Tetanus and diphtheria: Toxoid, pertussis vaccine and vaccination schedule.

Pertussis Tetanus diphtheria Toxoids

Tetanus and diphtheria

Diphtheria is an acute contagious disease caused by corynebacterium diphteriae, characterized by the formation of fibrinous pseudo membrane, usually on the respiratory mucosa, myocardial and neural tissue damage is also a secondary squeal to an exotoxin. The spread of diphtheria is usually through the secretions of the infected person directly or contaminated fomites. Humans are the only known reservoir for c.diphtheria. Sporadic cases generally result from exposure to carriers who may never have had an active course of disease. The incubation period ranges between 1 and 4 days, followed by a prodromal period of between 12 and 24 hrs. Initially patients present with tonsillar and faucial diphtheria with mild pain in the throat, difficulty in swallowing and low grade fever. Nausea, vomiting, fever, headache and are more common in children.

Tetanus is an acute infectious disease caused by clostridium tetani, and characterized by intermittent tonic spasms of the masseters resulting in what is commonly known as lock jaw. Generally the elderly patients and patients with significant urn injuries and surgical wounds are the most susceptible of developing tetanus. Clinically the disease does not confer immunity. Tetanus is a preventable disease of great significance particularly the neonatal form in developing countries. The manifestations of tetanus are caused by an exotoxin (tetanospasmin) elaborated by clostridium tetani, a gram positive anaerobic spore forming bacillus. Tetanus may follow trivial or even inapparent wounds if the oxygen content of the injured tissue is low. The toxin may enter the CNS along the peripheral motor nerves or maybe blood borne to the nervous tissue. The incubation period ranges from 2 to 50 days.

The primary immunization against tetanus with either the fluid or absorbed toxoid is superior to giving antitoxin at the time of injury. Routine diphtheria, tetanus, pertussis (DPT) immunizations and booster recommendations are given. These vaccines are toxoids prepared from corynebacterium diptheriae and clostridium tetani, respectively. The whole cell pertussis vaccine is composed of formaldehyde treated bacterial cell wall fragments from bordetella pertussis and combined with D and T. acellular pertussis vaccines consisting of the semi purified or purified components of the pertussis bacteria combined with D and T are primary series of vaccinations at 2, 4 and 6 months of age and booster vaccines the 4th and 5th doses at 15 to 20months and 4 to 6 years. The initial series of three primary doses of DTP is followed by a booster at age 15 to 20 months and another at 4 to 6 yrs. Subsequent routine tetanus booster which is recommended for both adults and children should be administered every 10 yrs. The use of adult type tetanus and diphtheria toxoids adsorbed TD is preferred for these boosters, and studies are underway to assess the use of DTaP in adolescents and adults. Because adverse reactions to toxoids may occur, more frequent Td boosters are unwarranted. At any interval after initial immunization, immunity can be re-established by a single booster, however after an interval of >10yrs from the last injection of tetanus toxoid the rate of antibody rise to the booster response may somewhat be slower.