Incidence of Typhoid Fever and the Validity of the Widal Test in Some Districts in Iraq
Al- Anbar Medical Journal,
2020, Volume 16, Issue 1, Pages 12-16
AbstractBackground:Typhoid fever is a serious infectious disease. In Iraq, the disease has a public health
burden because it’s endemicity and there is an overestimation of the cases because the diagnosis
almost depends on the Widal test.
Objectives:The study aimed to determine the occurrence of typhoid fever in four sentinel sites
in Iraq and to assess Widal test sensitivity and specificity.
Materials and methods:This cross-sectional observational study conducted in four districts
in Iraq which has a population ranging from 170 000 to 431 000.A consecutive sample of
(757) patients attended the outpatient or admitted to hospitals with any Widal positive case,
probable typhoid case and suspected typhoid case were included in the study.A questionnaire
including demographic, clinical, laboratory and exposure data was filled for each suspected case.
Confirmation of the diagnosis of typhoid fever was done by serological examination and culture
(blood, urine or feces) for each patient included in the study.
Al-Haweeja, Al-Hay, Al-Majar, and North Najaf districts respectively and this occurrence was
lower in three study districts when compared with the same period of 2010 and 2011. The mean of
the age of cases was 25.8 years±16.03 and the male to female ratio of confirmed cases was 0.7:1.
Also, this study showed that the sensitivity of the Widal test was 16.7% and the specificity was
36.2% when compared with culture results.
Conclusion:The incidence rate of typhoid fever was low in the four selected sites except for the
Al-Haweeja district. The sensitivity and specificity of the Widal test were low.
Incidence of Typhoid Fever and the Validity of the Widal testANB. MED. J. 16(1), 2020
based surveillance using case investigation form and depended
on clinical information taken by the specialist physicians in
The same incidence of fluctuation was illustrated in a study
implemented in Korea .This study showed that the an-
nual incidence rate of typhoid fever from eleven provinces in
that country shows certain fluctuation some provinces show
an increased incidence rate by more than two folds when com-
pared with an overall incidence rate of the previous nine years.
Sunmi Yoo et al suggest the occurrence of an unnoticed out-
Regarding the age and gender distribution, the results of
this study were consistent with other studies; the highest inci-
dence (44.6%) of typhoid fever in Greek  during the period
from 2001-2004 was among the young age group (25-44) and
the incidence was higher among women in different Korea
provinces during the period 1992-2000 (women: 40/100 000
persons, men: 0.34/100 000 persons) .
The low result of the Widal test sensitivity and specificity
of the current study was consistent with prior studies regard-
ing the validity of the test [14–16]. In the endemic area where
the population exposed to Salmonella organisms, elevated an-
tibody titers may be present in a significant proportion of
the normal population.This situation clarified by a study
done by the college of medicine in Diyala university re-
vealed that the Widal test gave false-positive results for H
antigen in 50% and O antigen in 55% of normal healthy peo-
ple. Also, it showed that Widal test gave false-positive results
for H antigen in 46% and O antigen in 40% of non-typhoid
febrile patients and also it revealed that the prevalence of
false-positive Widal test may imply subclinical infection with
Salmonella typhi, also Salmonella typhi shares the same O
and H antigens with many other Salmonellae.Another ex-
planation of the false-positive Widal test is that the reading
of rapid slide agglutination test after two minutes can give a
false result or the specimen is not at room temperature .
In Iraq, many studies were done and various cut off titers
was stated. Al-Rawi  considered an initial titer of 1/320
is the most reliable one in the consideration if Typhoid fever.
Al-Abbasi  also considered an initial titer of 1/320 as a
diagnostic value.Hameed  also considered the titer of
1/320 for both O and H antigens as a diagnostic value. Salah
 mentioned that a titer of 1/160 is highly specific but less
sensitive in the community of Basra.Al-Khushali  also
considered an initial titer of 1/160 as a diagnostic value.
The limitation of our study was the Widal test validity
according to titers were not assessed because of some missed
data. Therefore, further investigation is needed to assess the
validity of the test according to titers.
The occurrence of typhoid fever in the four selected sites
except the Al-Haweeja district was low during the first six
months of 2012 in comparison with the same period of 2010
and 2011.High prevalence of false-positive Widal test was
found in our study.The sensitivity and specificity of the
Widal test were low.The present situation underlines the
importance of case-based surveillance and laboratory confir-
mation of typhoid fever.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interest.
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