Diagnosis and Prevention and Treatment Methods for Campylobacteriosis in Chickens

Campylobacteriosis in chickens, also known as avian vibrionic hepatitis, is an infectious disease of young or adult chickens caused by Campylobacter infection. The disease is characterized by hemorrhagic necrotic hepatitis with fatty infiltration, high morbidity, low mortality, and often a chronic course. Campylobacter is an important food poisoning bacterium for humans and can cause symptoms such as fever, vomiting and diarrhea in humans. Therefore, it is listed as one of the key quarantine items for meat hygiene inspection.

1. Pathogen

The pathogen of this disease is a Gram-negative, motile, microaerophilic Campylobacter. The bacterium can grow in serum-containing broth culture, and can also grow on beef extract agar medium in a 10% carbon dioxide environment, forming small, round, moist, neatly edged, colorless and transparent colonies. It does not hemolyze on blood medium. It can produce hydrogen sulfide, does not ferment mannitol or xylose, and does not produce indole.

Campylobacter is extremely sensitive to drying, and drying and sunlight can quickly kill it. The bacterium survives no more than 2 hours at 20°C; in water at 4°C, its infectivity can be maintained for 4 weeks; in cut-up chicken stored at -9°C and -12°C, it can survive for 10 days; while when stored at -20°C, the bacterium can still be detected after 182 days.

The bacterium is relatively sensitive to various disinfectants. A 1:200000 dilution of 5% sodium perchlorate and 0.25% formalin solution can kill this bacterium within 15 minutes; 0.15% organic phenol, 1:50000 quaternary ammonium compound and 0.125% glutaraldehyde can all kill this bacterium within 1 minute.

2. Epidemiological Characteristics

Under natural conditions, this disease only infects chickens and turkeys, and is more common in hens that are about to start laying or have been laying for several months, and occasionally occurs in chicks. The main route of infection is the digestive tract. The pathogen is excreted with feces, contaminating feed, drinking water and equipment, and healthy chickens become infected after ingesting it. It mostly occurs sporadically or endemically. The disease has high morbidity, and the mortality rate is generally 2%-5%.

3. Clinical Symptoms

The disease mostly has a chronic course. Affected chickens show listlessness, weight loss, shrunken combs, and often watery diarrhea with yellow droppings. The disease progresses slowly, but very fat chickens may also die acutely, and they were still laying eggs within 48-72 hours before death. The flock cannot reach the expected peak egg production, and the laying rate decreases by 25%-35%. Chicks show stunted development, enlarged abdominal circumference, and develop anemia and jaundice.

4. Pathological Changes

The most obvious lesions of this disease are in the liver. Acute cases show degeneration of the liver parenchyma, enlargement, and friability, with hemorrhagic areas, hematomas and necrotic foci under the liver capsule. The liver surface appears mottled due to many bleeding points. Numerous stellate necrotic foci are scattered on the liver surface and within the parenchyma, or the liver is covered with cauliflower-like necrotic areas; the liver is yellow-brown, and the gallbladder is filled with viscous secretions. Acute internal bleeding and death often occur due to liver rupture. Chronic cases show liver cirrhosis and atrophy, accompanied by ascites; splenomegaly, with occasional yellow brittle infarct areas; ovarian follicles may show atrophy and degeneration, leaving only pea-sized remnants.

5. Diagnosis

A preliminary diagnosis can be made based on epidemiological characteristics, clinical symptoms and pathological changes, but confirmation requires laboratory examination.

6. Prevention and Treatment Measures

Prevention is mainly through comprehensive measures such as strengthening feed management, strict disinfection, and reducing stress, and drugs can also be added to the feed for prevention. For affected flocks, streptomycin can be used at 50000 international units per bird, intramuscular injection, twice daily. Tetracycline or oxytetracycline can also be mixed into the feed at 2 grams per kilogram of feed, fed continuously for 3-5 days.