Parasitological and serological studies on amoebiasis and other intestinal parasitic infections in the rural sector around Recife, northeast Brazil

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.

Determinants of Anemia among Children Aged 6–59 Months in Ethiopia: Further Analysis of the 2016 Ethiopian Demographic Health Survey

Background. Anemia among children is a global public health problem. The burden is high in developing countries including Ethiopia. Although there are some studies about anemia among children, there is a dearth of information about factors associated with anemia in Ethiopia. Therefore, this analysis was performed to identify factors associated with anemia among children aged 6–59 months in Ethiopia. Methods. We used the 2016 Ethiopian Demography and Health Survey (EDHS) data. EDHS was a community-based, cross-sectional study conducted from January 18, 2016 to June 27, 2016. The 2016 EDHS selected the participants using a two-stage stratified cluster sampling technique. A total of 8,462 children aged 6–59 months were included for this analysis. Both descriptive and logistic regression analyses were performed using Stata version14. A P value less than 0.05 at 95% confidence interval was set to test the statistical significance. Results. The analysis indicated that about 58% (95% CI: 55.1, 60.1) of children aged 6–59 months were anemic. Of those, 29.4% and 3.1% had moderate and severe anemia, respectively. The analysis revealed that stunted (AOR = 0.135, 95% CI: 1.13, 1.62) and underweight (AOR = 1.27, 95% CI: 1.04, 1.55) children had higher odds of being anemic. Besides, children aged 6–23 months (AOR = 1.39, 95% CI: 1.06, 1.82), 24–42 months of age (AOR = 1.26, 95% CI: 1.05, 1.51), and those with fever (AOR = 1.34, 95% CI: 1.07, 1.67) had higher odds of being anemic. Similarly, children from anemic mothers (AOR = 1.86, 95% CI: 1.58, 2.18) and poor households (AOR = 1.35, 95% CI: 1.09, 1.67) were at a higher risk of anemia. Children from households with large family sizes (AOR = 1.29, 95% CI: 1.03, 1.60), young mothers (15–24 years of age (AOR = 1.39, 95% CI: 1.06, 1.82) and 25–34 years of age (AOR = 1.26, 95% CI: 1.05, 1.51)), and developing regions (AOR = 1.44, 95% CI: 1.03, 2.02) also had higher odds of developing anemia. Conclusion. The overall prevalence of anemia among children aged 6–59 months in Ethiopia was high. Malnourished children (stunting and underweight); children with fever; children from anemic, uneducated, and young mothers; and children from large and poor families had higher odds to develop anemia. Therefore, preventing childhood illnesses and maternal anemia should be strengthened to reduce anemia among children.

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.

Molecular diagnosis of infectious diarrhea: focus on enteric protozoa

Robust detection of enteric protozoa is a critical step toward determining the etiology of diarrhea. Widespread use of conventional microscopy, culturing and antigen detection in both industrial and developing countries is limited by relatively low sensitivity and specificity. Refinements of these conventional approaches that reduce turnaround time and instrumentation have yielded strong alternatives for clinical and research use. However, advances in molecular diagnostics for protozoal, bacterial, viral and helminth infections offer significant advantages in studies seeking to understand pathogenesis, transmission and long-term consequences of infectious diarrhea. Quantitation of enteropathogen burden and highly multiplexed platforms for molecular detection dramatically improve predictive power in emerging models of diarrheal etiology, while eliminating the expense of multiple tests.

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.

Morbidity due to Schistosoma mansoni--Entamoeba histolytica coinfection in hamsters (Mesocricetus auratus)

Data on Schistosoma mansoni-Entamoeba histolytica coinfection are scarce in the literature. In the present study, hamsters that had been infected for 70 days with Schistosoma mansoni (LE strain) were inoculated via the portal vein with two strains of trophozoites of Entamoeba histolytica: ICB-EGG (highly virulent) and ICB-RPS (non-virulent). The most evident result of coinfection was increased morbidity and mortality, in comparison with either of the infections alone. Histologically, there were no evident signs of interaction between these two infections. The morphological findings of schistosomal granuloma and amoebic abscesses in the liver were similar to those seen in the respective single-infection controls. However, there was severe wasting of the animals with both infections and greater numbers of amoebic lesions in their livers. The results obtained indicated that schistosomiasis aggravates the course of amoebiasis in hamsters.

Prevalência de parasitos intestinais e aspectos socioambientais em comunidade indígena no Distrito de Iauaretê, Município de São Gabriel da Cachoeira (AM), Brasil

Situado em Terra Indígena do Alto Rio Negro, Iauaretê é o segundo maior pólo de concentração humana no município de São Gabriel da Cachoeira (AM) e agrega dez vilas, com 15 etnias. Esse distrito indígena vem sofrendo processo de transformação progressiva de padrão de ocupação disperso e ribeirinho para núcleo com feições urbanas, com aproximadamente 2700 habitantes, desencadeando problemas de saúde pública. Com objetivo de investigar a distribuição de prevalências de parasitos intestinais na população local e discutir a relação desse indicador de saúde com aspectos socioambientais no distrito de Iauaretê, foram realizadas análises da qualidade da água de abastecimento e exames parasitológicos em amostras de fezes e solo. Do total de amostras de água analisadas, 89,2% apresentaram resultado positivo para coliformes termotolerantes. Identificou-se que a vila Dom Bosco foi a que apresentou maior índice de prevalência em amostras fecais com 76% dos indivíduos parasitados. A vila São José apresentou o menor índice com 56%. Os parasitos mais prevalentes em amostras fecais positivas foram, em ordem decrescente, Ascaris lumbricoides (64,84%), Entamoeba coli (32,58%), Endolimax nana (14,84%) e Blastoyistis hominis (13,39%). Em amostras de solo as prevalências mais significativas foram de ovos de Ascaris sp (52,6%), cistos de Entamoeba coli (52,6%) e larvas de ancilostomídeos (52,6%). Concluiu-se que os altos índices de parasitoses intestinais na população, aliados à falta de saneamento básico e à manutenção de práticas sanitárias tradicionais constituem um quadro preocupante em saúde pública.

Synergistic associations between hookworm and other helminth species in a rural community in Brazil

OBJECTIVE

To identify possible synergistic associations of hookworm and other helminths.

METHOD

Cross-sectional survey of all households within 10 km2 of Americaninhas, a rural community in Minas Gerais, Brazil. We determined the prevalence and intensity of single and multiple helminth species infection in an age-stratified sample of 1332 individuals from 335 households.

RESULTS

Hookworm was the most prevalent helminth infection (68.2%), followed by Ascaris lumbricoides (48.8%) and Schistosoma mansoni (45.3%). Overall, 60.6% of individuals harboured mixed helminth infections. Multivariate analysis indicated significant positive associations for co-infection with hookworm and S. mansoni and for co-infection with hookworm and A. lumbricoides. Co-infections with hookworm and A. lumbricoides resulted in higher egg counts for both, suggesting a synergistic relationship between these species, although, we found important age differences in this relationship. However, the intensity of S. mansoni or A. lumbricoides co-infection did not differ from that of mono-infection.

CONCLUSION

These results have implications for the epidemiology, immunology and control of multiple helminth infections. More research is needed to examine the rates of re-infection and immune responses after chemotherapy, and to what extent the effects of polyparasitism are altered by chemotherapy.

Experimental schistosomiasis in the common marmoset Callithrix jacchus

In order to evaluate Callithrix jacchus as an animal model for mansoni schistosomiasis, a group of 10 male animals were once percutaneously exposed to 250 cercariae of the Schistosoma mansoni SLM (São Lourenço da Mata) strain. Animals were periodically bled for measuring serum level of enzymes and proteins and for blood cell counting. When comparing pre-infection to post-infection values, a significant increase was found for alkaline phosphatase at 15 to 120 days p.i., differential counts of eosinophil at 45 and 60 days, and total protein and global eosinophil counts at 120 days. No Schistosoma mansoni eggs were found in stools. Adult worms of small size were recovered from five animals. At day 120, the number of Schistosoma mansoni eggs/g of tissue was 0-289.7 (liver), 0-30.1 (large intestine) and 0-171.4 (small intestine). These findings lead us to classify Callithrix jacchus as a non-permissive host to the SLM strain of Schistosoma mansoni.

Factors associated with Hb concentration in children aged 6-59 months in the State of Pernambuco, Brazil

In 1997, the prevalence of anaemia was 40.9 % among children aged 6-59 months in the State of Pernambuco, north-east Brazil. Using the same sample of children, we have investigated possible reasons for this high prevalence. A representative sample was selected through a three-stage process: proportional systematic random sampling of municipalities in the State, systematic random sampling of census sectors within these municipalities, and finally, simple random sampling of households with children aged 6-59 months to obtain the sample of 650 children. Data collection included demographic, environmental, socio-economic and maternal variables, and nutritional status and dietary intakes of the children. Multiple linear regression analysis was based on a hierarchical model of factors associated with Hb concentration. The mean Hb concentration of children aged 6-23 months was 10 g/l lower than that of older children. In the regression analysis, child age explained 8.3 % of the variance in Hb concentration. The intake of bioavailable Fe explained a further 3.3, serum retinol 2.7, diarrhoea 2.4, water treatment 1.7, sanitation 1.3 and low birth-weight 0.5 %. The final model explained 23.4 % of the variance in Hb concentration. We conclude that child age, bioavailable-Fe intake, serum retinol concentration, diarrhoea, water treatment, sanitation and low birth-weight are independently associated with Hb concentration. In north-east Brazil, anaemia prevention programmes among children should focus on those aged <2 years and should consider feasible strategies to improve intakes of bioavailable Fe and vitamin A, and reduce infection. Supplemental Fe should be given to low birth-weight infants.

[The prevalence of intestinal parasitism in native villages of the Tembé tribe, the Brazilian eastern Amazon]

To determine the prevalence of intestinal parasitism in the Tembé settlements, parasitological examination was performed in December 1996 in the entire population (93 Indians). Hookworms were found in 29.0%, A. lumbricoides in 34.4%, E. histolytica in 12.9%, and G. lamblia in 4.3% of the individuals. The Turé-Mariquita settlement had the highest prevalence of hookworms and A. lumbricoides, while Acará-Mirim had the highest prevalence of E. histolytica and G. lamblia. No differences in mean age were found between Indians with parasites and Indians without parasites. The association between intestinal parasites and sex was nonsignificant, except for the prevalence of hookworms, which was very high in males (38.6%) compared to females (20.4%). The study showed a high prevalence of some intestinal parasites in the Tembé settlements, indicating that primary and secondary health measures should taken immediately for the prevention of intestinal parasitoses.

[Intestinal parasitism in a Parakanã indigenous community in southwestern Pará State, Brazil]

To determine the occurrence and epidemiological aspects of intestinal parasites among the Parakanã indigenous people in the Paranatinga settlement (in the eastern Amazon Region), parasitological tests were performed in April 1992 and February 1995. One fresh stool specimen was obtained and immediately processed using the Hoffman and direct methods. Some 126 samples were obtained in April 1992 (from a total population of 215 individuals). Some 80. 2% (101) of those tested were infected with at least one species of intestinal parasite. Hookworms were found in 33.3%, Ascaris lumbricoides 42.8%, Trichuris trichiura 0.8%, and Strongyloides stercoralis 5.6%. Entamoeba histolytica and Giardia lamblia protozoans were found in 65.0% and 46.8% of those tested, respectively. A second parasitological survey was performed on 174 individuals (from a population of 253) in February 1995. 88.5% were infected. Note that prevalence in February 1995 was higher than in April 1992 (p=0.04). It was lower for hookworms, E. histolytica, and G. lamblia, with no S. stercoralis (p<0.05). Despite provision of health care in the Paranatinga community, prevalence of intestinal parasites is still extremely high, suggesting that primary and secondary health care should be increased immediately to increase the efficacy of prevention of intestinal parasites.

Occurrence of a community with high morbidity associated with Schistosoma mansoni infection regardless of low infection intensity in north-east Brazil

To establish the relationship between schistosome-associated morbidity and infection intensity in northeast Brazil, a parasitological and ultrasonographical study was carried out on 484 inhabitants of 4 villages (I, II, III and IV) in São Lourenço da Mata, Pernambuco, Brazil, where schistosomiasis is endemic. Quantitative stool examination using Knight's method demonstrated a high prevalence and moderate intensity of Schistosoma mansoni infection, and also that the subjects in village IV had a significantly lower prevalence and intensity of infection than those of the other villages. By ultrasonography, periportal fibrosis (PPF) and splenomegaly were found in 52% of the 299 infected subjects and 66% of the 146 infected subjects aged over 16 years old, respectively; 32% and 31% of the 299 infected subjects had abnormally high values of total bile acid (TBA) and alkaline phosphatase (ALP) activity, respectively. Liver and spleen size, PPF, and serum level of TBA and ALP were not correlated with infection intensity. There was no significant difference in the morbidity assessed by liver and spleen size, PPF, and serum analysis between the subjects in village IV and the other villages. These findings suggest the occurrence of a community with high morbidity associated with schistosomiasis regardless of low infection intensity.

Ausência de amebíase invasiva em aidéticos homossexuais masculinos, no Recife

Estudou-se a incidência da Entamoeba histolytica entre aidéticos homossexuais masculinos com o objetivo de determinar se entre esses pacientes o protozoário, incapaz de produzir doença na população geral do Recife, causaria amebíase invasiva. Dos 77 pacientes incluídos na investigação, apenas um (1,3%) albergava a E. histolytica. A eletroforese em gel de amido da linhagem, isolada mostrou um perfil de isoenzimas compatível com o zimodema 1, não patogênico. Além disso, nenhum dos pacientes examinados apresentou no soro anticorpos anti-ameba, verificados pelos testes de precipitação em ágar e imunoenzimático. Estes resultados mostraram que, mesmo entre indivíduos de sistema imunológico comprometido, as linhagens de E. histolytica prevalentes no Recife carecem de potencialidades patogênicas. Não se justifica, portanto, o emprego do metronidazol nos portadores de cistos de ameba, sejam eles aidéticos ou não.

Prevalence and pathogenicity of Entamoeba histolytica in three different regions of Pernambuco, northeast Brazil

Parasitological examinations were carried out on 663 individuals of three different cities of Pernambuco State, Northeastern Brazil: Recife, Palmares and Bodocó. The population from a drought area of Pernambuco State, Bodocó, was investigated for amoebiasis and compared with Recife, metropolitan city (about 1.3 million of inhabitants) and another inland community, Palmares, located inside of the sugar-cane plantation region of the State. No evidence of invasive strains of E. histolytica were found in these inhabitants, provided that the isolated zymodemes I, III, IV, VIII, IX, X, XVII and XVIII are recognized as nonpathogenic strains of E. histolytica. Furthermore, the prevalence of intestinal helminths and other protozoan infections showed that these individuals are infected by other agents responsible for diarrhoeal diseases.

Analysis of pathogenicity by restriction-endonuclease digestion of amplified genomic DNA of Entamoeba histolytica isolated in Pernambuco, Brazil

The pathogenicity of 47 strains of Entamoeba histolytica isolated in Pernambuco, Brazil, was examined using the polymerase chain reaction (PCR) followed by restriction-endonuclease digestion. Electrophoretic patterns of PCR products digested with HinfI revealed that all strains were nonpathogenic. The results were entirely in accord with phenotypic properties such as isoenzyme patterns and the failure to bind a pathogenic-isolate-specific monoclonal antibody. When the sensitivity of PCR was examined, amplified products could be detected from template DNA equivalent to five trophozoites. These observations indicate that PCR amplification of genomic DNA and subsequent restriction-enzyme digestion is a useful strategy for obtaining a sensitive and accurate diagnosis. The present study also demonstrates that nonpathogenic strains of E. histolytica predominate in northeastern Brazil.