Widespread silent transmission of pertussis in families: antibody correlates of infection and symptomatology

Article Abstract:

Pertussis (whooping-cough), which is caused by the bacteria Bordetella pertussis, produces a cough that has a whooping sound during inspiration. Although whole cell vaccines are given during infancy, the safety and efficacy of these vaccines are controversial. Long-term immunity to pertussis is not well-understood. Toxins produced by the Bordetella bacteria and the bacterial protein filamentous hemagglutinin (FHA) produced during pertussis infections are currently being investigated. Vaccines are now under development that use components of the bacteria rather than the whole bacterial cell. However, vaccine effectiveness is hampered by the lack of information regarding disease transmission, the specific mechanisms involved in immunity and what is required to assure complete protection following immunization. The detection of pertussis and specific antibody responses were studied in four children with pertussis and 18 family members. Pertussis developed in 15 (83 percent of the household contacts), 10 of whom did not develop symptoms. The infection was detected by culture in three family members (20 percent). An average of 5.5 out of 10 different tests that measure the amount of antibody produced specifically for pertussis were positive over the course of the year. The number of positive tests was independent of the severity of symptoms, the age of the person or the immunization status. Tests that measure the antibodies against pertussis toxins and FHA were the most discriminating of the diagnostic tests. The antibody response and the timing of each response in the four infected children and the 15 infected contacts differed. Therefore, one specific test was unable to detect pertussis in all infected individuals. The test that measured the amount of pertussis antibody was more useful in patients with symptoms, while the FHA test was more effective in detecting infection in contacts without symptoms. Patients who had been immunized against pertussis had greater immunity to the disease than patients whose immunity was derived from previous infection. This study does not clarify the type and amount of specific antibodies that provide protection against infection of illness. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Disease transmission

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Pertussis and its prevention: a family affair

Article Abstract:

Interest in pertussis (whopping cough) infections has lately been renewed. Pertussis is caused by the bacteria Bordetella pertussis. Infected patients develop a whooping-like cough when breathing in. Vaccine toxicity and the increase in pertussis-related deaths among children living in third world countries are responsible for the increased concern over the disease. Adult infections, which are not reported often, are usually acquired from an infected child in the home. Evidence is emerging supporting the hypothesis that lifelong immunity is not achieved after immunization. Pertussis infections in adults are much more prevalent that originally thought. Furthermore, symptoms may not appear obvious. Infections have been found in adults who have been immunized in childhood and who have had a history of the disease. Undetected pertussis can be potentially dangerous if young infants are exposed. However, to maintain pertussis immunity, adults and older children would have be re-immunized with pertussis boosters. In one study, adults working in a hospital where a pertussis outbreak occurred received a booster immunization in doses similar to that of infant boosters. However, many adults experienced reactions to the booster that were unacceptable. Current technology has permitted the development of a vaccine that uses small components of the pertussis bacteria and not the whole cell to produce a vaccine. This type of vaccine has been used in Japan for eight years. However, the specific component antigens (of which there are many) that produce immunity to pertussis are not known. Furthermore, the level of antibody in the blood that assures immunity has not been ascertained. It is speculated that naturally formed antibodies in the blood can protect against disease but that secretory antibodies are needed to provide protection against infection. Although this would help explain why previously immunized people do not develop symptoms but have the infection, it does not explain why infants do not acquire adequate levels of antibodies from their mothers during pregnancy (transplacental antibody transfer). (Consumer Summary produced by Reliance Medical Information, Inc.)

Demographic aspects, Pertussis vaccines

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Natural history of pertussis antibody in the infant and effect on vaccine response

Article Abstract:

Pertussis is an infection caused by the bacteria Bordetella pertussis. The disease causes a cough with a whooping-like cough when breathing in. Children are vaccinated against pertussis using vaccines developed from whole-cell preparations. The pertussis toxin (lymphocytosis promoting factor, LPF) and filamentous hemagglutinin (FHA) are two protein components of the pertussis bacteria that are biologically active, and they are currently being used to develop a new pertussis vaccine (acellular vaccine). To help understand how antibodies against pertussis persist (or decline), the transfer of antibodies from the mother to her fetus during pregnancy was studied. The pertussis components LPF and FHA were studied in blood from three groups of patients: group one consisted of mother and infant pairs; group two consisted of children who were immunized in infancy; and group three consisted of children who were never immunized. The antibodies obtained through the maternal-fetal placental transfer lasted approximately six weeks after birth. By the fourth month of life, the maternally-derived LPF and FHA were not detectable in the infants. Infants who had higher antibodies to LPF had a weaker antibody response after they were immunized with the conventional whole-cell vaccine preparations. However, children who were immunized with vaccines developed from acellular components had a better antibody response with a higher level of antibody production. This was independent of the level of LPF antibody preceding the immunization. It is suggested that infants be immunized before the maternally-derived antibodies are lost. More research is needed to investigate the use of acellular pertussis vaccines in infants. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Immune response, Antibodies

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