Published Date: 2004-05-26 23:50:00
Subject: PRO/AH/EDR> E. coli O157, livestock exposure susp. - USA (NV)
Archive Number: 20040526.1411
E. COLI O157, LIVESTOCK EXPOSURE SUSPECTED- USA (NEVADA)
A ProMED-mail post
ProMED-mail, a program of the
International Society for Infectious Diseases
Date: Tue 25 May 2004
From: ProMED-mail <email@example.com>
Source: Union Democrat - Nevada USA [edited]
2 new _E. coli_ cases reported
New cases of _E. coli_ O157 surfaced Mon 24 May 2004 in 2 brothers who
attend Avery Middle and Bret Harte Union High schools, said Dr. Dean
Kelaita, the Calaveras County public health officer. The boys, aged 14 and
17, live in Murphys, he said. Their infection is thought to have resulted
from contact with livestock, possibly at the Calaveras County Fair, a
little more than a week ago, Kelaita said, and has "no clear connection" to
3 other cases discovered earlier in May in Angels Camp.
So far, the boys have suffered mild intestinal problems and have not had to
be hospitalized, he said. Their cases were discovered after doctors found
they each tested positive for the bacterium. As required, the Public Health
Department was notified. Despite an investigation into those cases, his
department still doesn't know how the 3 other children contracted _E. coli_.
A Public Health Department investigation into the new cases is now under
way, Kelaita said. And, he's working on what he calls an "educational
message" for parents to "allay some of their anxieties" about the chances
of their children contracting the bacteria, he said. Fliers went home with
Avery Middle students on Mon 24 May, and Kelaita said he gave Bret Harte
Principal Catherine Sargent some guidance on a memo to send home with her
students. Both Sargent and Hart said that they've never had to handle this
type of situation.
"It's a learning thing every day," Sargent said. She said she expected to
receive some information from the health department today [Tue 25 May] that
could be sent home in a flyer with students.
"I just hear talk about town that it could be related to animals," said
Avery Principal Kevin Hart. He said that, as an administrator, he's never
had to handle this type of situation. Added Hart, "We like to keep parents
informed when we have a concern. We don't want to cause alarm; we just feel
that we have an obligation to share the facts, because we feel that they
have a right to know."
Kelaita said parents should not be overly worried about a spread of the
bacteria. "It's not something that has a high potential for transmission in
that age group, "the way it does in younger kids", he said. "In middle and
high school ages, the potential for person-to-person transmission is much
lower. I don't want to create the impression that there's a high chance
that their kid's are going to get sick too."
It's possible, but unlikely, that the 2 new cases are related to those
diagnosed earlier in May, he said. Each person was diagnosed with the most
harmful strain, called _E. coli_ O157:H7. The 3 earlier cases occurred in a
4-year-old boy, his 8-month-old sister and a 3-year-old girl, who was being
taken care of by the 2 children's mother. Only the boy had a severe case,
with kidney shutdown due to a rare side-effect called hemolytic uremic
syndrome, and he required dialysis. Soon after, fluid collected in his
lungs, and he was put on a respirator. "He's doing much better," the mother
said Mon 24 May 2004, from Oakland Children's Hospital, where he has been
since Wed 5 May 2004.
Kelaita said it's uncommon for those who contract _E. coli_ O157 to suffer
from hemolytic uremic syndrome as well. "Most people with this infection
will develop a milder, and self-limiting, type of illness," he said. "It
tends to resolve itself. Why some children get [hemolytic uremic syndrome]
and some children don't, we don't have a good explanation for."
"E. coli O157:H7 is considered an emerging infection, and, each year, we
tend to see a little bit more of this kind of infection," he said. "Where
we live, in Calaveras County, we have people who are exposed to livestock.
They have a ranching component to their daily lives, and they're in closer
contact with animals."
"There doesn't appear to be a community source for this. There doesn't
appear to be an outlet where this is being passed."
[Byline: Erin Mayes]
[This posting illustrates a number of issues related to illness due to _E.
coli_ O157 that are relevant, including the chance of household-spread in
children, cases without a clear source (possibly food-related), and cases
that are not due to the classical route of poorly cooked beef, especially
hamburger. With the onset of summer in the northern hemisphere, and, with
it, the barbeque season, the importance of making sure that meat is
well-cooked, and that good kitchen hygiene is maintained (to avoid
cross-contamination), cannot be emphasized enough.
The issue of whether those in rural environments, with continuous exposure
to cattle, have the same risk as those who do not have this kind of
continuous exposure, has been discussed in postings in the past. Included
below are pertinent references from E. coli O157, acquired immunity? (03)
1. Wilson JB, Clarke RC, Renwick SA, et al. Vero cytotoxigenic
_Escherichia coli_ infection in dairy farm families. J Infect Dis 1996;
174: 1021-7. Human VTEC infection was negatively associated with age (P <
0.05) and was not associated with clinical illness. Many dairy farm
residents experience subclinical immunizing VTEC infections at a young age,
which frequently involve non-O157 VTEC found in cattle.
2. Evans J, Chalmers RM, Chart H, et al. Evidence of persisting serum
antibodies to Escherichia coli O157 lipopolysaccharide and Verocytotoxin in
members of rural communities in England. Eur J Epidemiol 2000; 16(10):
885-9. The techniques of enzyme linked immunosorbent assay (ELISA) and
immunoblotting were used to examine a total of 1667 serum specimens, from
apparently healthy members of rural communities in England, for antibodies
to the lipopolysaccharide (LPS) of _E. coli_ O157 and Verocytotoxins (VT).
29 specimens from 22 individuals were shown to have antibodies specific for
_E. coli_ O157 LPS. Some of these lived on livestock farms and had
occupational contact with cattle, suggesting that personnel working with
farm animals may produce serum antibodies to the O157 LPS antigens. 15
people had IgG class antibodies to O157 LPS, suggesting long-term exposure
to _E. coli_ O157, and 5 people had serum antibodies, on more than one
occasion, showing evidence of persistent antibodies to O157 LPS. 13
specimens, from 12 of 22 individuals, also contained antibodies to VT1,
VT2, or both toxins. 10 specimens contained antibodies to VT1 and VT2, 3
contained antibodies to VT2 only.
3. Aslani MM, Badami N, Mahmmoodi M, Bouzari S.
Verotoxin-producing _Escherichia coli_ (VTEC) infection in randomly
selected population of Ilam Province (Iran). Scand J Infect Dis 1998; 30:
473-6. In rural areas, most individuals carrying VTEC isolates were
asymptomatic, whereas in urban areas, a significant association was found
between VTEC isolation and diarrhea (p < 0.01).
4. Reymond D, Johnson RP, Karmali MA, et al. Neutralizing antibodies to
_Escherichia coli_ Vero cytotoxin 1 and antibodies to O157
lipopolysaccharide in healthy farm family members and urban residents. J
Clin Microbiol 1996; 34: 2053-7. These findings are consistent with a
greater level of exposure of dairy farm residents to VT-producing E. coli
(VTEC) strains. The high rate of seropositivity to VT1 in farm residents
probably reflects the booster effect of repeated VTEC exposures and argues
against a sustained generalized immunosuppressive effect of VT1.
Seroepidemiological studies may help in assessing the level of exposure of
different populations to VTEC strains.
5. Trevena WB, Willshaw GA, Cheasty T, et al. Transmission of Vero
cytotoxin producing _Escherichia coli_ O157 infection from farm animals to
humans in Cornwall and west Devon. Commun Dis Public Health 1999;2:263-8.
Cases associated with animal contact included farm visitors,
holiday-makers, and members of farming families and farm workers. - Mod.LL]