A surprising finding by a team of researchers at The John Hopkins University Bloomberg School of Public Health in Baltimore suggests that chicken trucks carrying live chickens from farms to slaughterhouses can be a source for disease-causing bacteria for the cars traveling behind them. Drivers and motorists stuck behind such a truck should "pass them quickly," study authors say.

Ana M. Rule, Ellen K. Silbergeld and Sean L. Evans collected air and surface samples from cars driving two to three car lengths behind the poultry trucks for a distance of 17 miles along the Delmarva peninsula. Air conditioners and fans were turned off, and the windows were all open. Broiler chickens are transported in open crates on the back of flatbed trucks with no effective barrier to prevent release of pathogens into the environment. The region connecting chicken farms in Maryland to a processing plant to the south in Accomac, Va. has one of the highest concentrations of broiler chickens per acre in the nation.

Researchers found increased concentration of bacteria that have the potential to threaten human health, including antibiotic-resistant strains, in air samples collected from inside the car and on surfaces in the car such as the door handle. Antibiotic resistance to the antibiotics tetracycline, erythromycin and dalfopristin was noted in three strains of bacteria from the chicken trucks.

"Our study shows that there is a real exposure potential, especially during the summer months, when people are driving with the windows down; the summer is also a time of very heavy traffic in Delmarva by vacationers driving to the shore resorts," said Ana Rule, a research associate at the Baltimore school’s environmental sciences department and co-author of the study. She said studies to determine if chicken trucks can make you sick are somewhere down the road.

The study is published in the first issue of the Journal of Infection and Public Health, which will publish research on the epidemiology, prevention and control of infectious disease. It is the fist study to look at whether poultry trucking exposes people to antibiotic-resistant bacteria. The study authors conclude that transporting chickens in open truck to slaughter could influence human and environmental health.

Poultry producers said the study was an attempt to discredit the poultry industry. They said the results of the study were obtained using "unrealistic" conditions.

Other researchers, however, said that getting sick that way was unlikely. None of the scientists who studied this problem got sick. Most healthy people, who are not so vulnerable and have a strong immune system, don’t suffer serious illness from these bacteria even if they are exposed to them in more conventional ways.

The authors say studies are needed to find safer ways to transport chickens from the farm to the slaughterhouse. The study raises new concerns over transportation methods and highlights the idea that we should consider improving these methods. Furthermore, more studies are needed to define how exposure to the antibiotic resistant bacteria affects humans, especially in areas where broiler chickens are raised.