Data were collected from June 29 to July 2, 2009. A probable case of 2009 pandemic A(H1N1) influenza was defined as any medical student who traveled to the Dominican Republic and had onset of ILI between June 19 and July 1, 2009. ILI was defined as recent onset of any of the following: fever,

cough, sore throat, rhinorrhea, asthenia, breathing difficulties, myalgia, or malaise. A confirmed case was defined as any probable case with influenza virus A(H1N1) infection confirmed by the laboratory testing described below. When a probable case was detected, measures to prevent the spread of the virus were recommended to all symptomatic cases, including home isolation, use of a separate bathroom, use of surgical masks when in contact with cohabitants, and regular hand washing. A secondary case was defined as a household contact Carfilzomib purchase who developed an ILI or laboratory-confirmed influenza within 7 days of symptom onset of the corresponding medical student case. Throat and nasal swabs were collected from all consenting students in the group of travelers,

whether symptomatic or not from June 29 to July 2. The samples were transported in 2.5 mL of viral transport medium (VTM) (fluid with 2% fetal bovine serum, penicillin 100 U/mL, streptomycin 100 g/mL, amphotericin B 20 g/mL, neomycin 40 g/mL, and NaHCO3 buffer). Respiratory specimens were placed in a tube containing VTM. Within the first 24 hours they were processed and stored at 2–4°C in several aliquots until use. Total nucleic acids NVP-LDE225 nmr were extracted from 200

µL of fresh specimen and eluted in 25 µL of RNase-free elution buffer using NucliSense easyMAG (bioMérieux, Marcy l’Etoile, France) according to the manufacturer’s instructions. Nucleic acids were kept frozen until use. Two specific one-step multiplex real-time reverse transcription-PCR were used for typing and subtyping the influenza virus, as previously described.10,11 An additional third assay amplified a housekeeping gene (RNase P) of human cells to assess the correct progress of DNA extraction and to underline the absence of PCR inhibitors as an internal control.12 The viral nucleotide sequences obtained from infected Rho students were compared using sequences of viruses in GenBank from the Dominican Republic and Spain. No additional tests were done to assess etiology of gastrointestinal illness. Differences in student characteristics between pandemic influenza A(H1N1) positive and negative students were evaluated using the chi-square test or Fisher’s exact test as necessary. Logistic regression models were used to assess risks factors for having a positive lab test for influenza A(H1N1) adjusting for time between onset of symptoms and collection of swabs. p Values ≤0.05 were considered statistically significant.