Serological Evidence of Subclinical Transmission of the 2009 Pandemic H1N1 Influenza Virus Outside of Mexico

Background: Relying on surveillance of clinical cases limits the ability to understand the full impact and severity of an epidemic, especially when subclinical cases are more likely to be present in the early stages. Little is known of the infection and transmissibility of the 2009 H1N1 pandemic influenza (pH1N1) virus outside of Mexico prior to clinical cases being reported, and of the knowledge pertaining to immunity and incidence of infection during April-June, which is essential for understanding the nature of viral transmissibility as well as for planning surveillance and intervention of future pandemics. Methodology/Principal Findings: Starting in the fall of 2008, 306 persons from households with schoolchildren in central Taiwan were followed sequentially and serum samples were taken in three sampling periods for haemagglutination inhibition (HI) assay. Age-specific incidence rates were calculated based on seroconversion of antibodies to the pH1N1 virus with an HI titre of 1: 40 or more during two periods: April-June and September-October in 2009. The earliest time period with HI titer greater than 40, as well as a four-fold increase of the neutralization titer, was during April 26-May 3. The incidence rates during the pre-epidemic phase (April-June) and the first wave (July-October) of the pandemic were 14.1% and 29.7%, respectively. The transmissibility of the pH1N1 virus during the early phase of the epidemic, as measured by the effective reproductive number R(0), was 1.16 (95% confidence interval (CI): 0.98-1.34). Conclusions: Approximately one in every ten persons was infected with the 2009 pH1N1 virus during the pre-epidemic phase in April-June. The lack of age-pattern in seropositivity is unexpected, perhaps highlighting the importance of children as asymptomatic transmitters of influenza in households. Although without virological confirmation, our data raise the question of whether there was substantial pH1N1 transmission in Taiwan before June, when clinical cases were first detected by the surveillance network

Septic Arthritis Caused by Vancomycin-Intermediate Staphylococcus aureus

Four methicillin-resistant Staphylococcus aureus isolates were consecutively isolated from synovial fluid and a knee wound of a patient with septic arthritis. Determination of the MIC of vancomycin and population analysis confirmed these isolates as vancomycin-intermediate S. aureus (VISA). Results of this study also revealed that cell wall thickness and reduced susceptibility to Triton X-100 were characteristic features of VISA

Acquisition and Cure of Autoimmune Disease Following Allogeneic Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) can either cause or eliminate autoimmune disease. Here, we report two cases. One was a 33-year-old woman with myelodysplastic syndrome (refractory anemia) who received bone marrow transplantation from her human leukocyte antigen (HLA)-identical sister who had a history of Graves' disease. Antithyroid antibodies, including antimicrosomal antibody and antithy-roglobulin antibody, appeared 4 months after transplantation. Clinical hyperthyroidism appeared 7 months after transplantation, and a hypothyroid state was noted 2 months later. The other case was a 50-year-old woman with Sjögren's syndrome and hypothyroidism who was diagnosed with peripheral T cell non-Hodgkin's lymphoma. She received allogeneic peripheral blood stem cell transplantation (PBSCT) from her histocompatible sister owing to only partial response to traditional chemotherapy. Cure of lymphoma and remission of Sjögren's syndrome was noted 4 years after PBSCT. These two illustrative cases, one of acquisition of hyperthyroidism and the other of remission of Sjögren's syndrome after transplantation, highlights that HSCT can induce adoptive autoimmune disease or cure coincidental autoimmune disease. Donor selection and attentive monitoring is required in such circumstances