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Biomedical subjects

I D Riley

Publications and source records attributed to I D Riley.

9 recordsLinked to original sources
PubMed1991

Effect of pneumococcal vaccine on morbidity from acute lower respiratory tract infections in Papua New Guinean children.

The effect of a 14-valent pneumococcal polysaccharide vaccine on morbidity from acute lower respiratory tract infection (ALRI) was determined in a randomized double-blind controlled trial in children under the age of 5 years living in the Paupa New Guinea highlands. The vaccine did not protect against mild ALRI. Vaccine efficacy in the study as a whole was 28% for moderate/severe ALRI, which was not statistically significant though consistent with the significant effect on mortality. Children entered the trial in five separate cohorts 4 months apart. The incidence of disease and vaccine efficacy varied between cohorts and with age. There was no vaccine effect in the first cohort, which had a much higher proportion of older children. The effect was greatest and statistically significant among those groups encountering an epidemic of moderate and severe ALRI at a young age. It was therefore in children at the most vulnerable age in times of greatest incidence of disease that the vaccine had its most potent effect. It is postulated that the efficacy of pneumococcal vaccine is dependent on the predominant invading serotypes in the period after vaccination, the age at which children develop immunocompetence to specific vaccine serotypes, and the levels of naturally acquired specific immunity already present in children at the time of vaccination, and that for all of these conditions there will be a cohort effect.

Acute Disease↗
PubMed1991

Reduction in the incidence of acute bronchitis by an oral Haemophilus influenzae vaccine in patients with chronic bronchitis in the highlands of Papua New Guinea.

Following the administration of a standardized questionnaire, 62 adult patients with chronic bronchitis were enrolled into a double-blind controlled trial of an oral killed Haemophilus influenzae vaccine in the highlands of Papua New Guinea. A 3-day course of vaccine or placebo was given monthly for 3 consecutive months. Participants were monitored weekly over 12 months for acute exacerbations; early morning sputum specimens were collected monthly and during acute exacerbations. Density of colonization by H. influenzae and H. parainfluenzae was determined by standard quantitative and semiquantitative techniques, and the latter method (quadrant score) was used to determine the density of growth of pneumococci. A total of 30 patients received vaccine and 32 placebo. The incidence rate of acute bronchitis in the vaccine group (0.011 episodes/person-weeks) was significantly lower than that in the placebo group (0.021 episodes/person-weeks), but there was no difference between the two groups in the incidence rates of more severe disease. Vaccine efficacy was maximal at times of peak incidence of disease. There was no evidence of a decline in vaccine efficacy for acute bronchitis over the 12-month follow-up period. The number of viable H. influenzae in the sputum declined in both vaccine and placebo groups over the 12-month follow-up period. The average concentration of H. influenzae in the vaccine group fell below that in the placebo group within 1 to 2 months after first immunization and remained so for 12 months, although the difference between the two groups narrowed during the follow-up period.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1986

Pneumococcal vaccine prevents death from acute lower-respiratory-tract infections in Papua New Guinean children.

In three double-blind placebo-controlled trials of pneumococcal capsular polysaccharide vaccines against death from acute lower-respiratory-tract infections (ALRI), children were vaccinated at 6 months to 5 years of age. The efficacy of the vaccines against ALRI as the sole cause of death was estimated at 59% in children vaccinated when younger than 5 years (p = 0.008) and 50% in children vaccinated when younger than 2 years (p = 0.043). Mortality from all causes was 19% less in the vaccinated group.

Acute Disease↗
PubMed1979

Pneumococcal disease and its prevention with polyvalent pneumococcal polysaccharide vaccines--a review.

Polyvalent pneumococcal polysaccharide vaccines have been shown to be safe, immunogenic and efficacious and are becoming available for use in patients at high risk of developing pneumococcal infections. Precise estimates of the role of the pneumococcus in human respiratory disease are difficult to obtain, as this organism is also a frequent commensal of the upper respiratory tract; and as the optimal techniques for the identification and proof of its role are not widely used. Nevertheless, the pneumococcus remains the principal cause of adult pneumonia and paediatric otitis media, and is also an important cause of death from bacteremia and meningitis. At present it seems likely that in Australia these vaccines will be most useful amongst people over the age of 50 years, those with chronic systemic disease, alcoholics, splenectomized individuals and disadvantaged groups such as Australian aborigines, all of whom are particularly susceptible to pneumo-coccal bacteremia which has a considerable mortality rate. The possibility of preventing pneumococcal otitis media in childhood is still being evaluated. Studies of the role played by the various pneumococcal serotypes in Australian populations are urgently needed.

Adult↗
PubMedDate not supplied

Bacterial colonization of the upper respiratory tract and its association with acute lower respiratory tract infections in Highland children of Papua New Guinea.

Acute lower respiratory tract infection (ALRI) is the major cause of death among children in Papua New Guinea. This longitudinal study reports the bacteriologic findings for children observed in their hamlets. A total of 1,449 nasal swab specimens from 158 children less than 5 years of age who were studied intensively for 18 months were examined. Non-serotypable strains of Haemophilus influenzae were isolated from 91% of specimens, and serotypable strains were isolated from 35% (8% H. influenzae type b) of specimens. All children had acquired Streptococcus pneumoniae by the age of 3 months. The most frequently occurring serotypes of S. pneumoniae were 6, 19, and 23. Children more frequently carried invasive pneumococci during an episode of ALRI than when they were healthy. Also, children more frequently carried serotypable strains of H. influenzae during the 2 weeks preceding an episode of ALRI than when they were healthy. Between-children analyses showed that children who were susceptible to attacks of ALRI and those who were not susceptible had similar rates of carriage of bacteria.

Age Factors↗
PubMedDate not supplied

Pneumococcal vaccine trials in Papua New Guinea: relationships between epidemiology of pneumococcal infection and efficacy of vaccine.

Field trials in Papua New Guinea have shown that pneumococcal capsular polysaccharide vaccine protects children less than 2 years of age from death due to acute lower respiratory infections (ALRI). The vaccine appears to reduce mortality by preventing bacteremia. Evidence suggests that highly invasive "adult" pneumococcal serotypes are comparatively more important as a cause of ALRI in developing countries where ALRI-related mortality is higher than in North America. Capsular polysaccharide vaccines are more likely to be immunogenic for these serotypes than for the "pediatric" serotypes. The evaluation of pneumococcal vaccines in areas where mortality is high should have the highest priority. For such trials investigators should, at minimum, define epidemiologic circumstances in terms of (1) the invasive serotypes of pneumococci, (2) the protective levels of antibody, (3) the antibody response to vaccination, and (4) the general immune status of the population.

Adult↗