Role of nonmigratory mottled ducks (Anas fulvigula) as sentinels for avian influenza surveillance.

The objective of this study was to evaluate the mottled duck (Anas fulvigula), a nonmigratory dabbling duck, as a sentinel species for avian influenza virus (AIV) surveillance. A total of 235 cloacal swabs from 147 live-captured and 88 hunter-harvested mottled ducks during summer (June-August 2007) and winter (November 2007 to January 2008), respectively, were collected along the upper Texas coast. Samples were screened for AIV using real-time reverse transcription polymerase chain reaction (rRT-PCR); all rRT-PCR-positive samples were processed for virus isolation. Three samples were positive for AIV by AIV-matrix rRT-PCR. One of these samples also was positive for H5 by rRT-PCR, and a low pathogenic H5N2 AIV was isolated. Although isolation of AIVs from mottled ducks during the winter has been reported previously, to the authors' knowledge, this is the first H5 isolate from mottled ducks. Interestingly, this isolation was made during the same season that other H5N2 viruses were obtained from migratory waterfowl on the Texas coast, which suggests AIV transmission among waterfowl on the wintering grounds and the potential role of mottled ducks as a naturally occurring sentinel species for AIV surveillance.

Prevalence and patterns of antimicrobial resistance in Campylobacter spp isolated from pigs reared under antimicrobial-free and conventional production methods in eight states in the Midwestern United States.

OBJECTIVE: To compare apparent prevalence and patterns of antimicrobial resistance in Campylobacter spp in feces collected from pigs reared with antimicrobial-free versus conventional production methods in 8 states in the Midwestern United States. DESIGN: Cross-sectional study. SAMPLE POPULATION: 95 swine farms that used antimicrobial-free (n = 35) or conventional (60) production methods. PROCEDURES: Fecal samples from 15 pigs/farm were collected. Biochemical and multiplex-PCR analyses were used to identify Campylobacter spp. The minimal inhibitory concentrations of erythromycin, azithromycin, ciprofloxacin, nalidixic acid, gentamicin, and tetracycline for these organisms were determined by use of a commercially available antimicrobial gradient strip. The data were analyzed by use of population-averaged statistical models. RESULTS: Campylobacter spp were isolated from 512 of 1,422 pigs. A subset (n = 464) of the 512 isolates was available for antimicrobial susceptibility testing. The apparent prevalence of Campylobacter spp isolates from pigs on conventional farms (35.8%) and antimicrobial-free farms (36.4%) did not differ significantly. Resistances to azithromycin, erythromycin, and tetracycline were significantly higher on conventional farms (70.0%, 68.3%, and 74.5%, respectively) than antimicrobial-free farms (20.1%, 21.3%, and 48.8%, respectively). Resistances to azithromycin, erythromycin, and tetracycline declined as the number of years that a farm was antimicrobial-free increased. CONCLUSIONS AND CLINICAL RELEVANCE: Production method did not affect the apparent prevalence of Campylobacter spp on swine farms. However, antimicrobial-free farms had a significantly lower prevalence of antimicrobial resistance. Although cessation of antimicrobial drug use will lower resistance over time, investigation of other interventions designed to reduce resistance levels is warranted.

Avian influenza surveillance in hunter-harvested waterfowl from the Gulf Coast of Texas (November 2005-January 2006).

The objectives of our study were to determine prevalence of avian influenza viruses (AIV) on wintering grounds on the Texas Gulf Coast, USA, and to compare real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) and virus isolation for detection of AIV in cloacal swabs from wild waterfowl. Cloacal swabs were collected from hunter-harvested waterfowl from November 2005 to January 2006 at four wildlife management areas. Seven AIV were isolated from four species of ducks: Green-winged Teal (Anas crecca) in November; Blue-winged Teal (Anas discors) in November; Mottled Duck (Anas fulvigula) in December, and Northern Shoveler (Anas clypeata) in January. Prevalence of AIV for each of these species during the sampling period was 1.4, 2, 6, and 0.6%, respectively. The AIV subtypes detected were H1N2, H1N4, H4N6, H6N2, and H10N7, all previously reported in North American waterfowl. Our study identified AIV subtypes not previously reported on the Texas Gulf Coast and provides baseline data for a multiyear surveillance project.