Bulletin of the World Health Organization

Sensitivity and specificity of typhoid fever rapid antibody tests for laboratory diagnosis at two sub-Saharan African sites

Karen H Keddy, Arvinda Sooka, Maupi E Letsoalo, Greta Hoyland, Claire Lise Chaignat, Anne B Morrissey & John A Crump

Volume 89, Number 9, September 2011, 640-647

Table 1. Comparative characteristics of three rapid tests for the detection of Salmonella Typhi antibodies

Characteristic Cromotest® – semiquantitative slide agglutination Cromotest® – single tube Widal TUBEX® Typhidot®
Antibody IgM and IgG IgM and IgG IgM IgM or IgG
Antigen O and H O and H O9 OMP
Turnaround time per test 2 minutes at room temperature O: 4 hours at 50 °C 3 minutes at room temperature 60 minutes at room temperature
H: 2 hours at 50 °C
Storage temperature (°C) 2–8 2–8 2–8 2–8
Equipment supplied by manufacturer Febrile antigen Febrile antigen Colour scale Predotted antigen strips
Positive control Positive control Blue and brown reagent Sample diluent
Negative control Negative control Negative control Washing buffer
Positive control Prediluted anti-human IgM and IgG
Reaction well strip Substrate A and B
Sealing tape Positive control
Coloured sticker Negative control
Timer Worksheet
Equipment supplied by laboratory Disposable slides Thermostatic waterbath (30–50 °C) Precision pipette Measuring cylinder
Saline solution Disposable sterile glass tubes (12 × 100 mm) Vortex Micropipettes and tips
Disposable stirrers Conical flask
Saline solution Forceps, wash bottle
Mechanical stirrer Filter paper, distilled water
Rocker platform
Aspirator
Aluminium foil
Dark reagent bottle/flask covered with aluminium foil
User comments Particles present before adding the antisera, rendering false-positive results. Simple to use and inexpensive. Particles present before adding the antisera, rendering false-positive results. Requires costly additional laboratory equipment. Subjective interpretation of colour reactions. Haemolysis may result in difficulty in interpretation. Simple to use and limited need for additional laboratory equipment. More complex assay requiring additional steps and preparation of consumables. Interpretation may be affected, as IgG can persist for more than 2 years after typhoid infection. Detection of specific IgG cannot differentiate between acute and convalescent cases. Requires costly additional laboratory equipment.

OMP, outer membrane protein.