Field evaluation of crystal VC Rapid Dipstick test for cholera during a cholera outbreak in Guinea-Bissau.

Objectives: To evaluate performance characteristics and ease of use of the new commercially available Crystal VC Rapid Dipstick (VC) test (Span Diagnostics, India) for Vibrio cholerae O1 and O139.

Methods: Whole stool was collected from patients presenting to a hospital cholera ward during a 2008 epidemic in Guinea-Bissau. The VC test on stool samples was conducted on-site; samples were subsequently stored in Cary-Blair transport media and sent to the Centers for Disease Control and Prevention for diagnostic testing by culture and polymerase chain reaction (PCR). In addition, four local laboratory technicians who were unfamiliar with the test were provided with stool samples, the VC test kit, and simple written instructions and asked to perform the test and interpret results.

Results: A total of 101 stool specimens were collected and tested. Compared with PCR, the test was 97% sensitive and 71-76% specific. Laboratory technicians in Bissau performed the test and interpreted results correctly using only simple written instructions.

Conclusions: The VC test may be useful for cholera diagnosis in outbreak situations where laboratory capacity is limited.