Analysis of spatial-temporal distribution characteristics and natural infection status of SFTS cases in Hefei from 2015 to 2021.

BACKGROUND: To analyze the prevalence and spatial-temporal characteristics of severe fever with thrombocytopenia syndrome (SFTS), clustering mode of transmission, and the serological dynamic detection results in multiple areas in Hefei from 2015 to 2021, and to provide the basis for SFTS prevention and control. METHOD: Case data were obtained from the Chinese Disease Control and Prevention Information System. Information on the clustering outbreak was obtained from the outbreak investigation and disposal report. Population latent infection rate information was obtained from field sampling in multiple-incidence counties in 2016 and 2021 by multi-stage random sampling. Epi data3.2 and SPSS 16.0 softwares were used to perform a statistical analysis of the data on SFTS cases, and QGIS 3.26 software was used to draw the incidence map with township (street) as unit. RESULTS: The an average annual reported incidence rate of SFTS in Hefei from 2015 to 2021 was 0.65/100,000, and the case fatality rate was 9.73%. The overall prevalence of SFTS epidemics in Hefei City showed a fluctuating upward trend from 2015 to 2021 (χ2trends = 103.353, P < 0.001). Chaohu City, Feixi County, Feidong County and Lujiang County ranked the top 4 in the city in terms of average annual incidence rate. The number of epidemic-involved towns (streets) kept increasing ((χ2trend = 47.640, P = 0.000)). Co-exposure to ticks accounted for the majority of clustered outbreaks and also human-to-human outbreaks. Population-based latent infection rate surveys were conducted in four SFTS multi-incidence counties, with 385 people surveyed in 2016 and 403 people surveyed in 2021, increasing the population-based latent infection rate from 6.75% to 10.91%, just as the incidence rate increased. CONCLUSIONS: The incidence rate of SFTS in Hefei is obviously regional, with an expanding trend in the extent of the epidemic involved. Co-exposure to ticks accounted for the majority of clustered outbreaks and the latent infection rate cannot be ignored.

Highly Prevalent SARS-CoV-2 Antigenemia in COVID-19 Patients.

Background: Many issues, such as severity assessment and antibody responses, remain to be answered eagerly for evaluation and understanding of COVID-19. Immune lesion is one of key pathogenesis of the disease. It would be helpful to understand the disease if an investigation on antigenemia and association was conducted in the patients with SARS-CoV-2 infection. Methods: A total of 156 patients admitted to the First People's Hospital of Hefei or Anhui Provincial Hospital on January to February 2020 were involved in this study. SARS-CoV-2 nucleocapsid (NP) antigen, specific IgM/IgG antibodies, and RNA were detected in sequential sera from three COVID-19 patients, and additional 153 COVID-19 patients by means of NP-antigen capture enzyme-linked immunosorbent assay, colloidal gold quick diagnosis, and real-time RT-PCR, respectively. The clinical types of COVID-19 patients were classified into asymptomatic, mild, moderate, severe, and critical, following on the Chinese guideline of COVID-19 diagnosis and treatment. The demographic and clinical data of patients were obtained for comparable analysis. Results: NP antigen was detected in 5 of 20 sequential sera collected from three COVID-19 patients with typically clinical symptoms, and 60.13% (92/153) expanded samples collected within 17 days after illness onset. No SARS-CoV-2 RNA segment was detected in these sera. The NP positive proportion reached a peak (84.85%, 28/33) on 6 to 8 days after illness onset. Both NP concentration and positive proportion were increased with the increase of clinical severity of COVID-19. Compared to NP negative patients, NP positive patients had older age [years, medians (interquartile ranges (IQR)), 49 (6) vs. 31 (11)], lower positive proportion of NP specific IgM [27.17% (25/92) vs. 59.02% (36/61)], and IgG [21.74% (20/92) vs. 59.02% (36/61)] antibodies, and longer duration [days, medians (IQR), 24 (10) vs. 21 (13)] from illness to recovery. Conclusions: SARS-CoV-2 NP antigenemia occurred in COVID-19, and presented highly prevalent at early stage of the disease. The antigenemia was related to clinical severity of the disease, and may be responsible for the delay of detectable SARS-Cov-2 IgM.

A hospital cluster combined with a family cluster of avian influenza H7N9 infection in Anhui Province, China.

OBJECTIVES: To identify human-to-human transmission of H7N9 avian influenza virus, we investigated a hospital cluster combined with family cluster in this study. METHODS: We obtained and analyzed clinical, epidemiological and virological data from the three patients. RT-PCR, viral culture and sequencing were conducted for determination of causative pathogen. RESULTS: The index case presented developed pneumonia with fever after exposure to chicken in a poultry farm. Case A presented pneumonia with high fever on day 3 after she shared a hospital room with the index case. Case B, the father of the index case, presented pneumonia with high fever on day 15 after he took care of the index case. H7N9 virus circulated in the local farm to which the index case was exposed. Full genomic sequence of virus showed 99.8-100% identity shared between the index case and case A or case B. Compared to the earliest virus of Anhui, a total of 29 amino acid variation sites were observed in the 8 segments. CONCLUSIONS: A hospital cluster combined with family cluster of H7N9 avian influenza infection was identified. Air transmission resulted in the hospital cluster possibly. A poultry farm was the initially infectious source of the cluster.

Prevalence of antibodies against enterovirus 71 in children from Lu'an City in Central China.

We performed preepidemic and postepidemic serologic surveys to elucidate the rate of enterovirus 71 (EV71) infection in Lu'an City, Anhui Province, Central China. For the preepidemic study, a total of 472 healthy infants and children (age range, neonates to 15 years) were randomly selected before the 2008 outbreak of EV71 in the region. Blood samples were collected and tested for neutralizing antibodies (NAbs) against EV71 by performing a microneutralization assay. The results of preepidemic serological survey showed that 43.2% (204/472) of the tested samples yielded positive results for NAbs against EV71. The seropositivity rates were 29.6% (93/314) in children who were 0-7 years of age and 74.6% (59/79) in children who were 12-15 years of age. The overall geometric mean titer was 18.1, and the highest antibody titers were detected in children who were 5-7 years of age; this suggests that this group was frequently exposed to EV71 infection. For the postepidemic study, 83 serum samples were collected from healthy children ≤15 years of age in 2010. The seropositivity rate of EV71 NAbs increased in this young population after the 2008 outbreak, especially in 2- to 11-year-old children. This report shows that EV71 was spreading in Lu'an City before the 2008 outbreak, and children under 7 years of age were the main susceptible population.

[Molecular characteristics of noroviruses causing outbreaks of acute gastroenteritis in Huzhou].

OBJECTIVE: To study the molecular characteristics of Noroviruses causing outbreaks of acute gastroenteritis in Huzhou. METHODS: From 2008 to 2010, total 119 fecal specimens collected from outbreaks of acute gastroenteritis were tested for Norovirus. Partial sequence of RNA dependent RNA polymerase (RdRp) of the positive samples were amplified by RT-PCR, then the PCR production were purified, sequenced and put into phylogenetic analysis. RESULTS: 50 of 119 specimens were positive for Norovirus by real-time RT-PCR. Out of those 50 Norovirus positive specimens, 9 were Norovirus Genogroup I (GI) positive, 35 were Norovirus Genogroup II (GII) positive, 6 was both Norovirus GI and GII positive. 12 PCR products for RdRp were selected for further studies on sequencing. Phylogenetic analysis revealed that the 5 GI norovirus isolates were belonged to genotype GI/2 and GI/3. Of the 7 GII norovirus isolates, 6 were belonged to genotype GII/4, 1 was belonged to genotype Glib. CONCLUSION: Norovirus is a major cause of outbreaks of acute gastroenteritis in Huzhou and the epidemic strains of norovirus isolated from Huzhou had a high degree of genetic diversity.

Genetic analysis of the VP1 region of enterovirus 71 reveals the emergence of genotype A in central China in 2008.

Enterovirus 71 (EV71) strains from children were characterized by full-length VP1 nucleotide sequencing. Out of 22 clinical specimens, five isolates identified as EV71 were recovered by virus isolation. The VP1 sequences of the five isolates had more than 97.4% sequence identity with prototype virus BrCr, clustering in the genotype A lineage. This represents the first record of genotype A EV71 in China since the BrCr prototype strain was discovered in the USA in 1969.