Neonatal tetanus despite protective serum antitoxin concentration

Retrospective anti-tetanus antibody responses of zoo-based Asian elephants (Elephas maximus) and rhinoceros (Rhinocerotidae)

Tetanus toxoids (TT) commercially available for use in horses and livestock are commonly used to vaccinate elephants and rhinoceros that are in human care. Although recommendations for booster intervals have changed in human and horse protocols to reduce the risks associated with hyper-immunity (i.e. B-cell anergy and hypersensitivity reactions) these have generally not been adopted in zoo protocols. Additionally, there is no evidence to demonstrate commercial TT immunogenicity in rhinoceros. In this study, a preliminary analysis of rhinoceros antibody responses to TT was conducted, in addition to an exploration of the impact of various booster frequencies on antibody responses in elephant. Retrospective analysis of archived serum samples was conducted for 9 Asian elephants (Elephas maximus), 7 southern black (Diceros bicornis minor), one southern white (Ceratotherium simum simum), and two greater one-horned (Rhinoceros unicornis) rhinoceros. Pre-vaccination (baseline) samples and those following priming vaccination (rhinoceros only), annual and non-annual boosters were targeted. A commercially available competitive ELISA kit was used to quantify serum anti-TT antibodies. Average baseline and post-vaccination anti-tetanus antibody concentrations were greater in elephant (92 mg/L ± 42, n = 3, N = 3; 125 ± 76, n = 82, N = 9) than in rhinoceros (47 mg/L ± 39, n = 8, N = 8; 44 mg/L ± 37, n = 16, N = 7). Rhinoceros antibody concentrations did not differ markedly following vaccinations from their naturally acquired high pre-vaccination concentrations. Eight elephants demonstrated antibody maintenance for 3-5 years without a tetanus booster. Additionally, although five out of nine elephants developed local reactions consistent with delayed type IV hypersensitivity following some boosters, there was no association between high antibody concentrations and increased incidence of adverse reactions. In addition, no decrease in antibody concentrations was detected as a result of annual vaccination in elephants, though this does not entirely rule out potential for B-cell anergy.

Ebola Virus Disease Survivors Show More Efficient Antibody Immunity than Vaccinees Despite Similar Levels of Circulating Immunoglobulins

The last seven years have seen the greatest surge of Ebola virus disease (EVD) cases in equatorial Africa, including the 2013-2016 epidemic in West Africa and the recent epidemics in the Democratic Republic of Congo (DRC). The vaccine clinical trials that took place in West Africa and the DRC, as well as follow-up studies in collaboration with EVD survivor communities, have for the first time allowed researchers to compare immune memory induced by natural infection and vaccination. These comparisons may be relevant to evaluate the putative effectiveness of vaccines and candidate medical countermeasures such as convalescent plasma transfer. In this study, we compared the long-term functionality of anti-EBOV glycoprotein (GP) antibodies from EVD survivors with that from volunteers who received the recombinant vesicular stomatitis virus vectored vaccine (rVSV-ZEBOV) during the Phase I clinical trial in Hamburg. Our study highlights important differences between EBOV vaccination and natural infection and provides a framework for comparison with other vaccine candidates.

A case of neonatal tetanus presented within 24 hours of life

Summary

Neonatal tetanus is still prevalent in developing countries such as India. Generally, neonatal tetanus is seen in babies of unimmunized mothers beyond the second day of life. A neonate presented to us on the 4th hour of birth with a periumbilical ulcer. The baby's antenatal and birth history was uneventful. The mother had been immunized against tetanus. At presentation, the baby was active, alert and sucking normally. Avery small ulcer was noted below the umbilicus. Subsequently, the baby developed rigidity and a tonic spasm of its body with recurrent seizures from the 18th hour of its birth and by 21st hour. It also had a full blown clinical picture of neonatal tetanus including: masseter spasm; generalized rigidity; a high pitched cry: and intermittent opisthotonos posturing. An ulcer gradually enlarged to 5 × 4 cm and a swab from ulcer showed Clostridium tetani (both on Gram staining and culture). A review of the published literature did not reveal any case that had presented so early. Therefore, this is probably the first case of neonatal tetanus being reported within the 21st hour of birth.

Significance of circulating toxin and antitoxin in unimmunized tetanus cases of neonates and infants

The level of circulating tetanus toxin, antitoxin and their individual influence on the outcome of tetanus cases were determined in unimmunized 125 neonatal and 39 infant cases of tetanus. PHA (passive haemagglutination) test showed 40% positive cases for toxin while its absence in the remaining cases indicated of either toxin fixation to the central nervous system (CNS) or it got neutralized by antitoxin. TN (toxin neutralization) and PHA test carried out in 46 sera samples revealed a strong positive correlation (r = 0.9) showing that 35/46 (76%) and 38/46 (82.6%) samples were positive for antitoxin, respectively. 25.4% of the neonate and infant cases and 34% of the control group had a protective serum tetanus antitoxin level. 42.5% of the paired sera from unimmunized mothers and their neonates showing nonprotective antitoxin levels suggested that a high level of antitoxin is needed for transplacental transfer, although transfer may not play a decisive role in the resistance against the disease. The presence of toxin or antitoxin in the clinical cases did not affect the outcome of the disease, although in neonates, presence of toxin was found to be a bad prognostic sign. This study explicitly advocates for the need to improve the vaccination coverage strategy.

Neonatal tetanus after home delivery: report of one case

Neonatal tetanus is a rare disease in developed countries, but remains common in developing countries. Pregnant women immigrating to Taiwan from developing countries may carry a risk of neonatal tetanus to the child, because of inadequate tetanus toxoid immunization and inappropriate postnatal cord care. Many young pediatricians in Taiwan are unfamiliar with this disease. Herein, we describe the clinical course of a newborn with neonatal tetanus, who was admitted with complaints of difficult feeding and muscle rigidity. After mechanical ventilation for 58 days and a prolonged hospital stay, the infant was discharged in good condition. It is important to maintain a high index of suspicion for neonatal sepsis when infants present with seizure-like symptoms, in order to allow its early diagnosis and appropriate treatment.

Generalized tetanus despite prior vaccination and a protective level of anti-tetanus antibodies

Because of the success of widespread vaccination, tetanus rarely occurs in developed countries such as the United States. Vaccination, however, is not entirely protective even if patients develop an adequate antibody response. We discuss a case of generalized tetanus in an individual with both a history of prior vaccination and a measurable level of anti-tetanus antibodies at the time of presentation. We speculate that the patient's preexisting antibodies may have moderated his course of illness.

Maternal and neonatal tetanus

Maternal and neonatal tetanus are important causes of maternal and neonatal mortality, claiming about 180 000 lives worldwide every year, almost exclusively in developing countries. Although easily prevented by maternal immunisation with tetanus toxoid vaccine, and aseptic obstetric and postnatal umbilical-cord care practices, maternal and neonatal tetanus persist as public-health problems in 48 countries, mainly in Asia and Africa. Survival of tetanus patients has improved substantially for those treated in hospitals with modern intensive-care facilities; however, such facilities are often unavailable where the tetanus burden is highest. The Maternal and Neonatal Tetanus Elimination Initiative assists countries in which maternal and neonatal tetanus has not been eliminated to provide immunisation with tetanus toxoid to women of childbearing age. The ultimate goal of this initiative is the worldwide elimination of maternal and neonatal tetanus. Since tetanus spores cannot be removed from the environment, sustaining elimination will require improvements to presently inadequate immunisation and health-service infrastructures, and universal access to those services. The renewed worldwide commitment to the reduction of maternal and child mortality, if translated into effective action, could help to provide the systemic changes needed for long-term elimination of maternal and neonatal tetanus.

Analysis of the relationship between immunogenicity and immunity for viral subunit vaccines

The prevention of viral infection by vaccination relies on stimulating an appropriate immune response in order to reduce the probability with which a virus can establish an infection. Post-vaccination antibody responses have therefore been associated with reducing the probability with which an individual can be infected (i.e., the vaccine's "impact"). Quantifying this relationship is essential in evaluating new vaccines, especially since comparisons between vaccines, and vaccine licensure, may be dependent on antibody responses alone. In this paper two principal questions are identified which need to be addressed in the evaluation of subunit vaccines: i) how do specific antibody levels relate to complete protection from infection or disease and ii) how do antigenic subunits interact in developing protection when combined together in a single vaccine. The aim is to identify explicitly certain assumptions that are frequently made implicitly in the discussion of vaccine action. First, antibody levels are related to levels of protection through a novel statistical analysis of incidence data from a published hepatitis B vaccine trial. The antibody response observed after influenza A virus infection is discussed in relation to the selection of neutralisation escape variants. Finally, by way of example, a theoretical situation is examined and three simple models of subunit vaccine action are constructed in order to describe how antibody levels may be related to population level phenomena such as the elimination of an infection by mass vaccination.

Antibodies to tetanus toxoid in women of childbearing age in Dar es Salaam and Bagamoyo, Tanzania

Our aim was to determine tetanus immunity in women of childbearing age (15-44 years) with histories and/or documentation of having been vaccinated with Tetanus Toxoid (TT) under the Expanded Programme on Immunization in Dar es Salaam and Bagamoyo, Tanzania. Using an ELISA technique, serum levels of TT antibody, antibody avidity and distribution of TT IgG subclass antibodies were determined in 207 apparently healthy women. A TT antibody level of 0.1 IU/ml was considered protective. 99% and 100% of women in Dar es Salaam and Bagamoyo, respectively, had a TT antibody level > or = 0.1 IU/ml. Anti-toxin binding avidity was found to be high in most of the women. In addition to TT IgG3 subclass antibody, TT IgG1 subclass antibody was the most dominant subclass type. A substantial number of women also had TT IgG2 and TT IgG4 subclass antibody responses. A better recording system on TT immunization is recommended to avoid hyper-immunization of women and to optimize the cost-effectiveness of the immunization programme.

Prognostic factors in neonatal tetanus

OBJECTIVE

Neonatal tetanus (NNT) is the leading cause of neonatal deaths in developing countries. The objective of this study was to determine prognostic indicators in NNT.

METHODS

We reviewed the clinical records of all neonates (n = 174) admitted to Ife State Hospital with the diagnosis of NNT from 1991 through 1995.

RESULTS

Delivery had occurred at home in 73.3% of cases. Only 37/164 of the mothers had had adequate immunization with tetanus toxoid. The umbilical cord appeared to be the portal of entry in 58.6% of cases. Mean age of infants at presentation was 7.2 days. Mortality was 57.5%; non-survivors succumbed after mean stay in the hospital of 5.0 days. Mortality was significantly associated with an incubation period of 6 days or less (P = 0.0026), infant's weight of less than 2.5 kg (P = 0.0113), lack of antenatal care in a health facility (P = 0.0279), birth at home (P = 0.0455), but not with lack of adequate maternal immunization (P = 0.2081; not significant). Multivariable analysis showed that a short (< or = 6 d) incubation period was the strongest predictor of mortality (OR = 3.11, P = 0.0030) while low infant weight (< 2.5 kg) was also a significant predictor (OR = 2.46, P = 0.0408).

CONCLUSIONS

Hygienic deliveries and adequate cord care are very important for the prevention of neonatal tetanus deaths, and universal prenatal care, including education programmes on appropriate perinatal and cord care, can significantly reduce NNT incidence and mortality in developing countries.

Concentration and avidity of anti-tetanus antibodies in mother-infant pairs: relation to immunization time

The concentration and avidity of anti-tetanus antibodies in two groups of mother-infant pairs were compared. Mothers immunized during pregnancy and their newborns (group A) had significantly higher antibody concentrations than mothers immunized at least a year before their last pregnancy and their newborns (group B) as measured by an indirect enzyme immunoassay (EIA) procedure. Antibody avidity of samples was measured by an inhibition EIA technique and urea denaturation test. Although antibody avidity was higher in group B, the differences were not significant. These findings may represent a secondary antibody response to a protein antigen, when considering that all mothers in both groups had received a primary tetanus vaccination during childhood. In mothers with a history of primary tetanus immunization, a single booster dose of tetanus toxoid during pregnancy is enough to induce protective levels of antibodies with reasonably high avidity in both mother and newborn.

Should adult tetanus immunization be given as a single vaccination at age 65? A cost-effectiveness analysis

OBJECTIVE

To compare three vaccination strategies for the prevention of adult tetanus. Each strategy includes childhood primary immunization and wound prophylaxis, and one of the following: 1) the currently recommended booster every ten years; 2) a single booster at 65 years of age; or 3) no intervention after age 6 except for wound prophylaxis.

METHODS

Cost-effectiveness analysis was used to compare the three different strategies. A Markov model, cycled annually from age 5 through age 85, was applied to each strategy to predict the incidence and costs of tetanus for the U.S. adult population.

RESULTS

The three strategies have very similar effects on life expectancy but different costs. Expressed incremental to no intervention after childhood primary immunization, the decennial booster strategy is least cost-effective, with a discounted incremental cost-effectiveness ratio of $143,138 per year of life saved compared with $4,527 for the single-booster strategy. Sensitivity analysis demonstrates that the decennial strategy is more effective but more costly over a wide range of model assumptions.

CONCLUSIONS

The current policy of recommending tetanus booster vaccinations every ten years is effective but much more costly than a more easily implemented policy that also provides considerable protection against tetanus. The authors recommend forsaking decennial boosters in favor of a policy of including a single booster at age 65 along with other recommended health maintenance maneuvers reserved for that age.

Neutralizing antibodies in 6-year-old children after five doses of tetanus toxoid

It has recently been suggested that multiple boosters of tetanus toxoid may enhance serum antitoxin titres but may not necessarily lead to an effective immune response. Tetanus antitoxin titres by haemagglutination inhibition and mouse toxin neutralization tests were determined in sera of 64 children, 5 and 6 years old. Primary vaccination against tetanus was given as four doses of diphtheria-pertussis-tetanus (DPT) vaccine beginning in the second or third month of life, and a booster dose given to schoolchildren at 6 years of age. In our area more than 90% of children receive five doses of tetanus toxoid before their seventh birthday. The children were given 0.5 ml of DPT or DT containing 10 Lf ml-1 tetanus toxoid at each injection. The haemagglutination titres and the toxin neutralization titres were much higher in 6-year-old than in 5-year-old children. We concluded that the fifth dose is an effective booster in 6-year-old children.