title: Household epidemiology of Cryptosporidium parvum infection in an urban community in northeast Brazil.
abstract: OBJECTIVE
  To examine the transmission of Cryptosporidium infection in households with an identified person with cryptosporidiosis.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  An urban slum in Fortaleza, Brazil.
  
  
  METHODS
  Thirty-one households with a child less than 3 years of age (index case) who was positive for Cryptosporidium parvum using acid-fast and auramine-stained stool smears.
  
  
  METHODS
  Three stool samples (at 0, 2, and 6 weeks after identification of the index case) and two serum samples (0 and 6 weeks) were collected from each family member in households with an index case of Cryptosporidium infection.
  
  
  RESULTS
  Forty-five percent of index cases of Cryptosporidium infection were associated with persistent (> 14 days) diarrhea. Secondary cases of Cryptosporidium infection were identified either by stool examination or seroconversion in 18 (58%) of 31 households involving 30 persons, yielding an overall transmission rate of 19%. Of the 202 persons in this study with at least one serum sample available for analysis, 191 (94.6%) had evidence of antibodies (either IgM or IgG) to Cryptosporidium.
  
  
  CONCLUSIONS
  Cryptosporidium parvum is highly transmissible and infective in the family setting, with transmission rates similar to other highly infectious enteric pathogens such as Shigella species. These data are cause for added concern because of the rapidly increasing rate of seropositivity for human immunodeficiency virus.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: R D
authors.initials: RD
authors.lastname: Newman
authors.forename: S X
authors.initials: SX
authors.lastname: Zu
authors.forename: T
authors.initials: T
authors.lastname: Wuhib
authors.forename: A A
authors.initials: AA
authors.lastname: Lima
authors.forename: R L
authors.initials: RL
authors.lastname: Guerrant
authors.forename: C L
authors.initials: CL
authors.lastname: Sears
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D003457:Cryptosporidiosis / Q000150:complications / Q000635:transmission*; D016785:Cryptosporidium parvum / Q000302:isolation & purification; D003967:Diarrhea / Q000469:parasitology; D005192:Family Health; D006798:Housing; D006801:Humans; D007223:Infant; D011446:Prospective Studies; D014504:Urban Health