Riemerella anatipestifer

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Riemerella anatipestifer
Phylum	Bacteroidetes
Class	Flavobacteria
Order	Flavobacteriales
Family	Flavobacteriaceae
Genus	Riemerella
Species	R. anatipestifer

Previously Known As: Moraxella anatipestifer — Pasteurella anatipestifer — Pfeifferella anatipestifer

Disease Known As: Duck Septicaemia — Goose Influenza — Infectious Serositis — New Duck Disease — Polyserositis — Riemerellosis

Introduction

Riemerella anatipestifer is a gram negative bacterial pathogen primarily causing septicaemia in ducks and geese. This may lead to high mortality and significant economic losses both from direct fatalities and carcass condemnation.

There are 21 known serotypes with no cross-reactivity between them. Multiple serotypes are often present in one outbreak.

Riemerella anatipestifer is not zoonotic.

Distribution

Worldwide – widespread in China, Thailand, Taiwan, USA, UK, Germany and Hungary and present to variable degrees in most other poultry producing countries.

Transmission occurs through infected birds and premises, the organism being shed in nasal and sinusoid secretions. These can contaminate water and drinkers/feeders. It can also enter through broken skin. No evidence of vertical transmission has been published. Infection spreads fast in confined houses. Healthy ducklings may also carry the infection asymptomatically in their respiratory tracts.

Hosts

Ducks and geese are the main hosts but turkeys, chickens, pheasants, guinea-fowl, quails and swans can also be infected.

Birds 1-8 weeks old are usually affected.

Clinical Signs

Systemic infection is common. However, infection may also become localised in joints and skin in chronic cases. In addition, localised infection of the oviduct of young layers can lead to permanent damage to the developing reproductive tract. This will prevent the proper formation or passage of eggs and result in the birds becoming "blind layers" when they grow up.

Disease is then multisystemic and can comprise of greenish diarrhoea, pyrexia, anorexia, growth retardation, nasal discharge, coughing, restlessness, polydipsia, ataxia, hypermetria, weakness, tremors and limb swelling. Nervous signs develop when the organism crosses the blood:brain barrier. Conjunctivitis, chemosis, scleral inflammation and ocular discharge sometimes also occur. In late disease, young birds may suffer from characteristic convulsions.

High mortality up to 75% occurs in ducklings and goslings. In most cases, death occurs within 12-24h of the onset of clinical signs.

Pathological Lesions

On post-mortem, infection causes a yellowish-white fibrinous exudate to cover the heart, liver and air sacs. Air sacs may also contain a caseous exudate and oviducts caseous plugs in female birds. The same yellow exudate can be found in the nervous tissue and also in the joints and skin in chronic cases, forming honey-comb like dermatitis. Carcasses are septicaemic and congested.

On histopathology, mononuclear and heterophilic cells infiltrate the serous surfaces of pericardium, air sacs and liver. Multinuclear giant cells may develop in the air sacs and skin lesions in chronic cases.

Diagnosis

Presumptive diagnosis is often made from history, clinical signs and lesions, based upon the nervous signs and fibrinous pericardial, perihepatic, meningeal and respiratory lesions and exudate. Although suggestive, these are not specific.

R. anatipestifer can be easily isolated, from brain, heart blood, air sacs, liver or oviduct and grows on soy media enriched with sheep blood or bovine serum forming non-haemolytic colonies. Incubation ideally under 5% carbon dioxide. Isolates can then be serotyped with agglutination and agar gel precipitation.

A PCR-based diagnostic test has also been developed.

ELISA and serum tube agglutination can be used for antibody detection, of which ELISA is the most sensitive.

Treatment

Enrofloxacin, Lincomycin, Novobiocin, Procaine Penicillin and Trimethoprim-Sulphonamides can be used, some as injectables, others in feed. However, current legislation in many countries does not allow the use of quinolones. Antibiotic sensitivity testing should be carried out prior to treatment.

Control

A multivalent vaccine is available in live and inactivated forms. The live form is administered as an aerosol spray at one day of age and the inactivated as two injections at 2 and 3 weeks of age.

Management, sanitation and minimisation of stress also play major roles in prevention.

Riemerella anatipestifer Learning Resources
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References

This article was originally sourced from The Animal Health & Production Compendium (AHPC) published online by CABI during the OVAL Project. The datasheet was accessed on 25 June 2011.