Field evaluation of a locally produced rapid diagnostic test for early detection of cholera in Bangladesh

Abstract

Background Cholera remains a substantial health burden in Asia and Africa particularly in resource poor settings. The standard procedures to identify the etiological organism V . cholerae are isolation from microbiological culture from stool as well as Polymerase Chain Reaction (PCR). Both the processes are highly lab oriented, labor extensive, time consuming, and expensive. In an effort to control for outbreaks and epidemics; an effective, convenient, quick and relatively less expensive detection method is imperative, without compromising the sensitivity and specificity that exists at present. The objective of this component of the study was to evaluate the effectiveness of a locally produced rapid diagnostic test (RDT) for cholera diagnosis. Methods In Bangladesh, nationwide cholera surveillance is ongoing in 22 hospitals covering all 8 divisions of the country since June, 2016. In the surveillance, stool samples have been collected from patients presenting to hospitals with acute watery diarrhea. Crystal VC TM (Span diagnostics, India) and Cholkit (locally produced RDT) have been used to detect V . cholerae from stool samples. Samples have also been sent to the main laboratory at icddr,b where the culture based isolation is routinely performed. All the tests were carried out for both direct and enriched stool samples. RDT sensitivity and specificity were calculated using stool culture as the gold standard. Results A total of 7720 samples were tested. Among these, 5865 samples were solely tested with Crystal VC and 1355 samples with Cholkit whereas 381 samples were tested with both the RDTs. In comparison with culture, direct testing with Crystal VC showed a sensitivity of 72% (95% CI: 50.6% to 87.9%) and specificity of 86.8% (95% CI: 82.8% to 90.1%). After enrichment the sensitivity and specificity was 68% (95% CI: 46.5% to 85.1%) and 97.5% (95% CI: 95.3% to 98.8%) respectively. The direct Cholkit test showed sensitivity of 76% (95% CI: 54.9% to 90.6%) and specificity of 90.2% (95% CI: 86.6% to 93.1%). Conclusion This evaluation has demonstrated that the sensitivity and specificity of Cholkit is similar to the commercially available test, Crystal VC when used in field settings for detecting V . cholerae from stool specimens. The findings from this study suggest that the Cholkit could be a possible alternative for cholera endemic regions where V . cholerae O1 is the major causative organism causing cholera.

Molecular detection of Vibrio cholerae from human stool collected from SK Hospital, Mymensingh, and their antibiogram

“…However, we do not rule out the possibilities of other four culture-positive isolates as Vibrio spp., without screening them with other primers available for the detection of Vibrio spp. Vibrio is the major cause of diarrhea in many countries of the world including Bangladesh [6,33]. A study conducted in Nepal showed that variation in geographical locations or primer used greatly influence the occurrence and detection of various Vibrio spp.…”

“…Among these, V. cholerae is considered as the most devastating agent [5]. Across the world, an estimated 1.3 billion people are at risk of cholera; of which Bangladesh jointly constitutes the largest share of the population at risk [6]. Recently, it has been reported that around 66 million people in Bangladesh are at risk for cholera with an incidence of about 1.64 per thousand people [7].…”

Two cases of cholera O1 in South Batinah, Oman, April 2019: lessons learned

“…Significantly, the South Sudan outbreak indicated that the Crystal VC RDT, when used with a simple step of enrichment in alkaline peptone water, demonstrated performance similar to that of culture [12]. RDTs are thus fast, practical, and effective tests for large-scale epidemics where containment of the infection from the beginning is critical [13]. While stool culture is still the gold standard for diagnosing cholera, the time required to obtain results, combined with deficiencies in laboratory infrastructure, sample transportation, and staff training, can significantly delay detection and control actions [12].…”

Immunogenicity of a killed bivalent whole cell oral cholera vaccine in forcibly displaced Myanmar nationals in Cox's Bazar, Bangladesh

“…The commonly reported public health problems among the FDMNs are acute watery diarrhea, measles, acute respiratory infections, diphtheria, malaria, other infectious diseases as well as malnutrition [10]. Cholera is endemic in Bangladesh [11] and it is prevalent in Cox's Bazar [12]. The aim of the study was to evaluate the immune responses to OCV among the healthy FDMNs in Bangladesh and to compare the immune response of the FDMN participants with data of the vibriocidal responses seen in adults and children in an earlier vaccination study carried out in the Mirpur urban area in Dhaka.…”