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Experimental infection of house finches with Mycoplasma gallisepticum
George V Kollias1, Keila V Sydenstricker, Heidi W Kollias
1Wildlife Health Laboratory, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA. gvk2@cornell.edu
Abstract:
Mycoplasma gallisepticum (MG) has caused an endemic upper respiratory and ocular infection in the eastern house finch (Carpodacus mexicanus) after the epidemic first described in 1994. The disease has been studied by a number of investigators at a population level and reports describe experimental infection in group-housed MG-free house finches. Because detailed observation and evaluation of individual birds in group-housed passerines is problematic, we studied individually housed house finches that were experimentally inoculated with the finch strain of MG in a controlled environment. To accomplish this, a study was conducted spanning the period of November 2001-April 2002 with 20 MG-free (confirmed by the rapid plate agglutination assay and polymerase chain reaction [PCR] assay) eastern house finches captured in the Cayuga Basin area of central New York (USA) in the summer of 2001. After a period of acclimatization and observation (12 wk), 20 finches were inoculated with a 0.05-ml aliquot of MG (3.24 x 10(5) colony-forming units/ml) via bilateral conjunctival sac instillations. Two additional finches acted as controls and were inoculated in the same manner with preservative-free sterile saline solution. After inoculation, all finches except the controls exhibited clinical signs of conjunctivitis within 2-6 days. The progression of the disease was evaluated by several methods, including PCR, behavioral observations, and physical examination including eye scoring, body weight, and body condition index. Over a period of 21 wk, MG-infected finches developed signs of disease and recovered (80%), developed signs of disease and progressed to become chronically infected (15%), or died (5%). We hypothesize that the high survival rate and recovery of these finches after infection was associated with the use of controlled environmental conditions, acclimatization, a high plane of nutrition, and low stocking (housing) density, all of which are factors documented to be important in the outcome of MG infections in domestic poultry and other species.
Insights
Mycoplasma gallisepticum (MG) causes respiratory and eye infections in house finches. This study found that individually housed finches in controlled environments showed high recovery rates from MG infection.
Area of Science:
- Avian pathology
- Wildlife disease ecology
- Infectious disease research
Background:
- Mycoplasma gallisepticum (MG) is an endemic pathogen causing respiratory and ocular disease in eastern house finches.
- Previous studies focused on population-level impacts and group-housed finches, limiting individual disease progression insights.
Purpose of the Study:
- To investigate the clinical progression and outcomes of Mycoplasma gallisepticum infection in individually housed eastern house finches under controlled conditions.
- To evaluate the efficacy of diagnostic methods like PCR and clinical scoring for monitoring MG infection.
Main Methods:
- Twenty MG-free eastern house finches were experimentally inoculated with Mycoplasma gallisepticum via conjunctival instillation.
- Birds were housed individually and monitored for 21 weeks using PCR, behavioral observations, physical exams, and eye scoring.
- Control birds received sterile saline solution.
Main Results:
- Within 2-6 days post-inoculation, 95% of infected finches exhibited clinical signs of conjunctivitis.
- Over 21 weeks, 80% of infected finches recovered, 15% became chronically infected, and 5% died.
- PCR and clinical assessments effectively tracked disease progression.
Conclusions:
- Individually housed finches in controlled environments with optimal nutrition and low density demonstrated high survival and recovery rates from Mycoplasma gallisepticum infection.
- These findings suggest environmental and nutritional factors significantly influence disease outcomes in house finches.
- The study highlights the importance of controlled housing for detailed observation of avian infectious diseases.
