Child-years Of Observation Research Articles

Incidences of vaccine-preventable Haemophilus influenzae type b pneumonia and meningitis in Indonesian children: hamlet-randomised vaccine-probe trial

Most studies of Haemophilus influenzae type b (Hib) disease in Asia have found low rates, and few Asian countries use Hib vaccine in routine immunisation programmes. Whether Hib disease truly is rare or whether many cases remain undetected is unclear. To estimate incidences of vaccine-preventable Hib pneumonia and meningitis among children younger than 2 years in Lombok, Indonesia, during 1998-2002, we undertook a hamlet-randomised, controlled, double-blind vaccine-probe study (818 hamlets). Children were immunised (WHO schedule) with diphtheria, tetanus, pertussis (DTP) or DTP-PRP-T (Hib conjugate) vaccine. Vaccine-preventable disease incidences were calculated as the difference in rates of clinical outcomes between DTP and DTP-PRP-T groups. Analyses included all children who received at least one vaccine dose. We enrolled 55073 children: 28147 were assigned DTP-PRP-T and 26926 DTP. The proportion of pneumonia outcomes prevented by vaccine ranged from less than 0 to 4.8%. Calculated incidences of vaccine-preventable Hib disease (per 10(5) child-years of observation) for outcome categories were: substantial alveolar consolidation or effusion, less than zero (-43 [95% CI -185 to 98]); all severe pneumonia, 264 (95% CI less than zero to 629); all clinical pneumonia, 1561 (270 to 2853); confirmed Hib meningitis, 16 (1.4 to 31); meningitis with cerebrospinal-fluid findings consistent with a bacterial aetiology, 67 (22 to 112); and admission for suspected meningitis or presenting to a clinic with convulsions, 158 (42 to 273). Hib vaccine did not prevent the great majority of pneumonia cases, including those with alveolar consolidation. These results do not support a major role for Hib vaccine in overall pneumonia-prevention programmes. Nevertheless, the study identified high incidences of Hib meningitis and pneumonia; inclusion of Hib vaccine in routine infant immunisation programmes in Asia deserves consideration.

Common infectious diseases and skin test anergy in children from an urban slum in northeast Brazil.

Acute respiratory infection (ARI), diarrheal disease (DD) and infective dermatitis (ID) are important causes of morbidity in children under five, in Northeast Brazil. (a) to evaluate the morbidity of ARI, DD and ID; and (b) to determine their association with cellular immunity in poor urban children from Fortaleza, Brazil. A prospective cohort study. At enrollment, multipuncture skin-tests (Multitest CMI) were performed and interpreted according to standard procedures. Children were followed for infectious diseases by weekly home visits. Seventy-one children aged 6 to 21 months were recruited in an ongoing cohort of newborns. A mean of 39 (6 to 63) home visits per child were made, which detected 184.5 symptomatic days per child-year of observation. ARI was present in 62% of the days of illness (6,378 out of 10,221), DD in 23% (2,296 days), ID in 6% (597) and other infections in 4% (373). Episodes per child-year were: 10 for ARI, 7 for DD and 1 for ID. Twelve (17%) out of 71 children were anergic. The incidences of ARI, DD and ID were similar in responsive versus anergic children. The mean duration of ID in anergy was 8.5 days, while it was 4.3 in the responsive group (P=0.007). Anergy was independent of age, sex and nutritional status. A high incidence of ARI and DD was found in these poor urban children. Skin-test responsiveness was not related to malnutrition, nor to morbidity due to ARI and DD, however anergic children had a longer duration of infective dermatitis.

Infección respiratoria aguda en niños que acuden a un centro de desarrollo infantil

To assess the incidence of acute respiratory infections and bacterial colonization in children attending a daycare center. A cohort study was conducted from April to Octuber 1999, among 85 children aged under four years, who attended the daycare center at Hospital Infantil de Mexico (Mexico City's Children's Hospital) "Federico Gómez". Acute respiratory infection incidence rates and quarterly point prevalence figures of nasopharyngeal colonization were obtained. Data were analyzed using descriptive statistics. A total of 85 children were studied (40 girls and 45 boys) during 9,090 children-days of follow-up. Three children had a history of atopia (3.5%), six a history of asthma (7%), and 39 (46%) were exposed to passive smoking. There were 258 events of respiratory tract infection for an incidence rate of 10.3 infections per person-year (95% CI 8.7-12.0). The main clinical syndromes were pharyngitis (95%), acute otitis media (3.5%), and bronchiolitis (1%). The incidence rates of otitis and bronchiolitis were 0.36 and 0.12 per child-year of observation, respectively. The prevalence figures of nasopharyngeal colonization for the three main bacteria were: S. pneumoniae 20.4%; nontypable H. influenzae 13%; and Moraxella catarrhalis 8%. Study results show a high prevalence of colonization due to invasive strains, as well as a two-fold incidence rate of acute respiratory infection, higher than those reported in community surveys. These results add to the description of this poorly documented infectious disease in Mexico. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

A decade (1989-1998) of pediatric invasive pneumococcal disease in 2 populations residing in 1 geographic location: implications for vaccine choice.

During 1 decade (1989-1998), data on invasive pneumococcal disease were collected prospectively to assess the burden of disease among Jewish and Bedouin children in southern Israel and the potential reduction in illness that can be achieved by using conjugate vaccines. Data on 513 children <15 years old with bacteriologically proven invasive pneumococcal disease were obtained. Among Jewish and Bedouin children <5 years old, incidence rates were 45 and 139 cases per 100,000 child-years of observation, respectively. Jewish and Bedouin children differed in clinical manifestations, seasonal patterns of disease, serotype distribution, and antibiotic susceptibility rates. The potential coverage by 7-, 9-, and 11-valent conjugate vaccines is 41%, 67%, and 71%, respectively, for Jewish children and 22%, 63%, and 65%, respectively, for Bedouin children. The 9- and 11-valent pneumococcal conjugate vaccines have the potential to substantially decrease invasive pneumococcal disease in southern Israel.

Population-based surveillance of Hib invasive infections in children in British Columbia Alberta and Ontario - 1995 to 1997.

To assess vaccine effectiveness through enhanced disease surveillance following the change in childhood immunization programs in 1995, when all provinces and territories chose to use polyribosyl ribitol phosphate-tetanus protein (PRP-T) Haemophilus influenzae type b (Hib) conjugate vaccine, generally in combination with diphtheria-pertussis-tetanus inactivated polio vaccine (DPT-IPV) (as PENTA vaccine) because the protective efficacy of this regimen had not been directly measured. Prospective, active, laboratory-based Hib case surveillance was implemented in British Columbia and Alberta, and enhanced, stimulated laboratory surveillance in Ontario during 1995 to 1997, centred on invasive infections in children. Case details and immunization histories were uniformly collected and centrally collated. Thirty-eight Hib cases were detected, but only 12 cases arose among PENTA-eligible children, an attack rate of 0.85 cases/100,000 child-years of observation. Annual case totals declined from 20 in 1995 to seven in 1997, when only one to three cases were encountered in each province and the incidence rate in children under age five years was 0.6/100,000. Only four cases occurred after primary immunization with PENTA, a failure rate of 0.28 cases/100,000 child-years of observation. Three cases among PENTA-eligible children reflected parental refusal of infant vaccinations, accounting for 25% of cases in eligible children. PRP-T conjugate vaccine was highly effective when given in combination with DPT-IPV vaccine. Provincial programs that used this regimen resulted in the near elimination of invasive Hib disease in children, but unimmunized children remain at risk.

Maternal knowledge and environmental factors associated with risk of diarrhea in Israeli Bedouin children.

Diarrhea is still a major cause of morbidity and mortality among children in developing countries. As it is due to multiple causative agents including viruses, bacteria and parasites, biological interventions are not currently available to markedly reduce incidence and severity. We examined maternal knowledge and reported behavior during diarrheal episodes, as well as environmental factors to determine their association with diarrhea. The children and mothers were from a Bedouin township in southern Israel, which has developed preventive and curative health care facilities. The Bedouin population in Israel is in transition from a nomadic to a settled life style. While almost all mothers exhibited good knowledge regarding food storage and prevention of diarrhea episodes in the children, the rate of illness in the children remained relatively high (two episodes per child year of observation). In a multivariate analysis, cessation of breastfeeding during diarrhea, child sleeping with siblings and lack knowledge about risk factors, were the major risk factors for illness with odds ratios (OR): 4.6, p = 0.02, 5.6, p = 0.03 and 1.7, p = 0.06, respectively. These data indicate that even in this population with free access to preventive medical care, greater efforts should be made to educate mothers regarding risk factor for diarrheal disease identification and the benefits of maintaining breastfeeding during diarrhea episodes.

Bacteremia in febrile human immunodeficiency virus-infected children presenting to ambulatory care settings.

Risk factors for bacteremia in febrile HIV-infected children are unknown. To describe the frequency of bacteremia in febrile HIV-infected infants and young children in ambulatory settings and its association with clinical and laboratory factors. In a birth cohort of 42 HIV-infected children, all febrile outpatient encounters at < or = 36 months of age were reviewed for HIV disease severity, presence of a central venous catheter (CVC) and the usage of antibiotics and/or intravenous immunoglobulin (IVIG). Blood culture results, highest temperature and white blood cell count (WBC) were noted. There was a mean of 1.8 febrile visits (210 visits/116.5 subject years) per child year of observation. Rapid HIV-disease progressors (n=14) were 4 times more likely to have a febrile visit than 28 non-rapid HIV disease progressors (P < 0.01). Blood cultures and WBCs were obtained for 87 and 89% of the febrile visits, respectively. Eleven of the 27 positive blood cultures grew Streptococcus pneumoniae and 16 grew CVC related organisms. The only pathogen identified (n=9) in 104 febrile visits in children without a CVC was S. pneumoniae, which was often (7 of 9) associated with mild illnesses. In children without a CVC temperature > or = 39 degrees C was significantly associated with S. pneumoniae bacteremia (P < 0.05). In 79 febrile visits by subjects with a CVC, temperature > or = 39 degrees C and WBC > or = 15000 cells/mm3 were frequently observed in the 16 bacteremic compared with the 63 nonbacteremic episodes (P < or = 0.05). There was a trend toward fewer S. pneumoniae bacteremias (3 of 11) in febrile subjects who were receiving antibiotics or IVIG. HIV-infected children younger than 36 months of age have a high incidence of S. pneumoniae and CVC-related bacteremias. Temperature > or = 39 degrees C, WBC > or = 15000 cells/mm3 and the presence of a CVC should be considered in the management of febrile HIV-infected children.

Longitudinal studies of infectious diseases and physical growth of infants in Huascar, an underprivileged peri-urban community in Lima, Peru.

Longitudinal studies of morbidity from infectious diseases and physical growth were completed from July 1982-June 1984 for 153 Peruvian newborns during the first year of life. Admission to the cohort was restricted to infants with birth weights greater than 2,500 g. Surveillance workers inquired about symptoms of diarrheal, respiratory, and other illnesses during thrice-weekly home visits; anthropometrists measured weight and length each month to assess the infants' patterns of physical growth and relative nutritional status. During 48,209 child-days of observation, upper respiratory infections were present on 13,409 child-days (27.8% prevalence) and diarrhea on 7,466 child-days (15.5% prevalence). The diarrhea incidence rate averaged 9.8 episodes per child-year of observation; all children had at least one episode of diarrhea. Average weights approximated those of the National Center for Health Statistics reference population during the first five to six months, but declined thereafter in relation to reference data. Average lengths were less than the reference data at all ages. The average weights for age and lengths for age of girls were generally greater than those of boys relative to the reference population. Rates of stunting and wasting increased progressively during the first year of life.