Rapid diagnosis of Naja atra snakebites

Abstract

Background. The clinical diagnosis of snakebites is critical and necessary in many parts of the world, especially in Southeastern Asia, where venomous snakebites are a burden on public health. It is difficult to define or recognize the species of venomous snake because of the overlapping clinical manifestations of envenomations. A quick and reliable method for identifying the snake species is necessary. We designed and tested a strip of lateral flow system for the diagnosis of cobra snake bites in Taiwan. Methods. We developed a kit based on an immunochromatographic method for rapid detection of cobra (Naja atra) venom in human serum. The test and control lines composed of 1 mg/ml polyclonal duck antivenom and 0.5 mg/ml goat anti-rabbit immunoglobulin antibody solutions, respectively, were coated on nitrocellulose strips. Colloidal gold was conjugated with rabbit polyclonal anti-cobra venom antibodies. From July 2007 to December 2012, we used the kit to test serum from snakebite patients and to examine the agreement between our rapid test and the currently used sandwich enzyme-linked immunosorbent assay (ELISA). Results. Our kit was able to detect cobra venom in serum samples in 20 minutes with a detection limit of 5 ng/ml. An absence of cross-reactivity with other non-cobra venoms from Taiwan was noted in vitro. A total of 88 snakebite patients (34 cobra and 54 other non-cobra) were tested. The sensitivity of the strips based on the ELISA results was 83.3% and the specificity was 100%. There was a strong agreement between the results of the ELISA and immunochromatographic strips (κ = 0.868). Discussion and conclusions. This data indicates that an immunochromatographic strip might be suitable for cobra venom detection and could be used as a quick diagnostic tool in cases of N. atra snakebite.

Keywords:

• Immunochromatography
• Cobra
• Snake bite

Acknowledgments

The authors thank the Vaccine Center of the Center for Disease Control (CDC) for their generous supply of lyophilized snakes’ antivenin.

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.

Part of this work was supported by the grants from the National Science Council, Taiwan (NSC 96-2314-B-039028 and 100-2923-B-039001).