Parents as source of pertussis transmission in hospitalized young infants.
OBJECTIVE
This study was planned to collect evidences of familial pertussis transmission to infants younger than 6 months of age. Understanding the dynamics of transmission of pertussis in families is essential to plan effective prevention strategies that could be integrated in pertussis control.


METHODS
The seroprevalence of IgG antibodies to pertussis toxin (PT-IgG) and prolonged cough symptoms were evaluated in parents of 55 infants aged <6 months hospitalized for confirmed pertussis. Parents of 33 infants with lower respiratory tract infection (LRTI) and parents of 57 healthy infants admitted as outpatients for hip ultrasound examination (HE) were enrolled as controls.


RESULTS
Parents of pertussis cases had PT-IgG levels significantly higher as compared to LRTI and HE parents. More than 40 % were compatible as transmitters of pertussis to their babies, since they had a level of PT-IgG ≥ 100 IU/ml, which is considered diagnostic for a recent pertussis episode. Based on serology, the percentage of pertussis cases that had at least one parent as source of infection was 49.1 %. When cough symptoms were taken into account, the percentage of parents putative transmitters of the infection to their infants increased to 56.4 %.


CONCLUSIONS
Parents are scarcely aware of the household transmission of pertussis to their newborns. Our study highlights the need to advise parents about the likelihood of transmission to the newborn and to be particularly aware of coughing symptoms in the household. Since infection can be asymptomatic, a serological survey of family members should also be considered.
Department of Infectious, Parasitic, and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy. giorgio.fedele@iss.it.
Giorgio
G
Fedele
Department of Infectious, Parasitic, and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.
Maria
M
Carollo
Department of Infectious, Parasitic, and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.
Raffaella
R
Palazzo
Department of Infectious, Parasitic, and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.
Paola
P
Stefanelli
Multifactorial Disease and Complex Phenotype Research Area, Bambino Gesù Children's Hospital, Rome, Italy.
Elisabetta
E
Pandolfi
Multifactorial Disease and Complex Phenotype Research Area, Bambino Gesù Children's Hospital, Rome, Italy.
Francesco
F
Gesualdo
Multifactorial Disease and Complex Phenotype Research Area, Bambino Gesù Children's Hospital, Rome, Italy.
Alberto Eugenio
AE
Tozzi
Immunology Area, B Cell Physiopathology Unit, Immune Diagnosis Unit, Department of Laboratories, Bambino Gesù Children Hospital, Rome, Italy.
Rita
R
Carsetti
Department of Pediatrics, Bambino Gesù Children's Hospital, Rome, Italy.
Alberto
A
Villani
Department of Pediatrics, Sapienza University of Rome, Rome, Italy.
Ambra
A
Nicolai
Department of Pediatrics, Sapienza University of Rome, Rome, Italy.
Fabio
F
Midulla
Department of Infectious, Parasitic, and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.
Clara Maria
CM
Ausiello
D000907:Antibodies, Bacterial / Q000097:blood; D000992:Antitoxins / Q000097:blood; D016022:Case-Control Studies; D005192:Family Health; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D010290:Parents; D016036:Seroepidemiologic Studies; D014917:Whooping Cough / Q000635:transmission*
D000907:Antibodies, Bacterial; D000992:Antitoxins; D007074:Immunoglobulin G
Infant; Pertussis; Serology; Source of infection