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The pneumococcal polysaccharide vaccine may be more effective in certain patient populations than in others. The pneumococcal vaccine is given to at-risk individuals to prevent community-acquired pneumonia and meningitis. Researchers examined the the effectiveness of the vaccine in 2,837 patients over five years old with an infection of the blood or cerebrospinal fluid between May 1978 and Apr 1992. The vaccine was 57% effective in preventing infections caused by the serotypes of Streptococcus pneumoniae included in the vaccine. It was 84% effective for patients with diabetes mellitus, 73% for those with coronary vascular disease, 69% for those congestive heart failure and 65% for those with chronic pulmonary diseases. The time since vaccination did not affect efficacy of the vaccine significantly.

There are a variety of strategies available that would be cost-effective in preventing group B streptococcus (GBS) infection in newborns. GBS infection is the most common cause of meningitis in newborns. Researchers evaluated three strategies for preventing streptococcal infection in newborns. The first strategy involves screening pregnant women for the presence of GBS at 26 and 28 weeks of pregnancy. Women who develop complications during labor would receive antibiotics at that time. The second strategy involves determining risk factors for GBS in different demographic areas. Under this plan, all pregnant women estimated to be at high risk for carrying GBS would receive treatment. The third strategy assumes the development and approval of a vaccine against GBS. In this strategy, all pregnant women would be vaccinated. The three strategies were all found to be as cost-effective as other prenatal screening programs now in effect. They were also found to have similar rates of prevention., Background. - Intrapartum antibiotics can prevent early-onset neonatal group B streptococcal (GBS) disease but have not been widely used. Obstacles include difficulty in implementing screening for GBS colonization and uncertainty about cost-effectiveness. The GBS vaccines for disease prevention are now being developed. Methods. - We developed a decision analysis model and used standard cost-effectiveness and cost-benefit analysis methods. We compared the outcomes and costs of the recent practice of no intervention with those expected for three prevention strategies: (1) intrapartum antibiotics administered to colonized women with labor complications, (2) an alternative strategy that does not require screening but uses epidemiologic criteria and labor complications to target intrapartum antibiotics, and (3) maternal vaccination. We used data from multistate population-based surveillance to estimate the potential impact of each strategy on disease and costs in the United States. Results. - Intrapartum antibiotic prophylaxis of high-risk women identified by screening could prevent approximately 3300 cases (47% of neonatal disease) annually in the United States and could save approximately $16 million in direct medical costs. Chemoprophylaxis of high-risk women identified using epidemiologic criteria could potentially be equally effective (3200 cases prevented) and would avoid the logistical difficulties of screening; the net savings would be approximately $66 million. Vaccinating 80% of pregnant women with a vaccine that prevents 80% of cases among infants born at or after 34 weeks of gestation would prevent approximately 4100 neonatal cases annually with a net savings of $131 million. Conclusions. - Universal prenatal screening for GBS and chemoprophylaxis of colonized women with labor complications is likely to be cost-beneficial in the United States. Development of alternative strategies should be further explored for populations in which GBS screening is impractical. Continued development of a GBS vaccine is an important public health priority. (JAMA. 1993;270:1442-1448)

The widespread use of vaccines against the bacterium Hemophilus influenzae type b (Hib) has led to a dramatic reduction in Hib disease in children under five years of age. Data from two surveillance systems at the Centers for Disease Control and Prevention show that the incidence of Hib disease dropped 71% between 1989 - one year after the vaccine was licensed for children 18 months of age or older - and 1991. Cases of Hib meningitis, which affects at least 60% of children with Hib disease, declined 82% between 1985 and 1991. Between 1988 and 1991, an estimated 30 million doses of vaccine were administered. The same data show that the incidence of Hib disease in infants also began to decline in 1988, but this was two years before the vaccine was licensed for infants. This could be explained if the vaccine reduces the number of carriers. If this is true, Hib disease might be eliminated by routine vaccination., Objective.--Effective Haemophilus influenzae type b (Hib) conjugate vaccines were first licensed for use in US children at least 18 months old in December 1987 and for infants at least 2 months old in October 1990. We evaluated trends in Hib disease associated with licensure of Hib conjugate vaccines. Design.--Data from two sources, an intensive laboratory-based active surveillance system and the National Bacterial Meningitis Reporting System (NBMRS), were used separately to evaluate disease incidence. Data from vaccine manufacturers on Hib vaccine doses distributed in the United States were compared with trends in Hib disease incidence. Results.--The age-specific incidence of Hib disease among children less than 5 years old decreased by 71% from 37 per 100000 persons in 1989 to 11 per 100000 persons in 1991 (active surveillance data). Haemophilus influenzae meningitis incidence decreased by 82% between 1985 and 1991 (NBMRS data). Increases in doses of Hib vaccine distributed in the United States coincided with steep declines in Hib disease. Both surveillance systems showed decreased rates of Hib disease in infants less than 1 year old before vaccine was licensed for use in this age group. Haemophilus influenzae type b disease incidence in persons at least 12 years old and pneumococcal meningitis incidence in children less than 5 years old did not change substantially during the same period; therefore, decreased Hib disease in children less than 5 years old is not likely to be explained solely by changes in surveillance sensitivity or decreases in bacterial disease due to changes in medical practice. Conclusion.--Our data suggest that conjugate vaccines have already had a marked impact on the incidence of Hib disease in the United States, preventing an estimated 10000 to 16000 cases of Hib disease in 1991. The decline of disease in infants less than 1 year old before licensure for this age group warrants further investigation. (JAMA. 1993;269:221-226)

Some food contaminated with the bacterium Listeria monocytogenes may be more likely to cause listeriosis than other foods contaminated with this bacterium. Listeriosis is an infection caused by Listeria monocytogenes that can cause encephalitis and meningitis. Of 123 listeriosis patients, 79 (64%) had a least one food item in their refrigerator that contained Listeria monocytogenes. The bacterium was isolated from 226 of 2,013 food items (11%) from patients' refrigerators that were tested. Twenty-six of the 79 patients (33%) with Listeria monocytogenes-contaminated food items in their refrigerator were infected with the same strain of the bacterium. Patients were more likely to have the same strain as that found in ready-to-eat foods, foods with high concentrations of the bacterium, or foods infected by the 4b strain of the bacterium. This information may help the food industry and regulatory agencies identify which foods contaminated with Listeria monocytogenes may cause listeriosis.

Patients with listeriosis may have contracted the disease from eating contaminated food. Listeriosis is an infection caused by the bacterium Listeria monocytogenes that can cause meningitis and encephalitis. Among 18 million individuals who were monitored between Nov 1988 and Dec 1990, the incidence of listeriosis was 7.4 cases per million people per year, and 23% of listeriosis patients died from the disease. Comparison of 165 patients with listeriosis to 376 healthy individuals found that patients were more likely than non-infected individuals to have eaten soft cheeses, or food from delicatessens. Thirty-two percent of the patients contracted listeriosis from these foods. Sixty-nine percent of the men and non-pregnant women with listeriosis had suppressed immune systems. Listeriosis patients who were immunosuppressed either had cancer or AIDS, were transplant recipients, or were being treated with corticosteroid drugs. Dietary counseling of high-risk patients may decrease their likelihood of developing listeriosis.

It is important to have an accurate estimate of the number of people who are at risk of developing acquired immunodeficiency syndrome (AIDS) so that better prevention strategies can be designed. Thus far, strategies used to estimate the number of people infected with the human immunodeficiency virus (HIV), the agent that causes AIDS, have suffered from severe drawbacks in methodology. A method was devised to estimate the size of the immunosuppressed HIV-infected population ('pre-AIDS') based on the incidence of Streptococcus pneumoniae, which is normally rare among young and middle-aged adults. Age-, sex-, and race-specific rates of pneumococcal disease were applied to low and high-incidence areas to determine the expected number of infections in counties in New Jersey. AIDS patients between 25 and 44 years of age were more than 300 times more likely to have an attack of invasive pneumococcal disease than noninfected adults, underscoring the need for pneumococcal vaccine early in HIV infection. If effective, pneumococcal vaccination would reduce the accuracy of using pneumococcal surveillance for estimating the size of the pre-AIDS population. Application of this method to other populations will test its validity and usefulness. (Consumer Summary produced by Reliance Medical Information, Inc.)

With an increase in the number of working mothers with children under six years of age, day care for small children has become necessary. However, day care centers can provide an environment for the transmission of infectious diseases and, in fact, are a risk factor for Hemophilus influenzae infections, which may be life-threatening in young children. The practices and policies of day care centers reporting cases of H. influenzae were compared with those of day care centers reporting no cases of H. influenzae. The centers with cases of H. influenzae were more likely to use handkerchiefs or towels to wipe noses, admit children who were not toilet trained, allow children with diarrhea to attend, have a narrower age range, and be a for-profit organization. Of all the risk factors listed, only towel and handkerchief use for wiping noses was statistically linked to cases of H. influenzae. It is recommended that this practice be abandoned. Other factors, such as admitting children with diarrhea, may have important implications in the transmission of other infectious diseases. (Consumer Summary produced by Reliance Medical Information, Inc.)

Although epidemics of meningococcal meningitis (bacterial infection of the membranes covering the brain and spinal cord) have not been a major concern in industrialized countries since the late 1940s, epidemics continue to ravage developing countries. There has been a long-standing clinical association between upper respiratory tract infection and the risk of developing meningococcal meningitis. The present study examines upper respiratory tract infection as a predisposing factor in the risk of meningococcal meningitis during an epidemic in the African country of Chad. In the spring of 1988 physicians in N'Djamena Chad noted an increased rate of hospitalization for meningococcal disease. In April a peak rate of hospitalization was reached (141 patients per day). In less than 3 months, 4,542 cases of meningococcal disease were reported; a group of 62 patients with meningococcal meningitis were included in the study. Various laboratory tests were conducted to determine the presence of infections of the upper respiratory tract. The risk of infection from respiratory virus and mycoplasma increased with age and the severity of upper respiratory tract symptoms, but these infections did not increase the risk of developing meningitis. Respiratory infections may be associated with meningococcal carrier status. Although the findings of this study are based on the experience of a developing nation, they are applicable to industrialized nations as well. (Consumer Summary produced by Reliance Medical Information, Inc.)

Streptococci are bacteria which come in a wide variety of types; many types are classified on the basis of immunological characteristics. Most of the human diseases related to streptococcal infection are caused by group A beta-hemolytic streptococci. However, group B streptococcus may also be a substantial cause of illness and death. Little attention has been paid to documenting the extent of group B disease in the general population. Many of the published studies have focused on group B disease occurring in pregnancy or in the neonatal period. A population-based study was therefore conducted to determine the importance of group B strep infection as a cause of human disease and to identify individuals who may be at greater risk. A total of 70 cases of group B disease were identified; 14 of these cases involved pregnant women. This number of cases works out to an average incidence of 2.4 cases per 100,000 people each year. Almost one third of the cases were fatal. An important finding was that the group B strep infection was almost invariably associated with some other underlying illness. Patients with diabetes are about 10.5 times as likely to suffer group B infection than members of the general population. The risk of group B infection is 16.4 times as high among patients with cancer. The present study also confirmed observations that pregnant women are at increased risk. In contrast with other patients, however, the pregnant women were generally healthy prior to the group B infection. (Consumer Summary produced by Reliance Medical Information, Inc.)

The bacteria Haemophilus influenzae type b can cause life-threatening infections, such as meningitis and epiglottitis, in very young children. Meningitis affects the membranes that cover the brain and spinal cord; epiglottitis affects tissue in the back of the tongue that covers the windpipe during swallowing. In 1985 a vaccine to prevent Haemophilus influenza type b was approved for use in the US. Based on post-licensure studies, the efficacy of this vaccine has been unclear and contradictory recommendations have been made concerning its use. A total of 244 cases of H influenzae type b invasive infection were diagnosed in a group of children between the ages of 24 and 59 months (not attending a day care center); they were compared with a similarly matched group made up of the infected children's acquaintances. The efficacy of the vaccine was estimated to be 62 percent. This assessment was not altered after adjustments for age and parental smoking (a link between parental smoking and hemophilus influenzae type b infection has been suggested). It is cautioned that an evaluation of the efficacy of a vaccine after the vaccine has already been licensed is difficult to interpret. Nonetheless, four out of five studies demonstrate that Haemophilus influenzae type b polysaccharide vaccine is effective. This vaccine was designed to be used temporarily until a next-generation vaccine, a polysaccharide-diphtheria toxoid conjugate, is licensed. It is hoped that the effectiveness of the new vaccine will be improved. (Consumer Summary produced by Reliance Medical Information, Inc.)

In August 1987, an outbreak of group A meningococcal meningitis occurred during the annual pilgrimage of Mecca, Saudi Arabia, resulting in an attack rate among American pilgrims of 640 per 100 000. To determine risk factors for carriage, throat cultures were taken from passengers arriving on four consecutive flights from Saudi Arabia to the United States. Pilgrims were more likely to be group A meningococcal carriers than were nonpilgrims (relative risk, 11.1; 95% confidence interval, 3.7 to 33.1). Smoking, crowding, and meningococcal vaccination were not significantly associated with group A carriage. Pilgrims complaining of recent fever or sore throat, however, were more likely to be group A carriers, consistent with previous reports linking carriage and disease to preceding viral infections. Serogrouping of invasive meningococcal isolates can be used to monitor for indigenous transmission of this unusual strain in the United States, and we recommend routine vaccination of pilgrims to prevent future outbreaks of miningococcal disease.

ABSTRACT: To assess the efficacy of the Haemophilus b polysacchaide vaccine following licensure and to evaluate the risk of Haemophilus influenzae type b (Hib) disease in the week following vaccination, we conducted a day care--based case-control efficacy study using cases of invasive Hib disease ascertained through active surveillance in areas with a total population of 34 million. For each patient 18 to 59 months old, up to three 18- to 59-month-old controls were chosen from the same day care classroom. Using conditional logistic regression, the vaccine efficacy was estimated to be 45% (95% confidence interval = - 1% to 70%) and did not change significantly after accounting for potential biases. In addition, three (3%) of 104 patients vs five (2%) of 207 controls were vaccinated within seven days before the patients' dates of admission (odds ratio = 1.8, 95% confidence interval=0.3 to 10.2), which does not suggest an increased risk of Hib disease in the week following immunization. This study suggests that the efficacy of the currently used HBPV is less than expected from previous studies and points out the usefulness of case-control studies for monitoring vaccine efficacy following licensure.

Listeria moncytogenes is a rod-shaped pathogen (disease-causing bacterium) that is related to illness in pregnant women, newborns, the elderly, and individuals with impaired immune systems. The organism is commonly found in the environment and has been found to be a foodborne pathogen. The organism has been linked to transmission through commercially prepared coleslaw, dairy products, and most raw meats and fish. It has been linked to four major epidemics in North America within recent years. Listeriosis has only recently been made reportable to the Federal government; it causes at least 1,700 serious infections and perhaps 450 deaths and 100 spontaneous abortions or stillbirths annually in the U.S. The disease in pregnant women often resembles an intestinal flu and can lead to severe and not infrequently fatal infections of the fetus. In nonpregnant adults, the symptoms may resemble meningitis or generalized sepsis (infection). Although recognized for more than fifty years, the general microbiology, clinical aspects and epidemiology are not clearly understood. Increase awareness, resulting in part from its reportable status, should encourage investigators to clarify many of these important outstanding medical issues.