High prevalence of Plasmodium infection in fighting cocks in Thailand determined with a molecular method

Molecular survey and genetic diversity of Plasmodium sp. infesting domestic poultry in northeastern Thailand

Introduction

Haemosporidian parasites are prevalent worldwide and can cause economic losses in poultry production. These parasites are arousing interest in Thailand and are found in many avian species. There is insufficient information on the genetic diversity of these alveolates from the largest families - Plasmodidae, Haemoprotidae and Leucocytozoidae - specifically parasitising ducks, turkeys, and geese.

Material and Methods

Blood samples from 116 backyard poultry (60 ducks, 36 turkeys and 20 geese) in northeastern Thailand were investigated for Plasmodium spp., Haemoproteus spp. and Leucocytozoon spp. infections using microscopic examination and molecular approaches.

Results

A total of 37/116 birds (31.9%) had confirmed Plasmodium infections. The prevalence was 69.4% (25/36) in turkeys, 18.3% (11/60) in ducks, and 5.0% (1/20) in geese. Of these 37 positives, 86.5% were Plasmodium sp., 10.8% were P. gallinaceum and 2.7% were P. juxtanucleare. Sequence analysis based on the cytochrome b gene identified seven lineages, of which two were new lineages in backyard poultry.

Conclusion

This is the first report on the prevalence of haemosporidian parasites in backyard poultry in northeastern Thailand. The results provide important data for better understanding the molecular epidemiology of haemosporidian parasites infection in poultry in this region, which will be helpful in controlling these blood parasites.

Comparison of Three Methods to Extract Plasmodium falciparum DNA from Whole Blood and Dried Blood Spots

This study aimed to compare the effectiveness of three DNA extraction methods: the GF-1 Blood DNA Extraction Kit (GF-1 BD Kit), which employs a spin column along with lysing and washing buffers; the tris-ethylenediaminetetraacetic acid and proteinase K (TE-pK) method, which utilizes a combination of TE buffer and proteinase K for cell lysis; and DNAzol® Direct (DN 131), a single reagent combined with heating for the extraction process. Plasmodium falciparum DNA was extracted from both whole blood and dried blook spots (DBSs), with consideration of DNA concentration, purity, cost, time requirement, and limit of parasite detection (LOD) for each method. The target gene in this study was 18S rRNA, resulting in a 395-bp product using specific primers. In the comparative analysis, the DN 131 method yielded significantly higher DNA quantities from whole blood and DBSs than the GF-1 BD Kit and TE-pK methods. In addition, the DNA purity obtained from whole blood and DBSs using the GF-1 BD Kit significantly exceeded that obtained using the TE-pK and DN 131 methods. For LOD, the whole blood extracted using the DN 131, GF-1 BD Kit, and TE-pK methods revealed 0.012, 0.012, and 1.6 parasites/µL, respectively. In the case of DBSs, the LODs for the DN 131, GF-1 BD Kit, and TE-pK methods were 1.6, 8, and 200 parasites/µL, respectively. The results revealed that the TE-pK method was the most cost-effective, whereas the DN 131 method showed the simplest protocol. These findings offer alternative approaches for extracting Plasmodium DNA that are particularly well-suited for large-scale studies conducted in resource-limited settings.

Morphological and molecular characteristics of Plasmodium juxtanucleare in layer chicken from three districts of Yogyakarta, Indonesia

Background and Aim

Blood parasite infections in poultry, such as Plasmodium, are a serious threat to the poultry industry due to their potential to cause economic losses. To date, there has been inadequate research on the morphological and molecular detection of the different Plasmodium species that infect poultry in Indonesia. Therefore, this study aimed to analyze the morphological and molecular characteristics of Plasmodium spp. and the several predisposing factors for Plasmodium infection in layer chickens from three districts of Yogyakarta, Indonesia.

Materials and Methods

One hundred and five blood samples from layer chickens were collected from 13 farms located in three districts of Yogyakarta (Sleman, Bantul, and Kulon Progo) between September and November 2022. Blood samples were subjected to microscopic and polymerase chain reaction (PCR) analyses. Sequencing was performed using basic local alignment search tools to identify the nucleotide structure of cytochrome b. Phylogenetic analysis of Plasmodium was performed using the MEGA-X software.

Results

Microscopic examination revealed that 17/105 positives (16.19%) were positive for blood parasite infection. Trophozoites, erythrocytic meronts, and microgametocytes of Plasmodium were found in blood samples. Based on the morphological examination, the species found in the samples was close to Plasmodium juxtanucleare. Polymerase chain reaction examination revealed that 21/60 samples were positive for Plasmodium (35%). The Plasmodium species identified from the sequenced samples were proven to be P. juxtanucleare. The P. juxtanucleare from Thailand was closely related to samples (99.64%-100%) with a genetic distance of 0%-1%. In addition, age, population, and cage type were not significantly associated with Plasmodium infection.

Conclusion

Based on microscopic and PCR examinations, the Plasmodium species found in the three districts of Yogyakarta was P. juxtanucleare. The genetic distance between samples from the three districts of Yogyakarta was closely related (0%-1%) to P. juxtanucleare from Thailand and Japan. There was no correlation between Plasmodium infection and age, cage type, or population.

Occurrence, Prevalence, and Distribution of Haemoparasites of Poultry in Sub-Saharan Africa: A Scoping Review

This review collated existing data on the occurrence, distribution, and prevalence of haemoparasites of poultry in sub-Saharan Africa. A literature search was conducted on three electronic search databases using search terms and Boolean operators (AND, OR). The results recorded 16 haemoparasites, viz., Leucocytozoon spp., L. marchouxi, L. neavei, L. sabrazesi, L. schoutedeni, Haemoproteus columbae, H. pratasi, Haemoproteus spp., Plasmodium spp., P. gallinaceum, P. circumflexum, P. juxtanucleare, Trypanosoma avium, T. gallinarum, T. numidae, and Hepatozoon spp. from a wide range of poultry species distributed across Nigeria, Kenya, South Africa, Tanzania, Uganda, Botswana, Zimbabwe, Ghana, Cameroon, and Zambia. Infections due to Haemoproteus and Leucocytozoon species were the most common and documented in eight of the ten reviewed countries. The presence of mixed infections was observed in quails, pigeons, chickens, ducks, turkeys, and guineafowls, but predominantly in chickens. Co-infections by Plasmodium spp. and Haemoproteus spp. were the most common, which may be attributed to the distribution of these species, coupled with the availability of vectors they are associated with in areas from which they were documented. The information generated in this review is essential for improving existing preventive and control measures of these parasites in sub-Saharan Africa.