title: Clustering of Toxoplasma gondii Infections Within Families of Congenitally Infected Infants.
abstract: BACKGROUND
  Family clusters and epidemics of toxoplasmosis in North, Central, and South America led us to determine whether fathers of congenitally infected infants in the National Collaborative Chicago-Based Congenital Toxoplasmosis Study (NCCCTS) have a high incidence of Toxoplasma gondii infection.
  
  
  METHODS
  We analyzed serum samples collected from NCCCTS families between 1981 and 2013. Paternal serum samples were tested for T. gondii antibodies with immunoglobulin (Ig) G dye test and IgM enzyme-linked immunosorbent assay. Additional testing of paternal serum samples was performed with differential-agglutination and IgG avidity tests when T. gondii IgG and IgM results were positive and serum samples were collected by the 1-year visit of the congenitally infected child. Prevalence of paternal seropositivity and incidence of recent infection were calculated. We analyzed whether certain demographics, maternal parasite serotype, risk factors, or maternal/infant clinical manifestations were associated with paternal T. gondii infection status.
  
  
  RESULTS
  Serologic testing revealed a high prevalence (29 of 81; 36%) of T. gondii infection in fathers, relative to the average seropositivity rate of 9.8% for boys and men aged 12-49 years in the United States between 1994 and 2004 (P < .001). Moreover, there was a higher-than-expected incidence of recent infections among fathers with serum samples collected by the 1-year visit of their child (6 of 45; 13%; P < .001). No demographic patterns or clinical manifestations in mothers or infants were associated with paternal infections, except for sandbox exposure.
  
  
  CONCLUSIONS
  The high prevalence of chronic and incidence of recent T. gondii infections in fathers of congenitally infected children indicates that T. gondii infections cluster within families in North America. When a recently infected person is identified, family clustering and community risk factors should be investigated for appropriate clinical management.
authors.affiliation: Department of Pediatrics, Division of Infectious Diseases Palo Alto Medical Foundation Toxoplasma Serology Laboratory, California.
authors.forename: Despina
authors.initials: D
authors.lastname: Contopoulos-Ioannidis
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Kelsey M
authors.initials: KM
authors.lastname: Wheeler
authors.affiliation: Palo Alto Medical Foundation Toxoplasma Serology Laboratory, California.
authors.forename: Raymund
authors.initials: R
authors.lastname: Ramirez
authors.affiliation: Palo Alto Medical Foundation Toxoplasma Serology Laboratory, California.
authors.forename: Cindy
authors.initials: C
authors.lastname: Press
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Ernest
authors.initials: E
authors.lastname: Mui
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Christine
authors.initials: C
authors.lastname: Van Tubbergen
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Sheela
authors.initials: S
authors.lastname: Prasad
authors.affiliation: Department of Pediatrics, Division of Infectious Diseases.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Maldonado
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Shawn
authors.initials: S
authors.lastname: Withers
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago Department of Pediatrics, Rush University Medical Center.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Boyer
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago Lurie Children's Hospital, Northwestern Memorial Hospital, Northwestern University, Chicago.
authors.forename: A Gwendolyn
authors.initials: AG
authors.lastname: Noble
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago North Shore University Hospital, Evanston, Illinois.
authors.forename: Peter
authors.initials: P
authors.lastname: Rabiah
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago Lurie Children's Hospital, Northwestern Memorial Hospital, Northwestern University, Chicago.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Swisher
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago Department of Pediatrics, Rush University Medical Center.
authors.forename: Peter
authors.initials: P
authors.lastname: Heydemann
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Kristen
authors.initials: K
authors.lastname: Wroblewski
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Theodore
authors.initials: T
authors.lastname: Karrison
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Grigg
authors.affiliation: Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine Palo Alto Medical Foundation Toxoplasma Serology Laboratory, California.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Montoya
authors.affiliation: Departments of Ophthalmology and Visual Sciences and Pediatric Infectious Diseases, Toxoplasmosis Center, Department of Public Health Sciences, University of Chicago.
authors.forename: Rima
authors.initials: R
authors.lastname: McLeod
mesh_terms: D000293:Adolescent; D000372:Agglutination Tests; D000913:Antibodies, Protozoan / Q000097:blood; D002641:Chicago / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005192:Family Health; D005220:Fathers; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D014123:Toxoplasmosis / Q000453:epidemiology*
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D007075:Immunoglobulin M
keywords: Toxoplasma gondii; clusters; congenital infections; toxoplasmosis