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Campylobacteriosis Of Pet Birds

Treatment and Control Strategy of Campylobacteriosis in Pet Birds

In 1886, Escherich observed Campylobacter like organisms in stool samples of children with diarrhoea. In 1913, McFaydean and Stockman first isolated and identified Campylobacter spp. in foetal tissues of aborted sheep. Confirmatory tests were also carried out by Smith in 1918 when similar organisms were isolated from aborted bovine foetuses.
In this period, the bacteria were known as Vibrio foetus. In 1963, due to certain differentiating characteristics, the bacteria were separated from Vibrionaceae family and the new genus Campylobacter (‘curved rod’) under Campylobacteriaceae family was proposed.

Etiology:

Campylobacter spp. is gram negative, comma shaped rods specially in infected tissues and young cultures. When two bacterial cells are found together in a microscopic field, occasionally it looks like ‘S’ or ‘wing of gull’ (‘flying seagull’).
They are motile by single unipolar/bipolar unsheathed flagella. Motility is darting or corkscrew type,  best observed by dark field microscopy.
Campylobacteriaceae family contains four genera namely Campylobacter, Arcobacter, Sulfurospirillum and Thiovulum. Currently there are 18 species and 6 sub species of the genus Campylobacter. Important species and sub species of Campylobacter are—Campylobacter jejuni ssp. jejuni, C. jejuni ssp. doyeli, C. coli, C. lari, C. fetus ssp. venerealis, C. fetus ssp. fetus. Thermotolerant Campylobacter (C. jejuni ssp. jejuni, C. coli, C. lari, some strains of C. upsaliensis) is isolated from pet birds with or without clinical syndrome. The thermotolerant species requires higher temperature for their growth (42 °C) which is provided by the pet birds due to high body temperature. Other than thermotolerant Campylobacter species, C. fetus and C. intestinalis have also isolated from parrots.

Host Susceptibility:

The pet birds such as tropical finches (juvenile Estrildidae), canaries, pigeons, parakeets [except red-crowned parakeet (Cyanoramphus novaezelandiae), dusky-headed parakeet (Aratinga weddellii), orange winged parrot (Amazona amazonica), red bellied macaws (Ara manilata)], emu, ostriches, waterfowls (mallard duck, shoveler duck, green-winged teal duck) are detected to harbour Campylobacter spp. In a study in Peruvian Amazon, parrots (Ara, Brotogeris and Pionites) were detected to be infected with Campylobacter spp.
 Wild and free-living birds, for instance, sparrows, crows, waders, black-headed gull (Larus ridibundus), sparrow hawk (Accipter nisus), jackdaw (Corvus monedula), hooded crow (Corvus cornix), dunnock (Prunella modularis), yellowhammer (Emberiza citrinella), white wagtail (Motacilla alba), dunlin (Calidris alpina), curlew sandpiper (Calidris ferruguinea), bald ibis (Geronticus eremita), little stint (Calidris minuta), broad-billed sandpiper (Limicola falcinellus), ruff (Philomachus pugnax), wood sandpiper (Tringa glareola), long-eared owl (Asio otus), starling (Sturnus vulgaris), reed warbler (Acrocephalus scirpaceus), winter wren (Troglodytes troglodytes), redwing (Turdus iliacus), blackbird (Turdus merula), song thrush (Turdus philomelos), fieldfare  (Turdus pilaris), blackbirds (Turdus merula), thrush (Turdus viscivorus) can act as reservoir of C. jejuni in nature. Certain clonal lineages of C. jejuni and species of wild birds are positively associated. Among the raptors (birds of prey), only hawks were detected to carry C. jejuni in their gut.
 Possession of Campylobacter spp. in birds depends on feeding habits. Gulls and crows have higher possession rate than the pigeons due to their preference for sewages. The shoveler ducks (Spatula clypeata) have higher carriage rate than green-winged teal duck (Anas acuta) because they prefer bottom sediments of aquatic environments containing molluscs as a feed.

Transmission:

Direct and indirect contact with infected birds and vectors (house flies, beetles, cockroaches, mealworms) are major ways of C. jejuni transmission in pet birds. C. jejuni is sensitive to oxygen and cannot grow below 31–32 °C temperature. So, they cannot survive in feed and drinking water for a prolonged period. Presence of C. jejuni in drinking water acts as an indicator for faecal contamination from wild birds or livestock. Sometimes, Campylobacter spp. can make a symbiosis with aquatic protozoa and survive in the environmental water.
 In human, major source of C. jejuni is contaminated poultry and its products, pork (with intact skin), beef, mutton and raw milk. Consumption of undercooked meat, milk or their products and handling poultry are the key ways of transmission.
 Direct or indirect contact with infected pet birds may play a role in zoonotic transmission of C. jejuni, although, not recorded in scientific literatures.

Pathogenesis:

In poultry, after transmission by faecal-oral route, C. jejuni colonizes at the mucous layer of caecal and cloacal crypts. The colonization is mediated by adhesin proteins like CadF (Campylobacter adhesin to fibronectin), PEB (Periplasmic/membrane-associated protein), CapA (Campylobacter adhesion protein A), JlpA (jejuni lipoprotein A), CiaB (Campylobacter invasin antigen B), flagella, and lipopolsaccharide (LPS). Occasional invasion of the intestinal epithelium takes place. No gross or microscopic lesions and clinical signs are produced in poultry during C. jejuni colonization or invasion. Similar type of C. jejuni colonization takes place in psittacines and canaries and they mostly act as asymptomatic carriers.
 Severe clinical signs and lesions are produced in tropical finches, especially in juvenile Estrildidae. The precise mechanism of C. jejuni infection in pet birds is still unexplored.

Clinical Symptoms:

No clinical signs and lesions are detected in canaries, psittacines, free-living (migrating passerines) and wild birds, and they act as asymptomatic reservoir of C. jejuni. In finches [juvenile Estrildidae, Gouldian finch (Chloebia gouldiae)], symptoms include sitting posture with its head under the wings, yellow droppings due to undigested starch (amylum), lethargy, and retarded moulting. High rate of mortality is observed among fledglings. In young ostriches, green coloured urination is the predominant sign.
 Recent study indicates the possible synergistic role of C. jejuni in proventricular dilatation disease (PDD) in parrots caused by avian bornavirus.

Lesion:

In tropical finches infected with C. jejuni, distinct cachexia, congestion in gastrointestinal tract, and presence of yellow coloured amylum or undigested seeds in gastrointestinal tract are the lesions. In sub-acute cases, hepatitis with focal necrosis and mucoid haemorrhagic enteritis is observed.

Diagnosis:

Clinical Specimens:
Fresh droppings (without urine) and cloacal swabs can be collected as clinical specimens. Post mortem samples include intestine or intestinal contents and liver.

Diagnostic Techniques:

(a) Direct Examination:

 A smear can be prepared from clinical samples and stained by dilute carbol fuchsin (DCF). Campylobacter spp. appears as pink coloured small curved rod arranged in a pair. Occasionally, the bacteria produce characteristic ‘S’ or ‘wing of gull’ appearance. The bacteria can also be demonstrated by wet mounts of collected droppings by phase contrast or dark field microscopy. Darting motility of the organisms is suggestive for Campylobacter spp.

(b) Isolation of bacteria from clinical samples:

 The selective media for Campylobacter isolation is broadly categorized into two types: charcoal based and blood based. Charcoal and blood components remove toxic derivatives of oxygen from the media. Examples of selective media are: modified charcoal, cefoperazone, deoxycholate agar (mCCDA), Karmali agar or CSM (charcoal-selective medium), Preston agar, Skirrow agar, Butzler agar and Campy-cefex agar. Commonly used non-selective media for isolation of Campylobacter spp. are blood agar with or without 0.1% sodium thioglycolate and antimicrobials (cephalosporins, trimethoprim, polymyxin, vancomycin, bacitracin, actidione, colistin, nystatin). Optimum growth condition for thermotolerant Campylobacter spp. (C. jejuni, C. coli) are 42 °C temperature for 24–48 h, pH 6.8, and 3–5% CO2 with 3–15% O2. C. jejuni produces non-haemolytic, finely granular, irregular margin, flat, greyish colonies. On charcoal based media, the colonies may produce ‘metallic sheen’. Thermotolerant Campylobacter spp. can be confirmed up to species level by staining, colony characteristics, and biochemical properties. Hippurate test can primarily differentiate C. jejuni and C. coli, but, it should be further confirmed by other tests.

(c) Detection of Campylobacter antigen:

 ELISA based kits are available for detection of Campylobacter antigen from human stool samples. They can be used for detection of Campylobacter antigen from droppings collected from the suspected pet birds, although yet not evaluated.

(d) Molecular biology:

 PCR can be used in combination with cultural technique for rapid detection of C. jejuni. A multiplex PCR is developed for detection of thermotolerant Campylobacter spp. such as C. jejuni (23SRNA gene); C. coli, C. lari, and C. upsaliensis (glyA).

Zoonosis:

Infection with C. jejuni in human causes watery or bloody diarrhoea, elevated body temperature, abdominal pain, nausea, and vomition. Septicaemia develops in a few diarrhoeic cases (0.15%) which may cause enlargement of the liver and spleen, endocarditis, arthritis, and meningitis. Rarely, a complicated auto-immune response is developed as a sequel, known as Guillain-Barré syndrome. It is a demyelating disorder which results muscle weakness and neuromuscular paralysis.

Treatment and Control Strategy:

In mild infection, treatment with antibiotics is not recommended due to possibility of antibiotic resistance development. In severe cases, several antibiotics such as clindamycin, gentamicin, tetracyclines, erythromycin, cephalothin, and fluoroquinolones (nalidixic acid) can be used under the supervision of a qualified veterinarian. Choice of antibiotic depends on sensitivity of the C. jejuni isolates, availability in suitable form, and species of the birds.
 In aviaries or personal collection, implementation of biosecurity practices such as regular cleaning and use of fly repellents in the cages is effective to prevent the introduction of Campylobacter spp. No vaccine against Campylobacter spp. is currently available for birds.

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