Chlamydiosis:

• It is infectious disease of animals affecting wide range of species like cattle, sheep, goat, birds, pig, dog and human.
• Chlamydial disease ranges from subclinical infections to death depending on the chlamydial species, host, and tissue infected.
• This disease is characterized by Sporadic Bovine Encephalomyelitis and Enzootic Bovine Abortion (2 forms).
• Causes Psittacosis or Parrot fever in birds, enzootic abortion in small and large animals.

Etiology:

• Disease is caused by bacteria of genus Chlamydia under family Chlamydiaceae.
• These are obligate, intracellular bacteria, gram-ve
• It is called as ATP parasites as it uses ATP produced by host cell.
• The family Chlamydiaceae contains a single genus, Chlamydia, which has 14 recognized species:

Epidemiology:

• Disease is distributed worldwide causing a wide range of illness in humans, food-producing animals, companion animals, mammalian wildlife, avian, reptile, amphibian, and aquatic species.
• The range of host animals of bacteria in the order Chlamydiales encompasses more than 500 species, including humans and wild and domesticated mammals (including marsupials), birds, reptiles, amphibians, and fish.
• Known chlamydial species host ranges are expanding, and most species can cross host barriers.
• Stress factor like dampness, temperature variation and overcrowding often precipitate the disease.
• Sero-prevalence of Chlamydia abortus infection is about 3.27% in Nepal.
• Animals >3 yrs. of age are susceptible to infection; however, all age groups can be affected.

Transmission:

• Organisms may be transmitted by handling infected animals and tissues directly, breathing in aerosolized dried feces or respiratory secretions, or other exposure.
• Contact with infected animals
• Chlamydia psittaci, felis and C. abortus have got zoonotic importance.
• Transovarian transmission also occurs in birds.

Pathogenesis:

Clinical Findings:

• Chlamydiosis typically lacks clinical picture. It affects multiple organs and generate a variety of clinical manifestation.
• Common clinical findings include arthritis, polyarthritis, blepharitis, bronchopneumonia
• Conjunctivitis, enteritis, pericarditis, rhinitis
• abortus is associated with abortion of pregnant animal in last trimester.
• Retention of placenta, calves born alive are smaller in size.
• Fever (104-107°F) persist until death.
• Depression, anorexia, weight loss, salivation, dyspnea, mild diarrhea
• Animal may show nervous symptoms such as:
  • Difficulty in walking
  • Stiff gait
  • Incoordination
  • Staggering
  • Opisthotonus
• Lambs delivered by ewes infected with C abortus may develop acute pneumonia; become febrile, lethargic, and dyspneic; and develop a nasal discharge.

C. abortus in equine has been associated with equine recurrent airway obstruction. In acute infection, there is fever and lethargy. Equines develop pneumonia accompanied by abortion in mares, polyarthritis in foals, hepatitis and fatal cases of encephalomyelitis.

1. avium infection in birds:

• avium in psittacine birds causes psittacosis which is zoonotic in nature.
• Birds develop non-specific signs such as fever, lethargy, anorexia, ruffled feathers.
• Other signs include:
  • Conjunctivitis
  • Fibrinous pericarditis
  • Ocular or nasal discharge
  • Diarrhea; greenish or yellow-greenish urates

Infection in dogs:

• Bronchopneumonia including fever, dry cough, keratoconjunctivitis, diarrhea, vomiting
• Neurological signs may also develop

PM Findings:

• Acute pulmonary lesions include bronchiolitis, severe focal pneumonia, and dystelectasis.
• Avian species often demonstrate multifocal hepatic necrosis, splenomegaly, and fibrinous air sacculitis, pericarditis, and peritonitis.
• Hyperemia and edema in brain
• Edema of S/C t/s & ascites in aborted fetus
• Liver congested, enlarged & nodular
• All LNs are enlarged by 3 times more
• Small intestinal lesions can be characterized by mild to severe villus atrophy with occasional villus necrosis

Diagnosis:

• Based on clinical findings
• Based on PM findings
• Cultural examination; especially tissue culture
• Chlamydiae need host metabolites for survival and do not grow on agar plates; they depend on cell culture or embryonated chicken eggs for their growth and isolation.
• Antigen detection on tissue samples can confirm chlamydial organisms.
• Modified Macchiavello, modified Gimenez, Giemsa, Castaneda, and modified Ziehl-Neelsen stain are favored to identify chlamydiae in direct smears.
• Monoclonal or polyclonal antibodies, fluorescein staining, and fluorescent microscopy are preferred methods to detect the organism in samples.
• CFT, ELISA
• Nucleic acid amplification tests are currently considered the first-choice method for diagnosing chlamydial infections. PCR is best method for nucleic acid amplification.

Differential Diagnosis:

1. Trichomoniasis:

• Protozoan disease-causing abortion
• Early abortion

2. Brucellosis:

• Positive test for brucellosis in serology
• Hygroma is present in most of cases in brucellosis
• Abortion usually takes place in last trimester.

3. Leptospirosis:

• Abortions is associated with jaundice or hemoglobinuria

4. Listeriosis:

• Abortion is usually associated with encephalitis.
• Typical circling is observed in affected cattle or sheep and goat.
• History of feeding contaminated silage.

5. Infectious Bovine Rhinotracheitis (IBR):

• Abortion usually occur at first and second trimester.
• Infected animals show conjunctivitis, respiratory signs especially red nose.

6. Newcastle Disease (ND):

• Respiratory signs and neurological signs; torticollis, wing paralysis are observed.
• Sudden onset with high mortality in poultry flock.

Treatment:

• Treatment usually varies across species.
• In case of pecorum in lambs, long-acting oxytetracycline (300mg/mL) is administered @ 30mg/kg (1ml/10kg).
• A limited number of antimicrobials, such as tetracyclines, macrolides (eg, erythromycin and azithromycin), and fluoroquinolones have shown good efficacy against chlamydiae.
• Doxycycline are administered in cases of avian chlamydiosis @ 25-50 mg/kg, b.wt., PO, OD
• Tylosin tartrate @ 5-10 mg/kg b.wt. x I/M or Slow I/V x OD x 5 days
• Citric acid in drinking water of birds can increase the level of antibody in blood.

Control Measures:

• Cleaning of premises with disinfectant such as 1% Lysol, 1:1000 dilution of quaternary ammonium compound, 1:100 dilution of household bleach.
• Proper disposal of carcass.
• Isolation and quarantine of all newly acquired birds for 6 weeks.
• Live and inactivated vaccines prepared from chick’s embryo sac membrane are available in some countries.
• To prevent abortion in small ruminants, C abortus live vaccines are available.
• Vaccines against C felis are available for pet cats.