The impact of school holidays on the social mixing patterns of school children.

School holidays are recognised to be of great epidemiological importance for a wide range of infectious diseases; this is postulated to be because the social mixing patterns of school children - a key population group - change significantly during the holiday period. However, there is little direct quantitative evidence to confirm this belief. Here, we present the results of a prospective survey designed to provide a detailed comparison of social mixing patterns of school children during school terms and during the school holidays. Paired data were collected, with participants recording their social contacts once during term time and once during the holiday period. We found that the daily number of recorded encounters approximately halved during the holidays, and that the number of close contact encounters fell by approximately one third. The holiday period also saw a change in the age structure of children's social contacts, with far fewer contacts of their own age, but an increase in the number of encounters with adults, particularly older adults. A greater amount of mixing between children at different schools was recorded during the holiday. We suggest, therefore, that whilst infections may spread rapidly within schools during term time, in the holiday period there are increased opportunities for transmission to other schools and other age groups

Zika virus epidemic in Brazil. I. Fatal disease in adults: Clinical and laboratorial aspects

BACKGROUND: Zika virus (ZIKV) was first detected in Brazil in May 2015 and the country experienced an explosive epidemic. However, recent studies indicate that the introduction of ZIKV occurred in late 2013. Cases of microcephaly and deaths associated with ZIKV infection were identified in Brazil in November, 2015. OBJECTIVES: To determine the etiology of three fatal adult cases. STUDY DESIGN: Here we report three fatal adult cases of ZIKV disease. ZIKV infection in these patients was confirmed by cells culture and/or real-time reverse transcriptase polymerase chain reaction (RT-qPCR) and by antigen detection using immunohistochemical assay. Samples of brain and other selected organs taken at autopsy from three patients were also analyzed by histopathological and immunohistological examination. RESULTS: The first patient, a 36-year-old man with lupus and receiving prednisone therapy, developed a fulminant ZIKV infection. At autopsy, RT-qPCR of blood and tissues was positive for ZIKV RNA, and the virus was cultured from an organ homogenate. The second patient, a previously healthy female, 16 years of age, presented classic symptoms of Zika fever, but later developed severe thrombocytopenia, anemia and hemorrhagic manifestations and died. A blood sample taken on the seventh day of her illness was positive RT-PCR for ZIKV RNA and research in the serum was positive for antinuclear factor fine speckled (1/640), suggesting Evans syndrome (hemolytic anemia an autoimmune disorder with immune thrombocytopenic purpura) secondary to ZIKV infection. The third patient was a 20-year-old woman hospitalized with fever, pneumonia and hemorrhages, who died on 13 days after admission. Histopathological changes were observed in all viscera examined. ZIKV antigens were detected by immunohistochemistry in viscera specimens of patients 1 and 3. These three cases demonstrate other potential complications of ZIKV infection, in addition to microcephaly and Guillain-Barre syndrome (GBS), and they suggest that individuals with immune suppression and/or autoimmune disorders may be at higher risk of developing severe disease, if infected with ZIKV