title: Factors influencing the time between onset of illness and specimen collection in the diagnosis of non-pregnancy associated listeriosis in England and Wales.
abstract: Listeriosis is an opportunistic bacterial infection caused by Listeria monocytogenes and predominantly affects people who are immunocompromised. Due to its severity and the population at risk, prompt clinical diagnosis and treatment of listeriosis is essential. A major step to making a clinical diagnosis is the collection of the appropriate specimen(s) for testing. This study explores factors that may influence the time between onset of illness and collection of specimen in order to inform clinical policy and develop necessary interventions.
  
  
  
  Enhanced surveillance data on non-pregnancy associated listeriosis in England and Wales between 2004 and 2013 were collected and analysed. The difference in days between onset of symptoms and collection of specimen was calculated and factors influencing the time difference were identified using a gamma regression model.
  
  
  
  The median number of days between onset of symptoms and collection of specimen was two days with 27.1 % of cases reporting one day between onset of symptoms and collection of specimen and 18.8 % of cases reporting more than seven days before collection of specimen. The median number of days between onset of symptoms and collection of specimen was shorter for cases infected with Listeria monocytogenes serogroup 1/2b (one day) and cases with an underlying condition (one day) compared with cases infected with serotype 4 (two days) and cases without underlying conditions (two days).
  
  
  
  Our study has shown that Listeria monocytogenes serotype and the presence of an underlying condition may influence the time between onset of symptoms and collection of specimen.
authors.affiliation: Gastrointestinal Infections Department, National Infection Service, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK. adedoyin.awofisayo@phe.gov.uk.|National Institute for Health Research, Health Protection Research Unit in Gastrointestinal Infections, Colindale, London, UK. adedoyin.awofisayo@phe.gov.uk.
authors.forename: Adedoyin
authors.identifier: 0000-0001-8535-5422
authors.initials: A
authors.lastname: Awofisayo-Okuyelu
authors.affiliation: Department of Statistics, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK.
authors.forename: Neville Q
authors.initials: NQ
authors.lastname: Verlander
authors.affiliation: Gastrointestinal Bacterial Reference Unit, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK.
authors.forename: Corinne
authors.initials: C
authors.lastname: Amar
authors.affiliation: Gastrointestinal Infections Department, National Infection Service, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Elson
authors.affiliation: Gastrointestinal Bacterial Reference Unit, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK.
authors.forename: Kathie
authors.initials: K
authors.lastname: Grant
authors.affiliation: Gastrointestinal Infections Department, National Infection Service, Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK.|National Institute for Health Research, Health Protection Research Unit in Gastrointestinal Infections, Colindale, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Harris
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007223:Infant; D007231:Infant, Newborn; D008089:Listeria monocytogenes / Q000145:classification / Q000302:isolation & purification*; D008088:Listeriosis / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D013048:Specimen Handling / Q000379:methods / Q000592:standards; D013997:Time Factors; D014852:Wales / Q000453:epidemiology
keywords: Bacterial Infections; Foodborne diseases; Listeria monocytogenes; Listeriosis