Frequency of Blastocystis hominis and other intestinal parasites in stool samples examined at the Parasitology Laboratory of the School of Pharmaceutical Sciences at the São Paulo State University, Araraquara

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.

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.

Current status of research regarding Blastocystis sp., an enigmatic protist, in Brazil

The present study aimed to evaluate the occurrence of Blastocystis sp. in Brazilian studies over a period of years (2000-2020), as well as point out relevant aspects of this enigmatic organism. We performed a literature search using six sources of international databases. The data were divided into diagnostic by parasitological and molecular techniques, and relevant aspects. After applying the inclusion and exclusion criteria, 52 studies were included in the final analysis. The occurrence of Blastocystis sp. in Brazil ranged from 0.5% to 86.6%, as determined using parasitological techniques. The highest occurrence was in the North (27.3%) and the lowest, in the Midwest region (13.4%). In Brazil, most studies have employed molecular techniques and are concentrated in the Southeast region. The Blastocystis sp. subtype ST3 had the highest average positivity, followed by ST1 and ST2. These findings represent a panorama that reflects the reality of Brazil; thus, we believe that the effectiveness of parasitological diagnosis should be considered with regard to making an appropriate choice of technique for detecting Blastocystis sp. Additionally, we emphasize the importance of further studies in the context of molecular epidemiology with regard to this genus. Blastocystis sp. is not well understood yet, and very little information regarding this genus is available; hence, further research regarding this genus is urgently needed.

Prevalence of Blastocystis sp. infection in several hosts in Brazil: a systematic review and meta-analysis

BACKGROUND

Blastocystis sp. affects a wide variety of animals and is the most common protozoan in human fecal samples with potential pandemic distribution. In the present study, a systematic review and meta-analysis were conducted to determine the prevalence and distribution of Blastocystis sp. in different classes of hosts in Brazil.

METHODS

Studies that analyzed hosts of various classes, including humans, domestic animals, wild animals or captive animals, were considered. The pooled prevalence of Blastocystis sp. infection was estimated by random effects models.

RESULTS

For humans, similar prevalence rates were found for males (31.0%, 95% CI: 17.0-45.0%; weight 10%) and females (28.0%, 95% CI: 16.0-41.0%; weight 10%); the state of Mato Grosso do Sul showed the highest prevalence, with 41.0% positivity (95% CI: 36.0-46.0%; weight 2.9%). The prevalence among immunocompromised patients was 5.0% (95% CI: 3.0-7.0%; weight 10%), and the most common cause of immunosuppression was hemodialysis, with 23.0% (95% CI: 17.0-29.0%; weight 12.4%). Among classifications according to interaction with humans, wild and domestic animals presented values of 19.0% (95% CI: 7.0-31.0%; weight 42.6%) and 17.0% (95% CI: 13.0-21.0%; weight 29.6%), respectively. Among these animals, mammals (39.0%, 95% CI: 21.0-56.0%; weight 47.3%) and birds (18.0%, 95% CI: 10.0-27.0%; weight 39.3%) exhibited the highest prevalence. Phylogenetic analysis of Blastocystis sp. revealed greater genetic diversity for clades of subtypes (STs) ST1, ST2 and ST3.

CONCLUSIONS

The overall prevalence of Blastocystis sp. in the Brazilian human population was 24%, which reflects the reality in the South, Southeast and Midwest regions, where prevalence rates of up to 40% were found. Among animals, mammals and birds exhibited the highest prevalence.

Immunopathological assessments of human Blastocystis spp. in experimentally infected immunocompetent and immunosuppresed mice

Blastocystis spp., one of the most common parasites colonizing the human intestine, is an extracellular, luminal protozoan with controversial pathogenesis. The host's immune response against Blastocystis spp. infection has also not been defined yet. Therefore, this research aimed to assess the potential pathogenicity of this parasite and its ability to modulate the immune response in experimental infected immunocompetent and immunosuppresed mice. These results demonstrated that the infected immunosuppressed mice were more affected than infected immunocompetent mice. Histopathological examination of the small intestine in the infected immunosuppressed mice showed that Blastocystis spp. infiltrated all the layers. Moreover, the epithelia showed exfoliation and inflammatory cell infiltration in submucosa compared to that of the infected immunocompetent mice. As well, examination of the large intestine of the infected immunosuppressed group showed severe goblet cell hyperplasia. Blastocystis spp. infiltrated all the large intestine layers compared to that of the infected immunocompetent group. Furthermore, there was a significant upregulation of the expression of proinflammatory cytokines: interleukin 12 (IL-12) and tumor necrosis factor alpha (TNF-α) in the infected immunosuppressed mice compared to that of the infected immunocompetent ones (p ≤ 0.004 and p ≤ 0.002, respectively). However, the expression of anti-inflammatory cytokines (IL-4 and IL-10) was significantly downregulated in the infected immunosuppressed group compared to that of the infected immunocompetent group one at 10 days postinfection (p ≤ 0.002 and p ≤ 0.001, respectively). The results of this study revealed that Blastocystis spp. affected the production of pro- and anti-inflammatory cytokines in both groups of mice compared to healthy normal (naive) group. Additionally, these data showed that there was a significant upregulation (p ≤ 0.005) of the locally synthesized antibody: secretary IgA (sIgA) in the gut of the infected immunocompetent mice when compared to that of the infected immunosuppressed ones.

OCCURRENCE OF Blastocystis spp. IN UBERABA, MINAS GERAIS, BRAZIL

Intestinal parasites are a problem for public health all over the world. The infection with Blastocystis, a protozoan of controversial pathogenicity, is one of the most common among them all. In this study, the occurrence of intestinal parasites, with emphasis on Blastocystis, in patients at the Universidade Federal do Triângulo Mineiro was investigated in Uberaba (MG) through microscopy of direct smears and fecal concentrates using Ritchie’s method. Feces of 1,323 patients were examined from April 2011 to May 2012. In 28.7% of them at least one intestinal parasite was identified, and the most frequent organisms were Blastocystis spp. (17.8%) and Giardia intestinalis (7.4%). The occurrence of parasitism was higher in children aged 6 -10 years old, and the infection with Blastocystis spp. was higher above the age of six (p < 0.001). The exclusive presence of G. intestinalis and of Blastocystis spp. was observed in 5.4% and 12.2% of the patients, respectively. Regarding patients with diarrheic feces, 8% revealed unique parasitism of Blastocystis spp. Other intestinal parasites observed in children were Ascaris lumbricoides(0.3%) and Entamoeba histolytica/dispar/moshkovskii (1.4%). The Ritchie’s method was more sensitive (92.8%) when compared to direct microscopy (89.8%), with high agreement between them (97.7%, kappa = 0.92). In conclusion, the occurrence of Blastocystis spp. in Uberaba is high and the presence of diarrheic feces with exclusive presence of the parasite of Blastocystis spp. was observed.

Laboratory diagnosis of Blastocystis spp. in diarrheic patients

Background:

Many laboratories currently diagnose Blastocystis spp. infections by looking for the presence of vacuolar forms in faeces and the amoeboid form in diarrheal stools.

Objectives:

To investigate the best direct method in diagnosis of Blastocystis spp. and to study different morphological forms of the parasite.

Materials and Methods:

The study was carried out on one thousand and two hundred diarrheic stool samples. All samples were examined using direct smear, iodine stained smear, formalin-ether concentration techniques, trichrome stained smear and in vitro cultivation using Jones' medium.

Results:

Using direct smear, Blastocystis spp was detected in 42 cases (3.5%) with a sensitivity (28.4%) and specificity (100%). Iodine stained smear detected 72 positive cases (6%) with a sensitivity (48.7%), specificity (100%). Formol ether concentration technique detected 120 positive cases (10%) with a sensitivity (81.1%) and specificity (100%). Trichrome stained smear detected 148 positive cases (12.3%). In vitro cultivation using Joni's medium detected 274 positive cases (22.8%) which was the highest number among all different diagnostic methods with a sensitivity (100%) ,specificity (88%), PPV (54.1%) and NPV (100%). It was found that, 49 blastocystosis cases had mixed infection with other intestinal parasites. Giardia lamblia was the most frequently associated parasite with Blastocystis spp.

Conclusion:

In vitro cultivation is more sensitive in detection of B. hominis than simple smear and concentration technique. Blastocystis spp. vacuolar form was the most common form that was found by all methods used in this study G. lamblia was the most frequent parasite associated with Blastocystis spp .

Prevalence of strongyloidiasis in Latin America: a systematic review of the literature

Strongyloides stercoralis is rarely recognized as a major public health issue, probably because its burden is largely underestimated. We reviewed the literature (both PubMed and 'grey' literature) about the prevalence of strongyloidiasis in Latin America, an area of presumable high endemicity. There were finally 88 papers involved in the analysis, covering the period between 1981 and 2011. Studies were heterogeneous in several aspects, such as the populations screened and the diagnostic methods used. Most of the studies relied on direct coproparasitological examination, which has low sensitivity for the detection of S. stercoralis larvae. The following countries presented areas of high prevalence (>20%): Argentina, Ecuador, Venezuela, Peru and Brazil. Globally, for most of the included countries it was not possible to define reliable data because of paucity and/or inadequacy of studies. S. stercoralis requires specific diagnostic methods for its detection; therefore, surveys should be specifically designed in order to avoid underestimation of the infection.

Strongyloidiasis--an insight into its global prevalence and management

BACKGROUND

Strongyloides stercoralis, an intestinal parasitic nematode, infects more than 100 million people worldwide. Strongyloides are unique in their ability to exist as a free-living and autoinfective cycle. Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T-lymphotropic virus or human immunodeficiency virus. Even though the diagnosis of strongyloidiasis is improved by advanced instrumentation techniques in isolated and complicated cases of hyperinfection or dissemination, efficient guidelines for screening the population in epidemiological surveys are lacking.

METHODOLOGY AND RESULTS

In this review, we have discussed various conventional methods for the diagnosis and management of this disease, with an emphasis on recently developed molecular and serological methods that could be implemented to establish guidelines for precise diagnosis of infection in patients and screening in epidemiological surveys. A comprehensive analysis of various cases reported worldwide from different endemic and nonendemic foci of the disease for the last 40 years was evaluated in an effort to delineate the global prevalence of this disease. We also updated the current knowledge of the various clinical spectrum of this parasitic disease, with an emphasis on newer molecular diagnostic methods, treatment, and management of cases in immunosuppressed patients.

CONCLUSION

Strongyloidiasis is considered a neglected tropical disease and is probably an underdiagnosed parasitic disease due to its low parasitic load and uncertain clinical symptoms. Increased infectivity rates in many developed countries and nonendemic regions nearing those in the most prevalent endemic regions of this parasite and the increasing transmission potential to immigrants, travelers, and immunosuppressed populations are indications for initiating an integrated approach towards prompt diagnosis and control of this parasitic disease.

Update on the mapping of prevalence and intensity of infection for soil-transmitted helminth infections in Latin America and the Caribbean: a call for action

It is estimated that in Latin America and the Caribbean (LAC) at least 13.9 million preschool age and 35.4 million school age children are at risk of infections by soil-transmitted helminths (STH): Ascaris lumbricoides, Trichuris trichiura and hookworms (Necator americanus and Ancylostoma duodenale). Although infections caused by this group of parasites are associated with chronic deleterious effects on nutrition and growth, iron and vitamin A status and cognitive development in children, few countries in the LAC Region have implemented nationwide surveys on prevalence and intensity of infection. The aim of this study was to identify gaps on the mapping of prevalence and intensity of STH infections based on data published between 2000 and 2010 in LAC, and to call for including mapping as part of action plans against these infections. A total of 335 published data points for STH prevalence were found for 18 countries (11.9% data points for preschool age children, 56.7% for school age children and 31.3% for children from 1 to 14 years of age). We found that 62.7% of data points showed prevalence levels above 20%. Data on the intensity of infection were found for seven countries. The analysis also highlights that there is still an important lack of data on prevalence and intensity of infection to determine the burden of disease based on epidemiological surveys, particularly among preschool age children. This situation is a challenge for LAC given that adequate planning of interventions such as deworming requires information on prevalence to determine the frequency of needed anthelmintic drug administration and to conduct monitoring and evaluation of progress in drug coverage.

Soil-transmitted helminths (STH) are part of the group of neglected infectious diseases (NID) in Latin America and the Caribbean (LAC), and are associated with several adverse chronic effects on child health. Although control interventions such as periodic administration of anthelmintic drugs, health education, improved access to safe water and sanitation, among others, are acknowledged to be an important means to reduce morbidity and to achieve control, epidemiological information on prevalence status is lacking at the lowest sub-national administrative levels (municipalities, districts or provinces) in many countries thus hindering decision making regarding not only the treatment, but also the monitoring of progress in deworming coverage, the assessment of epidemiological impact on parasite prevalence and load and, therefore, the achievement of the overall public health goals. Epidemiological surveys can be expensive and require time and effort for their implementation, which could explain the low number of studies published with data on prevalence and intensity of infection in the Americas. The use of alternative methodologies, for instance those based on geographical information systems and remote sensing technologies, or of sentinel surveillance in schools may help countries in the task of collecting information and support the implementation of integrated control programs against STH.

Prevalence and epidemiology of intestinal parasitism, as revealed by three distinct techniques in an endemic area in the Brazilian Amazon

This survey aims to estimate the prevalence of intestinal parasitic infections in Santa Isabel do Rio Negro, Amazonian Brazil, through three distinct techniques, correlating the prevalence rates with family income and age groups as well as assessing the household clustering of infections. Prevalence rates were assessed through Graham (n=113), Baermann-Moraes (n=232) and Ritchie (n=463) methods. The Graham method was adopted only for children under 5 years old, 15% of whom were positive for Enterobius vermicularis. By the Baermann-Moraes technique, 5·6% of the samples were positive for Strongyloides stercoralis larvae. The Ritchie technique disclosed the following results: Ascaris lumbricoides (26%), Trichuris trichiura (22·5%), hookworms (9·5%), Entamoeba histolytica/Entamoeba dispar (25·3%), Giardia lamblia (12·5%) and E. vermicularis (0·6%). Children aged 5-14 years presented the highest prevalence for pathogenic parasites. Giardiasis and hookworm infection rates were inversely related to family income. The presence of positive contacts in the same household substantially increased the risk of infection by enteric parasites: odds ratio (OR)=2·70, 95% confidence interval (CI)=1·69-4·29 for ascariasis; OR=2·17, 95% CI=1·34-3·51 for trichuriasis; OR=2·13, 95% CI=1·08-4·17 for hookworm disease; OR=3·42, 95% CI=1·86-6·30 for giardiasis; and OR=2·16, 95% CI=1·35-3·47 for amoebiasis, supporting infection clustering in the home. Intestinal parasitoses are extremely frequent in the studied area, and routine methods for diagnosis may underestimate the prevalence of enterobiasis and strongyloidiasis.

Epidemiological aspects of strongyloidiasis in Brazil

The objective of this review was to outline an epidemiological profile of Strongyloides stercoralis by parasitological and serological diagnosis in inhabitants, and to associate this profile with different immunosupression situations, in Brazil, over 20 years (1990-2009). The occurrence of S. stercoralis using parasitological methods was 5·5%, being 4·8% in rural and 5·0% in urban areas, characterizing the country as hyperendemic. There was a diversity of techniques used as a diagnostic tool and only 39·1% of the studies presented results based on at least 1 specific method. The occurrence increased with age, being 12·1%, for those over 60 that suggests an epidemiological condition of concern for the elderly population. Of the seroepidemiological studies in the general population the mean positivity in serum samples was 21·7% and 29·2%, using an immunofluorescence antibody test and enzyme-linked immunosorbent assay (ELISA), respectively. The occurrence of strongyloidiasis in immunosuppressed individuals was 11·8% by parasitological methods and 19·5% using immunological methods. Considering that Brazil is a tropical country and that the character of chronicity and autoinfection of the parasite that can result in severe forms of hyperinfection or dissemination makes strongyloidiasis an important medically and socially neglected problem.

Intestinal protozoan infections in relation to nutritional status and gastrointestinal morbidity in Colombian school children

While Giardia duodenalis infection has been consistently associated with nutrient malabsorption and stunting in children, the effects of other protozoans on nutritional status or gastrointestinal morbidity are less clear. We sought to determine whether infection with common intestinal protozoans including Giardia duodenalis, Entamoeba coli and Blastocystis hominis was associated with anthropometric and micronutrient status, gastrointestinal symptoms, visits to the doctor or school absenteeism in children 5-12 years of age from Bogotá, Colombia. We obtained stool samples from 442 children enrolled in primary schools in 2006 and examined the presence of intestinal protozoans in relation to height, body mass index, plasma concentrations of vitamins A and B12, ferritin and zinc and erythrocyte folate. In addition, we examined the associations between protozoan infections and the incidence of common gastrointestinal symptoms, which were registered prospectively in morbidity diaries. The prevalence rates of G. duodenalis, E. coli and B. hominis infection were 6.3, 23.1 and 22.4%, respectively. Giardia infection was associated with lower height-for-age z-score (p = 0.04), whereas E. coli infection was associated with low erythrocyte folate (p = 0.04), and B. hominis infection was related to higher vitamin A levels (p = 0.05). Infection with E. coli was also associated with a significantly higher incidence of fever but fewer visits to the doctor, while B. hominis infection was associated with significantly less diarrhea, diarrhea with vomiting, doctor visits and school absenteeism. In conclusion, G. duodenalis and E. coli infections were associated with indicators of poor nutritional status in this population, while B. hominis was related to apparently decreased morbidity.