant when P<0·05 in both crude analyses and those adjusted for possible confounding factors (e.g. socio-economic, demographic and health variables).

SETTING

Alagoas, Brazil.

SUBJECTS

In total, 666 and 782 children in the first and second Alagoas State Health and Nutrition Survey, respectively (probabilistic samples).

RESULTS

In 2005 and 2015, anaemia prevalence was 45·1 and 27·4 %, respectively (-39·1 %; PR=0·61; 95 % CI 0·52, 0·70). In both surveys, children aged ≤24 months were more affected (P24 months (67·2 v. 40·7 %; 27·0 v. 19·3 %, respectively).

CONCLUSIONS

The prevalence of anaemia reduced significantly in the evaluated period. Thus, it may no longer be a severe public health problem but can instead be considered a problem of moderate magnitude. It remains, however, above the level considered acceptable according to WHO criteria. These results justify the implementation of prevention and control actions.

Prevalence and associated risk factors for Giardia and Cryptosporidium infections among children of northwest Mexico: a cross-sectional study

BACKGROUND

G. intestinalis and Cryptosporidium spp. are responsible for gastrointestinal infections worldwide. Contaminated food, feces, drinking water and predictors such as poverty, cultural and behavioral aspects have been involved in their transmission. Published studies about these infections are limited in Mexico. Cananea, Sonora is located in northwest Mexico and is one of the regions with the lowest marginalization index in the Sonora state. However, its rate of gastrointestinal infections increased from 48.7/1000 in 2003 to 77.9/1000 in 2010 in the general population. It was estimated that the prevalence of giardiasis can range from 20 to 30% in the Sonoran childhood population. However, the prevalence of giardiasis and cryptosporidiosis are unknown in Cananea, Sonora and they are likely contributing to its gastrointestinal infections rates.

METHODS

A total of 173 children (average age 8.8 ± 2.8 years) participated in this cross-sectional study. Anthropometric measurements and stool analysis were performed. Socioeconomic, cultural and symptomatology information were collected. The association between the risk factors and intestinal parasitic infections was analyzed by multivariate analysis using the STATA/SE package at a significance level of p ≤ 0.05.

RESULTS

More than half of the children (n = 103, 60%) had intestinal parasitic infections. Cryptosporidium spp. showed the highest prevalence (n = 47, 27%), which was followed by G. intestinalis (n = 40, 23%). Children with giardiasis and cryptosporidiosis had lower H/A and BMI/A Z scores than children who were free of these infections. Children with giardiasis were at higher risk (OR = 4.0; 95%CI = 1.11-13.02; p = 0.030) of reporting abdominal pain, and children who drank tap water were at higher risk (OR = 5.0; 95% CI = 1.41-17.20; p = 0.012) of cryptosporidiosis.

CONCLUSIONS

This was the first epidemiological study conducted in children in the region of Cananea, Sonora in northwest Mexico. The findings revealed a high prevalence of cryptosporidiosis and giardiasis, and their interactions with multiple risk factors were investigated. This study suggested that giardiasis and cryptosporidiosis may play an important role as causative factors of gastrointestinal diseases in the study region. Regional authorities must analyze water for human consumption to search for Cryptosporidium spp. and G. intestinalis.

Socioenvironmental conditions and intestinal parasitic infections in Brazilian urban slums: a cross-sectional study

Methods

A cross-sectional study covering an agglomeration of urban slums was conducted between 2015 and 2016 using participants observation, a socioeconomic survey, and the spontaneous sedimentation method with three slides per sample to analyze fresh stool specimens ( n =595) searching for intestinal parasites.

Results

Endolimax nana ( n =95, 16.0%) and Entamoeba coli ( n =65, 10.9%) were the most frequently identified agents, followed by Giardia intestinalis ( n =24, 4.0%) and Ascaris lumbricoides ( n =11, 1.8%). Coinfections caused by E. nana and E. histolytica/dispar and by Entamoeba coli/A. lumbricoides were significant. The use of piped water as drinking water, the presence of A. lumbricoides , and contamination with coliform bacteria and Escherichia coli were more common in major area (MA) 1. Children (0-19 years) had a greater chance of living in poverty (OR 3.36; 95% CI: 2.50- 4.52; p <0.001) which was pervasive. The predominance of protozoa parasites suggests that a one-size-fits-all approach focusing on preventive chemotherapy for soil-transmitted helminths is not appropriate for all communities in developing countries. It is important that both residents and health professionals consider the socioenvironmental conditions of urban slums when assessing intestinal parasitic infections for disease control and health promotion initiatives.

Molecular diagnosis of Entamoeba spp. versus microscopy in the Great Cairo

Amoebiasis is a human disease produced by Entamoeba histolytica which causes widespread mortality and morbidity worldwide through diarrheal disease and abscess establishment in parenchymal tissues such as liver, lung, and brain. The true prevalence of infection is unknown for most areas of the world due to the difficulty to characterise Entamoeba histolytica versus other non-pathogenic amoebas with identical morphology, as Entamoeba dispar, and Entamoeba moshkovskii. To overcome microscopy misidentification issues, we tested a nested multiplex polymerase chain reaction (PCR) and a real-time PCR on 194 stool samples collected from incoming dysentery patients in Cairo hospitals diagnosed with E. histolytica by microscopy. Nested PCR showed only 20 (10.3%) samples positive to E. histolytica and 17 (8.7%) to E. dispar. The real-time PCR detected only 19 and 11 samples positive to E. histolytica and E. dispar respectively, showing less sensitivity than the nested PCR. The data show that prevalence of E. histolytica in Cairo is lower when specific diagnosis methods are used instead of traditional microscopy, allowing to differentiate between morphologically identical human amoebas species.

First molecular epidemiology of Entamoeba histolytica, E. dispar and E. moshkovskii infections in Yemen: different species-specific associated risk factors

OBJECTIVES

To investigate the molecular epidemiology of Entamoeba histolytica, E. dispar and E. moshkovskii infections among rural communities in Yemen.

METHODS

In a community-based study, faecal samples were collected from 605 participants and examined by wet mount, formalin-ether sedimentation, trichrome staining and nested multiplex PCR techniques. Demographic, socio-economic and environmental information was collected using a pre-tested questionnaire.

RESULTS

Overall, 324 (53.6%) of the samples were positive for Entamoeba cysts and/or trophozoites by microscopic examination. Molecular analysis revealed that 20.2%, 15.7% and 18.2% of the samples were positive for E. histolytica, E. dispar and E. moshkovskii, respectively. Multivariate analysis showed different sets of species-specific risk factors among these communities. Educational level was identified as the significant risk factor for E. histolytica; age and gender were the significant risk factors for E. moshkovskii; and sources of drinking water and consumption of unwashed vegetables were the significant risk factors for E. dispar. Moreover, living in coastal/foothill areas and presence of other infected family members were risk factors for both E. histolytica and E. moshkovskii infections.

CONCLUSION

The study reveals that Entamoeba spp. infection is highly prevalent among rural communities in Yemen, with E. histolytica, E. dispar and E. moshkovskii differentiated for the first time. Identifying and treating infected family members, providing health education pertinent to good personal and food hygiene practices and providing clean drinking water should be considered in developing a strategy to control intestinal parasitic infections in these communities, particularly in the coastal/foothill areas of the country.