Identification of molecular markers associated with alteration of receptor-binding specificity in a novel genotype of highly pathogenic avian influenza A(H5N1) viruses detected in Cambodia in 2013.

Human infections with influenza A(H5N1) virus in Cambodia increased sharply during 2013. Molecular characterization of viruses detected in clinical specimens from human cases revealed the presence of mutations associated with the alteration of receptor-binding specificity (K189R, Q222L) and respiratory droplet transmission in ferrets (N220K with Q222L). Discovery of quasispecies at position 222 (Q/L), in addition to the absence of the mutations in poultry/environmental samples, suggested that the mutations occurred during human infection and did not transmit further.

Cost Analysis of Tuberculosis Diagnosis in Cambodia with and without Xpert® MTB/RIF for People Living with HIV/AIDS and People with Presumptive Multidrug-resistant Tuberculosis.

BACKGROUND: The Xpert® MTB/RIF (Xpert) test has been shown to be effective and cost-effective for diagnosing tuberculosis (TB) under conditions with high HIV prevalence and HIV-TB co-infection but less is known about Xpert's cost in low HIV prevalence settings. Cambodia, a country with low HIV prevalence (0.7%), high TB burden, and low multidrug-resistant (MDR) TB burden (1.4% of new TB cases, 11% of retreatment cases) introduced Xpert into its TB diagnostic algorithms for people living with HIV (PLHIV) and people with presumptive MDR TB in 2012. The study objective was to estimate these algorithms' costs pre- and post-Xpert introduction in four provinces of Cambodia. METHODS: Using a retrospective, ingredients-based microcosting approach, primary cost data on personnel, equipment, maintenance, supplies, and specimen transport were collected at four sites through observation, records review, and key informant consultations. RESULTS: Across the sample facilities, the cost per Xpert test was US$33.88-US$37.11, clinical exam cost US$1.22-US$1.84, chest X-ray cost US$2.02-US$2.14, fluorescent microscopy (FM) smear cost US$1.56-US$1.93, Ziehl-Neelsen (ZN) smear cost US$1.26, liquid culture test cost US$11.63-US$22.83, follow-on work-up for positive culture results and Mycobacterium tuberculosis complex (MTB) identification cost US$11.50-US$14.72, and drug susceptibility testing (DST) cost US$44.26. Specimen transport added US$1.39-US$5.21 per sample. Assuming clinician adherence to the algorithms and perfect test accuracy, the normative cost per patient correctly diagnosed under the post-Xpert algorithms would be US$25-US$29 more per PLHIV and US$34-US$37 more per person with presumptive MDR TB (US$41 more per PLHIV when accounting for variable test sensitivity and specificity). CONCLUSIONS: Xpert test unit costs could be reduced through lower cartridge prices, longer usable life of GeneXpert® (Cepheid, USA) instruments, and increased test volumes; however, epidemiological and test eligibility conditions in Cambodia limit the number of specimens received at laboratories, leading to sub-optimal utilization of current instruments. Improvements to patient referral and specimen transport could increase test volumes and reduce Xpert test unit costs in this setting.