Status of diphtheria immunity in the Egyptian population

In an attempt to evaluate the levels of immunity against diphtheria in the Egyptian population, 709 healthy subjects aged 2 months-105 years and from six regions of Egypt were investigated. An ELISA was used to determine the serum concentration of anti-diphtheria IgG in each subject. Following widely-used criteria for defining levels of protection, 34.1% of the subjects were categorized as susceptible to diphtheria (with < 0.01 IU antitoxin/ml serum), 43.7% were considered to have basic protection (0.01- < 0.1 IU/ml) and only the other 22.1% appeared fully protected (> or = 0.1 IU/ml). The results revealed that most of the subjects aged 2 months-50 years had a basic or fully protective level of IgG against diphtheria, although males were slightly more likely to be unprotected than females (36.2% v. 31.6%) and certain age-groups appeared to be much more likely to be susceptible than others. If outbreaks of diphtheria like those seen in recent years in the former Soviet Union are to be avoided in Egypt, the most susceptible groups of the population need to be given booster immunizations.