Week 34. Respiratory bacterial diseases in poultry

Question 1

• Analyze the role of environmental factors in the transmission of fowl cholera

Answer 1

1. water sources - cholera bacteria survive extend periods in water ex. lakes and ponds
2. soil contamination - soil contaminated with feces from infected birds
3. wildlife - wild mammals and birds are carriers for Pasteurella multocida > shed bacteria in feces and nasal secretion
4. climate and weather conditions - temperature and humidity influence survival and transmission
5. migration pattern - migratory birds can carry fowl cholera bacteria over long distance
6. overcrowding and poor hygiene- inadequate hygiene practice and overcrowding - risk of fowl cholera transmission is increased

Question 2

Discuss the challenges in diagnosing avian infectious coryza during mixed infections.

Answer 2

1. similar clinical signs: AIC shares similar respiratory diseases clinical signs ex. with infectious bronchitis, Newcastle disease and mycoplasmosis. Similar clinical signs ex. nasal discharge, conjunctivitis, respiratory distress.
2. co-infections: presence of multiple pathogens can complicate clinical picture and challenging to isolate and identify causative agent of AIC.
3. laboratory diagnosis and sampling challenges: in cases of mixed infections-presence of other pathogens may interfere with isolation and identification process.
4. antibiotic treatment: without proper diagnostic confirmation problem with mixed infections ABs can promote developing of antimicrobial resistance and altering microbial balance in respiratory tract

Question 3

Compare and contrast the treatment options for ORT infection.

Answer 3

1. antibiotics: effective for treating ongoing infections but may contribute antibiotic resistance and require withdrawal periods
2. vaccination: prevents ORT infections but may not control ongoing outbreaks: efficacy can also vary
3. nutritional support: supports immune function and recovery but it is not standalone treatment for ORT infections: complements other strategies
4. biosecurity measures:crucial for preventing ORT spread but may not eliminate bacteria entirely : required ongoing vigilance

Question 4

Analyze the role of vertical transmission in the spread of mycoplasmosis within a poultry farm.

Answer 4

1. transmission from parent to offspring: mycoplasma bacteria is vertically spread from infected birds to their offspring through egg or during hatching
   2.. early infection: chicks can be infected before hatching, weakens their immune system and can lead constant flock infection
2. persistent infection: infected parent birds able to pass bacteria to successive generations - ensures persistent infection in flock
3. independent external factors- vertical transmission occurs independently of external factors > makes it difficult to control via biosecurity only
4. control challenges: culling may not eliminate pathogen if vertical transmission continues

Question 5

Describe the infectious cycle of Chlamydia psittaci based on the figure below. While describing the cycle, it is necessary to use other scientific sources. While using them, please ensure that sources are not older than 15 years.

Answer 5

1-2: attatchment and entry: Chlamydia psittaci attatches to host cells and enters them through endocytosis > primarily target cells are respiratory and gastrointestinal epithelial cells.
3: intracellular replication: within host cell > Chlamydia psittaci undergoes biphasic developmental cycle > transition between elementary bodies (EB) and replicative bodies (RB) through binary fission.
4-5: inclusion formation and expansion: bacterium resides within membrane-bound compartment called inclusion, which enlarges to accommodate bacterial replication. Host cell proteins and lipids are incorporated into inclusion membrane.
6-7: modulation of host responses: throughout the cycle > Chlamydia psittaci manipulated host cell signaling pathways to evade immune detection > inhibit apoptosis and manipulate lipid metabolism to promote its own survival and replication.

Question 6

Outbreak 1:
Three successive turkey flocks raised in the same brooder house have an unusually large number of poults showing lameness, severe leg deformities and dehydration by three weeks of age. Ten live poults from one of these flocks are submitted for investigation. They are 17-days-old white toms from a flock of 10,000 birds. In the flock, the leg problems, including tibial rotation, bent toes and arthritis are first noted at 9 days of age, average registered mortality on the day of submission is 15 poults per day. The flock has been treated with neomycin and oxytetracycline for four days before submission but without any response. The problem is not present in any other aviaries in the region or in any other aviaries of the same company.

Answer 6

What is the situation in the poultry farm? 3 successive turkey flocks raised in same brooder house experience lameness, severe leg deformities and arthritis in poults, with high mortality rate

What questions arise about the situation? Try to answer these questions. Is there evidence of respiratory symptoms ex. coughing, sneezing or nasal discharge? have any environmental or management factors been identified that could contribute to bacterial proliferation or transmission?

What problem needs to be solved? What additional information is needed? Where and how could it be found? determine if outbreak is caused by bacterial respiratory pathogen, identify any potential environmental or management factors contributing to outbreak and address them accordingly. antibiotic treatment; based on sensitivity testing results to treat bacterial infection. biosecurity measures: strict biosecurity protocols to prevent spreading

What may be the problem solving strategies? Evaluate the advantages, disadvantages, and underlying assumptions of these strategies. diagnostic testing-conducting bacterial culture and sensitivity testing on samples collected from affected birds > determine antibiotic susceptibility, can have human errors and many bacterias at same time > advantage to avoid antimicrobial resistance and to treat correct pathogen.

What criteria are used to evaluate the final solution and possible differential diagnoses? final solution should be effectively treat bacterial infection, reduce mortality rates and prevent further spread of disease within poultry farm. Ddx: respiratory pathogens in turkeys with dehydration, leg deformities or lameness > avian tuberculosis, avian mycoplasmosis

(here I suspect it was Mpl.iowae: due to tibial rotation in chicks-bent toes)

Question 7

Outbreak 2:
Eight 22-wk-old ring-necked pheasants (two dead and six live birds) are submitted for a necropsy. One hundred twenty pheasants have died over the previous 3 days and 100 more birds are ill. Clinical signs reported by the owner include sudden death, short-time depression, increased respiratory rate, secretion from the beak and eyes, diarrhea, and limping of more chronically affected birds. These pheasants came from a 3000-bird flock with a housing density of 20 ft2 (1.86 m2) per bird. The birds originated from a closed facility where they were hatched on the farm and raised in an outdoor facility with dirt floors and covered with flight netting. The birds were segregated according to age groups. After selling the raised pheasants to game ranches, the dirt floors are turned over, and the facility is left unoccupied for several weeks. The pheasant flock had not received any vaccination and was tested for Salmonella Pullorum annually.