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Fecal Occult Blood Testing Of Trichuris Infected Primary School ...

Am. J. Trop. Med. Hyg., 60(1), 1999, pp. 165–166
Copyright
1999 by The American Society of Tropical Medicine and Hygiene
FECAL OCCULT BLOOD TESTING OF TRICHURIS-INFECTED PRIMARY SCHOOL
CHILDREN IN NORTHEASTERN PENINSULAR MALAYSIA
S. MAHENDRA RAJ
Department of Medicine, School of Medical Sciences, Universiti Sains Malaysia, Kota Bharu, Kelantan, Malaysia
Abstract.
Stool specimens of 104 primary schoolchildren (mean
SD age
8.2
0.3 years) were examined
for helminth eggs and for occult blood to investigate the possibility that trichuriasis causes occult intestinal bleeding
in the absence of the overt Trichuris dysentery syndrome. A commercially available guaiac test was used to detect
fecal occult blood. Sixty-one children had Trichuris infection, 11 of whom had heavy infections (
10,000 eggs per
gram of feces [epg]), and 53 had Ascaris infections. No hookworm infection was detected. Baseline screening yielded
only one weakly positive occult blood test result in a child with a light (800 epg) Trichuris infection. Serial stool
occult blood testing on the 11 subjects with heavy trichuriasis and 8 uninfected controls yielded a single weakly
positive result in the control group. The results provide no evidence that trichuriasis predisposes to significant occult
gastrointestinal bleeding in children in the absence of the dysenteric syndrome.
Intense infection with Trichuris trichiura, a nematode that
ence of hydrogen peroxide and the peroxidase activity of
inhabits the colon causes a chronic dysenteric illness in chil-
hemoglobin.10
dren.1 However, this is a relatively uncommon event, Con-
The kit was validated in vitro by testing it on homoge-
sidering that the global prevalence of Trichuris infection is
nized stool spiked with various concentrations of whole
approximately 800 million,2 there is a remarkable dearth of
blood. The performance of the Coloscreen kit was tested
data on whether the infection predisposes to occult gastro-
initially on freshly prepared stool and later on stool stored
intestinal bleeding in the absence of the overt Trichuris dys-
for 72 hr, the first 24 hr of which was at room temperature
entery syndrome. There is evidence of an association be-
and the remainder at
20 C. The latter was done to simulate
tween heavy Trichuris infection and anemia even when the
the anticipated storage conditions during the field study. As
dysenteric illness is not present.3,4 Earlier studies that ad-
shown in Table 1, the in vitro sensitivity was high even at
dressed the question of gastrointestinal bleeding and trich-
a hemoglobin concentration of 2 mg/g. Assuming a hemo-
uriasis were conducted on small numbers of selected patients
globin concentration of 11g/dL and a daily stool output of
who may not be representative of the community.1–7 A larger,
approximately 100 g, this concentration translates to a daily
more recent study was community-based but conducted on
blood loss of approximately 2 ml/day. The upper limit of
a population with a high prevalence of concomitant hook-
normal intestinal blood loss as determined by radioisotope
worm infection that could have obscured the role of trichu-
studies have been reported to range from 1 to 3 ml/day.5,11,12
riasis in causing intestinal bleeding.8 The aim of the present
The stool samples were moistened with drops of distilled
study was to determine if trichuriasis predisposed to occult
water immediately prior to occult blood testing since rehy-
colonic bleeding among early primary school children in
dration has been shown to improve the sensitivity of the
northeastern peninsular Malaysia, a population with a rela-
guaiac test.13 The observer developing and reading the Co-
tively high prevalence of trichuriasis but a low prevalence
loscreen slide was blinded to the parasitologic result. Sub-
of hookworm infection.
jects with heavy Trichuris infections (
10,000 epg) and an
equivalent number of randomly selected uninfected control
subjects were each asked to furnish three additional samples
MATERIALS AND METHODS
of stool for repeat occult blood testing, which was again
Stool specimens from 104 children attending a single
performed by an observer blinded to the parasitologic result.
school on the outskirts of the town of Kota Bharu in north-
The study was approved by the Research and Ethics Com-
eastern peninsular Malaysia were collected and examined for
mittee of the School of Medical Sciences, Universiti Sains
helminth eggs. All 117 children in the second grade were
Malaysia. Parental consent was obtained for all participating
targeted for the study but stool specimens were obtained
children.
from only 104 subjects. Egg counts were determined using
a modification of Stoll’s method and expressed as eggs per
RESULTS
gram of feces (epg).9 Parasitologic examinations were gen-
erally performed on the day of stool collection. The stools
Of the 104 children, 53 were girls. The mean
SD age
were then stored at
20 C for up to 48 hr before being tested
of the children was 8.2
0.3 years. Sixty-one were infected
for occult blood using a commercially available slide test
with T. trichiura, 53 with Ascaris lumbricoides, and none
kit. This test consisted of guaiac-impregnated paper upon
with hookworm. Thirty-two children had no evidence of hel-
which a thin smear of stool was made (Coloscreen ; Helena
minthic infection. There was no difference in mean age and
Laboratories, Beaumont, TX). A positive test result was in-
sex ratio between the Trichuris-positive and -negative
dicated by a blue color change on adding two drops of the
groups. Among the Trichuris-positive children, the median
developer reagent on the slide. The guaiac test has been used
intensity of infection was 4,000 epg with an interquartile
in cancer screening programs and is based on the principle
range of 7,200 epg. Eleven children had heavy trichuriasis
that guaiac undergoes an oxidative color change in the pres-
(median
18,800 epg, range
10,400–84,600 epg). Five
165
166
RAJ
TABLE 1
The results of the present study show that occult colonic
In vitro performance of the stool occult blood test kit
bleeding is not a high-risk event in Trichuris-infected chil-
dren in the absence of the overt Trichuris dysentery syn-
Hemoglobin
concentration
Rate of positive test results
drome. However, the possibility that it may be a low-risk
in spiked
stool (mg/g)
Freshly prepared stool
Stool stored for 72 hr
event can only be excluded by testing even larger numbers
0
0/10
0/10
of individuals.
1
9/10*
3/10†
2
10/10
9/10*
Acknowledgments: I thank Roslan Mustapha and Roziyani Hashim
5
10/10
10/10
for assisting in the field work, as well as the teachers and pupils of
10
10/10
10/10
Tawang School, Kelantan Malaysia for cooperation.
* The observed color change in the positive test results was unequivocal but generally
weak.
Financial support: The study was funded by the government of Ma-
† The observed color change in the positive test results was very faint.
laysia.
Authors’ address: S. Mahendra Raj, Department of Medicine, School
of Medical Sciences, Universiti Sains Malaysia, Kota Bharu, Kelan-
of the 11 with heavy trichuriasis complied with the request
tan, 16150, Malaysia.
to provide an additional three samples each while the rest
provided nine additional samples. The stool recovery rate
REFERENCES
from children who served as controls for serial testing was
lower, with 13 samples being obtained from eight subjects.
1. Bundy DAP, Cooper ES, 1989. Trichuris and trichuriasis in Hu-
At baseline screening, all but one of the 104 stool samples
mans. Adv Parasitol 28: 107–173.
tested were unequivocally negative for occult blood. The sin-
2. Warren KS, Bundy DAP, Anderson RM, Davis AR, Henderson
gle positive test result was a weakly positive one observed
DA, Jamison JT, Prescott N, Senft A, 1993. Helminth infec-
tion. Jamison DT, Mosley VM, Measham AR, Bobadilla JL,
in a child with a light (800 epg) Trichuris infection. Repeat
eds. Disease Control Priorities in Developing Countries. New
fecal occult blood tests on serial samples from the children
York: Oxford University Press, 131–160.
with heavy trichuriasis and controls also yielded negative
3. Robertson LJ, Crompton DWT, Sanjur D, Neisheim MC 1992.
results except for one weakly positive result on a single sam-
Hemoglobin concentrations and concomitant infections of
ple from an uninfected control subject.
hookworm and Trichuris trichiura in Panamian primary
schoolchildren. Trans R Soc Trop Med Hyg 86: 654–656.
4. Ramdath DD, Simeon DT, Wong MS, Grantham-McGregor SM,
DISCUSSION
1995. Iron status of schoolchildren with varying intensities
of Trichuris trichiura infection. Parasitology 110: 347–351.
There was no significant difference in the rate of stool
5. Mahmood A, 1966. Blood loss caused by helminthic infections.
Trans R Soc Trop Med Hyg 60: 766–769.
occult blood positivity between Trichuris-positive and -neg-
6. Layrisse M, Aparcedo L, Martinez-Torres C, Roche M, 1967.
ative children. Although the in vitro sensitivity of the Co-
Blood loss due to infection with Trichuris trichiura. Am J
loscreen test was clearly high, the in vivo sensitivity of de-
Trop Med Hyg 16: 613–619.
tecting colonic bleeding may be lower due to factors such
7. Lotero H, Tripathy K, Bolanos O, 1974. Gastrointestinal blood
as the intermittent nature of bleeding or nonuniform mixing
loss in Trichuris infection. Am J Trop Med Hyg 23: 1203–
1204.
of blood in the stool. While even modest reductions in sen-
8. Stoltzfus RJ, Albonica M, Chwaya HM, Savioli L, Tielsch J,
sitivity are of critical diagnostic importance in individual
Schulze K, Yip R, 1996. Hemoquant determination of hook-
patients being screened for lesions such as colon cancer, they
worm-related blood loss and its role in iron deficiency in Af-
are less crucial for the purpose of this study, which was to
rican children. Am J Trop Med Hyg 55: 399–404.
9. Garcia LS, Bruckner DA, 1988. Diagnostic Medical Parasitol-
detect a difference in the propensity of colonic bleeding be-
ogy. New York: Elsevier Science Publishing Co., 395–396.
tween groups. In the original design of the study, provisions
10. Bresalier RS, Kim YS, 1993. Malignant neoplasms of the large
were made to repeat occult blood testing after treatment
intestine. Steisenger NM, Fordtran JS, eds. Gastrointestinal
based on the hypothesis that Trichuris-induced bleeding
Disease: Pathophysiology/Diagnosis/Management. Philadel-
would be reversed by treatment. The baseline results clearly
phia: W. B. Saunders Company, 1449–1493.
11. Roche M, Perez-Gimenez ME, Layrisse M, Di Prisco E, 1957.
obviated the need for the interventional phase of the study.
Study of urinary and fecal excretion of radioactive chromium
Furthermore, any reduction of in vivo sensitivity of the oc-
Cr51 in man. Its use in the measurement of intestinal blood
cult blood test due to the factors alluded to was at least
loss associated with hookworm infection. J Clin Invest 36:
partially compensated for by serial testing of stool in chil-
1183–1192.
12. Herzog P, Holtermuller KH, Preiss J, Fischer J, Ewe K, Schrei-
dren with heavy Trichuris infection; the group most likely
ber HJ, Berres M, 1982. Fecal blood loss in patients with
to have been occult blood–positive if the original hypothesis
colonic polyps: a comparison of measurements with 51chro-
were true. The definition of heavy infection on the basis of
mium labeled erythrocytes and with the Hemoccult test. Gas-
egg counts is somewhat arbitrary, and the one used for this
troenterology 83: 957–962.
study (
10,000 epg) was proposed by a World Health Or-
13. Macrae FA, St. John DJB, 1982. Relationship between patterns
of bleeding and Hemoccult sensitivity in patients with colo-
ganization expert committee.14 It is acknowledged that some
rectal cancers or adenomas. Gastroenterology 82: 891—898.
investigators consider 20,000 epg as a cut-off level between
14. WHO Expert Committee, 1987. Public Health Significance of
infections of moderate and heavy intensities.15 The results of
Intestinal Parasitic Infections. Prevention and Control of In-
this study are compatible with those of the recent study by
testinal Parasitic Infections. World Health Organ Tech Rep
Ser 749: 8–28.
Stoltzfus and others, who found no correlation between Tri-
15. Beaver PC, Jung RC, Cupp EW, 1984. Examination of speci-
churis intensity and stool hemoglobin concentration after ad-
mens for parasites. Clinical Parasitology. Ninth edition. Phil-
justing for hookworm intensity.8
adelphia: Lea & Febeiger: 733–758.

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