Epidemiological characteristics of SARS-CoV-2 infection outbreak in Shanghai in the Spring of 2022 / 上海预防医学

ObjectiveTo investigate the epidemiological characteristics and analyze the incidence trend of SARS-CoV-2 infection in Shanghai， China， and compare with the characteristics of the infection in Jilin Province of China during the same period in 2022 and Wuhan at the beginning of 2020. MethodsInformation of new locally-transmitted confirmed SARS-CoV-2 cases， imported confirmed COVID-19 cases， local asymptomatic SARS-CoV-2 carriers and imported asymptomatic SARS-CoV-2 carriers in Shanghai from March 1 to April 18， 2022 was collected for descriptive analysis. ResultsFrom March 1 to April 18， 2022， a total of 397 933 locally-transmitted SARS-CoV-2 cases were reported in Shanghai. Of those， 27 613 were clinically confirmed cases and 21 were severe cases. Ten deaths were related to COVID-19. The pathogen is Omicron variant BA.2 of SARS-CoV-2. The number of the infected subjects increased rapidly after March 24 and lead to a disease outbreak. Severe and deceased cases had severe comorbidity and were mostly unvaccinated with SARS-CoV-2 vaccines. Asymptomatic SARS-CoV-2 carriers accounted for 93.06%， which is significantly higher than that in Jilin Province during the same period （48.07%， P<0.001）. Daily increase in the number of clinically confirmed COVID-19 cases in Shanghai in 2022 was much lower than that in Wuhan， Hubei Province， in 2020. Number of daily newly imported confirmed COVID-19 cases and imported asymptomatic SARS-CoV-2 carriers declined during this period. ConclusionThe Omicron variant in Shanghai 2022 is highly infectious and less pathogenic. Omicron variant BA.2 replicates rapidly in asymptomatic carriers， which makes the carriers the major source of infection. Full-term vaccination of inactivated SARS-CoV-2 vaccine might decrease the pathogenicity and fatality of SARS-CoV-2 variants. SARS-CoV-2 of the Omicron BA2 strain is likely transmitted through aerosols and droplets， which poses a great challenge to the control of the COVID-19 pandemic in large cities with high population density and sophisticated public transportation.

Transmission of severe acute respiratory syndrome coronavirus 2 through asymptomatic carriers and aerosols: A major public health challenge

Abstract In the absence of vaccines and effective antiviral drugs, control of the spread of coronavirus disease (Covid-19) relies mainly on the adequacy of public health resources and policies. Hence, failure to establish and implement scientifically reliable control measures may have a significant effect on the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, severity of the disease, and death toll. The average number of secondary transmissions from an infected person, or reproduction numbers (R0 and R), and the points at which the collective immunity begins to reduce the transmission of the infection, or herd immunity thresholds, are important epidemiological tools used in strategies of Covid-19 control, suppression, and mitigation. However, SARS-CoV-2 transmission through asymptomatic carriers and, possibly, aerosols, has been ignored, and this may affect the effectiveness of Covid-19 control strategies. Therefore, consideration of the two possible ways of transmission would substantially increase the values of reproduction numbers, but if estimates of the contingent of the population naturally resistant to the virus, plus those with pre-existing cross-immunity to SARS-CoV-2 were considered, the evaluation of herd immunity thresholds should reach their real and achievable levels.

Staphylococcus aureus resistentes a meticilina (SARM) y productores de enterotoxina A aislados de portadores nasales asintomáticos entre estudiantes universitarios de México / Methicillin resistant Staphylococcus aureus (MRSA) and enterotoxin A producer isolated from asymptomatic nasal carriage among undergraduate students of Mexico

El objetivo de este estudio fue determinar la frecuencia de S. aureus, incluyendo resistentes a meticilina y la producción de enterotoxina A en fosas nasales de estudiantes universitarios en México. Este fue un estudio transversal realizado en 471 estudiantes universitarios de una ciudad del suroeste de México. Las muestras nasales y los datos sociodemográficos fueron obtenidos de los pacientes. Las cepas fueron identificadas como S. aureus basándose en la morfología, tinción de Gram, prueba de catalasa, prueba de coagulasa y fermentación en agar manitol salado. Las cepas se biotipificaron, se determinó la resistencia a meticilina por difusión en agar y la producción de enterotoxina A por Dot- Blot. La frecuencia de portadores nasales de S. aureus fue 10,40 %; 73,46 % resistentes a meticilina; 36,73 % producen enterotoxina A. En un análisis bivariado, se encontraron diferencias estadísticamente significativas en pacientes que viven cerca de aguas residuales y granjas con el estado de portador de S. aureus, (p=0,01, OR 2,59 [1,06-5,81]; p=0,01, OR 3,18, [1,07- 8,33]). Los portadores nasales muestran una diversidad de cepas de S. aureus, mayormente resistentes a meticilina, pero no todas producen enterotoxina A.

The aim at this study was determine the frequency of S. aureus, including methicillin-resistant and enterotoxin A production in nostrils of university students in Mexico. This was a cross-sectional study conducted in 471 university students from a city in southwestern Mexico. Nasal samples and sociodemographic data were obtained from the patients. Strains were identified as S. aureus based on morphology, Gram stain, catalase test, coagulase test and fermentation on salted mannitol agar. Isolated strains were subjected to biotyping, their methicillin resistance was analyzed using the agar diffusion method and examined their enterotoxin A (SEA) production by a Dot-blot analysis. The nasal carriage rate of S. aureus was 10.40%; 73.46% of the isolates were resistant to methicillin; 36.73% of the strains produced enterotoxin A. In the bivariate analysis, a statistically significant difference was found in patients who lived near sewage and farms with S. aureus carriage (p=0.012, odds ratio 2.59, [ 1.06-5.81]; p=0.009, odds ratio 3.18, [1.07- 8.33]) and the first group also associated with methicillin resistant S. aureus carriage (p=0.020, odds ratio 3.38, [1.30-8.06]). Nasal carriers show a wide variety of strains of S. aureus, mostly MRSA strains, but not all produce enterotoxin A.

Endemias e epidemias na Amazônia: malária e doenças emergentes em áreas ribeirinhas do Rio Madeira: um caso de escola / Endemics and epidemics in the Amazon

Após fazer uma análise da evolução da malária na Amazônia brasileira, detalhando em particular a situação em Rondônia e no município de Porto Velho, onde ocorreram episódios dramáticos de epidemias de malária no passado, os autores apresentam o quadro atual da prevalência de malária nas áreas do Vale do Rio Madeira, que sofrerão impactos com a construção das hidrelétricas de Santo Antônio e Jirau, e alertam sobre a situação particular da malária em áreas ribeirinhas. Nessas áreas, observam-se alta incidência de malária vivax e falciparum, a presença de grande número de portadores assintomáticos de parasitas e altas densidades do vetor Anopheles darlingi o ano todo. Esses elementos, associados à provável chegada de migrantes oriundos de áreas não-endêmicas de Rondônia e de outros Estados do país, atraídos pela possibilidade de trabalho nessas hidrelétricas e oportunidades de comércio, lazer, educação e atividades domésticas, criam condições favoráveis à ocorrência de epidemias de malária e de outras doenças tropicais se não forem realizadas intervenções adequadas de controle, em particular no domínio do saneamento.

Urban malaria in the Brazilian Western Amazon Region I: high prevalence of asymptomatic carriers in an urban riverside district is associated with a high level of clinical malaria

Cross sectional studies on malaria prevalence was performed in 2001, 2002, and 2004 in Vila Candelária, an urban riverside area of Porto Velho, Rondônia, in the Brazilian Western Amazon, followed by longitudinal surveys on malaria incidence. Vila Candelária is a working class district, provided with electricity, water supply, and basic sanitation. Previous preliminary surveys indicated high malaria incidence in this community. At the end of year 2000 regular diagnostic and treatment measures for malaria were introduced, with active search of febrile cases among residents. Despite of both rapid treatment of cases and relative good sanitary and housing conditions, the malaria incidence persisted at high levels during the following years with an annual parasite index of 150 to 300/1000 inhabitants. Parasite surveys in 2001, 2002, and 2004 achieved through microscopy and polymerase chain reaction to diagnose malaria showed a constant high prevalence of asymptomatic carriers for both Plasmodium falciparum and P. vivax parasites. It was concluded that asymptomatic carriers represent an important reservoirs of parasites and that the carriers might contribute to maintaining the high level of transmission. Comparing our findings to similar geo-demographic situations found in other important urban communities of the Brazilian Amazon, we propose that asymptomatic carriers could explain malaria's outbreaks like the one recently observed in Manaus.

Pathological Analysis of liver Biopsies in 115 Patients with Chronic Asymptomatic Carrier / 医学研究杂志

Objective To analyze the pathological features of Liver in chronic asymptomatic carrier (AsC) and to diagnose and treat AsC correctly.Methods 115 patients with AsC were examined with serological markers of B-hepatitis,liver function serum,HBV-DNA level,liver biopsy and immunohistochemistry.Results Of 115 patients with AsC,there were 8.7% patients with invisibly pathological lesions of hepatic tissue (G_0S_0),29.6% patients with chronic hepatitis,1.7% patients with cirrhosis.Through immunohistochemistry HBsAg and HBcAg test,there were 66.96% patients with HBsAg(+) and HBcAg(+),33.04% patients with single HBsAg(+).Conclusions Liver biopsy and immunohistochemistry can help to correct diagnose.It has important directional significance to treat AsC and establish treatment project of AsC.

ANALYSIS OF X GENE MUTATIONS IN HEPATITIS B VIRUS GENOME POSITIVE FOR ANTI-HBE BETWEEN ASYMPTOMATIC CARRIER AND PATIENTS WITH CHRONIC ACTIVE HEPATITIS / 解放军医学杂志

To elucidate whether the mutations in X region of hepatitis B virus (HBV) might be responsible for the different clinical profiles in cases positive for antibody to hepatitis B e antigen. The nucleotide sequences of X gene regions in serum HBV were examined in 14 asymptomatic carriers (AsC) and 14 chronic active hepatitis (CAH) patients with antibody to hepatitis e antigen. The results showed that 12 of 14 AsCs (85.7%) had insertions, deletions or point mutations in nucleotide sequence of X region resulting in truncation of the X protein by creating frame shift mutation or a new stop codon, whereas no patient with CAH had those X gene mutations( P

STUDY ON AFFINITY OF ANTI-HBc IN VIRAL HEPATITIS B PATIENTS AND ASYMPTOMATIC HBsAg CARRIERS / 中华传染病杂志

An assay for the affinity of serum anti-HBc in chronic hepatitis B patients and asymptomatic HBsAg carriers by 125I,22Na double isotope radioimmunoassay is described.In 7 asymmptomatic HBsAg carriers and 9 chronic hepatitis B patients.the affinity of anti-HBc was 3.25±2.13×106L/Mole in the former,whereas 0.75±0.56×106L/Mole in the latter.The titers of anti-HBc did not correlate to the affinity of anti-HBc and its possib]e role in the pathogenesis of hepatitis B is discussed.