Pathogenesis And Immunity

HuAst have been detected in all countries where they have been sought and thus have a worldwide distribution. In temperate countries, HuAst infection peaks in winter usually 4-6 weeks prior to the rotavirus peaks.[23] In general, HuAst diarrhea is predominantly a disease of infants with an age-specific incidence of 0.38 for those under 6 months and 0.40 for those aged 6-12 months.[24] However, further episodes of infection with different astrovirus serotypes do occur subsequently. These are usually milder than the first infection. Astrovirus is the second or third most important cause of diarrheal disease in children being responsible for 5-10% of cases in hospital-based studies and for 10-25% of cases in community-based studies.[25] Globally, serotype 1 is most frequently detected.[22,26-28] Recently, HuAst serotype 3 has been associated with higher stool viral levels and increased incidence of persistent diarrhea.[16] Outbreaks of astrovirus infection have been described involving the rarer serotypes.[29]

The incubation period was 3-4 days in adult volunteers but in children in Egypt was 24-36 hr.[24] The illness which consists of acute watery diarrhea with or without nausea and vomiting is usually milder than that due to rotavirus. It lasts on average 5-6 days.[30]

HuAst are transmitted by the feco-oral route,[15] either directly person-to-person or indirectly via contaminated food or water. During infection, between 108 and 1013 genome equivalents are shed per gram of feces.[16] The infectious dose is not known but thought to be low. Little is known of how HuAst cause diarrheal disease. However, in experimental infection in gnotobiotic lambs, ovine astrovirus caused infection of mature enterocytes in the upper two thirds of the villi resulting eventually in transient villous flattening and crypt hypertrophy.[17] In turkeys, astrovirus causes diarrhea in the absence of

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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