Incidence Rates Of Invasive Disease Research Articles

Seroprevalence of IgG and IgM antibodies to Haemophilus influenzae type a in Canadian children

BackgroundOver the last 2 decades, Haemophilus influenzae type a (Hia) has emerged as a significant cause of invasive disease in some geographic regions and populations. Recognition of the importance of Hia in the etiology of serious disease, particularly in young children, prompted the development of a new protein-capsular polysaccharide conjugate vaccine, similar in design to a vaccine against H. influenzae type b. At present, understanding of Hia immunology is incomplete; the immunological correlate of protection against invasive disease is unknown. MethodsOur objective was to study Hia antibody in children of various ages residing in a Canadian province with low incidence rates of invasive disease. The enzyme-linked immunosorbent assays were performed to quantify plasma IgG and IgM specific to Hia capsular polysaccharide in 133 children (3 months to 16 years). ResultsBoth anti-Hia IgG and IgM concentrations increased with age and were significantly higher in older children; a positive correlation between age and concentrations of Hia antibody was found. IgM antibody concentrations were significantly higher than IgG, with mean IgM concentrations over 10 times larger than IgG across all age groups. ConclusionsThe steady rise of naturally acquired, Hia-specific IgG and IgM concentrations in a pediatric population with low incidence rates of invasive Hia disease suggests the exposure to some cross-reactive environmental antigens as a major source of the antibody. However, the carriage rates of Hia in the region are unknown and further seroepidemiological studies are warranted. Although natural antibody may protect certain population groups against invasive disease, immunization of younger children will be essential to prevent serious infections if Hia continues to spread across North America.

Invasive Haemophilus influenzae disease in children less than 5 years of age in Manhiça, a rural area of southern Mozambique

To measure the disease burden and epidemiological characteristics of invasive Haemophilus influenzae in rural Mozambican children. As part of the clinical management of children admitted to Manhiça District Hospital, blood and cerebrospinal fluid samples were collected between May 2001 and April 2005 for children aged <5 years. The level of antibiotic resistance of the isolates was analysed. During the surveillance period, there were 106 episodes of invasive H. influenzae disease. The estimated minimum incidence rate of invasive disease among children <5 years of age was 125/100,000 per child-year-at-risk. Fifty-six (59/106) per cent of cases were infants aged 3 to <12 months. Confirmed meningitis explained 16% of the episodes (n = 17) but was probably underestimated, as meningitis surveillance was not well implemented in the setting during the study. The case-fatality-rate was 21%, being highest among children with meningitis (odds ratio = 4.38, P = 0.011). Resistance to the antibiotics most commonly used in Mozambique was high--chloramphenicol 39%, ampicillin 35% and cotrimoxazol 74%-- and had increased over the years (P < 0.001 for chloramphenicol). Invasive H. influenzae disease is of considerable public health importance in Mozambique; implementing H. influenzae type b vaccination in sub-Saharan Africa has the potential to increase child survival.

Cost-benefit and cost-effectiveness of the incorporation of the pneumococcal 7-valent conjugated vaccine in the routine vaccination schedule of Catalonia (Spain)

The health and economic costs and benefits of vaccinating a cohort of 60,000 children born in Catalonia in the year 2000 with the pneumococcal 7-valent conjugated vaccine were compared with the alternative of not implementing the vaccination programme. The time horizon fixed for the programme was 10 years for invasive disease, 2 years for all episodes of pneumonia and otitis media and 3.5 years for the placement of tympanostomy tubes. In the base case (incidence rate of invasive disease of 160 per 100,000 and price of the vaccine 50 euros) the net present value was negative, both from the societal perspective (−5.1 million euros) and from the provider's perspective (−9.2 million euros). The benefit-cost ratio was 0.59 euros from the societal perspective. The cost per disability adjusted life year (DALY) gained was 44,307 euros from the societal perspective and 80,291 euros from the provider's perspective.

Postlicensure evaluation of the effectiveness of seven valent pneumococcal conjugate vaccine

To evaluate the impact of the introduction and routine use of seven valent pneumococcal conjugate vaccine on the epidemiology of invasive pneumococcal disease within the Northern California Kaiser Permanente (KP) population. Surveillance for invasive pneumococcal disease has been in place within KP since 1995. Isolates from normally sterile sites in children are routinely sent for serotyping. Cases of invasive disease are identified through review of automated microbiology records within KP. Incidence rates of invasive disease were compared for the period before and after routine use of pneumococcal conjugate vaccine in children. The incidence of invasive pneumococcal disease caused by vaccine serotypes before the licensure and routine use of pneumococcal conjugate vaccine ranged between 51.52 and 98.15 cases per 100 000 person years in children <1 year of age and fell to 9.35 after introduction of vaccine. The incidence in children <2 years of age was 81.67 to 113.80 before introduction and 38.22 cases per 100 000 person years after introduction of the vaccine into the general population. These reductions in disease rates exceeded the average vaccine coverage substantially in each age group. No increase in disease incidence was observed for possibly cross-reacting serotypes or nonvaccine serotypes. The introduction and routine use of pneumococcal conjugate vaccine in our population have been associated with a substantial reduction in invasive disease incidence in children <5 years of age.

Uterine cervical carcinoma in Connecticut, 1935-1973: evidence for two classes of invasive disease.

The Connecticut Tumor Registry recorded 5,781 women with carcinoma in situ (CIS) and 7,614 with invasive cervical cancer from 1935 to 1973. True incidence rates for invasive disease were calculated. CIS rates indicated newly diagnosed cases, but true CIS incidence is unknown. Starting in 1945-49, the incidence of invasive cervical declined about 20% in Connecticut before CIS screening could have influenced the disease to that extent. Continuing declines in invasive disease rates after 1955 in Connecticut were probably attributable largely to screening. The persistent occurrence of invasive disease in screened populations and the rapid progression of cancer, with early death among some women with apparently localized disease at diagnosis, suggested that a second class of invasive cervical cancer may exist. Cancers in this class may develop and progress rapidly without a practical possibility of detection in the premalignant stage by cytologic methods. Other screening methods, e.g., metabolic, hormonal, immunologic, or virologic, may be required to control this disease.