Usefulness of the Widal test in diagnosing childhood typhoid fever in endemic areas.
Data are presented for 2382 children investigated for fever in a Malaysian hospital between 1984 and 1987 when Widal tests and blood cultures were a routine part of every fever screen. There were 145 children who were culture positive (TYP-CP) for Salmonella typhi, while 166 were culture negative but were diagnosed as having typhoid (TYP-CN). Analyses of the sensitivity and specificity of combinations of initial Widal titres in predicting a positive S. typhi culture in a febrile child (culture positive vs the rest) showed the best model to be an O- and/or H-titre of > or = 1 in 40 (sensitivity 89%; specificity 89%). While the negative predictive value of the model was high (99.2%) the positive predictive value remained below 50% even for very high titres of O and H (> 1 in 640), at which point the specificity was 98.5%, supporting the clinical view that a high proportion of the TYP-CN patients really were typhoid but were missed by culture. The TYP-CN patients showed a very similar clinical and age profile to TYP-CP patients. The length of history of fever did not affect the initial Widal titre in culture positive cases. The Widal test in children remains a sensitive and specific 'fever screen' for typhoid although it will not identify all cases. In children, lower cut-off points for O- and H-titres should be used than are generally recommended.
Choo
K E
KE
Department of Paediatrics, Universiti Sains Malaysia Medical School, Kubang Kerian, Kelantan.
Razif
A R
AR
Oppenheimer
S J
SJ
Ariffin
W A
WA
Lau
J
J
Abraham
T
T
D000373:Agglutinins / Q000097:blood*; D000942:Antigens, Bacterial / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008296:Malaysia / Q000453:epidemiology; D008297:Male; D011237:Predictive Value of Tests; D012485:Salmonella typhi / Q000276:immunology / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D014435:Typhoid Fever / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology
D000373:Agglutinins; D000942:Antigens, Bacterial