Experimental Infection of House Finches With Mycoplasma Gallisepticum

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.

Sickness behaviour acting as an evolutionary trap? Male house finches preferentially feed near diseased conspecifics

“…House finches (Carpodacus mexicanus) suffer from the directly transmissible bacterial pathogen Mycoplasma gallisepticum (MG) which causes visible conjunctival symptoms and behavioural changes (Kollias et al 2004). Since its emergence in 1994 (Ley et al 1996), MG has caused annual seasonal epidemics in eastern North American house finches.…”

Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus)

“…The time course of the study is justifiable because long-term infections are common among wild house finches. The symptoms of Mycoplasma gallisepticum (MG) infection, which include extreme inflammation of the conjunctiva of the eye, last on average 10weeks and up to 24weeks in captive experimentally infected house finches (Kollias et al, 2004;Sydenstricker et al, 2006). Active infections of avian pox can last as long as 3 months (McClure, 1989).…”

Effect of infection route and concurrent infectious bronchitis virus vaccination onMycoplasma gallisepticumdisease pathology in an experimental model

“…Routes of infection include aerosol, eye drop, intranasal, intratracheal, direct air sac injection, and spray application (Rodriguez & Kleven, 1980;Lin & Kleven, 1982;Levisohn et al, 1983;Levisohn & Dykstra, 1987;Nunoya et al, 1987;Naylor et al, 1992;Whithear et al, 1996;Ganapathy & Bradbury, 1998;Kollias et al, 2004;Feberwee et al, 2005). Co-infectious agents, including Newcastle disease virus (NDV), infectious bronchitis virus (IBV), and Escherichia coli, have also been used to study their effects on or the enhancement of the disease process (Rodriguez & Kleven, 1980;Bradbury, 1984;Nakamura et al, 1994).…”

“…Co-infectious agents, including Newcastle disease virus (NDV), infectious bronchitis virus (IBV), and Escherichia coli, have also been used to study their effects on or the enhancement of the disease process (Rodriguez & Kleven, 1980;Bradbury, 1984;Nakamura et al, 1994). Outcomes of these infections were measured through serology, blood parameters, re-isolation of MG and pathology including air sac lesions, tracheal lesions, increased tracheal mucosal thickness, and conjunctivitis (Rodriguez & Kleven, 1980;Nunoya et al, 1987;Nakamura et al, 1994;Branton et al, 1997b;Kollias et al, 2004). Infection results have also been measured in terms of commercial production parameters including egg production, egg quality characteristics, weight gain, and feed conversion (Branton & Deaton, 1985).…”