Duckling Flocks Research Articles

Comparative pathogenicity of duck hepatitis A virus genotype 3 in different duck breeds: Implications of the diagnosis and prevention of duck viral hepatitis

Duck hepatitis A virus (DHAV) infection in ducklings causes acute hepatitis with considerable economic losses. In this study, Pekin and Muscovy duckling flocks (n=9) suffering from high mortality and hepatic lesions were examined by RT-PCR for DVHA. 44.4 % (4/9) of samples were positive for DHAV (5′ UTR region), of which 100 % (4/4) were DVHA-3 (VP1 gene). VP1 sequencing and phylogenetic analysis of an isolate originated from Muscovy ducklings showed that it shared 96.8 % −100 %, 88.5–89.2 %, and 86.5–88.2 % nucleotide similarity (ns) with the Egyptian, Korean-Vietnamese, and Chinese DVHA-3 strains, respectively. It was distinguished from the DHAV-1 vaccine (67.6 % ns). The sequenced DVHA-3 isolate was used to experimentally infect 5-day-old Pekin and Muscovy ducklings vs. control groups. No apparent clinical signs or deaths were reported in the experimentally-infected groups. Pekin ducklings showed greater cloacal viral shedding than Muscovy until the 6th dpi (P<0.05). DVHA-3 induced a significant rise in IFN-β and IL-1β serum levels, where Muscovy ducklings' levels were higher than Pekin ducklings. Among the biochemical parameters, AST was only increased on the 4th dpi in both breeds vs. control (P<0.05). Compared to Muscovy ducklings at 2, 4, and 6 day post infection (dpi), the infected Pekin group had lower lipase levels (P≥0.05, p<0.05, and p<0.05, respectively), while ALT was higher at 4 and 6 dpi (P<0.05). The histopathological lesions supported the gross lesions, and their scores were dominant at 2 and 4 dpi in both breeds. At 6 and 8 dpi, Pekin showed more severe histopathological changes compared to Muscovy for the liver, heart, brain, and intestines; the pancreas, kidney, and lung showed the opposite pattern. In conclusion, Pekin ducklings displayed distinct DHAV-3 infection results from Muscovy ducklings, and more research utilizing a variety of DHAV-3 strains has to be carried out.

First Report of Duck Hepatitis A Virus 3 from Duckling Flocks of Egypt

Duck hepatitis A viruses (DHAV-1, DHAV-2, and DHAV-3) are the predominant causes of duck virus hepatitis (DVH), a disease of ducklings that leads to massive morbidities, mortalities, and economic losses. As a duck-producing country, Egypt suffered lately from several attacks of DVH, despite the regular vaccination of birds. Between Spring 2016 and Summer 2018, 54 duckling flocks in the Sharkia province of Egypt were tested using the reverse-transcription PCR (RT-PCR) based on the DHAV-3D targeting primers. Of them, 27.8% (15/54) were positive. Upon retesting of positive samples using RT-PCR and duck hepatitis A virus (DHAV)-3 VP1-based primers, 33.3% (5/15) contained DHAV-3 RNA. For further analysis at the molecular level, the VP1 and the 3D genes were sequenced using the same primer sets used earlier. The phylogenetic trees confirmed that study sequences belonged to DHAV-3. However, they were displayed as a separate cluster following a geographically dependent distribution. They were also completely unrelated to the Egyptian DHAV-1-based vaccine. This was further confirmed by low nucleotide and amino acid identities in relation to this vaccine. In addition, the VP1 and 3D genes had the same phylogenetic topography. The study VP1 sequences had three unique amino acid substitutions (L59, V208 only in one strain, and C219). As far as we know, this is the first report on DHAV-3 outside Asia, particularly in Egypt. Accordingly, the vaccination strategy against DHAV should be quickly updated to avoid further dissemination of the virus. The epidemiology, pathogenicity, and evolution of DHAV-3 should be carefully monitored in Egypt.

Outbreaks of Duck Hepatitis A Virus in Egyptian Duckling Flocks.

During 2015, duck farms (n = 27) in Sharkia Province, Egypt, experienced several disease outbreaks leading to mortality and nervous manifestations. Upon necropsy, the affected ducklings showed liver lesions, such as hemorrhage or necrosis, suggestive of duck virus hepatitis (DVH). Reverse transcription-PCR (RT-PCR), on the basis of the 3D gene, found duck livers from 21 farms to be positive for duck hepatitis A virus serotype 1 (DHAV-1). All duck breeds (Pekin, Mallard, and Muscovy) were infected. The virus was isolated in embryonated chicken eggs, which showed embryonic mortality (40%-80%) within 5-7 days, stunting or dwarfing (69.6%), and necrotic liver foci (60.9%). The VP1 gene of 11 DHAV-1 strains was characterized by RT-PCR and Sanger sequencing. All study strains were clustered in a monophyletic branch within subclade B2 of Group 4 and were separated from the Egyptian vaccine strain. Several amino acid (aa) residues, such as V129, S142 (only in four strains), L181, G184, and K217, were related to virus attenuation. However, two aa residues (N193 and E205), found in virulent DHAV-1 strains, were also observed in our strains. This study confirms the circulation of DHAV-1 (subclade B2) in Lower Egypt and elucidates the phylogenetic characters of the VP1 genes, which will be useful in following the local trends of DHAV-1 infections. Further studies are indicated to determine the correlation between these mutations and the virulence of the Egyptian DHAV-1 isolates.

Outbreak of duck viral hepatitis in duckling flocks in Poland - case report

Abstract The aim of the study was to determine the aetiologic agent causing deaths in two flocks of Pekin ducklings at the age of 12 d in Poland. on the basis of clinical symptoms and pathological changes, viral hepatitis infection was suspected in the birds. During the necropsy, liver sections were collected, from which total cellular RNA was isolated. Then, real-time polymerase chain reaction (RT-PCR) was performed using primers complementary to the pre-S region of the duck hepatitis virus genome. In all liver samples, the presence of a 530 bp PCR product was detected. The RT-PCR demonstrated the presence of genetic material of duck hepatitis virus type 1 (DH type 1) in the examined ducklings.

Longitudinal Study of Salmonella and Campylobacter Species from Two Laying Duckling Flocks in The Central Region of Thailand

Longitudinal Study of Salmonella and Campylobacter Species from Two Laying Duckling Flocks in The Central Region of Thailand

Improved duplex RT-PCR assay for differential diagnosis of mixed infection of duck hepatitis A virus type 1 and type 3 in ducklings

Infection with duck hepatitis A virus (DHAV) causes an acute, rapidly spreading, and fatal disease of young ducklings. DHAV type 1 (DHAV-1) and type 3 (DHAV-3) have been identified in China. In this study, a duplex RT-PCR assay was developed to identify DHAV-1 and DHAV-3 with mixed infection. The method was shown to be high specificity and sensitivity. The minimum detection limit of the method has been determined to be 10pg total RNA templates extracted from duck liver samples or 102 copies viral RNA of DHAV-1 and DHAV-3 respectively. Using the method, from 60 clinical liver samples of 26 duckling flocks in Shandong, Guangdong, Sichuan and Henan provinces of China, 15 (57.7%) flocks were identified as mixed infection of DHAV-1 and DHAV-3, and 9 (34.6%) flocks were DHAV-1 or DHAV-3 single infection. Among them, 38.3% (23/60) of duckling samples were detected as mixed infection of DHAV-1 and DHAV-3, and 48.3% (29/60) of samples were DHAV-1 or DHAV-3 single infection. These results indicated that the improved duplex RT-PCR method provides a rapid and cost-effective laboratory differential diagnosis for mixed infection of DHAV-1 and DHAV-3 in ducklings.

Salmonellaspp. Infection in Imported 1-Day-Old Chicks, Ducklings, and Turkey Poults: A Public Health Risk

The occurrence of Salmonella in 750 birds was assessed. The samples included the internal organs (caecal pouches, yolk sac, liver, and lung) of imported 1-day-old chicks (n = 150), grandparent chicks (n = 150), breeder chicks (n = 150), ducklings (n = 150), and turkey poults (n = 150), and paper-lined boxes (n = 250). Salmonellae isolated from the internal organs and paper-lined box of 1-day-old chicks, ducklings, and poults were mostly evident from the paper-lined box followed by caecal samples. Imported 1-day-old grandparent flocks were Salmonella free. Although 23.3% of the imported breeder flocks were positive for Salmonella, the imported duckling flocks and day-old turkey poults exhibited 19.3% and 12.6%, respectively. The widest diversity in isolated salmonellae was from the 1-day-old chicks where Salmonella Newport, Salmonella Kentucky, Salmonella Enteritidis, Salmonella Shubra, Salmonella Saintpaul, and Salmonella Agona were isolated. On the other hand, two Salmonella serovars were isolated from the imported breeders, Salmonella Shubra and Salmonella Shipley, and from the imported ducklings, Salmonella Shubra and Salmonella Saintpaul. The three Salmonella serovars isolated from the imported day-old turkey poults were Salmonella Shubra, Salmonella Newport, and Salmonella Saintpaul. The high percentage and diversity of Salmonella isolation from the imported birds cause concern because of the zoonotic potential of this agent and its economical importance to the local commercial poultry breeding industry. From 80 samples investigated for Salmonella, the positivity of the standard microbiological technique method was 17.5% and of the polymerase chain reaction method (Salmonella-specific invA gene) was 22.5%. The concordance between the two methods was 90% (k = 0.850). Our results indicated that the polymerase chain reaction approach is better than culturing for detecting Salmonella in poultry samples when using the preenriched medium combinations used in this study.

Incidence of Salmonella in imported day-old ducklings. Brazil, 1998-2003

The occurrence of Salmonella in a samples of 40 imported day-old duckling flocks was assessed from 1998 to 2003 according to the guidelines of the Brazilian National Poultry Health Program (Programa Nacional de Sanidade Avícola-PNSA). The pathogen was recovered from 26 flocks (65.0%). The most common serovars were S. Saintpaul and S. Kottbus. Up to four serovars were isolated from a single flock. Transportation box swabs (82.6%) and yolk sac pool (47.1%) showed the highest and the lowest frequency of Salmonella isolation, respectively. The high percentage of Salmonella isolation from imported day-old ducklings causes concern because of the zoonotic potential of this agent and its economical importance to commercial poultry breeding.

Mycotoxins and Feed Refusal by Pekin Ducks

High mortality occurred in two flocks of ducklings: 20% and 50% by 4 and 7 days of age, respectively. The feeds were found to contain 300 to 1176 ppb of deoxynivalenol (DON), 4.5 ppm of fumonisin, and 10 ppb of aflatoxin B1. No other mycotoxins were detected. Pathological analysis indicated that the ducklings were dehydrated with no feed in the gastrointestinal tract. Histopathology revealed no significant lesions. A necropsy diagnosis indicated a condition similar to starve-outs and feed refusal. An infectious cause of mortality was not suspected.

Furazolidone-Associated Cardiomyopathy in Two Indiana Flocks of Ducklings

Furazolidone (FZ)-induced congestive cardiomyopathy was diagnosed as the cause of high mortality and unthriftiness in two flocks of white pekin ducklings. Cumulative mortality at 7 weeks of age was 10.0-14.4%. Samples of FZ-supplemented feeds fed to flocks 1 and 2 from day 1 to day 14 had 140 and 150 mg FZ/kg, respectively. Both flocks had various degrees of water restriction. Clinically, the ducklings had dyspnea, incoordination, and abdominal distention. Necropsy findings included pulmonary edema and congestion, ascites, atrophic congested livers covered with sheets of fibrin, and cardiac enlargement with biventricular dilatation. Cardiac alterations were minimal by light microscopy. Ultrastructurally, scattered myocytes had myofibrillar lysis. These outbreaks occurred following intake of FZ at therapeutic dosages and emphasize the high susceptibility of young ducklings to FZ cardiotoxicity.

Studies in Duck Nutrition: 5. Bowed Legs in Ducks, a Nutritional Disorder

LEG weakness, characterized by a severe bowing of the legs ultimately resulting in complete crippling, has been observed at this laboratory in Pekin ducklings fed practical rations. (Heuser and associates, 1951; Scott and Heuser, 1952). Photographs showing this disorder in several degrees of severity are presented in Figure 1. Leg weakness similar in appearance to that observed here is encountered frequently in commercial flocks of ducklings in the Long Island area, representing an important economic problem since ducklings afflicted with the disorder usually do not make normal weight gains and therefore represent a loss at market time. Fritz and associates (1941) and Motzok and Branion (1948) have also reported the occurrence of bowed legs in ducklings raised under experimental conditions.In a preliminary experiment at this laboratory, it was found that the condition could not be prevented or corrected by the addition of high levels of cod liver oil, choline .