Occurrence and HAT-RAPD analysis of gastrointestinal helminths in domestic chickens (Gallus gallus domesticus) in Phayao province, northern Thailand

Assay for the simultaneous detection of Raillietina spp. (R. echinobothrida, R. tetragona, and R. cesticillus) and Ascaridia galli infection in chickens using duplex loop-mediated isothermal amplification integrated with a lateral flow dipstick assay

Raillietina species and Ascaridia galli are two of the significant intestinal parasites that affect chickens in a free-range system production. They destroy the intestinal mucosa layer, leading to several clinical symptoms such as weight loss, a slowed growth rate, and economic value loss. Thus, the objective of this study was to develop an assay for simultaneously detecting Raillietina spp. (R. echinobothrida, R. tetragona, and R. cesticillus) and A. galli in a single reaction using duplex loop-mediated isothermal amplification (dLAMP) coupled with a lateral flow dipstick (LFD) assay. The analytical specificity of the dLAMP-LFD assay showed a high specific amplification of Raillietina spp. and A. galli without non-target amplification. Regarding the analytical sensitivity, this approach was capable of simultaneously detecting concentrations as low as 5 pg/μL of mixed-targets. To evaluate the efficiency of the dLAMP assay, 30 faecal samples of chickens were verified and compared through microscopic examination. The dLAMP-LFD assay and microscopic examination results showed kappa values of Raillietina spp. and A. galli with moderate (K= 0.615) to high (K= 1) agreements, respectively, while the McNemar's test indicated that the efficiency between assays was not significantly different. Therefore, the developed dLAMP-LFD assay can be used as an alternative screening method to the existing classical method for epidemiological investigation, epidemic control, and farm management, as well as for addressing poultry health problems.

Morphological and phylogenetic analysis of Raillietina spp. indigenous chickens (Gallus gallus domesticus) in Bangladesh

Raillietina spp. (Cestoda: Davaineidae), the most common cestodes in indigenous chickens, cause a substantial production loss in poultry industry in Bangladesh. Here, we estimated the prevalence, confirmed the species and determined the genetic pattern of species of Raillietina using molecular tools. We collected and examined 375 chickens randomly from household of different villages of Mymensingh sadar and Gouripur upazila, Mymensingh district and adult parasites were isolated and identified. Genomic DNA was extracted from collected parasites, amplified ITS-2 and ND-1 genes, sequenced and analyzed. Out of 375 samples, 270 (72.0%) were found positive with Raillietina species and mean worm burden was 10.46 ± 0.56. Microscopically, three species of Raillietina, such as R. cesticillus (37.9%), R. echinobothrida (41.1%) and R. tetragona (52.8%) were detected on the basis of their morphological features. The total length, length and width of scolex, sucker and rostellum were also measured. Among different factors, age, farming nature and flock size of chickens were significantly (p < 0.05) influenced Raillietina infections. For further validation, the sequences of ITS-2 gene generated in this study were matched with reference sequences of R. cesticillus, R. echinobothrida and R. tetragona and found 99.63% - 100% similarity. The phylogenetic analyses of ITS-2 and ND-1 sequences were clustered together with the reference sequences of R. cesticillus, R. echinobothrida and R. tetragona confirming microscopic identification. This is the first confirmation of species of Raillietina along with the prevalence of the species, which will be helpful for the formulation of a control strategy and provide basic information for further molecular study.

First report of gastrointestinal nematodes and coccidia parasites from free-range chickens in Mafeteng district, Lesotho

Free-range chickens are an integral part of poultry production in many developing countries. In the Mountain Kingdom of Lesotho, the majority of the population own free-range chickens, which serve a variety of purposes including being a source of meat, eggs and use for cultural rituals amongst others. However, there is lack of scientific studies on occurrence of parasitic infections on free-range chickens in Lesotho. The aim of this study was to document common gastrointestinal parasites infecting free-range chickens in four villages of Mafeteng District in Lesotho. A total number of 462 pooled faecal samples were collected from various households in HaKubutu (n = 114), HaMatjeka (n = 120), HaMpalipali (n = 120) and Thabang Villages (n = 108) which were subjected to microscopic examination using McMaster technique. The prevalence of gastrointestinal parasite infection was as follows: Eimeria tenella (12.8%), Ascaridia galli (10.4%) and Heterakis gallinarum (5%). The prevalence for H. gallinarum and Ascaridia galli were comparatively higher during the hot-wet season (7.1% and 2.8% respectively) than the cold-dry season (3.2% and 1.9% respectively) and varied significantly (P < 0.05). For E. tenella, the oocysts per gram were slightly higher in the cold-dry season than the hot-wet season. Polymerase chain reaction only amplified DNA from six (29%) adult A. galli worms of which two amplicons were successfully sequenced. The obtained cytochrome C oxidase subunit 1 partial gene sequences displayed 98-100% identity with South African A. galli isolates. This is the first scientific study on prevalence and molecular characterization of nematodes and coccidia species infecting free-range village chickens in Lesotho. The findings can be used to review management of gastrointestinal nematodes and protozoal parasites of free-range chickens in Lesotho.

High-performance triplex PCR detection of three tapeworm species belonging to the genus Raillietina in infected poultry

Chickens and ducks are important sources of essential proteins and nutrition for global consumption, especially their eggs and meat. Tapeworm infections in chickens and ducks are the cause of serious poultry health and economic problems in the processing of livestock and food production systems. Raillietina are cosmopolitan in distribution and are possibly the most common tapeworm parasites. There are three important species regarding avian infection, with different pathogenicity, including Raillietina echinobothrida, R. tetragona, and R. cesticillus. Co-infection diagnosis of these tapeworms using morphological analysis can be performed, but this is time-consuming and complicated. Therefore, this study aimed to develop a triplex PCR for the detection and discrimination of three Raillietina species. The triplex PCR assay specifically amplified target DNAs with no inter-specific interference and produced a specific band for each species. According to the specificity test, there was no cross-amplification with the DNA template of related parasites and their hosts. The lowest detectable DNA concentrations were evaluated and provided sensitivities of 0.5 pg/μL for R. echinobothrida, 5 pg/μL for R. tetragona, 50 fg/μL for R. cesticillus, and 5 pg/μL for the combination of DNA from all three species. Simultaneous detection limits of egg capsules and gravid proglottids was also performed, with and without feces. The interference of feces in the reaction was related to a decrease in sensitivity, but simultaneous detection of three Raillietina species in amounts lower than one gravid proglottid and ten egg capsules was still successful. Thus, this study is the first triplex PCR assay for Raillietina detection and can be utilized as an alternative diagnostic tool for the detection and discrimination of R. echinobothrida, R. tetragona, and R. cesticillus infection in poultry through the verification of fecal specimens. In addition, it could improve the performance of specific treatments and promote veterinary healthcare.

Molecular detection of three intestinal cestode species (Raillietina echinobothrida, R. tetragona, R. cesticillus) from poultry in Thailand

RESEARCH HIGHLIGHTS

This study established specific primers for Raillietina species detection.The ITS2 region is an effective molecular marker for Raillietina identification.

Novel high-performance detection of Raillietina echinobothrida, Raillietina tetragona, and Raillietina cesticillus using loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD)

Cestodes belonging to the genus Raillietina are a major veterinary health problem in the poultry industry, especially in chickens (Gallus gallus domesticus) and ducks (Anas playtrhynchos domesticus). In this study, loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD) assay was established and validated for the detection of R. echinobothrida, R. tetragona, and R. cesticillus in one reaction. The LAMP-LFD assay can be completed in 75 min under isothermal conditions at 66 °C and the results can be obtained by observation with the naked eye. This assay was very specific and had no cross-amplification with other closely related parasites (Cotugnia sp., Diorchis formosensis, Fimbriaria sp., Echinostoma sp., E. miyagawai, Hypoderaeum conoideum, Prosthogonimus cuneatus, and Ascaridia galli) or their definitive hosts (G. g. domesticus, A. p. domesticus). The sensitivity of the LAMP-LFD assay was detected with three Raillietina species at 0.5 ng, which was enough for gravid proglottid DNA detection. The accuracy test showed that the LAMP-LFD assay demonstrated accurate verification results when compared to morphological results. This is a novel LAMP-LFD assay that is highly specific and sensitive for the detection of Raillietina species. It can be applied to detection for epidemiological investigations, monitoring programs, surveillance, control, and to solve veterinary health problems for the poultry industry in Raillietina endemic areas.

Preliminary data on Ascaridia galli infections in Gallus gallus domesticus and the development of a specific primer based on the NADH dehydrogenase subunit 4

One major problem of chicken (Gallus gallus domesticus) farming was various parasitic infections, especially Ascaridia galli that can cause the Ascaridiosis and is commonly found worldwide. The purpose of this study was to investigate the epidemiological situation of gastrointestinal tract parasitic infections and to develop species-specific primer for A. galli detection. A total of 247 chicken gastrointestinal tract specimens from 5 fresh markets in Bangkok. The species-specific primers of A. galli were manually designed using the mitochondrial genome at the NADH dehydrogenase subunit 4 (MT-ND 4) gene. As a result, PCR assays were optimized for the specific PCR product approximately 198 bp with the optimal temperature of 51 °C. In addition, sensitivity tests provided the detection of adult and egg stages at the minimum concentrations of 156.3 ng and 2.8 ng (70 eggs), respectively. This research can be used as preliminary information regarding the epidemic situation of gastrointestinal tract infections in chickens and detection of A. galli infection in definitive hosts, which plans programs for the effective control and prevention of parasitic infections.

Morphology and Molecular Identification of Echinostoma revolutum and Echinostoma macrorchis in Freshwater Snails and Experimental Hamsters in Upper Northern Thailand

Echinostome metacercariae were investigated in freshwater snails from 26 districts in 7 provinces of upper northern Thailand. The species identification was carried out based on the morphologies of the metacercariae and adult flukes harvested from experimental hamsters, and on nucleotide sequences of internal transcribed spacer 2 (ITS2) and nicotinamide adenine dinucleotide dehydrogenase subunit 1 (nad1) genes. Twenty-four out of 26 districts were found to be infected with echinostome metacercariae in freshwater snails with the prevalence of 40.4%. The metacercariae were found in all 6 species of snails, including Filopaludina martensi martensi (21.9%), Filopaludina doliaris (50.8%), F. sumatrensis polygramma (61.3%), Bithynia siamensis siamensis (14.5%), Bithynia pulchella (38.0%), and Anenthome helena (4.9%). The echinostome metacercariae found in these snails were identified as Echinostoma revolutum (37-collar-spined) and Echinostoma macrorchis (45-collar-spined) morphologically and molecularly. The 2-week-old adult flukes of E. revolutum revealed unique features of the cirrus sac extending to middle of the ventral sucker and smooth testes. E. macrorchis adults revealed the cirrus sac close to the right lateral margin of the ventral sucker and 2 large and elliptical testes with slight indentations and pointed posterior end of the posterior testis. The ITS2 and nad1 sequences confirmed the species identification of E. revolutum, and the sequences of E. macrorchis have been deposited for the first time in GenBank. The presence of the life cycle of E. macrorchis is a new record in Thailand and the snail F. doliaris as their second intermediate host seems to be new among the literature.

Heterakis gallinarum, the Cecal Nematode of Gallinaceous Birds: A Critical Review

Heterakis gallinarum is a heavily prevalent poultry parasite that thrives in the ceca of various species of gallinaceous birds. It is a small roundworm, measuring between 4 and 15 mm long, in the family Heterakidae. Heterakis gallinarum has a direct life cycle not requiring an intermediate host to complete development, and it is generally believed that poultry raised at high density on litter are at greatest risk for accumulating large numbers of the nematode. This species typically only causes mild pathology that does not significantly affect bird performance. However, H. gallinarum is recognized as an economically important parasite by the poultry industry because its ovum serves as the vector for the protozoal parasite Histomonas meleagridis, the cause of histomonosis in poultry. Diagnosis of the nematode typically relies on fecal egg counts, which are prone to false negative diagnoses. Molecular tools are available for studying the nematode and diagnosing infected flocks. Treating and preventing H. gallinarum infection is made difficult due to the low efficacy of anthelmintics for eradicating H. gallinarum from infected birds and of disinfectants for destroying H. gallinarum ova on contaminated farms.

Characterisation of gastrointestinal helminths and their impact in commercial small-scale chicken flocks in the Mekong Delta of Vietnam

Commercial small-scale chicken farms managed as all-in-all-out but operating with low standards of hygiene/biosecurity are increasingly common in Vietnam. These conditions facilitate the transmission of gastrointestinal helminths. However, there are no published data on helminths in these systems. We aimed (1) to determine the prevalence/burden of gastrointestinal helminths in small-scale commercial flocks in the Mekong Delta region and (2) to investigate the association between worm burdens and birds' weight and disease status. Randomly selected chickens (n = 120) from 'normal' flocks were investigated at the end of their production cycle (~ 18 weeks), as well as 90 chickens from 'diseased' flocks with signs of respiratory and/or severe disease. The gastrointestinal tract of chickens was dissected and all visible helminths were identified and counted. A total of 54.2% and 54.4% normal and diseased chickens contained helminths. Among colonised birds, the diseased ones harboured a higher mass of helminth worms than normal (healthy) birds (3.8 ± SD 8.6 g vs. 1.9 ± SD 6.3 g, respectively). Eight species were identified, including nematodes (Ascaridia galli, Cheilospirura hamulosa and Heterakis gallinarum), cestodes (Hymenolepis, Raillietina cesticillus, Raillietina echinobothrida, Raillietina tetragona,) and one trematode (Echinostomatidae). Heterakis gallinarum was the most prevalent helminth (43.3% and 42.2% in normal and sick chickens, respectively), followed by A. galli (26.7% and 41.1%). Colonised chickens weighed 101.5 g less than non-colonised birds. Colonisation was higher during the rainy months (May-November) for both H. gallinarum and A. galli. Anthelminthic usage was not associated with reduced helminth burdens. We recommend upgrading cleaning and disinfection and limiting access to ranging areas to control helminths in small-scale chicken flocks.

Morphological and molecular appraisal of cyclophyllidean cestoda parasite Raillietina saudiae sp. nov. infecting the domestic pigeon Columba livia domestica and its role as a bio-indicator for environmental quality

Pigeons members of the order Columbiformes are a cosmopolitan group of birds with abundant and large populations associated with human activities. Therefore, the current study was conducted to determine the parasitic infections within the domestic pigeon Columba livia domestica. Eighteen pigeons were examined for the presence of gastrointestinal helminths, of which 77.78% were infected with a cyclophyllidean cestoda parasites. The morphology of this parasite based on light and scanning electron microscopic studies, revealed the presence of gravid worms, 2.00-4.52 cm long and 0.23-0.59 mm wide; a scolex had four suckers equipped by 5-6 rows of minute hooks and retractable rostellum with 230-250 hooks; genital pores unilateral; oval testes with 27-37 in number; bilobed ovary; post-ovarian vitelline gland; and 24-28 egg capsules present in uterus with 5-6 spherical eggs in each capsule. Molecular analysis based on sequences of ITS2 and ND1 gene regions was performed to confirm the taxonomy of this parasite based on its morphology. This revealed close identity of up to 92.0% and 72.0% for ITS2 and ND1 gene regions, respectively, with other cestoda species obtained from GenBank. Phylogenetic analysis supported the placement of this cycllophylid species within Davaineidae with close relationships to the previously described species of R. chiltoni, R. dromaius, and R. beveridgei based on the ITS2 gene region and R. coreensis and R. sonini based on the ND1 gene regions. Heavy metals accumulation in the recovered parasite and its host showed significantly higher concentrations in the parasite compared to its host tissues. Generally, concentrations of metals exceeded the permissible limits recommended by the US Environmental Protection Agency. Therefore, pigeon cestodes can be regarded as useful bio-indicators when evaluating the environmental pollution of terrestrial ecosystems by heavy metals.

Morphology and Molecular Phylogeny of Raillietina spp. (Cestoda: Cyclophyllidea: Davaineidae) from Domestic Chickens in Thailand

Raillietina species are prevalent in domestic chickens (Gallus gallus domesticus) in Phayao province, northern Thailand. Their infection may cause disease and death, which affects the public health and economic situation in chicken farms. The identification of Raillietina has been based on morphology and molecular analysis. In this study, morphological observations using light (LM) and scanning electron microscopies (SEM) coupled with molecular analysis of the internal transcribed spacer 2 (ITS2) region and the nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) gene were employed for precise identification and phylogenetic relationship studies of Raillietina spp. Four Raillietina species, including R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp., were recovered in domestic chickens from 4 districts in Phayao province, Thailand. LM and SEM observations revealed differences in the morphology of the scolex, position of the genital pore, number of eggs per egg capsule, and rostellar opening surface structures in all 4 species. Phylogenetic relationships were found among the phylogenetic trees obtained by the maximum likelihood and distance-based neighbor-joining methods. ITS2 and ND1 sequence data recorded from Raillietina sp. appeared to be monophyletic. The query sequences of R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp. were separated according to the different morphological characters. This study confirmed that morphological studies combined with molecular analyses can differentiate related species within the genus Raillietina in Thailand.