Evaluation of a rapid dipstick test (Crystal Vc®) for the diagnosis of cholera in Maiduguri, Northeastern Nigeria

Abstract

Background: Cholera is a preventable diarrheal disease associated with rapidly progressing dehydration. Early detection of the causative agent, Vibrio cholerae (VC) among symptomatic patients is a key step in cholera outbreak management to minimize disease spread and mortality. Materials and Methods: We prospectively evaluated the performance of Crystal VC®, a commercially available test kit for rapid detection of VC serotypes 01 and 0139 directly from stool samples. Patients included in this study were those admitted to the cholera treatment unit from August 14, 2017, to September 20, 2017, during the cholera outbreak in Maiduguri, northeastern Nigeria. Conventional bacterial stool culture is considered the gold standard and was used as the comparator. Results: A total of 156 stool specimens were collected and tested. Compared with stool culture results, the Crystal VC® test had sensitivity (SE) of 95.1% and specificity (SP) of 59.3%. The positive and negative likelihood ratios were 2.33 and 0.08, respectively. The positive predictive value (PPV) was 81.5% while the negative predictive value (NPV) was 86.5%. There was no gender variation with respect to SE, SP, PPV, and NPV. Conclusion: The cholera rapid dispstick test (RDT), Crystal VC®, is a useful tool for diagnosis of diarrheal disease due to VC serotypes 01 and 0139 and may provide an initial alert in an outbreak situation. It may also be used for case surveillance in cholera epidemic prone situations resulting from displacement to camps or overcrowded shelters due to human conflict or natural disasters. Although it is less sensitive than conventional stool culture, it is a convenient and simple test to perform with faster turnaround time.