Identification of RT-PCR-Negative Asymptomatic COVID-19 Patients via Serological Testing.

Asymptomatic individuals with coronavirus disease (COVID-19) have been identified via nucleic acid testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, the epidemiologic characteristics and viral shedding pattern of asymptomatic patients remain largely unknown. In this study, serological testing was applied when identifying nine asymptomatic cases of COVID-19 who showed persistent negative RT-PCR test results for SARS-CoV-2 nucleic acid and no symptoms of COVID-19. Two asymptomatic cases were presumed to be index patients who had cleared the virus when their close contacts developed symptoms of COVID-19. Three of the asymptomatic cases were local individuals who spontaneously recovered before their presumed index patients developed symptoms of COVID-19. This report presents the epidemiologic and clinical characteristics of asymptomatic individuals with SARS-CoV-2 infection that were undetected on RT-PCR tests in previous epidemiologic investigations probably due to the transient viral shedding duration.

Influential impacts of combined government policies for safe disposal of dead pigs on farmer behavior.

Improper disposal of dead pigs by pig farmers may have an adverse impact on the ecological environment and food safety. In this paper, disposal of dead pigs by pig farmers in four main pig production provinces in China (Jiangsu, Anhui, Hubei, and Hunan) was empirically investigated. Then, pig farmers' awareness and evaluation of current combined government policies for the safe disposal of dead pigs were analyzed. Furthermore, the influential effects of combined government policies on the disposal of dead pigs by pig farmers were examined using Decision-Making Trial and Evaluation Laboratory (DEMATEL). Results indicated that the issue of disposal of dead pigs by farmers was very complex and was influenced by the combination of subsidy and compensation, facility and technology, and supervision and punishment policies. The findings also indicated that the different types of policies had different effects and interacted with each other. Among these three combinations, supervision and punishment policies were the most influential policies and facility and technology policies were in most urgent need to improve for regulating the current state of the disposal of dead pigs by farmers. These findings have implications for sustainable pig production.