17 January 2011

2 minute read

Oceania

In the first research of its type, hundreds of tests carried out at three vegetable-growing sites in Victoria and two in Queensland, found high numbers of Listeria monocytogenes in anaerobic sileage and baled hay fed to ruminants, such as sheep and cattle, reports The Weekly Times Now.

Global FS senior consultant Robert Premier said the livestock did not usually become infected, but the bacteria passed into the faeces where it was trapped until hot, dry weather dispersed it on the wind.

It then contaminated vegetables, especially leafy salad varieties that collected dust effectively, such as curly parsley.

About 60 cases of listeriosis are reported in Australia each year, with up to a third proving fatal.

At greatest risk are the young, the elderly and pregnant women.

Dr Premier said growers were required to pre-test produce as a condition of supplying supermarkets, but there was confusion over which test to use.

"More importantly the major problem is that growers have no idea how to reduce the incidence of Listeria monocytogenes in the field and they have no idea how this bacterium enters farming land to contaminate their crops," Dr Premier said.

"What is needed is an information package on this issue for the grower."

He said growers should avoid irrigating before extreme wind events because wet leaves attracted more dust.

He advised watering immediately after strong windsand wait 48 hours before harvesting, when produce should be placed in a turbulent wash-system containing sanitised water.

He said more work was needed to determine the virulence of the sub-types of Listeria monocytogenes found in vegetables, because they were more likely to be low virulence as their origin was from plant matter and not infected animals.

He also recommended the development of a DNA test to distinguish between virulent and non-virulent types.

TheCattleSite News Desk