title: The nature and consequences of coinfection in humans.
abstract: OBJECTIVE
  Many fundamental patterns of coinfection (multi-species infections) are undescribed, including the relative frequency of coinfection by various pathogens, differences between single-species infections and coinfection, and the burden of coinfection on human health. We aimed to address the paucity of general knowledge on coinfection by systematically collating and analysing data from recent publications to understand the types of coinfection and their effects.
  
  
  METHODS
  From an electronic search to find all publications from 2009 on coinfection and its synonyms in humans we recorded data on i) coinfecting pathogens and their effect on ii) host health and iii) intensity of infection.
  
  
  RESULTS
  The most commonly reported coinfections differ from infections causing highest global mortality, with a notable lack of serious childhood infections in reported coinfections. We found that coinfection is generally reported to worsen human health (76% publications) and exacerbate infections (57% publications). Reported coinfections included all kinds of pathogens, but were most likely to contain bacteria.
  
  
  CONCLUSIONS
  These results suggest differences between coinfected patients and those with single infections, with coinfection having serious health effects. There is a pressing need to quantify the tendency towards negative effects and to evaluate any sampling biases in the coverage of coinfection research.
authors.affiliation: Department of Animal and Plant Sciences, Alfred Denny Building, Western Bank, University of Sheffield, Sheffield S10 2TN, UK. e.griffiths@shef.ac.uk
authors.forename: Emily C
authors.initials: EC
authors.lastname: Griffiths
authors.forename: Amy B
authors.initials: AB
authors.lastname: Pedersen
authors.forename: Andy
authors.initials: A
authors.lastname: Fenton
authors.forename: Owen L
authors.initials: OL
authors.lastname: Petchey
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000453:epidemiology* / Q000401:mortality; D060085:Coinfection / Q000453:epidemiology* / Q000401:mortality; D006373:Helminthiasis / Q000453:epidemiology* / Q000401:mortality; D054884:Host-Pathogen Interactions; D006801:Humans; D009181:Mycoses / Q000453:epidemiology* / Q000401:mortality; D015995:Prevalence; D011528:Protozoan Infections / Q000453:epidemiology* / Q000401:mortality; D014777:Virus Diseases / Q000453:epidemiology* / Q000401:mortality