A total of 382 stool samples were examined during a survey of intestinal parasites in members of the Tapirapé ethnic group, who live in the Brazilian Amazon region of Mato Grosso. Fecal DNAs from Blastocystis-positive samples were extracted, polymerase chain reaction amplified using Blastocystis-specific primers targeting the small subunit rRNA gene, and sequenced. Three subtypes (STs) were identified: ST1 (41%), ST2 (32%), and ST3 (17%). Seven mixed infections were found (11%). The subtype distribution was markedly different from that reported in Europe in that ST4 was not detected and ST3 was not the most common subtype. This study is the first to include molecular characterization of Blastocystis in Brazil and in indigenous communities from Latin America.

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.

Little information is available on the occurrence and genetic variability of the diarrhoea-causing enteric protozoan parasite Giardia duodenalis in indigenous communities in Brazil. This cross-sectional epidemiological survey describes the frequency, genotypes, and risk associations for this pathogen in Tapirapé people (Brazilian Amazon) at four sampling campaigns during 2008–2009. Microscopy was used as a screening test, and molecular (PCR and Sanger sequencing) assays targeting the small subunit ribosomal RNA, the glutamate dehydrogenase, the beta-giardin, and the triosephosphate isomerase genes as confirmatory/genotyping methods. Associations between G. duodenalis and sociodemographic and clinical variables were investigated using Chi-squared test and univariable/multivariable logistic regression models. Overall, 574 individuals belonging to six tribes participated in the study, with G. duodenalis prevalence rates varying from 13.5–21.7%. The infection was positively linked to younger age and tribe. Infected children <15 years old reported more frequent gastrointestinal symptoms compared to adults. Assemblage B accounted for three out of four G. duodenalis infections and showed a high genetic diversity. No association between assemblage and age or occurrence of diarrhoea was demonstrated. These data indicate that the most likely source of infection was anthropic and that different pathways (e.g., drinking water) may be involved in the transmission of the parasite.

The genusEntamoebaincludes 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 ofEntamoebaspp. 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 ofEntamoebaspp. was calculated using the random-effects model. A total of 166 studies on humans and 16 on animals were included. The prevalence ofEntamoebaspp. 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 ofEntamoebaspp. 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 wereE. coli(86.5%),E. dispar(7.9%), andE. histolytica(3.1%). In conclusion, a high prevalence (22%) ofEntamoebaspp. was found in the Brazilian population, with a prevalence of up to 50% mainly in the northern, northeastern, and central-western regions. The pathogenic speciesE. histolyticais distributed in most Brazilian regions, with significant prevalence percentages. Among animals, unidentifiedEntamoebaspecies were most prevalent in mammals.

Prevalence of Toxoplasma gondii and Neospora caninum antibodies in sera of 325 dogs in 11 villages inhabited by the Tapirapé and Karajá ethnic groups in the south of the Brazilian Amazon was determined by the use of an indirect fluorescence antibody test. Antibodies (cutoff 1:16) to T. gondii were found in 169 (52%) and to N. caninum (cut-off 1:50) in 32 (9.8%) of 325 dogs. Seropositivity for both parasitic infections was widely prevalent in dogs from these villages and was higher in older dogs, indicating post-natal transmission.

In the Peruvian Amazon, there is no information about hematological parameters of parasitized fish maintained in fish farms. In this study, the effects of parasitism by Anacanthorus spathulatus on hemoglobin (Hb), hematocrit (Ht), red blood cells (RBC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), glucose levels, and leucocytes were analyzed in Colossoma macropomum. The low level of parasitism found in the fish was not responsible for alterations in Hb, Ht, RBC, MCV, MCH, MCHC, and leucocytes (0.05 > p). However, significant increases were observed to the levels of glucose (p < 0.05). This is the first report regarding hematology of cultivated freshwater fish which are infected with monogeneans in the Peruvian Amazon.