Neonatal tetanus in Peru: risk assessment with modified enzyme-linked immunosorbent assay and toxoid skin test

Tetanus immunization in pregnant women. Serum levels of antitetanus antibodies at time of delivery

The objective of this study was to determine the tetanus immunity status of pregnant women at the time of delivery according to tetanus toxoid (TT) vaccination coverage during their most pregnancy. The serum anti-tetanus antibody levels of 493 mothers who had live births at a hospital in Ankara were determined by enzyme-linked immunosorbent assay (ELISA). Protected women were defined as those with serum antibody levels > or = 0.6 IU/ml. Overall, 69.0% of mothers had protective tetanus antibody titers at the time of delivery. The rates of protection for mothers who had received no vaccination, one TT dose, or two TT doses during pregnancy were 46.4, 93.5, and 95.6%, respectively. Vaccinating every pregnant woman with at least one dose of TT would be an affordable and effective way to protect against neonatal tetanus, and would be a step toward eliminating the deaths that continue to occur due to this preventable disease in Turkey.

Immunity to tetanus among adults in Turkey

In 100 individuals > 18 y of age, living in urban or rural regions of Ankara, antitetanus immunoglobulin levels were determined using enzyme-linked immunosorbent assay and a brief questionnaire was administered. In total, 68% of subjects showed protective levels (> 0.01 IU/ml). Differences between rural (64%) and urban (72%) areas and between males (71.4%) and females (61.1%) were not significant (p > 0.05). Protective levels were found in 93.1% of subjects aged 18-30 y, 77.3% of those aged 30-40 y, 58.3% of those aged 40-50 y, 41.7% of those aged 50-60 y, 36.4% of those aged 60-70 y and 20% of those aged > 70 y. Only 35.7% of individuals aged > 50 y of age were found to be protected against tetanus (p = 0.004). The levels of antitetanus antibody in individuals vaccinated in the last 10 y were significantly higher than those in individuals vaccinated > 10 y ago and in those who did not remember the vaccination date (p = 0.009). Poor immunity against tetanus is a problem in elderly people in Turkey.

Rates of tetanus protection and transplacental tetanus antibody transfer in pregnant women from different socioeconomic groups in Peru

In developing countries, neonatal tetanus causes significant mortality. Using a new competitive enzyme-linked immunosorbent assay to measure anti-tetanus toxin antibody levels, we compared rates of protection, total antibody levels, and maternal-to-fetal antibody ratios between different socioeconomic groups in Peru. Upper-middle-class women 25 years and older had significantly lower rates of protection and mean anti-tetanus toxin antibody levels than did lower-class women of the same age. Nevertheless, the former had higher fetal-to-maternal antibody ratios, independent of maternal age, total antibody levels, or parity. We conclude that future vaccination programs in Latin America must target upper-middle-class as well as lower-class women.

Performance and potency of tetanus toxoid: implications for eliminating neonatal tetanus

Neonatal tetanus (NT) is a major cause of mortality in developing countries, with over 400,000 deaths estimated to occur annually. WHO has adopted the goal of eliminating NT worldwide, and a major strategy for its prevention is the administration of at least two properly spaced doses of tetanus toxoid (TT) to women of childbearing age in high-risk areas to protect passively their newborns at birth. In certain countries the locally produced TT vaccine has been shown to be subpotent, while other countries have reported NT among infants born to vaccinated women. An extensive review of production and quality control procedures was carried out between 1993 and 1995 in 8 of 22 TT-producing countries that also report NT cases, with a more superficial assessment being carried out in the remaining 14 countries. Only 4 of the 22 countries have a functioning national control authority to monitor TT production and vaccine quality. A total of 80 TT lots from 21 manufacturers in 14 of the 22 NT-reporting countries were tested for potency. Of these, 15 lots from eight manufacturers in seven countries had potency values below WHO requirements. TT potency can also be compromised by improper vaccine handling. To eliminate neonatal tetanus worldwide requires assurance that all doses of TT meet WHO production and quality requirements and that the field effectiveness of TT is monitored through systematic NT case investigations and assessment of coverage.