Blastocystis and its pathogenic potential: latest aspects

Blastocystis spp. Infection in Kidney Transplant Recipient

The Blastocystis sp. is a common enteric parasite found in humans and various animals. Blastocystis spp. infections may be asymptomatic or symptomatic, with gastrointestinal and extra-intestinal symptoms, such as diarrhea, nausea, abdominal pain, bloating, vomiting, or anorexia. The disease leading to symptoms is usually observed in participants with immune deficiency. We report the case of weight loss and diarrhea in a Blastocystis sp. infection in a 64-year-old renal transplant recipient.

Foodborne concerns of Blastocystis spp. in marine animals (fish, bivalves, and sponges): A systematic review and meta-analysis of global prevalence and subtypes distribution

Blastocystis spp. is a common intestinal parasite found in humans and various animals, including marine species like fish, bivalves, and sponges. While traditionally considered non-pathogenic, emerging evidence suggests potential foodborne concerns, especially for vulnerable populations. The present systematic review and meta-analysis reviewed four electronic databases (PubMed, Scopus, Google Scholar, and Web of Science) until June 13, 2024, for studies reporting the prevalence and subtypes (STs) distribution of Blastocystis spp. in marine animals, including fish, bivalves, and sponges, to assess foodborne concern and zoonotic importance. In the analysis of 11 studies involving 1329 marine animals from nine countries, five studies/datasets (742 samples) focused on fish, five studies/datasets (567 samples) on bivalves, and one (20 samples) on sponges. This review found that 12.4 % (95 % CI: 4.3-31 %) of marine animals globally were infected by Blastocystis spp., with bivalves showing the highest infection rate at 32 % (95 % CI: 13-59.7 %), exceeding sponges with a single study at 10 % (95 % CI: 2.5-32.4 %), and fish at 4.4 % (95 % CI: 2-9.3 %). Sensitivity analysis assessed changes in weighted prevalence after excluding certain studies. A subgroup analysis of Blastocystis spp. prevalence was conducted based on publication years, countries, continents, WHO regions, and sample sizes. The data collected indicated that marine animals serve as suitable reservoirs for various Blastocystis spp. STs (ST1-ST4, ST7, ST8, ST10, ST14, ST23, ST26, and ST44), with most (except for ST26 and ST44) having the potential for zoonotic transmission. Overall, the findings emphasize the potential for foodborne risk posed by Blastocystis spp. in marine animals and highlight the need for improved monitoring and control measures to ensure food safety.

Enteric protozoa in the developed world: a public health perspective

Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.

Differences in clinical significance and morphologic features of Blastocystis sp subtype 3

Blastocystis is a polymorphic intestinal parasite that is common in humans. A total of 51 asymptomatic and symptomatic patients positive for Blastocystis only were included in the study. Symptoms were mainly nonspecific gastrointestinal symptoms. Blastocystis isolates were xenically cultured and subtyped. Blastocystis species subtype 3 was the predominant subtype. Intrasubtype differences (vacuolar/amoeboid presence) in subtype 3 morphotypes were observed in 32 asymptomatic and symptomatic subtype 3 cases and could possibly be related to Blastocystis pathogenic potential. Diverse morphologic features (vacuolar transiting to amoeboid), probably reflecting the progression from an asymptomatic to a symptomatic state, were observed in an asymptomatic subtype 3 carrier who later had symptoms. Searching for amoeboid forms might be helpful to presumptively screen symptomatic patients with subtype 3 or to follow up an asymptomatic subtype 3 carrier in case symptoms become evident before antiprotozoal treatment was attempted. Further studies on the roles of morphologic features and variation within Blastocystis species subtypes as predictors of symptoms are encouraged.