Diagnosis and Treatment of Campylobacter jejuni Outbreak in Peafowl
Campylobacteriosis in peafowl is a bacterial infectious disease of young and adult peafowl caused by Campylobacter infection. The disease generally takes a chronic course, with few reports of acute cases. In June 2004, about 200 30-day-old blue peafowl chicks raised by a specialized breeding household in Tancheng County experienced an outbreak characterized mainly by ascites and liver enlargement. According to statistics, the incidence rate was 26.7%, and the mortality rate was 9.8%. Through clinical observation and laboratory diagnosis, the disease was finally confirmed as Campylobacter jejuni infection, and integrated traditional Chinese and Western medicine prevention and treatment measures were adopted to control the condition. The diagnosis and treatment situation is reported as follows.
1 Epidemiological situation
According to the breeder and technician, the peafowl chicks were hatched by the farm itself, and their growth condition after hatching was good; after 25 days of age, ascites was observed. It was initially thought to be colibacillosis, and various drugs were used in feed and drinking water, but not only did the symptoms not lessen, instead the number of affected birds increased rapidly; around 30 days of age, the peak incidence was reached, and deaths continued to occur.
2 Clinical symptoms and necropsy changes
The affected chicks were lethargic, depressed, and insensitive to external stimuli; in severe cases, they stood dully with the neck drawn in and eyes closed, had reduced appetite, and diarrhea at the beginning of the disease, with desire to drink, and the area around the anus was covered with thin feces containing pus. Some passed red thin feces, the abdomen was obviously enlarged, and the comb was pale. Some peafowl died acutely, and before death were in a state of stupor or swimming motions. Some affected peafowl turned chronic, showing listlessness, pale, dry, and shrunken comb, visible scaly dander, gradual emaciation, and reduced feed consumption. Necropsy of 9 representative dead peafowl found that most carcasses had a large amount of ascites in the abdominal cavity, the liver was enlarged and reddish-brown, with yellow necrotic foci of varying sizes, and the liver surface had different degrees of petechiae or scattered grayish-white pinpoint-sized necrotic spots. Some had pulmonary congestion, 2 cases had pulmonary atrophy, and 1 case had pulmonary edema; some had splenomegaly, and a few had petechiae. The mucosa of the muscular stomach, proventriculus, and jejunum had different degrees of hemorrhage and congestion. The duodenum, especially the rectum, had severe hemorrhage and catarrhal enteritis. The gallbladder was enlarged and yellow-green in color. The kidneys were enlarged and pale, and the myocardium had yellow necrotic foci.
3 Laboratory diagnosis
3.1 Microscopic examination of smears from diseased materials. Heart blood, bile, and liver touch smears from dead peafowl were taken for Gram staining and microscopic examination. Gram-negative organisms were seen, appearing as seagull-shaped, S-shaped, curved, and spiral forms.
3.2 Isolation and culture of pathogenic bacteria. Aseptically, the liver and bile of dead peafowl were taken and streaked separately onto blood agar medium, then placed in a 10% carbon dioxide incubator at 42 degrees C. After 24 to 48 hours of culture, pinpoint-sized, round, smooth, non-hemolytic, slightly raised, almost completely transparent small colonies grew on the surface of the medium. The above single colonies were selected for pure culture, and the liquid culture of the pure culture was inoculated into the yolk sac of 8-day-old chicken embryos, with 0.2 mL inoculated per embryo, 16 embryos in total. Three embryos that died within 24 hours after inoculation were discarded. Six died from 24 to 72 hours, and the remaining 7 died from 72 to 120 hours. Necropsy of chicken embryos showed skin surface hemorrhage and liver necrosis. The allantoic fluid and yolk of dead chicken embryos were collected, and smear staining and microscopic examination showed morphology identical to that described in "3.1"; the same drop of allantoic fluid suspension was placed on a glass slide and observed under dark-field microscopy, showing spiral movement of the bacteria; flagellar staining and microscopic examination showed flagella at one end of the bacterial body.
3.3 Biochemical tests. The pure culture of the bacteria was placed under low-oxygen (5%) conditions for biochemical reactions, and it was found that this bacterium did not ferment carbohydrates such as glucose, fructose, and sucrose; indole, V.P., M.R., H2S, urea, sodium citrate, malonate, gelatin, and others were all negative; oxidase and catalase tests were positive; nitrate reduction was positive. This basically conforms to the biochemical characteristics of Campylobacter jejuni.
3.4 Animal regression experiment. Aseptically, the above allantoic fluid and the liver, bile, and spleen of affected peafowl were ground and diluted 1:5 with normal saline to make a suspension, and 2 healthy 28-day-old peafowl chicks were orally inoculated with each. As a result, all became ill within 24 hours, and both died within 1 week. The necropsy lesions and microscopic examination were the same as those of the aforementioned affected peafowl.
Comprehensive diagnosis: Through the above clinical examination, laboratory testing, animal experiments, and other means, the infection was confirmed as Campylobacter jejuni infection in peafowl chicks. Due to conditions at the time, its serotype was not identified.
3.5 Drug sensitivity test. The routine disk method was used to conduct drug sensitivity tests on 12 antibiotics. The results showed that the bacterium was sensitive to ampicillin, erythromycin, streptomycin sulfate, and sulfadimidine, with inhibition zones above 15 mm; it had a certain degree of resistance to the others.
4 Comprehensive prevention and treatment measures
4.1 Isolation, disinfection, and strengthened sanitation management. Affected peafowl were strictly isolated and raised. The peafowl house was changed from disinfection once a week to once a day with peafowl present; 3% hypochlorous acid, 3% peracetic acid, and 2% Baidusha were used alternately for disinfection. The environment was disinfected once every 1 to 2 days with 3% hot alkaline water; water troughs and feed troughs were cleaned once daily with disinfectant solution; feces and filth were centrally subjected to harmless treatment; dead peafowl were disinfected and deeply buried; at the same time, feeding management was strengthened to improve the resistance of the peafowl flock.
4.2 Prophylactic medication. To prevent continued spread of the disease, the entire presumed healthy peafowl flock was fed 500 g doxycycline per ton of feed for 5 to 7 days. After medication, no new cases occurred.
4.3 Treatment. For peafowl houses with severe cases, each peafowl was injected intramuscularly with 10 mg ampicillin, with 3 to 5 days as one treatment course; at the same time, chloramphenicol aqueous solution was used for drinking for 7 days. After feeding 500 g doxycycline per ton of feed for 5 days, chloramphenicol was used in drinking water for 5 days.
Traditional Chinese medicine was used in combination. Prepared rehmannia, angelica, white chrysanthemum, and goji berry 100 g each, and bupleurum, Celosia argentea seed, cassia seed, plantain seed, Scutellaria baicalensis, and Leonurus japonicus seed 70 g each, decocted in water, for oral administration to 100 peafowl chicks, 1 dose per day, for 5 to 10 consecutive days.
After treatment, the condition gradually improved after 5 days. Except for a few severe cases whose death could not be controlled, the rest basically returned to normal within 10 days.
5 Summary
5.1 Through epidemiology, clinical and pathological examination, and pathogen isolation and identification, it was determined that the infectious disease outbreak in peafowl was caused by Campylobacter jejuni infection.
5.2 Comprehensive measures should be taken to treat this disease. Drug selection should be based on drug sensitivity tests. From the results of this drug sensitivity test, Campylobacter jejuni had varying degrees of resistance to many antibiotics, which may be related to the long-term unscientific and unreasonable use of drugs on the farm causing Campylobacter jejuni to develop resistance to some antibiotics, leading to poor early treatment results after infection. Therefore, when diagnosing this disease, samples should be taken for bacterial culture and identification, and drug sensitivity tests should be performed on the pathogenic bacteria, selecting specific drugs or using combination therapy, which has significant therapeutic effects.
5.3 Campylobacter jejuni is a zoonosis, and many animals carry this bacterium. It is an opportunistic pathogen. When animals are subjected to stress (such as sudden feed change, cold stimulation, foul air, cold, etc.), resistance decreases, which can induce this disease. The main cause of this outbreak was neglect in feeding management. At that time, light rain fell for several consecutive days, the air was humid, and the temperature dropped. Measures were not taken in time, causing some peafowl chicks to catch cold, and their body immunity decreased, thus allowing Campylobacter jejuni to seize the opportunity to multiply massively in the peafowl chicks. The main measures to prevent this disease are: (1) strengthen routine feeding management and improve the resistance of the peafowl flock; (2) pay attention to sanitation and epidemic prevention work to eliminate disease transmission; (3) use antibiotics reasonably and scientifically to avoid or reduce bacterial resistance.