Health status of free-ranging ring-necked pheasant chicks (Phasianus colchicus) in North-Western Germany

Being a typical ground-breeding bird of the agricultural landscape in Germany, the pheasant has experienced a strong and persistent population decline with a hitherto unexplained cause. Contributing factors to the ongoing negative trend, such as the effects of pesticides, diseases, predation, increase in traffic and reduced fallow periods, are currently being controversially discussed. In the present study, 62 free-ranging pheasant chicks were caught within a two-year period in three federal states of Germany; Lower Saxony, North Rhine-Westphalia and Schleswig-Holstein. The pheasant chicks were divided into three age groups to detect differences in their development and physical constitution. In addition, pathomorphological, parasitological, virological, bacteriological and toxicological investigations were performed. The younger chicks were emaciated, while the older chicks were of moderate to good nutritional status. However, the latter age group was limited to a maximum of three chicks per hen, while the youngest age class comprised up to ten chicks. The majority of chicks suffered from dermatitis of the periocular and caudal region of the head (57-94%) of unknown origin. In addition, intestinal enteritis (100%), pneumonia (26%), hepatitis (24%), perineuritis (6%), tracheitis (24%), muscle degeneration (1%) and myositis (1%) were found. In 78% of the cases, various Mycoplasma spp. were isolated. Mycoplasma gallisepticum (MG) was not detected using an MG-specific PCR. Parasitic infections included Philopteridae (55%), Coccidia (48%), Heterakis/Ascaridia spp. (8%) and Syngamus trachea (13%). A total of 8% of the chicks were Avian metapneumovirus (AMPV) positive using RT-PCR, 16% positive for infectious bronchitis virus (IBV) using RT-PCR, and 2% positive for haemorrhagic enteritis virus (HEV) using PCR. All samples tested for avian encephalomyelitis virus (AEV), infectious bursal disease virus (IBDV) or infectious laryngotracheitis virus (ILTV) were negative. The pool samples of the ten chicks were negative for all acid, alkaline-free and derivative substances, while two out of three samples tested were positive for the herbicide glyphosate. Pheasant chick deaths may often have been triggered by poor nutritional status, probably in association with inflammatory changes in various tissues and organs as well as bacterial and parasitic pathogens. Theses impacts may have played a major role in the decline in pheasant populations.

Investigation into diseases in free-ranging ring-necked pheasants (Phasianus colchicus) in northwestern Germany during population decline with special reference to infectious pathogens

The population of ring-necked pheasants (Phasianus colchicus) is decreasing all over Germany since the years 2008/2009. Besides impacts of habitat changes caused by current rates of land conversion, climatic influences or predators, a contribution of infectious pathogens needs also to be considered. Infectious and non-infectious diseases in free-living populations of ring-necked pheasants have been scarcely investigated so far. In the present study, carcasses of 258 deceased free-ranging pheasants of different age groups, predominantly adult pheasants, collected over a period of 4 years in the states of Lower Saxony, North Rhine–Westphalia and Schleswig-Holstein, were examined pathomorphologically, parasitologically, virologically and bacteriologically, with a focus set on infectious pathogens. A periocular and perinasal dermatitis of unknown origin was present in 62.3% of the pheasants. Additional alterations included protozoal cysts in the skeletal musculature (19.0%), hepatitis (21.7%), enteritis (18.7%), gastritis (12.6%), and pneumonia (11.7%). In single cases, neoplasms (2.6%) and mycobacteriosis (1.7%) occurred. Further findings included identification of coronaviral DNA from trachea or caecal tonsils (16.8%), siadenoviral DNA (7.6%), avian metapneumoviral RNA (6.6%), and infectious bursal disease viral RNA (3.7%). Polymerase chain reaction (PCR) on herpesvirus, avian influenza virus (AIV), paramyxovirus type 1 (PMV-1), avian encephalomyelitis virus (AEV), and chlamydia were negative. Based on the present results, there is no indication of a specific pathogen as a sole cause for population decline in adult pheasants. However, an infectious disease can still not be completely excluded as it may only affect reproduction effectivity or a certain age group of pheasants (e.g., chicks) which were not presented in the study.

[Role of the poultry red mite (Dermanyssus gallinae) in the transmission of avian influenza A virus]

OBJECTIVE

The aim of this study was to investigate the role of the poultry red mite (Dermanyssus [D.] gallinae) in the horizontal transmission of avian influenza A virus (AIV) to chickens. This mite is the most common ectoparasite in poultry worldwide, and may play a role in the spread of infectious agents including AIV. Currently, the control of mites is difficult due to frequently developed resistance to many acaricides, their nocturnality and their ability to survive hidden without feeding for months.

MATERIALS AND METHODS

D. gallinae were collected in a commercial layer farm and housed in self-made fibreboard boxes. SPF chickens were intravenously infected with AIV strain A/turkey/Ontario/7732/1966 (H5N9). The viraemia in chickens was monitored and at an appropriate time point about 1000 mites were allowed to suck on the AIV infected chickens. Re-isolation of the virus from blood-filled mites was tried daily for 14 days using chicken embryo fibroblast cultures and embryonated chicken eggs. Subsequently, the virus containing mites were placed into boxes that contained naïve SPF chickens to enable virus transmission from mites to chickens. Possible transmission to the chickens was examined using clinical signs, serology, gross lesions, histopathology and immunohistochemistry.

RESULTS

Chickens developed a dose-dependent viraemia one day after infection, therefore this day was chosen for the bloodmeal of the mites. AIV was detected in mites after bloodsucking on AIV-infected chickens over a 10-day period. Naïve SPF chickens were infected during bloodsucking of AIV carrying mites. AIV isolates in mites and in chickens were undistinguishable from the original AIV inoculum by RT-PCR.

CONCLUSIONS

D. gallinae ingested AIV during bloodmeals on AIV infected chickens and are able to transmit AIV to SPF chickens. Therefore, mites serve as mechanical vector of AIV and may play a major role in the circulation of AIV within a facility or area although the life span of infectious virus in the mite is limited.

CLINICAL RELEVANCE

The proven transmission requires more than ever a systematic control of this ectoparasite in order to maintain poultry health and productivity. The demonstrated vector function of this mite is of great significance for poultry flocks all over the world.

[Multicausal infectious respiratory tract disease of young fattening turkeys]

The outbreak of the disease occurred in a large multiple-age farm with about 50,000 meat turkeys, where groups of 6-8000 one-day-old birds were stalled up every 14 days. All the turkey poults housed were affected mostly in the 1.-3. week of the life. The respiratory disease spread rapidly within the flocks and were characterised clinically by inclination of huddle, ruffled feathers, anorexia, stunted growth, swelling of the infraorbital sinus and nasal discharge. The clinical apparent disease lasted 3 to 4 weeks on the average in the affected flocks and were associated with a mortality from 7-20 percent. The main pathoanatomical lesions were catarrhal-fibrinopurulent rhinitis, sinusitis, tracheitis, bronchopneumonia and air sacculitis as well as atrophy of the thymus. Fibrinous adhesive peri- and epicarditis, perihepatitis, miliary necrotic foci in the liver and diarrhea have been found less frequently. The results of cultural and serological examinations of moribund and dead turkey poults of 6 different flocks indicate that Bordetella avium and Chlamydia psittaci are the primary inciting agents of the respiratory disease. However, the following severe course of the disease were mainly caused by concurrent infections with Klebsiella pneumoniae subsp. pneumoniae, Escherichia coli and Pseudomonas fluorescens. In some cases coccidiosis with lesions in ceca were additionally diagnosed. Campylobacter jejuni could be always isolated culturally from the liquid cecal content of diseased birds.

[Comparative studies of paramyxovirus isolates from wild birds]

As a result of a surveillance programme in North-Germany, paramyxovirus-isolates of serogroup 1 with different pathogenicity were isolated from different species of feral birds (Black-headed gull, mallard, tawny owl, tree sparrow, mute swan). In chick embryo fibroblast monolayers these isolates produced plaques exhibiting different plaque morphology. After cloning the isolates, further physicochemical, serological and pathogenicity testings were performed. On the basis of mean death time and intracerebral pathogenicity index, two of the isolates were found to be avirulent (lentogenic), whereas the others proved to be virulent (velogenic). SDS-Polyacrylamide-gel-electrophoresis showed polypeptide patterns similar to that of the PMV-1 reference strains. Summarizing all relevant findings of these investigations under consideration of the suggestions for the virological description of avian PMV (Alexander, 1987; Alexander et al., 1987; Who-Expert-Committee, 1980), including the recently established serotyping by means of monoclonal antibodies, the following designations of the PMV isolates tested herein are proposed: 1. PMV-1/black-headed gull/Germany/SSP-233/83, lentogenic NDV, monoclonal antibody group G 2. PMV-1/mallard/Germany/SSP-284/83, lentogenic NDV, monoclonal antibody group H 3. PMV-1/tawny owl/Germany/SSP-262/84, velogenic NDV, monoclonal antibody group B 4. PMV-1/tree sparrow nestling/Germany/SSP-352/84, velogenic NDV, monoclonal antibody group B 5. PMV-1/mute swan/Germany/SSP-204/85, velogenic NDV, monoclonal antibody group B.

[The "diseased" or "dead" guillemots (Uria aalge), three-toed gulls (Rissa tridactyla), silver gulls (Larus argentatus) and laughing gulls (Larus ridibundus) found in the area of the German Bay, 1982-1985]

Between 1982 and 1985 the cadavers of 50 Guillemots (Uria aalge), 41 Kittiwakes (Rissa tridactyla), 26 Herring Gulls (Larus argentatus) and 34 Black-headed Gulls (Larus ridibundus) were examined pathological, bacteriological and virological. The probable cause of death was established. Parasitosis were particularly prevalent in Herring Gulls (49%), where the main infection--as in Black-headed Gulls--was with Cestoides. In Kittiwakes and Guillemots mainly Spiruroideae were recorded. The commonest bacterium isolated in organs and intestinal tract was Escherichia coli, followed by Aeromonas hydrophila and Clostridium perfringens. Salmonella were found in the organs of 5% and in the intestinal tract of 3% of the birds. The species of Salmonella most frequently isolated was Salmonella typhimurium varieties copenhagen. Also recorded were Yersinia intermedia Serovar 0:17 (1x), Pseudomonas spp. (2x), bacteria of the Haemophilus-Pasteurella-Actinobacillus group (1x), Pasteurella multocida (2x), Moraxella septicaemiae (1x), Campylobacter spec. (1x), Mycoplasma spec. (6x), DNase positive Staphylococcus spec. (4x) and Streptococcus spec. (6x). Less in evidence among the birds examined were fungus diseases with Aspergillus spec. (4x) and Blastomyces spec. (4x). As for viruses one Guillemot was found to have an Adenovirus and another one to have a Paramyxovirus. From one of the Herring Gulls there also was isolated a Paramyxovirus, from a second one to a Reovirus. Three other species isolated have get to be identified. The chief cause of sickness and death in the Guillemots was oil-contamination. The majority of the examined Kittiwakes and Herring Gulls were victims of pathogenic agents. Many of the Black-headed Gulls died through traumata as gunshots or road traffic etc. In order to establish the causes of sickness and death in seabirds and to ascertain the importance of the various species as possible carriers of infectious diseases, a systematic series of investigation will be necessary. Without this it will not be possible to assess their epidemiological relevance for other wild birds, domestic poultry and humans.