Amebiasis in Ethiopia: Problems in diagnosis and determination of prevalence of infection
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Date
2005-02
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Abstract
Al though in thiopia int stin al am bias i is beli ved to b as ociat with many as of
diarrhea, diagnos is is based on xamination of fre h stoo l sampl s b micros op)" a m thod
that cannot discriminate the potential in asi e Entamoeba hi loly li a from th commensal
Entamoeba dispar . The annual reports from Wonji Hospital and th Ethio- eth rlands AID
Research Project indicate intes tinal am biasis to be a common infect ion \ ith the highest
prevalence compared to other paras ites. Des pite a considerably high reporting of intes tin al
amebias is, a twenty-year hospital reco rd among 117080 admitted pati nt showed on ly 47
suspected li ver abscess cases, suggesting overdiagnosis. Though the preval nce of E.
hi loly lica/E. dispar by microscopy \ as 24.9 % in Wonji and Akaki, the speci.fic PCR did not
confirm the pres nce of an E. hislolylica infection. E en after carefu l microscopic analysis,
by using qu ali ty control meas ures on 246 pat ients with di arrhea, micro co p d monstrated 40
% pos iti ity of Entamoeba infection. Ho\ e er, appl ication of PCR, a mol cular diagnostic
method that can distingu ish E. hi lolyli a [rom E. di par did not confi rm an E. hi loly li a.
onl % harboured E.di par . Coproantigen detection ELI in th sam pati nts sho\ d
clear lack of nsitivity and speciucit \ hereb onl 11 .4 % sp cim ns in th g nus
' nlamo ba p cific LI A \ r IJ1 agr m nt \ ith th P R. and non of th eight E.
hi lo/y li a antig n po iti v as confirm d. Th ab nce or /'.,. hi 'lOlylica in ~ ction in onJI
and kak i \ as b It r justiu d \ ith 10 \ r eropo iti it ( % findi ng. Ling r combinant
surfac an tig n of '. hi IOlYli a. Furth r stud among h alth. primary-s hool tud nt and
pn on r I~•. Ii par in lion. h 0 Ih ampl \\
Enlam ba inG lion, b ' ar ful ml ro py \\ ilh 0 ular m ur m nl, of
G rm 1- Ih r on ntral . 0 \Vas th n 'Ira t d [rom th 21 s mpl 27.6% round
Enlamo ba-p siti and run in a raj-lim P R \ ith primer , b d on th -r g n
S qu n of E. hi '1OlYli a and E. di par , Ihal aJ lo\ 0 from th two sp I to be
di tingui h d. lthough E. dispar 0 \ as id nti fi d in 19- 91. %), no E. hi lolyO a Dr
\ as d I cled . This finding is con islen l \ ith the pre iou in stigation that rrk1I1y am bic
inG ctions in Ethjopia are inco rrect I attribut d to E. hi {Oly liea and th n treated LIM c ssarl .
In order to further confirm the actuaJ occurrence of E. hi IOlyli a, 110 susp ct d
haematophagous trophozoites were co llected from diffe rent hospitaJs and heaJth center . Only
three (2.7 %) E. hi 'LOlYliea cases \ ere detected by real-time PCR \ hil 71.3 % \ re 'f .
dispar. The Gnding was similar among HIV / AIDS patients \ ith diarrh a ',: here microscop
re ealed 12 % E. hi loly lieal£. di par, but none with E. hi •/oly liea. The trad.i tion of
microscop in a routine diagnostic set-up appears unsatisfactory to rel.iabl differentiate RBCengulfing
ameba from non-in vasi e ameba. The public health Lmplication of this study is that
patient managem nt and alidity of epid emiological surveys are qu tionable as long as
microscopy is the only diagnostic tool. There is also a need to continue \ ork to establish the
aet iology of diarrhea wrongly associated with amebae and xplain th en.igma of patients
recovering following ' anti-amebic' treatment. The commonl repo ned complaints of bloody
mucoid di arrhea and association of 10\ D4 vith E. dispar infl ction among AID pat i nts
r quir aJ t mati e explanation. Training in microscop n d impro m nl. if not to diagnose
th inG clion aCC UJat I at lea t to minimize th 0 r-r porting. This \ ork emphasiz s th
n c ssit of capacit building for important diarrh al patho::, n wi th m I cular diagno ti at
reG rral levl
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Amebiasis in Ethiopia: