| Summary: | Avian malaria and leucocytozoonosis can cause fatal diseases, whereas avian trypanosomiasis is reported to be harmless in chickens. Backyard chickens can be infected by several pathogens, including blood parasites, that may shed to industrial poultry production, with a consequently higher economic impact. This study aimed to investigate the presence of several blood parasites (<i>Plasmodium</i>, <i>Leucocytozoon</i> and <i>Trypanosoma</i>) in backyard chickens raised in Southern Thailand, using PCR-based detection and microscopic methods. From June 2021 to June 2022, 57 backyard chickens were sampled. Fresh thin blood smears were prepared from 11 individuals, and buffy coat smears were prepared from 55 of them. Both thin blood smears and buffy coat smears were used for microscopic analysis. Two nested PCR protocols that amplify a fragment of cytochrome <i>b</i> (<i>cytb</i>) and small subunit rRNA (<i>SSU</i> rRNA) genes were used to identify Haemosporida and <i>Trypanosoma</i> parasites, respectively. The number of positive samples was higher with the application of nested PCR than when buffy coat smears were used. Three new <i>Plasmodium</i> lineages (GALLUS47-49) and thirteen <i>Leucocytozoon</i> lineages (GALLUS50-62) were found. Trophozoites, meronts and gametocytes of <i>Plasmodium gallinaceum</i> (GALLUS01) were present in one thin blood smear. All thin blood smears revealed <i>Leucocytozoon</i> infections, but only three samples were a single infection. These three samples revealed the presence of fusiform host cell–parasite complexes, of which the morphological features resembled those of <i>Leucocytozoon macleani</i> (possible synonym is <i>Leucocytozoon sabrazesi</i>), while the <i>cytb</i> showed that this parasite is closely related to the lineage GALLUS06-07, described as <i>Leucocytozoon schouteni</i>. The <i>Trypanosoma</i> prevalence was 33.33%; it was present in only one of the thin blood smears, and it resembles <i>Trypanosoma calmettei</i>. This study showed the prevalence of a high diversity of <i>Plasmodium</i> (64.91%) and <i>Leucocytozoon</i> (89.47%) in Thai chickens. Both nested-PCR and buffy coat smear can be used as the diagnostic tool for the testing of <i>Plasmodium</i>, <i>Leucocytozoon</i> and <i>Trypanosoma</i> for parasitic control in backyard chickens and poultry farms. The information on the parasite species that can be found in chickens raised in Southern Thailand was also considered as the baseline information for further study.
|
|---|