Trichomonas gallinae

Jing, Shengfan, Li, Yi, Li, Qiaoqiao, Huang, Yanyi, Han, Shuyi, Zhang, Qingxun, Fan, Jinghui & He, Hongxuan, 2024, Epidemiological investigation of Trichomonas gallinae in beijing, China, International Journal for Parasitology: Parasites and Wildlife 24, pp. 100957-100957 : 100957-

3.1. Prevalence of Trichomonas gallinae

The microscopic examination revealed an overall positive rate of 21.3% (88/413) for various bird species. The PCR assay, which was optimized for specificity, amplified a product of approximately 356 base pairs from the T. gallinae samples, but not from the heterologous control. Concurrent to the microscopy, all 88 positive samples by microscopy were confirmed by PCR, while an additional 44 negative microscopy samples yielded positive PCR results, indicating the heightened sensitivity of the PCR method. Thus, the subsequent analysis was based on the PCR outcomes.

Infestations were recorded in domestic pigeons, wild pigeons, and red-necked turtledoves, but not in other wild birds, such as mynas, magpies, crows, red-billed queleas, grey francolins, black swans, mallards, red kites, and peregrine falcons. The chi-squared test results revealed significant differences in prevalence among bird species (X 2 = 132.88, df = 3, p <0.001), with the highest prevalence in domestic pigeons (55.0%, 110/200), followed by wild pigeons (16.7%, 16/96) and collared doves (33.3%, 6/18). Among the other wild birds, no infections were detected. On the region level, the highest prevalence was found in Miyun (45.6%, 36/79), while the other regions had a lower prevalence: 38.8% (31/80) in Shunyi, 33.7% (29/86) in Fangshan, and 22.2% (36/162) in Daxing. Domestic pigeons in Miyun (68.0%, 34/50) had the highest prevalence, while those in Daxing had the lowest prevalence (46.0%, 23/50). For wild pigeons, the highest prevalence was in Shunyi (23.1%, 3/13), and for red-necked turtledoves, the highest prevalence was in Daxing (50.0%, 4/8). No infections were detected in other wild birds across all districts.

The age-related prevalence trends indicated that domestic and wild pigeons, as well as red-necked turtledoves, were most commonly infected among the nestling birds, with domestic pigeons showing the highest prevalence (79.0%, 79/100). For adolescent birds, red-necked turtledoves had the highest prevalence (33.3%, 5/15), followed by domestic pigeons (31.0%, 31/100) and wild pigeons (13.8%, 12/87). Trichomonas gallinae infection was detected in domestic pigeons, wild pigeons, and red-necked turtledoves from January to March, with a particularly high incidence in January for domestic pigeons (54.8%, 57/ 104). A significant difference in T. gallinae incidence was observed across different growth environments (X 2 = 94.65, df = 1, p <0.001), with domestic pigeons from large-scale breeding farms having the highest incidence (55.0%, 110/200), when compared to wild birds from wetlands, forest parks, and nature reserves (10.3%, 22/213) ( Table 2).

3.2. PCR and sequence analysis

The PCR amplification of positive samples led to the sequencing of 132 T. gallinae ITS 1/ 5.8S /ITS2 gene sequences. These sequences were processed and subjected to evolutionary analysis ( Fig. 2 ). The results identified 10 distinct genotypes: OQ807110, OQ807111, OQ807112, OQ807113, OQ807114, OQ807115, OQ807116, OQ807117, OQ807118, and OQ807119. Among these, OQ807110, OQ807111, OQ807112, OQ807113, and OQ807114 exhibited evolutionary relationships similar to those of the reference sequences ( KU954107 , KT869155, KJ721785, MH733817 and EU215368) downloaded from GenBank. All of these belonged to the same branch, and were classified as genotype A. The remaining five sequences ( OQ807115 , OQ807116, OQ807117, OQ807118, and OQ807119 ) were identified on the same evolutionary branch as multiple sequences downloaded from GenBank, which included KJ721784, LC136936, KX459474, EU881912, and MH733820 . These were classified as genotype B. Genotype A accounted for 41.7% (55/132), and was distributed in the Daxing and Fangshan districts, while genotype B constituted 58.3% (77/132), and was distributed in the Shunyi, Miyun, Daxing, and Fangshan districts. Wild pigeons predominantly harbored genotype A, while domestic pigeons were mainly associated to genotype B ( Figs. 1 and 2 ) .

Figures

Fig. 2. Phylogenetic tree based on the ITS1/5.8S/ITS2 gene locus of Trichomonas gallinae using the Bayesian method. Note: ● represents the isolates in the study.

Fig. 1. Phylogenetic tree based on the ITS1/5.8S/ITS2 gene locus of Trichomonas gallinae using the neighbor-joining and maximum likelihood method. Note: ● represents the isolates in the study.