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

Economic impact of chicken diseases and other causes of morbidity or mortality in backyard farms in low-income and middle-income countries: a systematic review and meta-analysis

BACKGROUND

Backyard chicken farming is usually subsistence and predominates in low-income countries and, to a lesser extent, in middle-income countries. Chicken flocks are generally raised by households in a low-input, low-output system in contact with other flocks, livestock, and wildlife. This low biosecurity setting predisposes chickens to diseases and injuries. A systematic review was conducted to assess the impact of diseases and other causes of mortality in backyard chickens from low income and middle-income countries.

RESULTS

The systematic literature review was conducted following the PRISMA guidelines. Databases consulted included: PubMed, Medline in OVID, Scopus, Web of Knowledge, CAB direct, AGRIS, AgEconSearch, Agricola, Google Scholar, CyberLeninka, CNKI, LILACS, TCI, SID and Civilica. Of the 40,121 studies identified, 78 studies were selected. Only a limited number of studies (n = 7) assessed the impact on productivity (weight and egg production losses). Results from the meta-analyses showed that the three main causes of mortality in a production cycle are viral diseases (24.5%, 12.4-42.7), the mix of bacterial and viral diseases (24.2%, 6.2-58.2) and bacterial diseases (11.2%, 4.6-25.0). These three causes of mortality also account for the highest proportion of economic losses for infectious diseases. In the case of non-infectious causes, predation and cachexia are responsible for the highest economic losses in backyard chickens.

CONCLUSIONS

Infectious diseases account for the highest economic and mortality losses examined in the selected studies. However, losses due to other causes, such as predation, should not be overlooked. These results could be used to support animal health policy in informing resource allocation to preventive measures to improve food security.

Morphological and molecular identification of Heterakis gallinarum in Gallus gallus and its phylogenetic analysis based on ITS1-5.8S-ITS2 rDNA fragment in Kashmir valley, India

Heterakis gallinarum is one of the most common round worms infecting wide range of terrestrial birds including domestic fowl. H. dispar and H. isolonche are the species of same genus which infect other hosts predominantly aquatic birds, but show morphological similarities mainly females of these species are difficult to identify. Here, we described the morphologically distinct features of H. gallinarum along with identification through molecular analysis using ITS1-5.8S-ITS2 ribosomal DNA. Four hundred gastrointestinal tracts of domestic fowl were analysed for a period of 2 years. Light microscopy and Scanning electron microscopy (SEM), was used for determining the morphometric measurements and characteristic morphological features of H. gallinarum. A PCR based DNA sequencing of ITS1-5.8S-ITS2 ribosomal DNA was used for molecular characterization and phylogenetic analysis was carried out through MEGA 11. Ninety gastrointestinal tracts were found to be infected with Heterakis gallinarum. The male worm displayed well developed lateral and caudal alae, caudal end had an anal sucker, 12 pairs of caudal papillae and cloaca from which 2 unequal spicules emerged. Female had visible vaginal bends, vulva present approximately in the middle of the body, and caudal end had a long pointed tail. Sequence analysis revealed that the PCR products of ITS1-5.8S-ITS2 rDNA were 600 bp in size and showed 96-98% similarity with the ITS1-5.8S-ITS2 sequences of H. gallinarum on BLAST analysis. Our ITS sequence of H. gallinarum showed a nucleotide divergence of 4.9% with H. gallinarum of Lucknow India. The phylogenetic analysis clearly differentiated H. gallinarum from the other representatives of the genus and revealed the relationship among different Heterakis species. The study revealed the infection status of Heterakis gallinarum prevailing among domestic fowl, and need of strategic control measures. The results of the study suggest that ITS rDNA would serve as a potential molecular marker in identification, diagnosis and systematics of Heterakis species.

Global and regional prediction of heterakidosis population prevalence in extensive backyard chickens in low-income and middle-income countries

Extensive backyard chickens are one of the most common production systems in low-income and middle-income countries (LMICs). In this production system, chickens are exposed to infectious forms of parasites as a result of the outdoor access and scavenging behaviour. Heterakis gallinarum is one of the most common nematode parasites present in the environment, and estimating its global and regional prevalence is essential for attributing the economic losses in extensive backyard chickens. The objective of this study is to predict the prevalence of heterakidosis in extensive backyard chickens at global and regional levels in LMICs using regression imputation methods. A binomial random effect model was developed using empirical data on heterakidosis prevalence and climatic factors as main predictors. Prevalence data were then imputed in all regions based on the regression model. Global and country prevalence were estimated based on regional predictions and their beta distributions. Minimum precipitation, minimum temperature and maximum temperature were selected as significant predictors. The population prevalence of heterakidosis was 0.24 (0.19-0.29). Countries with continental and dry climates had a higher mean prevalence, whereas countries with tropical climates had a lower mean prevalence of heterakidosis. As more empirical data on heterakidosis prevalence become available, this model and predictions should be redefined and updated to capture a more representative association and increase the accuracy of the predictions. The results of this study can be used to attribute the economic losses of extensive backyard chickens, taking into account a holistic approach as promoted by the GBADs programme and therefore, to identify which diseases are more costly to backyard farmers. Furthermore, results can be also served as a proxy for the risk of histomoniasis in extensive backyard chickens.

Global and regional prediction of coccidiosis and ascaridiosis prevalence in extensive backyard chickens in low-income and middle-income countries

Backyard chickens usually have open housing and scavenge for food, facilitating contact with infective forms of parasites present in the environment and increasing the risk of parasitic infections. Coccidiosis and ascaridiosis are two internal parasites in scavenging chickens that cause production losses to farmers. Prevalence data of these two diseases are scarce in low-income and middle-income countries (LMICs) but necessary to assess the burden of disease in backyard chickens. This study estimates the clinical prevalence of coccidiosis and ascaridiosis at the country and regional levels in all LMICs using regression imputation methods. Regression models were developed with data of known prevalence of these parasites and using primarily climatic factors as predictors. A binomial random effects model was developed for each disease to impute prevalence. The overall estimated prevalence of coccidiosis was 0.39 (95 % CI: 0.37-0.42), with a higher mean prevalence in tropical countries. The overall estimated prevalence of ascaridiosis was 0.23 (95 % CI: 0.22-0.25) with a higher mean prevalence in countries with tropical, temperate and continental climates. The findings of this study can aid to identify the burdens of coccidiosis and ascaridiosis infections across countries and regions, which can inform disease control plans and, and encourage international alliances to facilitate access to preventive measures, improving animal health and reducing production losses.

Interactions between the helminth and intestinal microbiome in smallholder chicken farming systems

Helminth parasite infections are widespread in smallholder farming systems affecting farmers and livestock animals. There are pathogenic parasites that populate the gut of their host and coexist closely with the gut microbiota. The physical and immunological environment of the gut can be modified by parasites and microbiota creating a wide range of interactions. These interactions modify the development of infection, affects overall host health, and can modify the way a host interacts with its bacterial microbiota. In addition, where there is a high worm burden parasites will affect the health of the host and intestinal tract colonization. This review highlights key studies on the interaction between helminth parasites and the intestinal microbiome to understand the relationship between parasitic worm infections and gut microbiome health in chickens. Finally, the review discusses modulations, molecular changes, and the importance of helminth-microbiome interactions for the host.

Anthelmintic efficacy of Holarrhena pubescens against Raillietina spp. of domestic fowl through ultrastructural, histochemical, biochemical and GLCM analysis

Globally, traditional knowledge systems are a powerhouse of information which can revolutionise the world, if decoded accurately and logically. Plant-based ethno-traditional and folklore curatives/medicines has a firm basis in the psyche of the common masses of West Bengal and Holarrhena pubescens is a representative example of it. This article communication on depicting the anthelmintic efficacy of ethanolic extract and Ethyl acetate fraction of the stem bark of Holarrhena pubescens against the cestode Raillietina spp. through efficacy studies, ultra-structural observations, histochemical and biochemical analysis on some tegumental enzymes i.e., Acid Phosphatase (AcPase), Alkaline Phosphatase (AlkPase), Adenosine Triphosphatase (ATPase) and 5'-Nucleotidase (5'-Nu) along with Gray Level Co-occurrence Matrix (GLCM) analysis of histochemical study. Praziquantel was used as the reference drug. Investigations revealed 10mg/ml dosage of crude extract was the most efficacious dose and amongst the fractions the ethyl acetate fraction showed the most anthelmintic property. Ultrastructural studies through Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) clearly depicted the damage in head, sucker, proglottids, proximal and distal cytoplasm (DC), microtriches (MT), basal lamina (BL), nuclear membrane (NM), and, nucleolus (NL) in the treated worms. Histochemical studies revealed decrease in staining intensity for all the tegumental enzymes in the treated worms compared to control. The GLCM analysis strongly supported the result of histochemical studies. Biochemical studies revealed marked reduction in enzyme activity in the treated worms with maximum reduction in the activity of 5'- Nu (77.8%) followed by ATPase (63.17%).

Prevalence of endoparasites by microscopic analysis in free-range chickens in a Brazilian semiarid region

The aim of this study was to evaluate the prevalence and diversity of endoparasitic fauna and the risk factors associated with parasite infections in free-range chickens in the state of Paraíba, northeastern Brazil. Ten municipalities were visited and, in each of them, ten farms, to collect animal feces and apply epidemiological questionnaires. Feces from 417 poultry were used to perform EPG (eggs per gram) and OoPG (oocysts per gram) tests. Prevalences of 40.52% (169/417) and 39.08% (163/417) were observed for nematodes and coccidia, respectively. In 17% (71/417), mixed infections by nematodes and coccidia were observed. Nematodes of Heterakoidea superfamily were present in 100% of the positive samples (169/169), followed by Trichuris spp. (57.3%; 97/169). All the protozoan oocysts observed belonged to the genus Eimeria (100%; 163/163). The variable of presence of drooping wings was considered to be a factor associated with infection by coccidia (odds ratio = 5.412; confidence interval: 1.179-24.848; p = 0.030). It was concluded that there is high prevalence of nematodes and coccidia in free-range chickens in the state of Paraíba, Brazil. Better sanitary management measures, with greater hygiene of facilities, together with chemical control of parasites, can improve productivity by reducing the rate of gastrointestinal parasites.

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

Small-scale farming of meat chicken flocks using local native breeds contributes to the economy of many rural livelihoods in Vietnam and many other low- and middle-income countries (LMICs). These systems are also the target of high levels of antimicrobial use (AMU); however, little is known about the profitability and sustainability of such systems. Since small-scale farms are commercial enterprises, this knowledge is essential to develop successful strategies to curb excessive AMU. Using longitudinal data from 203 small-scale (100−2,000 heads) native chicken flocks raised in 102 randomly selected farms in Dong Thap province (Mekong Delta, Vietnam), we investigated the financial and economic parameters of such systems and the main constraints to their sustainability. Feed accounted for the largest financial cost (flock median 49.5 % [Inter-quartile range (IQR) 41.5−61.8 %]) of total costs, followed by day-old-chicks (DOCs) (median 30.3 % [IQR 23.2−38.4 %]), non-antimicrobial health-supporting products (median 7.1 % [IQR 4.7−10.5 %]), vaccines (median 3.1 % [IQR 2.2−4.8 %]), equipment (median 1.9 % [IQR 0.0−4.9 %]) and antimicrobials (median 1.9 % [IQR 0.7−3.6 %]). Excluding labor costs, farmers achieved a positive return on investment (ROI) from 120 (59.1 %) flocks, the remainder generating a loss (median ROI 124 % [IQR 36–206 %]). Higher ROI was associated with higher flock size and low mortality. There was no statistical association between use of medicated feed and flock mortality or chicken bodyweight. The median daily income per person dedicated to raising chickens was 202,100 VND, lower than alternative rural labor activities in the Mekong Delta. In a large proportion of farms (33.4 %), farmers decided to stop raising chickens after completing one cycle. Farmers who dropped off chicken production purchased more expensive feed (in 1000 VND per kg): 11.1 [10.6−11.5] vs. 10.8 [10.4−11.3] for farms that continued production (p = 0.039), and experienced higher chicken mortality (28.5 % [12.0−79.0 %] vs. 16 [7.5−33.0 %]; p = 0.004). The rapid turnover of farmers raising chickens in such systems represents a challenge to the uptake of messages on appropriate AMU and chicken health. To ensure sustainability of small-scale commercial systems, advisory services need to be available to farmers as they initiate new flocks, and support them in the early stages to help overcome their limited experience and skills. This targeted approach would support profitability whilst reducing risk of emergence of AMR and infectious disease from these systems.

Assessment of risk factors associated with prevalence of gastrointestinal parasites in poultry of central plain zone of Punjab, India

Background and Aim

Parasitic diseases are an important hurdle to the economy for the developing poultry industry due to their deleterious effects resulting into malnutrition, diminished feed conversion ratio, weight loss, decreased egg production, and mortality in young birds. The aim of this study was to assess the prevalence and associated risk factors of gastrointestinal (GIT) parasites in poultry farms of central plain zone of Punjab.

Materials and Methods

A total of 490 pooled droppings and 351 intact intestines of poultry from slaughterhouses from seven districts of central plain zone of Punjab state, India, were collected and analyzed from September 2016 to May 2018 by qualitative and quantitative techniques.

Results

An overall prevalence of GIT parasites was 38.36% with significantly (p<0.01) highest (74.1%) in Ludhiana and lowest (12.0%) in Shri Fatehgarh Sahib. The most predominant (86.2%) infection was coccidia. The birds reared under a deep litter system were having a higher (p<0.01) fecal load of helminthic eggs and coccidian oocysts (54.4%) compared to the cage system (37.5%). Infection rate was apparently more (40%) in broilers than layers (35.7%). Prevalence of GIT parasites was higher (p<0.01) in monsoon season (58.5%) and lower in summer season (24.48%). The broilers in the age group of 0-2 weeks possessed a significant higher (p<0.05) level of GIT parasitic infection (57.5%), while in case of layers, a higher infection rate (46.66%) was observed in birds between 9 and 18 weeks of age as compared in other groups. Higher (p<0.05) infection rate of GIT parasites was seen in crossbred (45.55%) birds as compared to desi birds (20.00%).

Conclusion

The study showed that coccidiosis was the predominant infection among all GIT parasites based on fecal and intestinal tract content analysis. The risk factors associated with the prevalence of GIT parasitic infections were geographical location, deep litter system, broilers, age, crossbred breeds, and monsoon season.

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

Gastrointestinal helminth parasites are a concern for the poultry industry worldwide as they can affect the health, welfare, and production performance. A systematic review of the prevalence over time in different countries may improve our understanding of gastrointestinal helminthiasis in chickens and subsequently lead to improved poultry health. The aim of this systematic review and meta-analysis was to provide an overview of the published information regarding the epidemiology and the diagnostic approaches of chicken helminth infection. Six databases were searched for studies, and a total of 2,985 articles published between 1942 and 2019 were identified and subsequently screened for eligibility using title or abstract and full text assessment, resulting in 191 publications to be used in the study. Postmortem diagnostics (73.8%) and the flotation technique (28.8%) were commonly used to detect helminth infections with a pooled prevalence of 79.4% ranging from 4 to 100%. More than 30 helminth species in chicken populations were identified including Ascaridia galli (35.9%), Heterakis gallinarum (28.5%), Capillaria spp. (5.90%), and Raillietina spp. (19.0%) being the most prevalent. The reported prevalence of helminth infection decreased over time in developing countries while it increased in the developed world. Chicken kept in backyard and free-range systems had a markedly higher pooled prevalence of helminth infection (82.6 and 84.8%, respectively) than those housed in cage production systems (63.6%). This may indicate the need for more rigorous control and prevention measures in free-range and backyard production systems using regular deworming coupled with access to early and accurate diagnosis allowing for early intervention.

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

In the Mekong Delta region of Vietnam, small-scale chicken farming is common. However, high levels of disease or mortality in such flocks impair economic development and challenge the livelihoods of many rural households. We investigated 61 diseased small-scale flocks (122 chickens) for evidence of infection with 5 bacteria, 4 viruses, and helminths. Serological profiles (ELISA) were also determined against 6 of these pathogens. The aims of this study were the following: (1) to investigate the prevalence of different pathogens and to compare the probability of detection of bacterial pathogens using PCR and culture; (2) to investigate the relationship between detection of organisms in birds' tissues and the observed morbidity and mortality, as well as their antibody profile; and (3) to characterize risk factors for infection with specific viral or bacterial pathogens. We used PCR to test for viral (viruses causing infectious bronchitis [IB], highly pathogenic avian influenza [HPAI], Newcastle disease, and infectious bursal disease [IBD]) and bacterial pathogens (Mycoplasma gallisepticum, Pasteurella multocida, Avibacterium paragallinarum, and Ornithobacterium rhinotracheale [ORT]). The latter two were also investigated in respiratory tissues by conventional culture. Colisepticemic Escherichia coli was investigated by liver or spleen culture. In 49 of 61 (80.3%) flocks, at least one bacterial or viral pathogen was detected, and in 29 (47.5%) flocks, more than one pathogen was detected. A. paragallinarum was detected in 62.3% flocks, followed by M. gallisepticum (26.2%), viruses causing IBD (24.6%) and IB (21.3%), septicemic E. coli (14.8%), ORT (13.1%), and HPAI viruses (4.9%). Of all flocks, 67.2% flocks were colonized by helminths. Mortality was highest among flocks infected with HPAI (100%, interquartile range [IQR]: 81.6–100%) and lowest with flocks infected with ORT (5.3%, IQR: 1.1–9.0%). The results indicated slight agreement (kappa ≤ 0.167) between detection by PCR and culture for both A. paragallinarum and ORT, as well as between the presence of cestodes and ORT infection (kappa = 0.317). Control of A. paragallinarum, viruses causing HPAI, IBD, and IB, M. gallisepticum, and gastrointestinal helminths should be a priority in small-scale flocks.