Milk-borne Outbreaks Due to Serologically Typed Hemolytic Streptococci

Abstract

Using the Griffith method of standardizing streptococci, the authors report on 9 milk-borne outbreaks of hemolytic streptococcus throat infections in New York State. This type has been encountered in each outbreak with the exception of 3 due to Type 3. A description is given in detail of a recent outbreak (44 cases, Type 3). This infection was found to be transmitted by raw milk secured at a cheese plant. Although the plant handled milk representing the output of > 6000 cows, it is believed that the cow responsible for the outbreak was located by means of Breed smear examination of cans of milk received at the plant and subsequent veterinary and bacteriological follow-up of suspected herds. On the involved farm prior to the outbreak there had been 1 case each of scarlet fever, sore throat, and "grippe." The suspected cow had suffered a'' teat injury followed by the development of acute mastitis upon manipulation of the injured part by the person with the sore throat. To prevent any possibility of transmission of infection through the cheese, that produced during the outbreak was embargoed and released only after being reprocessed by a method involving heating the product above 170[degree] F for several minutes.