The protective effect of immunisation against diphtheria, pertussis and tetanus (DPT) in relation to sudden infant death syndrome

Abstract

Epidemiological evidence indicates infants immunised against diphtheria, pertussis and tetanus (DPT) are at decreased risk of sudden infant death syndrome (SIDS). Asymptomatic whooping cough and pyrogenic toxins of Staphylococcus aureus have been implicated in the aetiology of SIDS. The objectives of the present study were: (1) to determine if the DPT vaccine induced antibodies cross-reactive with the staphylococcal toxins; (2) to determine if antibodies to the pertussis toxin (PT) and the staphylococcal toxins were present in the sera of women during late pregnancy; (3) to examine the effects of infant immunisation on levels of antibodies to PT and the staphylococcal toxins; (4) to assess the effects of changes in immunisation schedules in the UK on the incidence and age distribution of SIDS. Enzyme-linked immunosorbent assays (ELISA) were used to measure binding of rabbit or human IgG to the DPT vaccine, PT, toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxins A (SEA), B (SEB) and C (SEC). Neutralisation activity of anti-DPT serum was assessed by a bioassay for induction of nitric oxide from human monocytes by the staphylococcal toxins. Anti-DPT serum bound to the DPT vaccine, PT and each of the staphylococcal toxins. It also reduced the ability of the four toxins to induce nitric oxide from monocytes. In pregnant women, levels of IgG to PT, SEC and TSST-1 decreased significantly in relation to increasing weeks of gestation while antibodies to SEA and SEB increased. In infants' sera there were significant correlations between levels of IgG bound to DPT and IgG bound to PT, TSST-1 and SEC but not SEA or SEB. Antibody levels to the toxins in infants declined with age; sera from infants < or = 2 months of age had higher levels of IgG bound to the toxins than those older than 2 months. This pattern was observed for infants whose immunisation schedules began at 2 months of age or 3 months of age. The decrease in IgG bound to the toxins was, however, less for those immunised at 2 months. The decrease in SIDS deaths after the change in immunisation schedules was greatest in the 4-6-month age range. While DPT immunisation might prevent some unexplained infant deaths due to asymptomatic whooping cough, these data indicate that immunisation with DPT also induces antibodies cross-reactive with pyrogenic staphylococcal toxins implicated in many cases of SIDS. Passive immunisation of infants who have low levels of these antibodies might reduce further the numbers of these infant deaths.

A Controlled Study of the Relationship BetweenBordetella pertussisInfections and Sudden Unexpected Deaths Among German Infants

“…[30][31][32] Although this may indicate that immunization against pertussis protects children from death attributable to unrecognized B pertussis infection, a recent study suggested that immunization with diphtheria-tetanus-pertussis vaccine also induces antibodies that cross-react with pyrogenic staphylococcal toxins, which have been implicated in several cases of SIDS. 33 As an initial surprise to us, the rates of positive PCR findings were similar for case subjects and control subjects and the rate was actually higher for control subjects (5.3%) than case subjects (1.7%) when NPS results were compared. A significant decrease in positivity rates from the first year to the second year of the study (6.7% vs 2.9%) was observed (data not shown).…”

Association between sudden infant death syndrome and diphtheria-tetanus-pertussis immunisation: an ecological study

“…B. pertussis infection may have indirect effects such as the impairment of the immune system and an increased likelihood of co-infections [ 31 , 34 ]. DTP immunisation may also induce cross-reactivity to other agents and their products [ 35 ]. These findings may indicate either a lack of sensitivity in diagnostic testing or a protective effect of the immunisation, independent of direct prevention of B. pertussis infection.…”

Sudden unexpected death in infants under 3 months of age and vaccination status – a case‐control study

“…As for older SIDS cases, DTPP±Hib vaccination does not constitute a risk factor for early SIDS, even in infants vaccinated before 3 months of age. Moreover, recent epidemiological evidence indicates that infants immunized against DTP are perhaps at decreased risk of SIDS (25, 26).…”