Pertussis vaccination in mixed markets: Recommendations from the Global Pertussis Initiative

The Global Pertussis Initiative is an expert scientific forum that publishes consensus recommendations concerning pertussis for many regions of the world. Here, we give recommendations for the primary vaccination of infants in those countries where whole-cell pertussis (wP)- and acellular pertussis (aP)-containing combination vaccines are used in parallel. A selective literature review was performed concerning the influence on safety, immunogenicity, and effectiveness of mixing wP- and aP-containing vaccines for primary immunization of infants. In addition, local data were collected from various countries and the results discussed in a face-to-face meeting. Very few data addressing issues of mixing combination vaccines were identified, and no data were available concerning the effectiveness or duration of protection. It was also found that pharmacovigilance data are scarce or lacking in those countries where they would be needed the most. We then identified frequent problems occurring in low- and middle-income countries (LMICs) where both vaccine types are used. Relying on local knowledge, we give practical recommendations for a variety of situations in different settings. Specific needs for additional data addressing these issues were also identified. International bodies, such as the World Health Organization (WHO), as well as vaccine producers should try to find ways to highlight the problems of mixing wP- and aP-containing combination vaccines with robust data. Countries are urged to improve on their pharmacovigilance for vaccines. For practicing physicians, our recommendations offer guidance when wP- and aP-containing vaccines are used in parallel during primary immunization.

What to do and what not to do in serological diagnosis of pertussis: recommendations from EU reference laboratories

Bordetella pertussis-specific antibodies can be detected by enzyme-linked immunosorbent assays (ELISAs) or multiplex immunoassays. Assays use purified or mixed antigens, and only pertussis toxin (PT) is specific for B. pertussis. The interpretation of results can be based on dual-sample or single-sample serology using one or two cut-offs. The EU Pertstrain group recommends that: (i) ELISAs and multiplex immunoassays should use purified non-detoxified PT as an antigen, that they should have a broad linear range and that they should express results quantitatively in International Units per millilitre (IU/ml); (ii) a single or dual diagnostic cut-off for single-serum serology using IgG-anti-PT between 50 and 120 IU/ml should be used, and diagnostic serology cannot be validly interpreted for one year after vaccination with acellular pertussis (aP) vaccines; (iii) IgA-anti-PT should only be used with indeterminate IgG-anti-PT levels or when a second sample cannot be obtained. This group discourages using: (i) other antigens in routine diagnostics, as they are not specific; (ii) micro-agglutination, due to its lack of sensitivity; (iii) immunoblots for pertussis serodiagnosis, as results cannot be quantified; (iv) other methods, such as complement fixation or indirect immunofluorescence, due to their low sensitivity and/or specificity.

International Bordetella pertussis assay standardization and harmonization meeting report. Centers for Disease Control and Prevention, Atlanta, Georgia, United States, 19-20 July 2007

An international meeting on Bordetella pertussis assay standardization and harmonization was held at the Centers for Disease Control and Prevention (CDC), Atlanta, GA, 19–20 July 2007. The goal of the meeting was to harmonize the immunoassays used for pertussis diagnostics and vaccine evaluation, as agreed upon by academic and government researchers, regulatory authorities, vaccine manufacturers, and the World Health Organization (WHO).

The primary objectives were (1) to provide epidemiologic, laboratory, and statistical background for support of global harmonization; (2) to overview the current status of global epidemiology, pathogenesis and immunology of pertussis; (3) to develop a consensus opinion on existing gaps in understanding standardization of pertussis assays used for serodiagnosis and vaccine evaluation; and (4) to search for a multicenter process for addressing these priority gaps. Presentations and discussions by content experts addressed these objectives. A prioritized list of action items to improve standardization and harmonization of pertussis assays was identified during a group discussion at the end of the meeting. The major items included: (1) to identify a group that will organize, prepare, maintain, and distribute proficiency panels and key reagents such as reference and control sera; (2) to encourage the development and identification of one or more reference laboratories that can serve as an anchor and resource for other laboratories; (3) to define a performance-based assay method that can serve as a reference point for evaluating laboratory differences; (4) to develop guidance on quality of other reagents, e.g., pertussis toxin and other antigens, and methods to demonstrate their suitability; (5) to establish an international working group to harmonize the criteria to evaluate the results obtained on reference and proficiency panel sera; (6) to create an inventory to determine the amount of appropriate and well-characterized sera that are available globally to be used as bridging reagents for vaccine licensure; and (7) to seek specific guidance from regulatory authorities regarding the expectations and requirements for the licensure of new multicomponent pertussis vaccines.

Pertussis: An old disease in new clothes

In this issue of Eurosurveillance, two articles report data about pertussis.

[Pertussis: incidence, symptoms and costs]

BACKGROUND AND OBJECTIVE

A prospective sentinel study into the population-based incidence of pertussis in adults was done between 2001 and 2004 in Rostock (former East Germany) and Krefeld (former West Germany).

PATIENTS AND METHODS

971 outpatients, who consulted general practitioners or internists, were included. Clinical inclusion criteria were coughing for one week or more and no chronic respiratory diseases. Bordetella infection was diagnosed by PCR on nasopharyngeal swabs and ELISA for serology (IgG-anti-PT, IgA-anti-PT, IgG-anti-FHA, IgA-anti-FHA).

RESULTS

We found a total of 97 cases of pertussis in this cohort. The main symptom was coughing for a median of 7-8 weeks. Population-based incidence was estimated in Krefeld at 169 cases/100000 population per year, and in Rostock at 160/100000 per year. Resource use was 120 EUR of direct medical cost and 434 euro of indirect medical cost, not including hospitalization in this study.

CONCLUSIONS

Pertussis is a frequent cause of longer lasting cough in German adults, and it causes significant morbidity and costs.

Pertussis of adults and infants

Bordetella pertussis continues to circulate even in populations where a high vaccine coverage of infants and children is achieved. Cases in adolescents and adults are reported with increasing frequency in many countries. Adults are a reservoir for infections in very young infants, in whom pertussis may be severe and life-threatening. The salient clinical feature of pertussis in adolescents and adults is prolonged coughing, and recognising that pertussis does occur in these age groups is the most important step in its diagnosis. A laboratory diagnosis can be made by bordetella-PCR from nasopharyngeal swabs or secretions and by detection of antibodies, mainly to pertussis toxin; laboratory diagnosis is, however, not well standardised. Vaccination of adolescents and adults is now possible with acellular pertussis vaccines, which are well tolerated, immunogenic, and effective. Adolescent boosters and the vaccination of health-care workers are already included in vaccination calendars in some countries. Vaccine-recommending bodies and national health-care organisations must have locally relevant information on the transmission of pertussis from adults to infants to be able to make decisions on the advisability, feasibility, and priority for booster immunisation against pertussis.

Effectiveness of acellular pertussis vaccine assessed by hospital-based active surveillance in Germany

We assessed the effectiveness of complete and partial pertussis vaccination in Germany--a country where acellular vaccine is predominantly used--for the prevention of cases of pertussis requiring hospitalization. Vaccine effectiveness was estimated by means of a screening method. Vaccine coverage of children born during the period of June 1996 through December 1998 was assessed by a telephone survey. Data from hospitalized children with pertussis in 1997-1998 and from patients with pertussis complications in 1997-2000 were acquired by a nationwide, hospital-based, active surveillance system. Age-adjusted vaccine effectiveness of completed primary vaccination was estimated to be 99.8% (95% confidence interval [95% CI], 98.9-100). After receipt of 1 dose of vaccine, vaccine effectiveness was as high as 68.0% (95% CI, 45.6-81.1), increasing to 91.8% (95% CI, 84.7-95.7) after receipt of the second dose. Vaccine effectiveness was even slightly higher for pertussis with complications. Thus, even after partial vaccination, acellular pertussis vaccine is highly effective in preventing hospitalizations for pertussis.

Recommendations are needed for adolescent and adult pertussis immunisation: rationale and strategies for consideration

Pertussis vaccination of infants has dramatically reduced disease, complications and deaths in infancy and early childhood. But there is still a major public health challenge--to deal with the morbidity and economic burden of illness in older children, adolescents and adults. Furthermore, it is these groups that form a major source of infection for non-immunised and partially immunised infants who are at high risk of severe complications. Adult-type acellular pertussis vaccine confers safe and effective protection against pertussis. There are several strategies to consider for immunising older individuals. Universal vaccination of all age groups would be the best available strategy for protecting individuals. It would also reduce the potential for transmitting the disease to other susceptibles, particularly infants. However, such a policy may be difficult both logistically and economically at this time. More easily achievable as a first step would be a strategy of universal adolescent booster vaccination combined with a programme targeted at adults most likely to have contact with very young babies including healthcare and childcare workers, parents and close family contacts. There is also potential for offering vaccination to adults (and their carers and close contacts) whose medical conditions or advanced age may place them at increased risk of more severe pertussis disease. Specific details of immunisation programmes must be made on a country by country basis depending on local circumstances.

Stability of antibodies to Bordetella antigens in German adults

To estimate the rate of asymptomatic exposure to Bordetella pertussis antigens in the German adult population and to evaluate the stability of antibodies to these antigens, antibody levels against Bordetella antigens and their variability over time were measured in German adult blood donors. One hundred forty-six regular blood donors (41 females, 105 males) were tested repeatedly for antibodies of isotypes IgG and IgA to pertussis toxin, filamentous hemagglutinin (FHA) and pertactin over a period of 2-5 years. Overall, 86% and 56% had IgG or IgA antibodies to pertussis toxin, respectively, 100% and 92% had IgG or IgA antibodies to FHA, respectively, and 83% and 93% had IgG or IgA antibodies to pertactin, respectively. One significant titer increase of both IgG anti-FHA and IgG anti-pertactin, one of IgG anti-FHA, and two of IgA anti-FHA as well as one significant decrease of IgG anti-pertussis toxin were observed during an observation period of 480.5 person-years. Antibody concentrations in men and women were not different. The data show that the level of antibodies to pertussis toxin, FHA, and pertactin remains stable over several years. Furthermore, depending on the definition of serological evidence, the rate of significant increases or decreases suggesting unrecognized exposure to Bordetella antigens was estimated to be between <0.2 and 1.0 per 100 person-years in the population studied.

Pertussis in Germany: regional differences in management and vaccination status of hospitalized cases

The incidence of pertussis requiring hospitalization in children younger than 16 years was estimated by the use of an active surveillance-system. Of special interest were differences between West and East Germany following different vaccination strategies before reunification. In 1997 and 1998, 754 pertussis cases required a total of 11,151 hospital inpatient days. The incidence of hospitalized pertussis was 2.68/100,000 person years and this was significantly higher in East than in West Germany. In East Germany an unusually high percentage of hospitalized cases was found in children aged 6-15 years (45% versus 13% in West Germany). The difference between the regions may be due either to a different perception of the disease or to an increased immunity induced by prior disease or vaccination. In East Germany, pertussis was rare until reunification but it has increased significantly since then. Older children may thus represent a population at risk of pertussis having not had previous exposure to pertussis antigens.

Epidemiological typing of Bordetella pertussis isolates: recommendations for a standard methodology

Pertussis is re-emerging in vaccinated populations, and to gain insight into the reasons for this development population-based studies are necessary. Unfortunately, various techniques are used to study Bordetella pertussis populations, hampering comparison between studies. A standard methodology for epidemiological typing of Bordetella pertussis isolates is proposed which is based on serotyping, pulsed-field gel electrophoresis and gene typing. Such a standard approach will allow comparisons between studies performed in different laboratories. Comparisons may reveal whether the epidemiological differences observed between countries are due for instance to different Bordetella pertussis populations or different vaccines used.

Evaluation of a single-sample serological technique for diagnosing pertussis in unvaccinated children

This study was performed to evaluate the sensitivity of immunoglobulin (Ig)G and IgA antibodies to pertussis toxin and filamentous hemagglutinin in diagnosing pertussis from a single serum sample. The pertussis group was defined according to the World Health Organization pertussis case definition. The control group coughed for 21 days or more but had no microbiological or serological evidence of Bordetella infection. Both cohorts were divided into infants (< 12 months of age), toddlers (1-4 years) and school children (5-10 years). There were 525 subjects in the pertussis group and 321 in the control group, with an even distribution of genders. IgG and IgA antibodies to pertussis toxin and filamentous hemagglutinin were measured in a standardized enzyme immunoassay. Antibody levels beyond the 95 percentile of the control cohort were regarded as indicative of recent contact, setting the specificity level at 0.95. Acute serum samples drawn between 1 week and 3 weeks after the onset of coughing showed a low sensitivity (2-19%) for diagnosing pertussis. In convalescent samples taken 5-10 weeks after the onset of symptoms, detection of IgG anti-pertussis toxin was the best single test, with a sensitivity of 61%, 65%, and 74% in infants, toddlers and school children, respectively. A combination of IgG anti-pertussis toxin and IgA anti-filamentous hemagglutinin using age-specific reference values had a sensitivity of 81-89% in diagnosing pertussis from a single serum sample taken 5-10 weeks after the beginning of symptoms.

Pertussis complications in Germany--3 years of hospital-based surveillance during the introduction of acellular vaccines

Between 1 November 1993 and 31 October 1996, admissions to paediatric departments for Bordetella pertussis complications were reported to a nationwide, hospital-based active surveillance system. The case definition included pertussis complicated by pneumonia, apnoea requiring assisted ventilation, seizures, encephalopathy or a combination of these. Two hundred sixteen cases of pertussis complications were registered. 57.4% of them were in infants, 50.9% of them less than 6 months old. There were five deaths, three previously healthy children died. At the time of hospital admission, 106 cases would have been eligible for at least three doses of pertussis vaccine, only four (3.8%) had received the recommended number of immunisations. From the second quarter of 1995, the reported number of cases declined. The decrease coincides with an improvement of pertussis vaccination coverage between 1992 and 1995 due to an increased use of acellular vaccines. The reduction of complicated pertussis was observed even in age-groups too young for the recommended vaccinations. The observed decrease could be due to the increase in vaccination coverage with interruption of the chain of transmission to the younger age-groups, to a cyclic decrease in pertussis cases, or to a combination of both. Continued surveillance will provide information on the epidemiological trend of hospitalisations for pertussis complications in the first European country to have introduced vaccination with acellular vaccines on a large scale.

A serologic study of organisms possibly associated with pertussis-like coughing

OBJECTIVE

To assess the frequency of serologic evidence for an infection with microorganisms other than Bordetella pertussis in children with pertussis-like coughs.

METHODS

The study was performed within a protective efficacy trial of an acellular pertussis vaccine. Children who coughed for >7 days and had no laboratory evidence of recent infection with B. pertussis were eligible for the present study. Antibodies to Mycoplasma, Chlamydia, respiratory syncytial virus and influenza viruses A and B were measured by complement fixation, and antibodies to adenovirus and parainfluenza viruses 1, 2 and 3 were measured by enzyme-linked immunosorbent assay (ELISA) in acute and convalescent serum samples. Significant titer rises (4-fold titer rise in complement fixation, 100% increase of units in ELISA) and concentrations of antibodies beyond age-specific reference values were regarded as indicative of recent infection. In some children IgM antibodies to Epstein-Barr virus and to cytomegalovirus were also measured by ELISA.

RESULTS

A total of 149 of 1179 (12.6%) children had no laboratory evidence of B. pertussis infection. Serologic evidence for other infections were found in 56% (83 of 149). Adenovirus (33), parainfluenza viruses 1, 2 and 3 (18), Mycoplasma pneumoniae (15) and respiratory syncytial virus (14) were most common. Of this group 48% had been vaccinated against pertussis.

CONCLUSION

We present data that a proportion of pertussis-like coughs in children may be caused by adenovirus, parainfluenza viruses, respiratory syncytial virus and Mycoplasma. The differential diagnosis of pertussis-like coughs by laboratory methods should include these infections, especially in vaccinated children.

Factors influencing the spread of pertussis in households

The objective of this study was to compare the spread of pertussis in children and adults being secondary contacts after household exposure. The study was nested in an efficacy trial of an acellular pertussis vaccine. The spread of the disease was also monitored with respect to gender and antibiotic therapy. A total of 453 index cases, of which 133 were monitored for adult disease, fulfilled the WHO definition of pertussis. They had contacts to 173 unvaccinated children aged 6-47 months, and a total of 101 adults with pertussis were followed. Detection of the bacteria, or a significant increase of specific antibodies confirmed the diagnosis. Secondary spread of the disease was assumed, when a household member coughed for 7 days or more and had laboratory evidence for pertussis. Crude attack rates (AR) were 69% in children and 31% in adults (P < 0.05). AR in children were independent of gender but more women than men (P=0.02) were affected in those households where the index case was a child. Erythromycin treatment of the index case reduced the AR in exposed toddlers from 80% to 57% (P=0.06), and in exposed adults from 40% to 21% (P=0.2). Erythromycin therapy in contacts did not alter the clinical course of the disease significantly.

CONCLUSIONS

In a household study of pertussis, 69% of children and 31% of adults (more women than men) contracted the disease. Erythromycin reduced the number of infections in household contacts, but did not alter the clinical course in those who contracted pertussis.

Acinetobacter baumannii colonization in ventilated preterm infants

The role of Acinetobacter baumannii in infections in ventilated preterm infants was evaluated in 15 colonized infants (11 male, 4 female) in a pediatric intensive care unit. These cases were randomly matched by birth weight and gestational age with ventilated non-colonized controls (8 male, 7 female). Case records were reviewed for signs and symptoms of infection. Colonized infants were ventilated significantly longer (p < 0.05) than controls, and had body temperatures of > 37 degrees C for a significantly longer period of time (p < 0.05). No other parameter of infection differed significantly between the groups. The duration of intensive care treatment did not differ between cases and controls, nor did the weight gain during intensive care treatment. No fatalities occurred in either group.

Immunogenicity and reactogenicity of HbOC vaccine administered simultaneously with acellular pertussis vaccine (DTaP) into either arms or thighs of infants

To evaluate the reactogenicity and immunogenicity of a Haemophilus influenzae type b conjugate vaccine (HbOC) and of a tricomponent acellular pertussis vaccine (DTaP) when injected simultaneously into either contralateral arms or into contralateral thighs, 110 infants were enrolled to receive three doses of DTaP at 3, 4, and 5 months and two HbOC doses at 3 and 5 months of age. Administration of either of the two vaccines into arms was associated with significantly more local side effects than administration into thighs. There was no difference in geometric mean concentration (GMC) values for any of the four vaccine antigens between subjects who had been vaccinated into arms or thighs. After immunization, all children had protective antibody titers to diphtheria toxin. While post vaccination the mean anti-tetanus toxoid GMC was > or = 1.25 IU/ml, there was no significant rise as compared to the GMC before vaccination. GMCs of antibodies against the various pertussis antigens were similar to those observed before with the same DTaP vaccine. The simultaneous administration of DTaP and HbOC was safe and immunogenic irrespective of the site of vaccine administration, but significantly more local reactions occurred when vaccines were injected into arms.

Factors influencing the analysis of secondary prevention of pertussis

The aim of this study was to evaluate factors that influenced the spread of pertussis in secondary contacts after household exposure. The data were acquired during a prospective household-contact study into the efficacy of an acellular vaccine. The spread of the disease was monitored with respect to various case definitions of pertussis, socio-economic factors, household composition, and antibiotic therapy. A total of 453 index cases had contact with 173 unvaccinated children aged from 6 to 47 months. Depending on the clinical case definition, the attack rates (AR) in children with a laboratory-confirmed Bordetella infection increased from 55% for the WHO definition to 69%, when a less stringent definition was used. AR in children were independent of age and gender. The social status of the family had no significant influence on the AR in children. Erythromycin treatment of the index case reduced the AR from 64% to 51% (p = 0.08). These factors should be taken into consideration when studies into the secondary prevention of pertussis by acellular vaccines are initiated.

Epidemiologic aspects and diagnostic criteria for a protective efficacy field trial of a pertussis vaccine

Pertussis was a major childhood disease in parts of West Germany in 1990. Before a prospective household contact trial into the efficacy of an acellular pertussis vaccine was undertaken, the epidemiology of the disease was studied in one area. This study showed that pertussis had an annual incidence of 4%-6% in the first 6 years of life. During the trial, a total of 1223 pertussis cases were diagnosed by laboratory methods. Isolation rates of Bordetella organisms varied by the pediatrician who did the nasopharyngeal swab and decreased with time required for swab transport. Analysis of the serologic results showed that if IgG and IgA anti-pertactin antibodies had been considered, overall sensitivity would have been only marginally increased. Several pertussis patients had antibodies to parapertussis antigens, indicating a lack of complete cross-protection. The serologic response in secondary household contacts differed by vaccination status. However, this difference was unlikely to have influenced the point estimate of efficacy of the acellular vaccine.

Acellular pertussis vaccines: the rationale for an efficacy trial in Germany

After concern about the safety of diphtheria-tetanus toxoid-whole cell pertussis vaccines (DTPw), the recommendation to vaccinate children with DTPw was withdrawn in 1974 in the former West Germany. This led pertussis cases to increase to an estimated 100,000 annually. Despite renewal of the vaccination recommendation in 1991, vaccine use remained low. The German health care structure assures regular contact between most children and pediatricians. This enabled the conduct of a large efficacy trial with a diphtheria-tetanus toxoid-acellular pertussis (DTPa) vaccine. Because a placebo-controlled trial was not ethically possible, a prospective household contact study with a blinded clinical follow-up was done. Possible study participants were screened by their pediatrician, who also initiated diagnostic procedures. Clinical follow-up was done by another locally based but independent and blinded physician. Vaccine efficacy was calculated to be 89% (95% confidence interval, 76.6%-94.6%). None of the identified confounding factors biased results in favor of the DTPa vaccine.

Analysis of proteins encoded by the ptx and ptl genes of Bordetella bronchiseptica and Bordetella parapertussis

Bordetella pertussis is the only bacteria] species which is known to produce pertussis toxin (PT); however, both Bordetella bronchiseptica and Bordetella parapertussis contain regions homologous to the ptx genes of B. pertussis that encode the toxin subunits. After finding that several children with B. parapertussis infections exhibited modest antibody titers to PT, we examined the ptx genes of both B. parapertussis and B. bronchiseptica to determine whether they would encode stable, functional proteins even though their promoters are thought to be inactive under the conditions that have been examined. We inserted a functional promoter directly upstream of the ptx-ptl region of both species and examined culture supernatants of the resulting strains for PT activity. Biologically active PT was found in the culture supernatants of both engineered species. The toxin encoded by the B. parapertussis ptx genes appeared more labile in culture supernatants than did toxin produced by either B. pertussis or the engineered strain of B. bronchiseptica. This lability might be due to the lack of a full-length S2 subunit. We also investigated the ptl genes of these species, which are necessary for the secretion of this toxin, and found that both B. bronchiseptica and B. parapertussis contain at least certain of these genes, including ptlE and ptlF. Moreover, B. bronchiseptica appeared to contain all essential ptl genes since the introduction of a functional promoter directly upstream of the ptx-ptl region resulted in both production and efficient secretion of toxin. These results indicate that despite a number of amino acid changes in the sequences of the toxins, the toxins encoded by B. bronchiseptica and B. parapertussis are active.

Pertussis in adults: frequency of transmission after household exposure

Although pertussis in adults is well documented, opinions differ about incidence of adult disease and about the role of adults as reservoirs of infection. We made use of a prospective household contact study of an acellular pertussis vaccine to collect data about pertussis in adults. All members of families with an index case of pertussis were monitored for respiratory symptoms, and pertussis was confirmed by laboratory tests. In 122 households, 104 children (85%) and 18 adults (15%) were the source of pertussis. These households consisted of 265 adults (aged 19-83 years), in 84 of whom (31%) pertussis was confirmed. Of these 84, 81% had respiratory symptoms for 21 days or more. The spread of pertussis was independent of whether a child (74/104) or an adult (14/18) was the index case. Most adult index cases had no pertussis recall (odds ratio 11.8). The overall attack rate in adult contacts was 0.267 and was independent of the social status and the size of the family and of a pertussis recall, although it differed significantly between women and men (p < 0.05). Erythromycin treatment of the index case reduced the attack rate significantly (p < 0.05). Patients whose first pertussis episode dated back more than 20 years had similar symptoms and attack rates to patients without a recall. We conclude that adults are often involved in the spread of pertussis, and that they can be susceptible to reinfection 20 years after a first pertussis episode.

[Efficacy of acellular pertussis vaccines]

Acellular vaccines against pertussis could be developed because various virulence factors of B. pertussis have been characterized. Acellular pertussis vaccines should retain the efficacy but have lower side effects, as compared to the conventional whole-cell vaccine. Lacking any correlate of antibacterial resistance, the efficacy of the vaccines had to be tested in large field trials. Such trials have been conducted and are being conducted in various European and in one African country. These trials used different designs, and various different vaccines were tested. All available efficacy data show that acellular pertussis vaccine can effectively protect against typical pertussis. It also seems probable that the efficacy of vaccines, which contain more than two pertussis components may be better than a vaccine containing pertussis toxoid or pertussis toxoid with filamentous hemagglutinin. A three-component acellular pertussis vaccine has been licensed for use in primary vaccination in infants in Germany in early 1995.

Isolation of a Bordetella avium-like organism from a human specimen

The isolation of a strain of Bordetella for which the species could not be determined but which most closely resembled Bordetella avium is reported. The strain was isolated in mixed culture from an ear swab of a patient suffering from chronic otitis media. The bacterium showed the typical biochemical reactions of Bordetella avium but differed in antimicrobial resistance pattern, protein and fatty acid composition, and DNA-DNA and DNA-rRNA hybridization. Further studies will clarify the taxonomic status of this strain within the Bordetella-Alcaligenes ribosomal RNA cluster.

Symptoms and complications of pertussis in adults

There is increasing evidence that pertussis occurs frequently in adults, but there is limited information on the clinical course of this disease beyond childhood. A household contact study on the efficacy of an acellular pertussis vaccine was used to study the symptoms of pertussis in adults. Among 257 patients with pertussis identified in 121 families during a two-year period in one study center with a low whole-cell pertussis-vaccine uptake, 79 (30.7%) were adults, aged 19-83 years (mean age: 36 years) with a 1:1.8 male to female ratio. Ninety-one percent of the adults suffered from coughing (mean duration: 54 days), and in 80% this cough lasted > or = 21 days. Whoops were rare (8%), whereas cough followed by vomiting and/or choking (53%) and cough disturbing sleep (52%) were common. This is the first report to describe sweating attacks as symptom of pertussis (14%). Pharyngeal symptoms (37%), influenza-like symptoms (30%), sneezing attacks (22%), hoarseness (18%), sinus pain (16%) and headaches (14%) were also observed. Various complications were seen in 23% of the patients. In order to minimize the spread of the organism, microbiological diagnostics should be vigorously applied to all symptomatic contacts of a patient with pertussis but also to all patients with long lasting cough-irrespective of age.

Bordetella hinzii sp. nov., isolated from poultry and humans

A polyphasic taxonomic study that included DNA-rRNA hybridizations, DNA-DNA hybridizations, DNA base ratio determinations, whole-cell protein and fatty acid analyses, and an examination of classical phenotypic characteristics was performed in order to classify human and veterinary isolates that resemble Bordetella avium. Twelve poultry isolates and two human isolates were assigned to a new species, for which we propose the name Bordetella hinzii. The position of this organism in the family Alcaligenaceae and various genotypic, phenotypic, and chemotaxonomic characteristics are described.

[Streptococcal myositis in children: four case histories]

We report about four children, who suffered from myositis caused by beta-hemolytic group A streptococci (GAS). The cases were observed during the last 12 months, and differed much in severity. Soft tissue infections caused by GAS are reported with increasing frequency from the USA, Australia and Europe. They occur in hitherto healthy children and young adults, mostly without a predisposing trauma. In children, a preceding varicella infection is often found. Some patients develop a streptococcal toxic shock syndrome with a letality of 20-50%. The bacteria, which can be isolated from normally sterile body sites, are morphologically inconspicuous, and are mostly of the serological type M1 or M3.

Role of pertussis toxin in causing symptoms of Bordetella parapertussis infection

Whooping cough can be caused by either Bordetella pertussis or Bordetella parapertussis. Although the two species share an almost complete DNA identity, Bordetella parapertussis does not produce pertussis toxin, which is thought to be the main virulence factor of Bordetella pertussis. In order to elucidate the role of pertussis toxin in causing the typical symptoms of whooping cough, clinical information from 33 patients with culture-positive Bordetella parapertussis infection was collected and compared to that from 331 patients with infection caused by Bordetella pertussis. Isolated strains of Bordetella parapertussis lacked pertussis toxin expression, as was demonstrated by negative tests for histamine sensitization. This was further substantiated in vivo by a significantly lower leukocyte count in the parapertussis group as compared to the pertussis group. Frequencies of typical symptoms of whooping cough, such as paroxysmal coughing, whooping and vomiting, were almost identical in the two groups. Nocturnal coughing and contact anamnesis were noted more often in the Bordetella pertussis group. Children in the parapertussis group were significantly more often vaccinated with whole-cell pertussis vaccine than children infected with Bordetella pertussis. The results indicate that pertussis toxin may not play a decisive role in causing the typical symptoms of whooping cough, such as paroxysmal coughing, whooping and vomiting.

[Sexually transmitted diseases by agents other than viruses and treponema]

The current concepts about sexually transmitted diseases (STD)--excluding syphilis and viral STD--are presented in a condensed form. The focus of attention is directed to complications or sequelae of these infections, and to the epidemiology of STD.

[Hepatitis viruses and pregnancy]

Infections with hepatitis virus A, B, C, D or E can also be observed during pregnancy. Furthermore, pregnant carriers of hepatitis B virus, occurring at various frequencies in different populations, represent an important source of infection. The course and the outcome of hepatitis A, B, C and D do not seem to be significantly affected by pregnancy. A fulminant hepatitis E, however, which is observed only rarely in Europe, can be induced by pregnancy and labor. Fetal malformations have not been attributed to any hepatitis virus. A perinatal transmission of hepatitis B virus often occurs, whereby the circulating HBe antigen or the amount of viral DNA in blood can be used as prognostic markers. Perinatal transmission of hepatitis C virus has also been documented; its frequency, however, seems to be less than 10%. A general screening of pregnant women for HBs antigen is suitable in interrupting transmission of hepatitis B virus. Children born from hepatitis B virus carriers should receive a postpartal passive-active immunization.

[Epidemic occurrences of multiresistant Acinetobacter baumannii strains in a neonatal intensive care unit]

In a period of nine months (May 1991 to January 1992), 39 infants were colonized with Acinetobacter baumannii in a paediatric intensive care unit. Colonization was observed mainly in premature infants, weighing between 680 g and 2,000 g, who were artificially ventilated. Shortly after birth, A. baumannii was isolated regularly from tracheal washings, and less frequently from other material, such as gastric juice, catheter tips, and umbilical swabs. In older children or adults, the bacteria were found only in very low frequency. In the intensive care unit, A. baumannii could be isolated from tap water, sinks, water traps of the ventilation devices, the inner wall of incubators, and from the hands of medical personnel. Patients strains of A. baumannii, and those isolated monitoring the intensive care unit had an identical biochemical profile and a similar pattern of antimicrobial resistance, as well as a similar reaction in other typing methods. Anti-infective measures are discussed.

[Acellular pertussis vaccines]

Each vaccine is normally rated according to its efficacy and to the frequency and severity of unwanted side effects. The efficacy of whole-cell pertussis vaccines is beyond doubt, its frequent side effects, however, stimulated research into less reactogenic acellular vaccines. Several acellular pertussis vaccines of different composition have been developed. All of these produced significantly less local and systemic side effects, as compared to the conventional whole-cell vaccine. Various epidemiological data strongly suggest the efficacy of these vaccines. An equivalence of protective efficacy between whole-cell vaccines and acellular pertussis vaccines can, however, only be documented in controlled field trials, which are now ongoing in several countries.

[The epidemiology of whooping cough]

Due to a low acceptance of active immunisation against Bordetella pertussis, whooping cough continues to be a frequent childhood disease in parts of Germany. The age distribution in the lower Rhine area showed a peak incidence at 4.3 years of age, whereas 11% of all cases were observed in infants, and 6% were observed in adults. A significant sex difference was not found in children suffering from pertussis; in adult patients, however, women were more often affected. Whooping cough occurred during the whole year, its peak incidence was found during early winter. In children, paroxysmal coughing fits, vomiting and whooping were the primary symptoms of disease; adults and infants, however, developed these symptoms only in reduced frequency. About 25% of all cases showed an atypical course, and could only be diagnosed by laboratory tests. While leukocyte count and ESR did not have diagnostic significance, a combination of microbiological and serological tests showed a high diagnostic sensitivity and specificity. In contrast to the former GDR and to most European neighbours, the former Federal Republic overrated the side effects of active vaccination as compared to the various risks of natural infection. This resulted in a decline of vaccine acceptance to less than 10% in several areas of the former FRG. It is anticipated that the altered recommendation in favour of vaccination, and especially the future application of acellular vaccines with less side effects, will result in the elimination of whooping cough in all areas of Germany.

[Outbreak of a nosocomial infection of SHV2-beta-lactamase-containing Klebsiella pneumonia strains in an operative intensive care unit]

Resistant strains of Klebsiella pneumoniae were found in increasing frequency as a cause of nosocomial infection in an intensive care unit between July and October 1990. The isolated strains had an almost identical biochemical profile, showed a similar pattern of antibiotic resistance, and produced type SHV2-broad-spectrum betalactamase. Thus, it was assumed that the isolates were copies of identical strains, causing an outbreak of nosocomial infections. The bacteria were resistant to third-generation cephalosporins, such as cefotiam, cefotaxime and ceftriaxone, and also to aminoglycosides and acylaminopenicillins. Approximately half of the strains were resistant to ceftazidim and aztreonam. The bacteria were sensitive in vitro to ciprofloxacin, imipenem, latamoxef and cefotetan. During three months, 10% (11) of all patients became infected; four of these patients (36%) died from septicemia. After conventional hygiene programs had failed to stop the outbreak, the intensive care unit was closed and disinfected, a measure, which effectively interrupted the infection.

[Whooping cough in adults]

Within a period of four years the diagnosis of pertussis was made in 169 adults (105 women, 64 men; mean age 35.8 [18-79] years). based on symptoms, specific antibodies and bacteriological examination of nasopharyngeal swabs (in 53). The findings were compared with those obtained in a control group of 2,771 children (1,381 females, 1,390 males; mean age 4.3 years). In the adult the dominant symptom was persisting cough, at times convulsive, while the other symptoms, characteristic in children, of rib retraction and vomiting were significantly less common in adults (retraction: 3% vs 40%; vomiting 12% vs 59%). A history of contact was elicited in only 17% of adults (38% in children). Confirmation of the diagnosis was obtained by growing Bordetella pertussis from a nasopharyngeal swab (6 of 53 patients [11%]; in children 45%), or finding significantly elevated antibody concentration or titre rise of specific antibodies against B. pertussis (IgG: 81% vs 68%; IgA: 91% vs 73%; IgM: 44% vs 72%). Half the adult patients were aged between 20 and 35 years. Contrary to the sex distribution of pertussis in children, significantly more women than men contracted the infection (P less than 0.01). It is concluded that even in adults pertussis should be considered in the differential diagnosis of persisting cough.

Histomorphology of experimental listeriosis

This paper is a survey of the histomorphology of experimental listeriosis based on cooperative studies performed within the past ten years. The influence of various parameters of the infectious agent (pathogenic Listeria monocytogenes serovar 4b, nonpathogenic Listeria innocua serovar 6b etc.) as well as of the host (euthymic NMRI-mice conditioned with dextran sulfate 500 or cyclosporin A, athymic nude mice etc.) on the course, morphology and outcome of the Listeria infection was investigated. From the experimental models used and the studies performed much could be learned concerning the factors that determine the histomorphological manifestations of listeriosis in humans.

Alteration of non-specific resistance to infection with Listeria monocytogenes

The experimental infection of murine hosts with Listeria monocytogenes is often used as a model for cell-mediated immunity. However, the natural immunity or non-specific resistance to listeriosis can be influenced by the parasite itself and also by a wide array of endogenous and exogenous host factors. The most important host factor in inbred mouse strains is their genetically determined susceptibility or resistance to Listeria monocytogenes. Secondly, the age of the mice is crucial for the outcome of infection. Resistance is only slowly developed by newborn mice, while aged mice possess an increased non-specific resistance as compared to young adult animals. Resistance is further influenced by the nutritional status, by pregnancy or by a simultaneous second antigenic stimulation. Regarding exogenous factors, macrophage blocking agents can totally abolish the resistance to listeriosis, while a lot of immunomodulating agents, such as BCG, killed Bordetella pertussis or Propionibacterium acnes organisms, lipopolysaccharides, suramin etc., can either increase or decrease the resistance. The mononuclear phagocyte system seems to be the main target of all these immunomodifiers. The timing between listeria infection and application of the immunomodulator determines the effect on non-specific resistance. A simultaneous injection of parasite and immunomodulator results in a decrease of resistance, while the application of immunoadjuvants several days before infection can dramatically increase the resistance to listeriosis. The delicate equilibrium of the mononuclear phagocyte system must therefore be taken into account, when infection with Listeria monocytogenes is used to test for immune-modifying agents, which are intended for use in humans or animals.

[Effect of anti-D prevention on the incidence of irregular erythrocyte antibodies in pregnant patients]

The immunohaematology results found during antenatal care from 1963-1981 were used to try to answer the question whether and how much the anti-D-prophylaxis, which was started in 1967 and was given to German and foreign pregnant women post partum or after abortion, had affected the frequency of immunization to D and other erythrocyte antigens. The results allow the following statements: 1. From 1973-3 or 4 years after the general introduction of anti-D prophylaxis-until 1981, a continuously sustained decline in the frequency of anti-D in the German pregnant women was found. This could not be found in the corresponding group of foreign pregnant mothers. 2. Additionally, a statistically significant reduction in the frequency of anti-D + C could only be found in the German group. 3. After 1973, other erythrocyte antibodies in combination with anti-D were only found sporadically. A rise in the frequency of other erythrocyte antibodies, such as anti-C, was not observed. 4. The frequency of "non-anti-D antibodies" was significantly higher in the foreigners than in the German group during the whole observation period. This was due to the significant increase in anti-Lea, anti-Leb, anti-H, anti-P1 and the nonidentifiable antibodies in the foreign group.

[The significance of "nonpathogenic" Corynebacteria as a cause of opportunistic infections]

A lot of corynebacterial species, summarized as "diphtheroids" has its normal habitat on the human skin. Consequently, these bacteria are often isolated from various clinical materials and mostly regarded as indeginous flora. The same bacteria, however, can cause serious infections, when the balance between host and microorganisms is impaired. Multiresistant corynebacteria group JK are used as an example to describe the development of such infections. Central venous catheters and other plastic devices can facilitate the entry of the bacteria. Simultaneously, resistant strains of corynebacteria benefit from a concurrently administered antimicrobial chemotherapy. Subsequently, these bacteria can be found as a cause of septicemia, endocarditis, wound infection, osteomyelitis, peritonitis and meningitis. The antimicrobial chemotherapy is hampered by the extreme resistance and vancomycin is the only antibiotic of choice. Colonization or infection of the single patient can be differentiated by clinical criteria only. According to the individual risk, a microbiological monitoring can be helpful in the early detection of colonization and infection.