Risk assessment for epidemic spread of the quarantined potato pathogen Synchytrium endobioticum in the Republic of Georgia

Synchytrium endobioticum (causal agent of potato wart) is a devastating soilborne pathogen. Eradication is difficult and infestation can result in 100% yield loss, making this a strictly quarantined pathogen worldwide. Emerging epidemics pose a high risk to production in Georgia where potato is an essential staple, grown primarily by smallholder farmers, and yields are among the world’s lowest. S. endobioticum was first reported in Georgia in 2014 in a localized outbreak in Adjara. Because pathogen dissemination is primarily via human transport of infested tubers, understanding the local potato seed system is critical. This study was the first to systematically characterize the actors involved in seed and ware potato production and trade in Georgia. To collect this information, an expert elicitation was conducted in 2017 across a broad range of participants from the Georgian potato production sector. We present a model of the current potato seed exchange network for the most important agroecological regions. We integrated network analysis in a risk assessment for S. endobioticum spread in Georgia under 1) no intervention, 2) quarantine, 3) introduction of host plant resistance, and 4) combined quarantine and resistance deployment. Preliminary analyses suggest that under no intervention, risk of spread is high, while rapid and consistent quarantine can be effective. Methods presented here provide a general framework for future seed system risk assessments

Smear plus Detect-TB for a sensitive diagnosis of pulmonary tuberculosis: a cost-effectiveness analysis in an incarcerated population

Background: Prison conditions can favor the spread of tuberculosis (TB). This study aimed to evaluate in a Brazilian prison: the performance and accuracy of smear, culture and Detect-TB; performance of smear plus culture and smear plus Detect-TB, according to different TB prevalence rates; and the cost-effectiveness of these procedures for pulmonary tuberculosis (PTB) diagnosis. Methods: This paper describes a cost-effectiveness study. A decision analytic model was developed to estimate the costs and cost-effectiveness of five routine diagnostic procedures for diagnosis of PTB using sputum specimens: a) Smear alone, b) Culture alone, c) Detect-TB alone, d) Smear plus culture and e) Smear plus Detect-TB. The cost-effectiveness ratio of costs were evaluated per correctly diagnosed TB case and all procedures costs were attributed based on the procedure costs adopted by the Brazilian Public Health System. Results: A total of 294 spontaneous sputum specimens from patients suspected of having TB were analyzed. The sensibility and specificity were calculated to be 47% and 100% for smear; 93% and 100%, for culture; 74% and 95%, for Detect-TB; 96% and 100%, for smear plus culture; and 86% and 95%, for smear plus Detect-TB. The negative and positive predictive values for smear plus Detect-TB, according to different TB prevalence rates, ranged from 83 to 99% and 48 to 96%, respectively. In a cost-effectiveness analysis, smear was both less costly and less effective than the other strategies. Culture and smear plus culture were more effective but more costly than the other strategies. Smear plus Detect-TB was the most cost-effective method. Conclusions: The Detect-TB evinced to be sensitive and effective for the PTB diagnosis when applied with smear microscopy. Diagnostic methods should be improved to increase TB case detection. To support rational decisions about the implementation of such techniques, cost-effectiveness studies are essential, including in prisons, which are known for health care assessment problems

Select the best. Positive selection to improve farm saved seed potatoes (Georgian)

This training manual is designed to provide step-by step instructions to trainers in teaching potato farmers positive selection, that is, to ‘select the best’. Positive selection can be used to improve the quality of the seed potatoes saved from the farmers own crop

An integrated seed health strategy and phytosanitary risk assessment: Potato in the Republic of Georgia

CONTEXT: Potato is an essential food staple and a critical crop for rural livelihoods in the Republic of Georgia, where many phytosanitary risks threaten production. OBJECTIVE: The objectives of this study were, first, to characterize the current seed and ware potato transaction network, value chain, varietal adoption, and phytosanitary risks for Georgia. Second, we modeled scenarios for the spread of an emerging pathogen, Synchytrium endobioticum, in Georgia as part of a geographic risk assessment analysis. Third, we coupled risk estimated in our simulation experiments with risk of reintroduction or invasion of pathogens via international trade or habitat connectivity. We found that a majority of seed potato is obtained from local sources in Georgia, and is of unknown phytosanitary quality