National case definition: Congenital syphilis

Date of last revision/review: January 2024

National notification

Only confirmed cases of disease should be notified

Type of surveillance

Routine case-by-case notification to the federal level

Case classification

Confirmed case: Early congenital syphilis

Laboratory confirmation of infection in a live birth:

• identification of Treponema pallidum by nucleic acid detection (PCR or equivalent), fluorescent antibody or equivalent examination of material in an appropriate clinical specimen (see Laboratory comments)

  or

• reactive serology (non-treponemal and treponemal) from venous blood (not cord blood) in an infant or in a child with clinical, radiographic or other laboratory evidence of congenital syphilis^{Footnote a}

  or

• infant's RPR titre at least fourfold higher than the mother/birthing parent's RPR titre in samples collected during the immediate postnatal period

  or

• persistent positive treponemal serology in a child older than 18 months of age

and

• younger than two years of age at the time of meeting the criteria and no other suspected source of exposure

Confirmed case: Late congenital syphilis

Laboratory confirmation of infection:

• identification of Treponema pallidum by nucleic acid detection (PCR or equivalent), fluorescent antibody or equivalent examination of material in an appropriate clinical specimen (see Laboratory comments)

  or

• reactive serology (non-treponemal and/or treponemal) in an individual with clinical, radiographic or other laboratory evidence of congenital syphilis^{Footnote a}

and

• two or more years of age at the time of meeting the criteria and no other suspected source of exposure

Probable case: Early congenital syphilis

Does not meet criteria for "Confirmed case: Early congenital syphilis"

and

• reactive serology (non-treponemal and/or treponemal) from venous blood (not umbilical cord blood) in an infant or in a child whose mother/birthing parent had untreated or inadequately treated^{Footnote b} syphilis prior to delivery

and

• younger than two years of age at the time of meeting the criteria and no other suspected source of exposure

Confirmed case: Syphilitic stillbirth

A fetal death that occurs after 20 weeks' gestation or in which the fetal weight is greater than 500 g with laboratory confirmation of infection [i.e., identification of Treponema pallidum by nucleic acid detection (PCR or equivalent), fluorescent antibody or equivalent examination of material in an appropriate clinical specimen (see Laboratory comments)]

Probable case: Syphilitic stillbirth

Does not meet criteria for "Confirmed case: Syphilitic stillbirth"

and

• a fetal death that occurs after 20 weeks' gestation or in which the fetal weight is greater than 500 g where the mother/birthing parent had untreated or inadequately treated^{Footnote b} syphilis prior to delivery

and

• no other cause of stillbirth established

Laboratory comments

In addition to venous blood samples, appropriate clinical specimens for the diagnosis of congenital syphilis include nasal secretions, skin lesions, fluid from blisters or exudative skin rashes, placenta, umbilical cord, or autopsy clinical material. Cord blood should not be used for infant testing.

Syphilis serological results can be affected by the timing of maternal/birthing parent infection. If syphilis is acquired close to delivery, maternal/birthing parent and newborn serological tests may initially be negative. Reactive syphilis serological tests in an infant can represent infant infection or trans-placental passage of antibodies. In the absence of congenital infection, antibodies are expected to decline and clear by 18 months of age. Infant non-treponemal titres at least fourfold higher than maternal/ birthing parent titres (using the same non-treponemal test) at birth supports a diagnosis of congenital syphilis. A fourfold or greater rise in infant non-treponemal titre supports a diagnosis of congenital syphilis.

ICD code(s)

ICD-11 codes

1A60

ICD-10 codes

A50

Comments

Case re-classification may be necessary as more information is collected about a case e.g., if treponemal serology is persistently positive in a child aged between 18 and 24 months without clinical, laboratory or radiographic evidence of congenital syphilis, the case classification should be amended from "Probable case: Early congenital syphilis" to "Confirmed case: Early congenital syphilis."

Diagnosis of congenital syphilis requires a combination of history, including epidemiologic risk factors or exposure, physical examination and laboratory tests, as there is no single optimum diagnostic criterion.

Congenital syphilis includes cases of perinatally-acquired syphilis in infants and children. It can be challenging to differentiate congenital from acquired syphilis in children. Infants with congenital syphilis may be asymptomatic for months to years. Radiographic changes in the metaphysis and epiphysis of long bones support a diagnosis of congenital syphilis; normal imaging does not rule out congenital syphilis. Cerebrospinal fluid abnormalities can be found in either congenital or acquired syphilis. Consider the possibility of sexual abuse if acquired syphilis is diagnosed in a child.

Stillbirth is defined by Statistics Canada as "death prior to the complete expulsion or extraction from its mother of a product of conception irrespective of the duration of pregnancy; the death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles. Only fetal deaths where the product of conception has a birth weight of 500 grams or more or the duration of pregnancy is 20 weeks or longer are registered in Canada."

References

• Arnold SR, Ford-Jones EL. Congenital syphilis: A guide to diagnosis and management. Paediatr Child Health. 2000 Nov;5(8):463-9. doi: 10.1093/pch/5.8.463.
• Public Health Agency of Canada. Syphilis guide: Treatment and follow-up. [Internet]. 2023. [cited 2024 January 29]. Available from: https://www.canada.ca/en/public-health/services/infectious-diseases/sexual-health-sexually-transmitted-infections/canadian-guidelines/syphilis/treatment-follow-up.html
• Robinson JL; Canadian Paediatric Society Infectious Diseases and Immunization Committee. [Internet]. Congenital syphilis: No longer just of historical interest. 2018. [cited 2024 January 29]. Available from: https://cps.ca/en/documents/position/congenital-syphilis
• Singh AE, Levett PN, Fonseca K, Jayaraman GC, Lee BE. Canadian Public Health Laboratory Network laboratory guidelines for congenital syphilis and syphilis screening in pregnant women in Canada. Can J Infect Dis Med Microbiol. 2015 Jan-Feb;26 Suppl A(Suppl A):23A-8A. doi: 10.1155/2015/589085.
• Statistics Canada. Data quality, concepts and methodology: definitions. [Internet]. 2023 [cited 2024 January 29]. Available from: https://www.statcan.gc.ca/en/statistical-programs/document/3231_D5_T9_V1