![]() The total annual rainfall typically ranges from 1400 to 2400 mm, with a rainy season from May to November, accounting for ~ 90% total rainfall. The climate in the Mekong Delta is tropical, with an average temperature of 27.8 ☌, with little seasonal variation. Their main agricultural outputs are rice, fruits, fisheries and livestock (ducks, chickens and pigs). The province has a population density of ~ 510 per km 2 (Anon. This study was carried out in Dong Thap, a province located in the Mekong Delta region (southwest of Vietnam). Specific objectives were (1) to determine the prevalence and burden of gastrointestinal helminths in small-scale, confined flocks and (2) to investigate the potential association between the burdens of helminth infection on the birds’ weight and disease status, as well as other farms, husbandry and climatic variables. We carried out a field survey aimed at characterising gastrointestinal helminths in healthy flocks representative of small-scale production of the Mekong Delta of Vietnam, as well as in flocks presenting with severe symptoms of the disease to the veterinary authorities. However, such studies were based on chickens collected in local markets, and factors that determine the assemblages of their helminth faunas were not investigated. Studies from Asia (India and Thailand) on chickens marketed for meat production have evidenced a high (> 70%) prevalence of colonisation with helminths (Yadav and Tandon 1991 Ayudthaya and Sangvaranond 1997 Katoch et al. However, to date, there are no published studies on gastrointestinal helminths in chickens flocks in Vietnam. The number of farms raising more than 100 chickens in Vietnam has increased by 41.5% from 2011 to 2016 (Anon. However, in recent years, many Mekong Delta farmers have been upgrading from the backyard to confined ‘all-in-all-out’ systems, although based on traditional, slow-growing native breeds. This production mostly takes place in mixed-species farms where chickens are raised in backyards, gardens and orchards. Most of the chicken production in the area is non-intensive and is based on slow-growing native breeds. 2018), and about half of rural households are engaged in poultry production (Lan Phuong et al. The Mekong Delta hosts about a fifth of Vietnam’s poultry population (Anon. Furthermore, gastrointestinal helminths can transmit pathogenic agent such as Histomonas meleagridis, which causes high morbidity and up to 20% mortality in chicken flocks (McDougald 2005). In addition, helminths may increase disease susceptibility and compromise the immunological response to vaccination (Ayudthaya and Sangvaranod 1997 Pleidrup et al. These helminths interfere with the host’s metabolism, resulting in poor feed utilisation, thus impairing growth and productivity (Gauly et al. Gastrointestinal helminth parasites represent a major constraint to the productivity of small-scale and backyard poultry farming worldwide (Swayne 2013). We recommend upgrading cleaning and disinfection and limiting access to ranging areas to control helminths in small-scale chicken flocks. Anthelminthic usage was not associated with reduced helminth burdens. Colonisation was higher during the rainy months (May–November) for both H. Colonised chickens weighed 101.5 g less than non-colonised birds. Heterakis gallinarum was the most prevalent helminth (43.3% and 42.2% in normal and sick chickens, respectively), followed by A. 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). Among colonised birds, the diseased ones harboured a higher mass of helminth worms than normal (healthy) birds (3.8 ± SD 8.6 g vs. A total of 54.2% and 54.4% normal and diseased chickens contained helminths. The gastrointestinal tract of chickens was dissected and all visible helminths were identified and counted. 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. 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. However, there are no published data on helminths in these systems. ![]() ![]() These conditions facilitate the transmission of gastrointestinal helminths. Commercial small-scale chicken farms managed as all-in-all-out but operating with low standards of hygiene/biosecurity are increasingly common in Vietnam.
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