Efficacy of polysaccharide pneumococcal vaccine in adults in more developed countries: the state of the evidence

We review studies on the efficacy against disease caused by Streptococcus pneumoniae of the 23-valent polysaccharide pneumococcal vaccine in adult populations in the more developed countries. Meta-analyses of primary vaccine trials have attempted to reduce uncertainty from lack of power. Vaccine efficacy calculated from studies in South African gold-miners and in Papua New Guinea, with high attack rates and differing serotype patterns, cannot automatically be applied to more developed countries. Meta-analyses will overestimate a protective effect if this clinical heterogeneity is ignored. Meta-analyses limited to trials in the more developed setting show no protective effect against pneumococcal pneumonia and a non-significant protective effect against bacteraemia. Lack of a specific diagnosis limits the ability to detect a protective effect against pneumococcal pneumonia. Most, but not all, observational studies confirm a protective effect against bacteraemia. An effect on mortality in more developed countries has yet to be documented.

Prospective study of measles in hospitalized, human immunodeficiency virus (HIV)-infected and HIV-uninfected children in Zambia

Measles in persons coinfected with human immunodeficiency virus (HIV) has been reported to be unusual in its presentation and frequently fatal. To determine the effect of HIV coinfection on the clinical features and outcome of measles, a prospective study of hospitalized children with measles was conducted between January 1998 and October 2000 in Lusaka, Zambia. One-sixth (17%) of 546 children hospitalized with laboratory-confirmed measles were coinfected with HIV. One-third of the HIV-infected children hospitalized with confirmed measles were <9 months old, compared with 23% of HIV-uninfected children (P=.03). Few differences in clinical manifestations, complications, or mortality were found between HIV-infected and HIV-uninfected children with measles. HIV-infected children constitute a significant proportion of children hospitalized with measles in countries with high HIV prevalence and are more likely to be younger than the age for routine measles immunization.

Suppression of human immunodeficiency virus replication during acute measles

To determine the effect of measles virus coinfection on plasma human immunodeficiency virus (HIV) RNA levels, a prospective study of hospitalized children with measles was conducted between January 1998 and October 2000 in Lusaka, Zambia. Plasma HIV RNA levels were measured during acute measles and 1 month after hospital discharge. The median plasma HIV RNA level in 33 children with measles who were followed longitudinally was 5339 copies/mL at study entry, 60,121 copies/mL at hospital discharge, and 387,148 copies/mL at 1-month follow-up. The median plasma HIV RNA level in children without acute illness was 228,454 copies/mL. Plasma levels of immune activation markers were elevated during the period of reduced plasma HIV RNA. Plasma levels of several potential HIV suppressive factors also were elevated during acute measles. HIV replication is transiently suppressed during acute measles at a time of intense immune activation.

Malaria in pregnancy: adverse effects on haemoglobin levels and birthweight in primigravidae and multigravidae

BACKGROUND

In areas of endemic transmission, malaria in pregnancy is associated with severe maternal anaemia and low birthweight babies. The prevalence of infection is highest in primigravidae (PG), and hence control efforts are usually geared towards this high risk group. Using a sensitive measure of placental infection, we investigated the relationship between active-acute, active-chronic and past placental infection with maternal anaemia and low birthweight in women of all gravidities.

METHODS

Between January 1996 and July 1997, 912 women delivering in Kilifi District Hospital, Kenya, were recruited. Haemoglobin and peripheral malaria slides were taken prior to delivery, placental biopsies and smears were taken at the time of delivery and birthweight and maternal height and weight were measured soon after birth. Information was obtained on socio-economic and educational status. The association between placental malaria, severe anaemia and low birthweight was investigated for women of different gravidities.

FINDINGS

By placental histology, the prevalence of active or past malaria in all gravidities was high, ranging from 64% in PG to 30% in gravidities 5 and above. In gravidities 1-4, active malaria infection was associated with severe maternal anaemia, adjusted OR 2.21 (95% CI 1.36, 3.61). There was a significant interaction between chronic or past malaria and severe anaemia in their effects on birthweight, whereby the risk of low birthweight was very high in women with both chronic or past placental malaria and severe anaemia: OR 4.53 (1.19, 17.2) in PG; 13.5 (4.57, 40) in gravidities 2-4.

INTERPRETATION

In this area of moderate malaria transmission, women of all parities have substantially increased risk of low birthweight and severe anaemia as a result of malaria infection in pregnancy. The risk of low birthweight is likely to be particularly high in areas with a high prevalence of severe anaemia.

Rotavirus G and P genotypes in rural Ghana

An epidemiological study of rotavirus infection was conducted on specimens collected from patients with gastroenteritis and domiciled in the rural Upper Eastern Region of Ghana during 1998. Fifty isolates, randomly selected from 165 human group A rotavirus-positive samples, were G and P characterized by a reverse transcription (RT)-PCR assay using a seminested multiplex method. Rotaviruses of the G3 genotype were found to be the predominant strain (78%), followed by G2 (14%) and G1 (2%). Mixed infections, as shown by combinations of G3 and G2 (4%) and G3 and G1 (2%), were also observed. P typing showed P[4] (72.34%) to be the prevalent strain, followed by P[6] (21.3%), P[8] (2.13%), and a combination of P[4] and P[6] (4.3%).

Prolonged measles virus shedding in human immunodeficiency virus-infected children, detected by reverse transcriptase-polymerase chain reaction

A reverse transcriptase-polymerase chain reaction assay was used to detect measles virus RNA in peripheral blood mononuclear cells, urine, and nasopharyngeal specimens from Zambian children during hospitalization and approximately 1-2 months after discharge. Of 47 children, 29 (61.7%) had prolonged measles virus shedding, as defined by detection of measles virus RNA in > or =1 specimen obtained 30-61 days after rash onset. Ten (90.9%) of 11 human immunodeficiency virus (HIV)-infected children had prolonged measles virus shedding, compared with 19 (52.8%) of 36 HIV-uninfected children (P=.02). Prolonged measles virus shedding did not correlate with levels of measles virus-specific antibody. HIV-infected children with measles may have a prolonged infectious period that potentially enhances measles virus transmission and hinders measles control.

Respiratory syncytial virus: an underestimated cause of respiratory infection, with prospects for a vaccine

Respiratory syncytial virus (RSV) infects most people by the time they are 2 years old and reinfects throughout life. RSV is best recognised for causing bronchiolitis in infants--it is one of the most important respiratory pathogens in childhood in industrialised countries. The clinical manifestations of RSV infection in adults and elderly people, from upper respiratory tract infection to pneumonia, are less well known. Part of the burden of winter mortality in elderly people is attributable to RSV infection and it may be as important a cause of death as influenza. Recent advances in RSV vaccines have made RSV a more important topic for epidemiological research and surveillance. Basic research required before vaccine programmes can be developed includes describing the natural history of RSV infection in adults, quantifying the burden of disease attributable to RSV, and defining the best surveillance methods with which to evaluate different vaccination strategies.

Implications of the human immunodeficiency virus epidemic for control and eradication of measles

Human immunodeficiency virus (HIV)-infected persons may be important, unrecognized transmitters of measles virus, thwarting eradication efforts. We reviewed the published English-language literature on measles and measles immunization in HIV-infected persons to investigate the clinical features of measles, the responses to measles immunization, and the safety of measles vaccine in HIV-infected persons and, conversely, the effect of measles and measles immunization on HIV infection. HIV-infected persons with measles are likely to have uncharacteristic clinical findings and severe illness, with high rates of pneumonitis and death. Primary and secondary failure of measles vaccine in HIV-infected children may permit transmission of measles virus in spite of high rates of immunization coverage. A factor that complicates measles-control efforts in areas of high prevalence of HIV is the potential for fatal infection with measles vaccine virus. Further research on the impact of the HIV epidemic on measles and measles immunization is necessary to guide strategies for the eradication of measles.

Intermittent sulphadoxine-pyrimethamine to prevent severe anaemia secondary to malaria in pregnancy: a randomised placebo-controlled trial

BACKGROUND

In areas of endemic transmission, malaria in pregnancy is associated with severe maternal anaemia and low-birthweight babies. We studied the efficacy of intermittent treatment doses of sulphadoxine-pyrimethamine in preventing malaria and severe anaemia in pregnancy in a double-blind placebo-controlled trial among primigravid women living in Kilifi District, Kenya.

METHODS

Between January, 1996, and April, 1997, 1264 primigravid women were recruited when they attended for antenatal care, and randomly assigned sulphadoxine-pyrimethamine (640) or placebo (624). Women received one, two, or three doses of study medication depending on the duration of gestation at enrolment. Primary outcome measures were severe anaemia (haemoglobin <8 g/dL) and malaria parasitaemia, assessed at 34 weeks of gestation. Analyses were based on intention to treat among women who had study blood tests at 34 weeks.

FINDINGS

30 (5.3%) of 567 women in the sulphadoxine-pyrimethamine group and 199 (35.3%) of 564 in the placebo group had peripheral parasitaemia (protective efficacy 85% [95% CI 78-90], p<0.0001). 82 (14.5%) and 134 (23.7%) had severe anaemia (protective efficacy 39% [22-52], p<0.0001). Even women who booked late and received only one dose of sulphadoxine-pyrimethamine benefited significantly from the intervention. The effects were seen both in women who owned insecticide-treated bednets and in women who did not.

INTERPRETATION

Intermittent presumptive treatment with sulphadoxine-pyrimethamine is an effective, practicable strategy to decrease the risk of severe anaemia in primigravidae living in malarious areas.

Comparison of a commercial enzyme immunoassay with plaque reduction neutralization for maternal and infant measles antibody measurement

The most practicable assay for measurement of measles IgG (mIgG) in large numbers of sera is an enzyme immunoassay (EIA). To assess how EIA results would agree with those by the gold standard method of plaque reduction neutralization (PRN) we compared the results from the two methods in 43 pairs of maternal and umbilical cord sera, and sera from the corresponding infants when aged 11-14 months. In maternal-cord sera, the differences between mean antibody levels by EIA or PRN were not statistically significant, though in individual sera, differences could be large. However, agreement was less good for infants sera, in which levels of mIgG were very low. The conclusions of a study of transplacental transport of mIgG would not be affected by the use of either technique. When studying waning immunity in infants, PRN should be the method of choice, while results from studies using EIA should be interpreted with caution.

Calibration and use of an in-house anti-measles IgG standard serum

For the purpose of research a large quantity of anti-measles IgG working reference serum was needed. A pool of sera from five teenagers was prepared and named Alexandre Herculano (AH). In order to calibrate the AH serum, 18 EIA assays were performed testing in parallel AH and the 2nd International Standard 1990, Anti-Measles Antibody, 66/202 (IS) in a range of dilutions (from 1/50 to 1/25,600). A method which compared parallel lines resulting from the graphic representation of the results of laboratory tests was used to estimate the power of AH relative to IS. A computer programme written by one of the authors was used to analyze the data and make potency estimates. Another method of analysis was used, comparing logistic curves relating serum concentrations with optical density by EIA. For that purpose an existing computer programme (WRANL) was used. The potency of AH relative to IS, by either method, was estimated to be 2.4. As IS has 5000 milli international units (mIU) of anti-measles IgG per millilitre (ml), we concluded that AH has 12,000 mIU/ml.

[Anti-measles igg concentration in maternal blood and in umbilical cord blood: according to the mother's vaccination status]

A study on passive immunity against measles was conducted in four hospitals of Oporto, Portugal. The objectives were to assess whether maternal measles vaccination status was associated to the levels of measles IgG in maternal and cord sera, and with the transplacental transport efficiency. Cord and venous maternal blood samples were collected from 1539 mother-child pairs enrolled. An enzyme immunoassay was used to measure measles IgG levels in the study sera. Results were expressed in mIU/ml. Vaccination records were consulted. Geometric mean concentration of measles IgG among vaccinated mothers (730 mIU/ml; 95% CI 602 to 884 mIU/ml; n = 79) was significantly (P < 0.0001) lower than among their unvaccinated counterparts (1535 mIU/ml; 95% CI 1460 to 1613 mIU/ml; n = 1317). The same was observed in the corresponding cord sera: those born to vaccinated mothers had significantly (P < 0.0001) lower levels of measles IgG (1083 mIU/ml; 95% CI 908 to 1291) than the newborns of unvaccinated mothers (2230 mIU/ml; 95% CI 2119 to 2347). Transplacental transport efficiency was not related with maternal vaccination status (P = 0.67). Measles IgG levels observed in this Portuguese study were similar to those observed in a study conducted in South Africa, but higher than those reported in a British study. The differences in measles IgG levels between vaccinated and unvaccinated mothers (and corresponding newborns) are consistent with similar findings already published in different countries. The lower levels of measles IgG among children born to vaccinated mothers may lead to the anticipation of the recommended age to vaccinate against measles in Portugal.

Patterns of antimicrobial use and antimicrobial resistance among healthy children in Bolivia

OBJECTIVE

To determine the incidence of antimicrobial-resistant, nonpathogenic Escherichia coli among healthy children aged 6-72 months in Camiri town and a rural village, Javillo, in south-eastern Bolivia.

METHOD

A community-based survey: stool samples were obtained from 296 healthy children selected by modified cluster sampling in Camiri and all 25 eligible children in Javillo. E. coli isolates were tested for antimicrobial susceptibility according to the standard disc diffusion method. By a questionnaire survey of 12 pharmacies and by using simulated patients, we investigated the antimicrobial availability and the usage patterns in Camiri town.

RESULTS

In Camiri, over 90%, and in Javillo over 70% of children carried E. coli resistant to ampicillin, trimethoprim-sulphamethoxazole (TMP/SMX) or tetracycline. Overall, 63% of children carried E. coli with multiple resistance to ampicillin, TMP/SMX, tetracycline and chloramphenicol. In the simulated patients study, antimicrobials were dispensed inappropriately for 92% of adults and 40% of children with watery diarrhoea, and were under-prescribed for males with urethral discharge (67%) or females with fever and dysuria (58%). The dose and/or duration of antimicrobials dispensed was almost always too low.

CONCLUSION

Our study showed a disturbingly high prevalence of carriage of nonpathogenic E. coli resistant to antimicrobials. The prevalence of resistance to ampicillin and TMP/SMX was higher than that previously reported in developing countries. The existence of a large reservoir of resistance genes in healthy individuals in developing countries represents a threat to the success of antimicrobial therapy throughout the world. Programmes to improve rational and effective drug use in developing countries are urgently needed.

The use of mass campaigns in the expanded program on immunization: a review of reported advantages and disadvantages

The use of mass immunization campaigns (MICs) has been and remains controversial. To evaluate these campaigns, the authors review the literature relating to their effectiveness, sustainability, and cost-effectiveness in controlling diseases and raising immunization coverage levels, and their impact on the subsequent development of routine immunization services. Well-conducted campaigns have increased vaccine coverage levels and decreased disease morbidity and mortality. Their use in the Americas has been associated with the apparent elimination of poliomyelitis. However, unless health care infrastructure is improved, or campaigns are repeated, gains in coverage levels may not be sustained. Studies suggest that MICs are often not as cost-effective for raising coverage as the delivery of vaccines through routine services, but the use of coverage as the only outcome measure is questionable. Mass immunization campaigns can increase awareness of vaccination and may be appropriate in situations where new programs are to be initiated, in refugee situations where people congregate into areas with little infrastructure, and in disease eradication efforts when specific time goals are set. Little information is available on whether MICs strengthen or interfere with the development of routine services. To be successful, MICs require a well-coordinated and planned effort on the part of national authorities with the identification of specific goals, intensive social promotion, and strong management. In addition, research is needed to clarify how MICs should be evaluated.

Measles incidence, case fatality, and delayed mortality in children with or without vitamin A supplementation in rural Ghana

Data on measles incidence, acute case fatality, and delayed mortality were collected on 25,443 children aged 0-95 months during the course of a community-based, double-blind, placebo-controlled, randomized trial of vitamin A supplementation in rural, northern Ghana between 1989 and 1991. Measles vaccine coverage in these children was 48%. The overall estimated measles incidence rate was 24.3 per 1,000 child-years, and acute case fatality was 15.7%. There was not significantly increased mortality in survivors of the acute phase of measles compared with controls (rate ratio = 1.22, 95% confidence interval (CI) 0.65-2.30). Reported incidence rates and case fatality were higher in families with low paternal education, in the dry season, and in unvaccinated children, and case fatality was higher in malnourished children. There was no sex difference in incidence, but acute case fatality was somewhat higher in girls than boys (adjusted odds ratio = 1.3, 95% CI 0.9-2.1). Measles incidence was lower in vitamin A-supplemented groups (23.6 per 1,000 child-years) than in placebo groups (28.9 per 1,000 child-years), but this difference was not statistically significant (p = 0.33). Among 946 measles cases in clusters randomized to receive vitamin A or placebo, there was no marked difference in acute measles case fatality between vitamin A-supplemented and placebo groups (15.4% vs. 14.5%, respectively). The biologic effects of vitamin A supplemented on the subsequent clinical manifestations and severity of measles need further elucidation.

Ethical dilemmas in current planning for polio eradication

Intensification of polio eradication efforts worldwide raises concerns about costs and benefits for poor countries. A major argument for global funding is the high benefit-cost ratio of eradication; however, financial benefits are greatest for rich countries. By contrast, the greatest costs are borne by poor countries; the Pan American Health Organization has estimated that host countries bore 80% of costs for polio eradication in the Americas. The 1988 World Health Assembly resolution setting up the Polio Eradication Initiative carried the proviso that programs should strengthen health infrastructures. Drastic cuts in donor funding for health make this commitment even more important. Two international evaluations have reported both positive and negative effects of polio and Expanded Programme on Immunization programs on the functioning and sustainability of primary health care. Negative effects were greatest in poor countries with many other diseases of public health importance. If poor countries are expected to divert funds from their own urgent priorities, donors should make solid commitments to long-term support for sustainable health development.

Maternal and child health indicators in a rural South African health district

OBJECTIVE

To measure important maternal and child health indicators in a rural health district as part of the process of developing a comprehensive district health information system.

DESIGN

A modified Expanded Programme on Immunisation cluster sample survey.

SETTING

Hlabisa health district, KwaZulu-Natal.

PARTICIPANTS

480 mothers (or carers) of children aged 12-35 months surveyed in 32 clusters.

INTERVENTIONS

A questionnaire was administered and Road-to-Health cards were examined.

MAIN OUTCOME MEASURES

Proportion of women receiving antenatal care and delivering in a health facility; knowledge and understanding of vaccination; and recall of vaccination history. Proportion of children with a Road-to-Health card, overall coverage of each vaccine, coverage at 12 months of age and proportion receiving an immunogenic dose.

RESULTS

Most mothers (91%) had attended antenatal care, 77% had received tetanus toxoid and 83% delivered in a health facility. Only 14 children (3%) had never received a Road-to-Health card and 73% had one available at the time of the survey. Overall immunisation coverage was high (80-98%), as was the proportion receiving an immunogenic dose of each vaccine (78-98%). However, only 76% had received all the vaccines due to a 12-month-old child, and only 88% of these had received all doses by 12 months of age.

CONCLUSIONS

While the key maternal health indicators measured here are reassuring, there is still room for improvement in the child health indicators. The proportion of women receiving antenatal care and delivering in a health facility is very high, but the proportion of children receiving all vaccines can be improved upon, as can the timing of immunisation. The results of this survey are being used to strengthen further the primary health care services in the district.

Measles immunity and response to revaccination among secondary school children in Cumbria

The prevalence of antibody to measles virus in 759 children aged 11-18 years attending a secondary school in Cumbria was measured using a salivary IgG antibody capture assay. Serum IgG antibody levels were measured using a plaque reduction neutralization assay in subjects whose saliva was antibody negative. Vaccination histories were obtained from the child health computer and general practice record. A total of 662 pupils (87% of those tested) had detectable measles-specific IgG in saliva. Of the remaining 97, 82 provided blood samples and 29 had serum neutralizing antibody levels above 200 mIU/ml. Afer adjusting for non-participation rates, the proportion considered non-immune (no IgG in saliva and < or = 200 mIU/ml in serum) was 9% overall, ranging from 6% in vaccinated children to 20% in unvaccinated children. Measles-mumps-rubella vaccine was given to 50 children of whom 38 provided post-vaccination serum and 32 saliva samples. Thirty (79%) had a fourfold or greater rise in serum neutralizing antibody and 28 (88%) developed IgG antibody in saliva. Half of the children considered non-immune by antibody testing would have been overlooked in a selective vaccination programme targeted at those without a history of prior vaccination. A programme targeted at all school children should substantially reduce the proportion non-immune since a primary or booster response was achieved in three quarters of previously vaccinated children with low antibody levels and in all unvaccinated children. While it is feasible to screen a school-sized population for immunity to measles relatively quickly using a salivary IgG assay, a simple inexpensive field assay would need to be developed before salivary screening and selective vaccination could substitute for universal vaccination of populations at risk of measles outbreaks. The salivary IgG assay provided a sensitive measure of a booster response to vaccination.

The effect of stay in a maternity waiting home on perinatal mortality in rural Zimbabwe

A hospital-based cohort study was carried out in a district hospital in Zimbabwe to evaluate the effect of a maternity waiting home on perinatal mortality. Information on antenatal risk factors, use of antenatal care, access to the hospital and stage of labour on arrival was collected for each woman delivering at the hospital during the period 1989-1991 (n = 6438). Women who stayed in the maternity waiting home had a lower risk of perinatal death compared to women who came directly from home to the hospital during labour. The crude relative risk of perinatal death for the women coming from home was 1.7 (95% confidence interval (CI) 1.1-2.6; P < 0.05). After adjusting for the effect of potential confounding variables, the relative risk decreased to 1.5 (95% CI 0.95-2.5, P = 0.07). However, when the analysis was restricted to women with antenatal risk factors there was a significant 50% reduction in the risk of perinatal death for the women who stayed at the maternity waiting home compared to women who came from home during labour (adjusted relative risk 1.9; 95% CI 1.1-3.4; P < 0.05). The use of maternity waiting homes has the potential to reduce perinatal mortality in rural areas with low geographic access to hospitals and merits further evaluation.

Effects of a maternity waiting home on adverse maternal outcomes and the validity of antenatal risk screening

OBJECTIVES

To evaluate the effect of a maternity waiting home (MWH) on adverse maternal outcomes and the validity of antenatal risk criteria in predicting dystocia.

METHOD

A hospital-based cohort study was conducted at a district hospital in Zimbabwe. Information on the presence of antenatal risk factors, stay at an MWH, and mode and outcome of delivery was collected for each woman delivering at the hospital during 1989-1991.

RESULTS

The risk of obstructed labor was 16 times higher for those not attending an MWH (n = 2915) than for those who did attend an MWH (n = 1573) (1 vs. 0.06%, P < 0.005). Among the non-users, 0.3% suffered a ruptured uterus compared with none of the MWH users. The presence of any one of the antenatal risk criteria used in Zimbabwe had a sensitivity of 78%, a specificity of 51% and positive predictive value of 25% for predicting dystocia.

CONCLUSION

MWHs and antenatal risk screening are policy options for safe motherhood programs in settings where emergency obstetric services are not easily accessible.

Obsessive-compulsive disorder: prediction of outcome from behavioural psychotherapy

Prediction of outcome after behavioural psychotherapy was determined in 178 outpatients with obsessive-compulsive disorder. For women (n = 103), factors significantly associated with good outcome included paid employment at time of assessment, having a co-therapist and low initial ratings on global phobia, work and home activity impairment and the compulsion checklist. In men, the only factor to approach statistical significance as a predictor of outcome was solitary abode, associated with "less improved" status.