From researchers in Finland, writing in the April edition of Emerging Infectious Diseases. Edited bits below, the complete report is available at http://wwwnc.cdc.gov/eid/article/18/4/11-1310_article.htm.

Shiga toxin–producing Escherichia coli (STEC) is a pathogen that causes gastroenteritis and bloody diarrhea but can lead to severe disease, such as hemolytic uremic syndrome (HUS). STEC serotype O78:H– is rare among humans, and infections are often asymptomatic.

A boy born on Oct. 3, 2009, in Finland, the third child of healthy parents, was breast-fed and healthy. But by 2-weeks-old, he became irritable, started feeding poorly, and produced large volumes of watery feces with some blood. At 17-days-old he was taken to the Vaasa Central Hospital in Finland for medical care.

A blood culture showed a gram-negative rod, which was identified as E. coli. Results of a test for the O157 antigen were negative. Because the neonate was severely ill, he was referred to the University Hospital in Pirkanmaa Hospital district, and the s E. coli train isolated from his blood was forwarded to the Helsinki University Hospital Laboratory, where the invasive strain from fecal specimens of the neonate and all 4 asymptomatic family members — the mother (31 years-old), father (32 years), sister (3 years), and brother (2 years) — was confirmed by detection of Stx. The 6 strains isolated from the blood and fecal samples of the neonate and from the fecal samples of his asymptomatic parents and 2 siblings showed a sorbitol-fermenting STEC serotype O78:H– that carried the virulence genes stx1 and hlyA.

The boy recovered, but required a kidney transplantation, supplied by his father and performed in April 2011. The operation and posttransplantation period went without complications.

HUS develops in ≈5%–15% of patients <10 years of age in whom E. coli O157:H7 infection is diagnosed and occurs 2–14 days after diarrhea onset. In contrast to the O157-related HUS cases, less information is available about the non–O157-related HUS cases. Some risk factors, including an elevated leukocyte count, administration of antimicrobial drugs, use of antimotility agents, and very young age, are associated with increased risk for HUS

Ruminants, such as cattle and sheep, are the major reservoir of STEC. None of the family members, however, had contact with any farm animals, and the family had no pets. One of the family members of the neonate might have been infected with STEC by eating contaminated food, but these food items were not available for investigation. Moreover, because all the family members were asymptomatic, estimating the exact date of their infections is difficult. Secondary infections among family members most likely resulted from person-to-person transmission or from food given to the children with contaminated hands of other family members or from some other cross-contamination. Family clusters have been reported to be common. In Finland, ≈50% of STEC infections are family related.

Handwashing practices may be of greater relevance than food as a source of infection in infants and very young children because the infection might result from an infected person or animal in the home. Prolonged excretion of STEC and intimate caring of infants by family members provide a risk for cross-infections. Therefore, to limit the risk for STEC infection, thorough handwashing before touching food or young babies is particularly necessary.

Our findings demonstrate that contrary to earlier suggestions, STEC under certain conditions can invade the human bloodstream. Moreover, this study highlights the need to implement appropriate diagnostic methods for identifying the whole spectrum of STEC strains associated with HUS.