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

Abstract

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.

Characterization of viral, bacterial, and parasitic causes of disease in small-scale chicken flocks in the Mekong Delta of Vietnam

“…The present investigation revealed a high prevalence (67.2%) of colonization with gastrointestinal helminths, the most common species being the nematodes H. gallinarum and A. galli . A recent study in the same area reported a higher burden of A. galli in diseased chickens than in healthy ones ( Van et al., 2019 ).…”

“…A number of bacteria such as Pasteurella multocida ( Mariana and Hirst, 2000 ), Avibacterium paragallinarum ( Chukiatsiri et al., 2010 ), and Mycoplasma gallisepticum ( Fujisawa et al., 2019 ) have all been reported to circulate in Southeast Asia. The low standards of hygiene and biosecurity typical of small-scale chicken farms in the area also facilitate the presence of gastrointestinal helminth burdens in these flocks ( Van et al., 2019 ). However, most studies to date have typically focused on single etiological agents, and the investigation of a wider panel of pathogens is required to prioritize disease control strategies.…”

Global and regional prevalence of helminth infection in chickens over time: a systematic review and meta-analysis

“…As a result, poultry production is making a significant and increasing contribution to the national economy of most countries ( Dube et al., 2010 ; Adang et al., 2014 ; Ferdushy et al., 2016 ). However, the production performance of poultry can be significantly reduced because of various intestinal helminth parasites ( Permin et al., 1997 ; Ruff, 1999 ; Ogbaje et al., 2012 ; Adang et al., 2014 ; Bachaya et al., 2015 ; Van et al., 2019 ).…”

Small-scale commercial chicken production: A risky business for farmers in the Mekong Delta of Vietnam

“…The main explanatory factors for the losses identified were a small flock size and high mortality. The (high) observed cumulative mortality (median 18%) is likely to reflect a high incidence of bacterial, viral and parasitic diseases identified in the area (Carrique-Mas et al, 2019b; Nguyen T. B. Van et al, 2020; Nguyen Thi Bich Van et al, 2020).…”

“…Chicken production in the area is predominantly semi-intensive (including backyard and small-scale), and is typically based on slow-growing native breeds (Duc and Long, 2008; Lan Phuong et al, 2015). Production is however hampered by a high incidence of parasitic (Nguyen T. B. Van et al, 2020), viral and bacterial diseases (Nguyen Thi Bich Van et al, 2020), often resulting in high mortality losses (Carrique-Mas et al, 2019b).…”