More Listeria Found At Massachusetts Milk Plant

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Main Category: Nutrition / Diet
Also Included In: Pregnancy / Obstetrics
Article Date: 21 Jan 2008 - 12:00 PDT

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Health officials confirmed last Friday, 18th January, they have more evidence that the strain of Listeria linked to three deaths and two further cases of listeriosis came from a milk processing plant in Shrewsbury, Massachusetts.

The Massachusetts Department of Public Health (MDPH) is carrying out a lengthy investigation into the Listeria monocytogenes (Listeria) outbreak, which was first detected in September last year. So far over 100 samples of environmental and milk samples have been taken from the Whittier Farms milk processing plant, which remains closed for the foreseeable future. It will not open until it is cleared by the MDPH Food Protection Program and Regional Milk Specialists from the US Food and Drug Administration (FDA).

So far nine samples from the plant have tested positive for the same strain of Listeria that was found in four of the five people who fell ill with Listeriosis after consuming products from the plant. No sample was available to test the fifth case, a 31 year old woman who has since made a full recovery and been delivered of a healthy baby.

Officials have not been able to establish the exact source of the contamination, but they believe the bacteria has settled somewhere in the plant and entered the milk products at a point in the production process. So far the plant has met federal standards for effective pasteurization, but more tests will be carried out, since the nature of the contamination is consistent with the bacteria entering the production cycle during post-pasteurization and bottling.

One suggestion is that the bacteria got in while the production system was being cleaned. Three of the four plant samples that tested positive for Listeria came from the post pasteurization areas.

Another puzzling aspect of the investigation is why most of the bacteria appears to be in the flavoured milk products, this is also under close scrutiny, said the MDPH. One theory is that the flavoured products have a higher sugar content, which favours bacterial growth.

Five people have fallen ill with listeriosis after consuming milk products from Whittier Farms. Three elderly men have died, and the two women, who were pregnant, have survived. No other cases have been identified, said the MDPH.

Outbreaks of Listeria in milk products are extremely rare, and MDPH said in this outbreak the source appears to be confined to Whittier Farms and the general milk supply is safe.

MDPH said it is working with the management of Whittier Farms to develop a recovery plan for the Shrewsbury plant. In the meantime the plant will remain closed while it is cleared of the contamination and tests confirm that all milk products are proven safe.

Other agencies are also involved such as the FDA and the Massachusetts Department of Agricultural Resources. Following the investigation will be a review of state and federal regulations to see if any changes are needed to the way dairy farms and plants are inspected and tested.

Whittier Farms is a small business that sells its own milk in its farm shop and through home delivery. Previous inspections have always given the plant high marks.

Click here for full press statement from MDPH including list of milk products affected and the associated Listeria strains.

Written by: Catharine Paddock
Copyright: Medical News Today
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