EID Journal Home> Volume 14, Number 2-February 2008

Volume 14, Number 2-February 2008
Dispatch
Transmission of Hepatitis C Virus during Computed Tomography Scanning with
Contrast
Helena Pañella,* Cristina Rius,* Joan A. Cayl�E* and the Barcelona Hepatitis C
Nosocomial Research Working Group1
*Agència de Salut Pública de Barcelona, Barcelona, Spain

Suggested citation for this article

Abstract
Six cases of acute hepatitis C related to computed tomography scanning with
contrast were identified in 3 hospitals. A patient with chronic hepatitis C had
been subjected to the same procedure immediately before each patient who
developed acute infection. Viral molecular analysis showed identity between
isolates from cases with acute and chronic hepatitis C.

The most common mechanism involved in transmission of hepatitis C virus (HCV) is
exposure to contaminated blood; sharing of syringes between drug users is
currently the most frequent factor. However, in 40% of cases, the mechanism
cannot be identified, and nosocomial transmission has an increasingly important
role (1).

In recent years, transmission of HCV from an infected patient to a susceptible
person during various healthcare-related procedures has been reported (2,3). The
risk of transmission depends on the mechanism responsible, as well as on the
prevalence of infected persons. Thus, in addition to use of shared vials for
administration of heparin (4), physiological saline solution (5-7) or
anesthetics (8,9), procedures carried out with contaminated equipment (10,11) or
inappropriate practices of health personnel (12) have been proposed as
mechanisms of nosocomial transmission. Molecular analysis of HCV has permitted
comparison of different viral sequences to confirm transmission.

Hepatitis C infection is a mandatory reportable disease in Spain and is reported
as a suspected infection as soon as it is clinically diagnosed. In Barcelona,
after initial reporting of a case of hepatitis C, an epidemiologic survey is
conducted by trained personnel from the epidemiologic service to identify
possible sources of infection (sexual or household contact with an HCV case, use
of multidose medications, transfusions, surgical interventions or other invasive
procedures during their hospital stay) and to implement appropriate control
measures. The aim of the present study was to describe several cases of
nosocomial HCV transmission affecting patients in which the identified possible
source of transmission was a computed tomography (CT) scan with contrast in
different hospitals in Barcelona in 2004.

The Study
From August through November 2004, 6 cases of acute hepatitis C associated with
a CT scan with contrast were diagnosed in 2 public hospitals and 1 private
diagnostic center. Only 1 was detected by active case finding. Three cases were
women and 3 were men (ages 29, 47, 55, 57, 58 and 61 years, respectively) . All
but 1 had symptoms compatible with acute hepatitis with dates of onset from July
8 to September 18, 2004. All had increased serum transaminase levels, positive
serologic results for hepatitis C, and HCV RNA detected by reverse
transcription-PCR. All cases were investigated and other sources of transmission
were ruled out; all participants were outpatients with appointments and did not
undergo any specific tests before or after the scan. None shared any equipment
or locations with carriers, none received multidose injectable medications or
contaminated saline flushes, and none shared other exposures during their CT
procedure. All patients had recently undergone a CT
scan with contrast: 3 patients on June 11, and 1 each on June 25, June 29, and
August 9. An epidemiologic study was conducted that defined a hepatitis C case
as a person who satisfied the following 3 criteria: 1) diagnosis of acute
hepatitis C according to the case definition of the Catalan Surveillance System
(13); 2) having undergone a CT scan with contrast in the 6 months before
diagnosis; and 3) the case was detected from August through November 2004. All
persons tested with the same multidose contrast equipment; a reported case were
screened to detect possible HCV carriers.

Transmission was demonstrated by similarity of HCV sequences isolated from acute
hepatitis cases with those sequences isolated from carriers with chronic
hepatitis C by using phylogenetic analysis. Briefly, glycoprotein E2 coding
sequence (nt 1301-1808 encompassing hypervariable region 1) was amplified by
nested PCR as previously described (3,4). This analysis was performed in 2
laboratories: Hospital Clinic and Hospital Vall d'Hebron.

Figure 1

Figure 1. Phylogenetic tree of the partial glycoprotein E2 sequences of
hepatitis C virus from patients investigated in 2 public hospitals and 1 private
diagnostic center...


Figure 2

Figure 2. Equipment for contrast administration in computed tomography scan.

Four independent carrier-case events were identified, as shown in Table 1. Three
cases on the same day were related to the same carrier, 2 cases were identified
immediately after the carrier, and 1 case (asymptomatic) was not consecutive
(only 1 person between cases 2 and 3), resulting in a secondary attack rate of
60.0% (95% confidence interval [CI) 17.04-92.74) (Table 2) In the other 3
events, the case was scanned immediately after the carrier; global secondary
attack rate was 26.08% (95% CI 11.08-48.68). The first event was probably caused
by a carrier viral load greater than that of the other events. All cases
involved the immediately prior scan of an HCV carrier and they clustered in the
same node, on the basis of 1,000 resamplings, with a value �E00%; some part of
the contrast injection equipment had been used for all cases (Figure 1). All
transmission events resulted in well-defined, highly supported monophyletic
groups when samples involved in the outbreak were
analyzed (>95%). Conversely, sequences from unrelated samples did not show
bootstrap support (4 persons. The contrast solution arrived in a prefilled
bottle (manufactured by different pharmaceutical companies) that is loaded
through a connection tube into the injector. We investigated this procedure and
did not detect any risk of blood contamination. Replacement of the injector
varied among hospitals, and use time ranged from 8 hours to several days. All
equipment was connected to the patient by the intravenous route through an
extension tube fitted with a nonreturn valve. This extension tube was the only
part of the equipment that was changed for each patient. One maneuver involving
risk of blood contamination of the extension tube was identified in all
hospitals. Contamination could have occurred through the hands of health
personnel manipulating the extension tube by disconnecting the tube from the
patient first and then from the equipment without changing gloves
between these manipulations. Other factors that could have contributed to
transmission were lack of written instructions to guarantee proper practice;
training of new technicians by experienced technicians, which may perpetuate
errors; and work overload, with a maximum time of
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"Hepatitis C, Be Tested, there is no vaccine for HCV"








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