# PCR-based detection of Enterocytozoon bieneusi in diarrheic patients from Guangdong, Shandong, Shanghai, and Zhejiang Provinces, China: a study on prevalence and genotypic characteristics

## TL;DR

This study found that Enterocytozoon bieneusi, a microsporidian causing diarrhea, is prevalent in China, with varying rates across regions and age groups, and identified both known and new genotypes.

## Contribution

The study reports five novel genotypes of Enterocytozoon bieneusi and highlights regional and demographic differences in infection rates.

## Key findings

- 4.9% of diarrheic patients tested positive for Enterocytozoon bieneusi.
- Shanghai had the highest prevalence (14.3%) compared to other regions.
- Five novel genotypes and seven known genotypes were identified in infected patients.

## Abstract

Enterocytozoon bieneusi is the most prevalent microsporidian species infecting humans and causing diarrhea. Epidemiological investigations seldom focus on this pathogen, and its disease burden has been underestimated. This research investigated the prevalence and genotypic characteristics of E. bieneusi in patients with diarrhea from Guangdong (Zhuhai), Shandong (Qingdao), Shanghai and Zhejiang (Wenzhou) Provinces, China.

A total of 691 fecal specimens from patients exhibiting diarrhea were collected and subjected to polymerase chain reaction (PCR) detection, targeting the internal transcribed spacer (ITS) region of the E. bieneusi genome. Genotypes were identified by sequencing PCR products, and zoonotic risk was evaluated through homology and phylogenetic analysis.

4.9% (34/691) of patients were positive for E. bieneusi. The patients from Shanghai had the highest incidence at 14.3% (21/147), which was significantly higher than those in Qingdao (2.9%, 5/171), Wenzhou (3.3%, 3/90), and Zhuhai (1.8%, 5/283) (χ2 = 35.5, P < 0.001). Meanwhile, the positive rate was 7.1% (18/254), 3.1% (10/325) and 5.4% (6/112) among children, adults, and the elderly, respectively. Additionally, the positive rate of patients in rural areas was 8.6% (26/302), significantly higher than that in urban areas, which was 2.1% (8/389) (χ2 = 15.6, P < 0.001). Twelve genotypes of E. bieneusi were identified, including seven known genotypes: CHG3 (n = 17), CHG19 (n = 3), EbPigITS7 (n = 3), Type IV (n = 3), CHG5 (n = 1), EbpA (n = 1), and S7 (n = 1), as well as five novel genotypes (SHH1, WZH1, ZHH1, ZHH2 and ZHH3), each represented by a single sample. The identified genotypes can be categorized into Groups 1, 2, 12, and 13 through phylogenetic analysis.

This study offers insights into the epidemiology and genetic diversity of E. bieneusi among patients experiencing diarrhea in four provinces of China. It also underscores the necessity of ongoing monitoring and management to prevent the spread of this pathogen.