Characterization of Enteric Disease in Children by Use of a Low-Cost Specimen Preservation Method.

Diarrhea is a leading cause of death in children under five. Molecular methods exist for the rapid detection of enteric pathogens; however, the logistical costs of storing stool specimens limit applicability. We sought to demonstrate that dried specimens preserved using filter paper can be used to identify diarrheal diseases causing significant morbidity among children in resource-constrained countries. A substudy was nested into cholera surveillance in Cameroon. Enrollment criteria included enrollment between 1 August 2016 and 1 October 2018, age of <18 years, availability of a stool specimen, and having three or more loose stools within 24 h with the presence of dehydration and/or blood. A total of 7,227 persons were enrolled, of whom 2,746 met enrollment criteria and 337 were included in this analysis using the enteric TaqMan array card. Bacterial pathogens were compared to severity of diarrhea, age, and sex, among other variables. One hundred seven were positive for enterotoxigenic Escherichia coli, of which 40.2% (n = 43) had heat-labile enterotoxin (LT) and the heat-stable enterotoxin STh, 19.6% (n = 21) had LT and the heat-stable enterotoxin STp, and 49.5% (n = 53) had LT only. Major colonization factors (CFs) were present in 43.9% of enterotoxigenic E. coli (ETEC)-positive patients. Ninety-six were positive for Shigella, of whom 14 (14.6%) reported dysentery. Model-derived quantitative cutoffs identified 116 (34.4%) with one highly diarrhea-associated pathogen and 16 (4.7%) with two or more. Shigella and rotavirus were most strongly associated with diarrhea in children with mixed infections. Dried-filter-paper-preserved specimens eliminate the need for frozen stool specimens and will facilitate enteric surveillance and contribute to the understanding of disease burden, which is needed to guide vaccine development and introduction. This study confirms rotavirus, Shigella, and ETEC as major contributors to pediatric diarrheal disease in two regions of Cameroon.

Laboratory and Field Evaluation of the Crystal VC-O1 Cholera Rapid Diagnostic Test.

Cholera is a severe acute, highly transmissible diarrheal disease which affects many low- and middle-income countries. Outbreaks of cholera are confirmed using microbiological culture, and additional cases during the outbreak are generally identified based on clinical case definitions, rather than laboratory confirmation. Many low-resource areas where cholera occurs lack the capacity to perform culture in an expeditious manner. A simple, reliable, and low-cost rapid diagnostic test (RDT) would improve identification of cases allowing rapid response to outbreaks. Several commercial RDTs are available for cholera testing with two lines to detect either serotypes O1 and O139; however, issues with sensitivity and specificity have not been optimal with these bivalent tests. Here, we report an evaluation of a new commercially available cholera dipstick test which detects only serotype O1. In both laboratory and field studies in Kenya, we demonstrate high sensitivity (97.5%), specificity (100%), and positive predictive value (100%) of this new RDT targeting only serogroup O1. This is the first field evaluation for the new Crystal VC-O1 RDT; however, with these high-performance metrics, this RDT could significantly improve cholera outbreak detection and improve surveillance for better understanding of cholera disease burden.

Cost-effectiveness of Diagnostic Algorithms for Tuberculosis in Children Less Than 5 Years of Age.

BACKGROUND: The objective of this analysis was to assess the cost-effectiveness of TB diagnosis using microscopic observation drug susceptibility (MODS), Xpert MTB/RIF (Xpert) and empiric treatment for all patients, in addition to current clinical diagnostic practices in children less than 5 years of age in a national tuberculosis (TB) referral hospital in Uganda. METHODS: A decision analysis was conducted from the healthcare perspective, with a primary outcome of incremental cost-effectiveness expressed as cost per year of life gained (YLG). RESULTS: Cost-effectiveness of the algorithms depended strongly on 3 variables: the prevalence of TB, probability of death if TB was untreated and accuracy of existing diagnostic algorithms. Xpert and MODS had similar cost-effectiveness profiles and were preferred in settings where the prevalence of TB and probability of death from untreated TB were low. As the underlying probability of TB disease and death increased, treating all children with clinically suspected disease became more cost-effective. In settings where the probability that an untreated child will die of TB-whether a result of high prevalence of TB or high mortality from untreated TB-treating all children for TB is likely to be the most cost-effective approach until better diagnostic tests can be developed. CONCLUSIONS: The cost-effectiveness of diagnostic tools for TB in children depends on the population, natural history of untreated TB and existing diagnostic practices. In settings where the risk of TB death is high, empiric treatment of all children for TB should be considered until a more sensitive, low-cost diagnostic test is available.