Diseases in chicks and laying hens during the first 12 years after battery cages were banned in Switzerland.

Between 1992 and 2003, a period of 12 years after the definitive ban on battery cages in Switzerland, more than 10,000 replacement chicks and laying hens were examined postmortem. There was a significant decrease in the incidence of viral diseases, mostly due to a reduction in Marek's disease, but there was a marked increase in bacterial diseases, particularly since 1999, mainly due to colisepticaemia in young laying hens. There was a steady decrease in parasitic infections, but the incidence of non-infectious diseases varied from year to year, with no clear trends. There were no significant emerging diseases or economic losses in the alternative housing systems. Vaccination and hygiene were the most effective precautions against infections, and control strategies brought about a marked decline in notifiable diseases, especially for Salmonella Enteritidis. Fifteen years after the ban on battery cages in Switzerland, the health and egg production of laying hens is good.

Characterization of western European field isolates and vaccine strains of avian infectious laryngotracheitis virus by restriction fragment length polymorphism and sequence analysis.

Infectious laryngotracheitis is a dramatic disease of the upper respiratory tract in poultry caused by a herpesvirus. In this study we investigated the characteristics of western European field isolates of infectious laryngotracheitis virus (ILTV) to gain more information on their diversity. The examined 104 isolates, collected from acute outbreaks during the last 35 years, originated from eight different countries: Switzerland (48), Germany (21), Sweden (14), the United Kingdom (9), Italy (5), Belgium (4), Austria (2), and Norway (1). Two vaccines, a chicken embryo origin product and a tissue culture origin product, were included in the survey. Polymerase chain reaction (PCR) was performed to amplify a 2.1-kb DNA fragment of ILTV using primers generated for the thymidine kinase (TK) gene. After digestion of the resulting PCR products by restriction endonuclease HaeIII, restriction fragment length polymorphism analysis was carried out. PCR amplicons of three field isolates and both vaccine strains were selected for sequencing. Here 98 field isolates showed the same cleavage pattern and were identical to both vaccine strains (clone 1). They differed from five Swiss isolates with identical cleavage pattern (clone 2) and one Swedish isolate (clone 3). The present study demonstrated that at least three clones of ILTV have been circulating in western Europe during the last 35 years. The 104 isolates analyzed showed a high genetic similarity regarding the TK gene, and a large majority of the field isolates (98/104) were genetically related to the vaccine strains.

[Avian leukosis subgroup J in broiler breeders in Switzerland]. / Aviäre Leukose Subtyp J bei Mastelterntieren in der Schweiz.

Since a new envelope subgroup (J) of the avian leukosis-sarcomatosis-complex was isolated for the first time from broiler breeders in the United Kingdom in 1989 and was characterized and associated with myeloid leukosis (syn. myelocytomatosis) the emergence of this subgroup was reported from all over the world. Thus the first known case of subgroup J avian leukosis in Switzerland in four imported broiler breeder flocks will be described. A total of 53 broiler breeder birds from four flocks showing reduced performance and increased mortality were submitted for postmortem examination. Approximately 20 blood samples from each flock were monitored serologically for antibodies against avian leukosis virus subgroup J (ALV-J). On necropsy myeloid leukosis (ML) was diagnosed in all four flocks. Furthermore the blood samples of three flocks showed significant ELISA-titres for ALV-J.

[Reasons for condemnation of slaughtered broilers from two large Swiss producers]. / Konfiskationsursachen bei geschlachteten Broilern aus zwei grossen schweizerischen Mastorganisationen.

30 broiler flocks from two majors Swiss broiler producing companies were examined for lesions relevant to meat inspection between November 1995 and April 1996. 71.8% of condemned carcasses and viscera were assigned to ascites syndrome, bacterial infections and runting. Other diseases and lesions due to injury or processing were rare. Escherichia coli was responsible for the majority of infections. The average condemnation rate (1.0%) corresponded to findings in literature.

[Detection of Salmonella enteritidis in suspected flocks of laying hens]. / Zum Salmonella enteritidis-Nachweis in verdächtigen Legehennenherden.

60 birds and environmental samples from 41 suspect flocks (S. enteritidis in faeces or litter, positive serology, close connection with human cases) were investigated to define material and minimal number of birds for detection of infection. S. enteritidis was found in 26/41 (63%) flocks with marked differences in prevalence. S. enteritidis was isolated from ovary (96% of positive flocks), oviduct and liver (87%), spleen (83%), caecal contents (50%) and faeces from the litter floor (57%), but never from egg shells and membranes. As a consequence of this study the bacteriological examination of birds is highly recommended.

[Infectious laryngotracheitis (ILT) in Switzerland: recent situation and thoughts about future possibilities for control]. / Die Infektiöse Laryngotracheitis (ILT) in der Schweiz: Aktueller Stand und Gedanken zu zukünftigen Bekämpfungsmöglichkeiten.

This short review highlights the characteristics of infectious laryngotracheitis, the diagnostic methods and the actual disease situation in Switzerland and other European countries. Recommendations for a future control policy are outlined.

[Salmonella gallinarum-pullorum infection of poultry: experiences in Switzerland]. / Die Salmonella gallinarum-pullorum-Infektion des Huhnes: Erfahrungen in der Schweiz.

37 Salmonella gallinarum-pullorum-strains were isolated from dead poultry between 1986 and 1996. All strains except one belonged to the biovar pullorum. 33 isolates were from fancy poultry flocks, four from backyard flocks. 10 of 12 chicks and 10 of 25 adult birds showed clinical signs of disease. The growing significance of fancy and backyard flocks as a reservoir for S. gallinarum-pullorum is emphasized in view of the increase in free range management of commercial layer and broiler flocks.

The Swiss control programme for Salmonella enteritidis in laying hens: experiences and problems.

The Swiss control programme for Salmonella Enteritidis began at the end of 1993. All efforts are focused on the elimination of infected parent and layer flocks and on the production of S. Enteritidis-free eggs. The new Zoonosis Order and more stringent import regulations help to identify S. Enteritidis-positive parent layer and layer flocks. Other measures, such as additional voluntary monitoring of parent layer flocks, hatcheries and layer flocks, increased hygiene on poultry farms and the use of heat-treated feed, serve to prevent the spread of S. Enteritidis. An important point of concern is the elimination of S. Enteritidis from contaminated poultry farms, particularly from free-range farms. In the last two years, the number of reported infections of S. Enteritidis in humans has almost fallen to the level of 1988 (the year before the onset of S. Enteritidis infection in laying hens in Switzerland).

Etiological agents of mycobacterioses in pet birds between 1986 and 1995.

Between May 1986 and June 1995, mycobacteriosis was diagnosed by histology and microscopy in 204 (3.8%) of 5,345 necropsied pet birds. The predominant macroscopic changes were enlargement of the liver and spleen and thickening of intestinal walls. Attempts to cultivate mycobacteria were made in 110 cases. Acid-fact bacilli grew in 66 specimens (60%) only. In 18 cases we failed to obtain subcultures. Therefore, species identification could be performed for only 48 isolates. Identification was carried out by conventional biochemical tests as well as by PCR-mediated sequencing of the 16S rRNA gene. The majority of the isolates were Mycobacterium genavense (34 isolates), followed by M. avium complex (8), M. fortuitum (2), M. tuberculosis (2), M. gordonae (1), and M. nonchromogenicum (1). The significance of M. genavense as a zoonotic agent remains to be determined.

[Mycobacteriosis of ornamental birds--frequency, pathologo-anatomic, histologic and microbiologic data]. / Die Mykobakteriose des Ziervogels--Häufigkeit, pathologisch-anatomische, histologische und mikrobiologische Befunde.

Mycobacteriosis was diagnosed in 146 (3.8%) of 3801 necropsied pet birds between 1986 und 1991. Gross changes in 62 pet birds with histologically and culturally confirmed mycobacteriosis were predominantly enlargement of liver and spleen and thickening of intestinal walls. Three histological patterns could be observed: granulomas, sheet-like proliferations of mycobacteria-laden epithelioid cells and single scattered macrophages filled with acid-fast bacteria. Mycobacteria grew in 27 (43.6%) of 62 cultures, but the species could only be identified in 13 (21.0%) cases (5 x M. avium-Complex, 3 x M. genavense, 2 x M. fortuitum, 1 x M. gordonae, 1 x M. nonchromogenicum and 1 x M. tuberculosis). The significance of mycobacteriosis in pet birds as a zoonosis remains to be determined.

Molecular epidemiology of Salmonella enteritidis.

Sixteen strains of Salmonella enteritidis isolated in 1991 from 13 unrelated poultry-associated sources, 7 strains from 2 community outbreaks, and 18 human sporadic isolates were investigated by phage typing, analysis of rRNA gene restriction patterns (ribotyping) and plasmid profiles. Four different phage types and 10 SphI patterns were found, whereas plasmids were identical in all but 4 isolates. Only one ribotype (RT A) occurred among both human and avian strains. This particular ribotype was also responsible for the two outbreaks investigated, suggesting that such strains may be of special significance for the increase of S. enteritidis infections.

[Diarrheal diseases in 1 to 4 week old suckling piglets from problem herds: microbial spectrum, histology, enzyme histochemistry]. / Durchfallerkrankungen bei 1 bis 4 Wochen alten Saugferkeln aus Problembetrieben: Erregerspektrum, Histologie, Enzymhistochemie.

Postmortem investigation was performed on 54 scouring (soon after onset of diarrhea) and 23 healthy suckling piglets. The animals were 1 to 4 weeks of age and were collected from 27 herds. In 21 herds diarrhea had been observed for a long time in piglets in this age group. Coccidia were found in 34 piglets, rotavirus in 2, cryptosporidia in 2, enterotoxigenic E. coli in 6, attaching and effacing E. coli in 1, Cl. perfringens type C in 1, Campylobacter coli in 53 and C. hyointestinalis in 8 piglets. Some of these microorganisms were isolated from healthy piglets as well. TGE- and PED-Virus antigen, as well as Salmonella were not recovered from any of the pigs. Results of the histopathological and enzyme histochemical investigations were in agreement with data from the literature. They confirmed and emphasized the role of coccidia as enteropathogenic agents in the animals examined. On the other hand evidence was shown, that C. coli is non-pathogenic. The role of C. hyointestinalis could not be fully elucidated. At least one sort of enteropathogenic agent was detected in about 68% (n = 37) of the scouring pigs or was present in 81% (n = 17) of the herds, respectively.

Use of IgG- and IgM-specific ELISAs for the assessment of exposure status of chickens to Eimeria species.

Simple and reliable methods for the determination of the exposure status of chickens to Eimeria species are required. For this purpose an enzyme-linked immunosorbent assay (ELISA) detecting specific IgG and IgM antibodies in serum samples was evaluated. Sera from chickens hyperimmunized by intramuscular injection of a saline extract of Eimeria tenella sporozoites were used to determine optimal reaction conditions in the ELISA which were found to be at a serum dilution of 1:100 and an antigen concentration of 0.2 microgram per reaction well. Saline extracts of sporulated oocysts and purified sporozoites of E. tenella were also potent antigens but most studies were carried out with sporozoite antigen. In a trial with 80 chickens, concentrations of serum IgM directed against sporozoite antigen increased significantly 9 days after primary infection with 10,000 oocysts of E. tenella per animal. IgM levels subsequently decreased rapidly reaching a plateau level only slightly higher than uninfected controls by about 15 days post-infection. In chickens challenged with 10,000 oocysts 21 days after primary infection significant increases of IgM levels were observed 2, 6 and 12 days later. In contrast IgG levels increased only slightly after primary infection but significant increases occurred after challenge infection so that by Day 12 after challenge sporozoite-specific IgG levels were much higher than in control chickens. Thus, it may be possible to discriminate between chickens actually infected with Eimeria (as indicated by high levels of antiparasite IgM), chickens which have been repeatedly exposed to Eimeria (as indicated by high levels of antiparasite IgG) and unexposed birds. The applicability of this ELISA, using sporozoite antigen of E. tenella to practical situations was substantially confirmed, since sampling of over 1000 sera from commercially reared broilers and laying hens indicated that broilers, maintained on medicated food, had low levels of IgM and IgG whereas 84-97% of the laying hens, receiving drug-free feed, had relatively high IgG concentrations. These results reflect low and rare exposure to Eimeria infections in broilers and repeated exposure of the hens.