Symptomatic and Asymptomatic Protist Infections in Hospital Inpatients in Southwestern China

Area of Science:

• Medical Parasitology
• Molecular Epidemiology
• Gastroenterology

Background:

• Enteric protists such as Blastocystis sp., Giardia duodenalis, Entamoeba histolytica, and Cryptosporidium spp. are recognized causes of gastroenteritis.
• These protists can also be asymptomatic gut inhabitants in healthy populations, posing diagnostic challenges.

Purpose of the Study:

• To investigate the prevalence and genetic diversity of key enteric protists in a Chinese population.
• To determine if co-infections with these protists are associated with clinical symptoms or specific demographic factors.

Main Methods:

• Molecular detection (PCR and Sanger sequencing) of Blastocystis sp., G. duodenalis, E. histolytica, and Cryptosporidium spp. in 507 stool samples.
• Genotyping of identified isolates to determine subtypes and sub-assemblages.
• Statistical analysis to assess co-occurrence patterns and associations with clinical symptoms and age.

Main Results:

• Overall carriage/infection rate for enteric protists was 12.4%, with Blastocystis sp. (9.5%), G. duodenalis (2.2%), and E. histolytica (2.0%) detected. Cryptosporidium spp. was absent.
• Commonly identified G. duodenalis sub-assemblages were AI (90.9%) and BIV (9.1%). Five Blastocystis subtypes (ST3, ST1, ST7, ST4, ST2) were identified.
• No statistical association was found between protist infections (individually or co-infections) and the presence of clinical symptoms or patient age.

Conclusions:

• Enteric protist infections, including co-infections, are common and largely asymptomatic in the studied population.
• The co-occurrence of these protist infections appears to be random, without specific epidemiological patterns.
• Molecular methods are crucial for accurate detection and genotyping of enteric protists for epidemiological studies.