Seronegative Children Research Articles

Pulmonary manifestations in HIV seropositivity and malnutrition in Zimbabwe

Over a 10 month period 184 children, aged 5 years or less, who died at home had their nutritional status and HIV serostatus established; necropsies were also carried out. The...

Response to Hepatitis A Vaccine in Children after a Single Dose with a Booster Administration 6 Months Later.

Background: Children are of an age group susceptible to infection by the hepatitis A virus (HAV). Active immunization of children against HAV became reality in 1993, when the first pediatric hepatitis A vaccine was licensed. This initial vaccine required two injections to induce a full immune response in recipients. The purpose of this study was to assess the feasibility of a single dose primary vaccine plus a booster after 6 months against hepatitis A in children. Methods: A total of 60 healthy and seronegative children between 2 and 13 years of age were administered inactivated hepatitis A vaccine, containing 720 enzyme-linked immunosorbent assay (ELISA) units (EL.U) of hepatitis A antigen, intramuscularly in the deltoid region at months 0 and 6. Symptoms were recorded by parents or guardians on individual diary cards. Antibodies against HAV (antiHAV) were measured using an ELISA inhibition assay, and a seropositive titer was defined as being >=20 mIU/mL. Results: Fifteen days after the single primary dose, 96% of the vaccinees were seropositive with a geometric mean titer (GMT) of 351 mIU/mL. The seropositivity rate reached 100% 1 month after the first dose, with a GMT of 305 mIU/mL. Prior to the second dose at month 6, 93% remained seropositive, and the GMT was 153 mIU/mL. By month 7, 1 month after the second vaccination, the seropositivity rate recovered to 100% with a rise in GMTs to 3644 mIU/mL. Local symptoms were reported after 23.9% of doses, and general symptoms after 19.7% of doses. All symptoms were of short duration and resolved spontaneously. Conclusions: This inactivated vaccine against hepatitis A is safe, well-tolerated, and excellently immunogenic when administered to children following a single dose plus booster course at months 0 and 6.

An Evaluation of Measles Revaccination Among School-entry-aged Children

A two dose measles vaccination schedule is recommended routinely for all school-entry-aged children. We evaluated this recommendation by determining both measles antibody seroprevalence and the response to revaccination in seronegative children in this age group. Children 4 to 6 years of age who had received a single dose of measles vaccine between the ages of 15 to 17 months were tested for measles antibody by using enzyme-linked immunosorbent assay (ELISA) microneutralization technique. Seronegative children were revaccinated and again tested for measles antibody (immunoglobulin M [IgM] and neutralizing). Of 679 children tested, 37 (5.4%) were seronegative. Seronegativity was not significantly associated with age, sex, race, age at initial vaccination, time since vaccination, or maternal year of birth. However, children mothers with a college degree were 12 times more likely to be seronegative than children of mothers who never attended college (P < .01). Of the 37 seronegative children, 36 seroconverted after revaccination--33 producing IgM measles antibody, suggestive of a primary immune response. The cost per seroconversion would have been an estimated $415 if all 679 children had been revaccinated. Revaccination reduces the pool of children who are susceptible to measles. Although the cost per seroconversion is high, a two-dose schedule should reduce the substantial costs of controlling measles out breaks by reducing the number of outbreaks.

Hepatitis C infection in children who received extracorporeal membrane oxygenation

Objective: To determine the prevalence of antibody to hepatitis C virus (HCV) in a cohort of neonates who received extracorporeal membrane oxygenation (ECMO) therapy, and to determine risk factors associated with seropositivity. Design: Eighty-three patients who had been treated with ECMO as neonates (from August 1986 through January 1992) at Children's Hospital, Boston, were tested for antibodies to HCV. The medical records were reviewed, and information regarding neonatal history was obtained. Anti-HCV seronegative and seropositive children were compared using univariate and multivariate analyses. Results: Seven patients (8%) were anti-HCV seropositive. Of the seven seropositive children, four (57%) currently have ALT values of more than 1.5 times the upper limit of normal; only five of the 52 (9.6%) seronegative patients have values this high ( P < .001). Patients in the seropositive group had received blood screened by “surrogate markers” (6 of 50) or by ELISA-1 anti-HCV testing (1 of 33). Significant differences between the seropositive and seronegative patients were found with respect to the aminotransferase and bilirubin levels during the initial ECMO hospitalization. The last ALT value before discharge was the only significant predictor of HCV infection in the multivariate model. Conclusion: Neonates treated with ECMO are at risk for the development of HCV infection. Neonates who received blood products from donors screened by surrogate markers or ELISA-1 anti-HCV testing should be considered at risk. Neonates who had an abnormal ALT value at the time of discharge are most likely to be anti-HCV seropositive.

HIV SEROPREVALENCE AMONG CHILDREN ADMITTED IN A GENERAL PEDIATRICS HOSPITAL IN SÁO PAULO 985

Brazil has the largest number of AIDS cases in the Americas after the United States and most of the cases are concentrated in S. Paulo city. Santa Casa is a tertiary general hospital in downtown Sao Paulo. The study enrolled 283 children under two years old admitted between April 1994 and May 1995 in a general pediatric ward. Every child was evaluated for HIV associated symptoms and after maternal consent, collected blood for HIV-1 specific antibody using an enzyme linked immune absorbent assay. Tests that resulted positive were repeated. All the mothers were asked about behaviors risk factors for HIV infections. The children were admitted to the hospital due to respiratory infections (35.9%), diarrhea (22.3%), meningitis (5.3%), sepsis(4.3%) and others (32.2%). Parents behavior risks for HIV infection were present in 30.8%. Of the 283 children enrolled in the study 24 (8.5%) were HIV seropositive, 9 of then admitted due to diarrhea (14% of the diarrhea children), 10 due to acute respiratory infections (6.8% of the acute respiratory infections children) and 5 with others diagnosis. Of the 24 seropositive children, 10 had HIV associated symptoms like oral thrush, prolonged diarrhea, prolonged fever or failure to thrive. Those findings were also present in 24.2% of the seronegative children. Behavior risk of parents were present in 18 (75%) of the 24 HIV positive children and absent in 6(25%). We concluded that HIV infections are surprisingly prevalent in our hospital and in communities where behavior risk are frequent it is useful to screen all the admitted patients for implementation of preventive measures.

A Live Human Parainfluenza Type 3 Virus Vaccine Is Attenuated and Immunogenic in Healthy Infants and Children

The safety, infectivity, immunogenicity, and phenotypic stability of the cold-passaged (cp) candidate vaccine cp-45, a cold-adapted (ca), temperature-sensitive (ts) mutant of the JS strain of human parainfluenza virus type 3 (HPIV-3), was evaluated in 114 children 6 months to 10 years old in a randomized, placebo-controlled, double-blind trial. The cp-45 vaccine was well tolerated when given intranasally to parainfluenza virus type 3 (PIV-3)-seropositive and -seronegative children. With 10(4) or 10(5) TCID50 of cp-45 vaccine, 86% of seronegative vaccines were infected, 83% of whom shed virus at a mean peak titer of 10(22) pfu/mL. Virus present in respiratory specimens retained the ts phenotype, and each of 86 PIV-3 isolates tested retained both the ca and ts phenotypes. One dose of 10(5) TCID50 of vaccine induced a serum hemagglutination-inhibiting antibody response in 81% of vaccinees; the geometric mean titer was 1:32. These studies indicate that the cp-45 HPIV-3 vaccine is satisfactorily attenuated, infectious, immunogenic, and phenotypically stable and merits further evaluation in infants and young children.

Prevalence of hepatitis-C antibody seropositivity in healthy Egyptian children and four high risk groups.

We studied the prevalence of HCV antibody seropositivity and serum alanine concentrations in a random sample of healthy Egyptian children (n = 110) as well as in four high risk groups of children. Group 1 included 18 children with thalassemia major, group 2 included 17 children with insulin-dependent diabetes mellitus (IDDM), group 3 included 21 children with schistosomal hepatic fibrosis (SHF), and group 4 included 20 children with chronic rheumatic heart disease (RHD). The prevalence rate of HCV seropositivity was 12 per cent in normal children, 44 per cent in thalassemic children, 29 per cent in children with IDDM, 38 per cent in children with SHF and 0 per cent in patients with RHD. The liver size was significantly larger in HCV seropositive normal children as well as in HCV seropositive children with thalassemia and SHF compared to the seronegative children in each group respectively (P < 0.05). In all groups serum alanine transferase concentrations were significantly higher in HCV seropositive v. seronegative children. This pointed out to the high risk of continuous parenchymal hepatic damage in these children following acute HCV infection. In summary, our data revealed a relatively high prevalence of HCV antibody seropositivity in healthy Egyptian children compared to reports from other countries, and a significantly high prevalence of HCV seropositivity in children with thalassemia, IDDM, and SHF which carries a considerably high risk for development of chronic liver disease in these patients.

Early diagnosis of HIV-1 infection in infants in Dar es Salaam, Tanzania

Objectives: To evaluate two simple methods, an immune complex dissociation (ICD) p24 antigen assay and an HIV-1-specific IgA antibody assay, for the early demonstration of HIV-1 infection in infants, using the polymerase chain reaction (PCR) as the reference method. Design and setting: Group A: 143 HIV-1-seropositive and 134 -seronegative mothers and their infants were recruited at delivery at the main hospital in Dar es Salaam, Tanzania. Group B: 26 HIV-PCR-positive hospitalized children in Dar es Salaam, 3–15 months old and suspected of having an HIV-related illness. Methods: Blood samples were taken from mothers and infants in group A at intervals during the children's first 24 months and once from each of the children in group B. Peripheral blood mononuclear cells were tested by nested PCR for viral DNA. Plasma samples were tested by the Coulter p24 antigen (ag) enzyme-linked immunosorbent assay (ELISA) after acid dissociation of p24 antigen-antibody complexes. All p24-ag-positive reactions were confirmed by neutralization. Viral specific IgA antibodies were demonstrated in plasma by a modified ELISA. Results: One hundred and sixty-three of 174 samples from seropositive mothers were PCR-positive (sensitivity 93.7%) and 612 of 614 samples from seronegative mothers and children of seronegative mothers were PCR-negative (specificity 99.7%). Twenty-nine of 145 (20.0%) children born to seropositive mothers were positive by PCR when tested during the first year of life. By use of both the p24 ag ELISA and the IgA antibody ELISA in combination, HIV-1 infection was detected in 9 of 17 (53%) PCR-positive children 1–8 weeks old, in 15 of 18 (83%) PCR-positive children 9–26 weeks old and in 23 of 24 (96%) PCR-positive children 27–52 weeks old. The specificities of the p24 ag ELISA and the IgA ELISA were 100%. Conclusions: The p24 ag assay and the IgA antibody ELISA, when used in combination, had a high sensitivity and specificity for detection of HIV-1 infection in infants, especially in those above the age of 6 months.

A Prospective Study of Mother-To-Infant HIV Transmission in Tribal Women from India

The transmission of human immunodeficiency virus type 1 from infected mothers to their babies was assessed by serologic, virologic, and clinical means. Of the 160 antibody-positive women enrolled at the beginning of the study, 13 had overt clinical symptoms (CDC stage III/IV). Termination of pregnancy was done, on request, in seven of these cases. The rest delivered prematurely. A total of 143 parturient women and their infants were followed prospectively until the babies were 18 months of age. Fifteen infants (9%) died of AIDS before 14 months of age. The remaining 128 children (91%) were alive at the end of the study period. Seventy-four seropositive children (46%) became seronegative and were considered noninfected. None of the seronegative children reverted to seropositive status despite the fact that they were breast-fed. The majority of the seropositive children (63%) became symptomatic and clinically ill during infancy. The overall mother-to-infant vertical transmission rate was 48%.

Cytolytic activity against mycobacterial antigens: differences between haemophiliacs with and without HIV infection.

Although asymptomatic haemophiliacs have been shown to have abnormalities of their immune response, independent of HIV, clinical evidence of significant immunosuppression is limited. The only clinical report has been an outbreak of M. tuberculosis in which a group of haemophilic boys appeared unduly susceptible to infection. These boys are now all HIV seropositive. Along with a group of HIV seronegative children with coagulation disorders and non-haemophilic HIV seropositive men, these boys have been restudied to examine immune response to PPD. The HIV seropositive haemophilic boys that had had M. tuberculosis infection had reduced cytolytic response to PPD pulsed macrophages comparable to the non-haemophilic HIV seropositive men. The HIV seronegative children with coagulation disorders showed a reduction in cytolytic activity at low effector:target ratios compared to normal controls. In vitro studies showed that exogenous factor VIII concentrate could inhibit cytolytic activity to PPD pulsed macrophages. The possible role of chronic blood-borne virus infection and factor VIII concentrates in the original outbreak are discussed.

Intestinal Parasites in HIV-seropositive Zambian Children with Diarrhoea

We undertook a study over a period of 9 months to define the frequency of parasitic infections in hospitalized children with diarrhoea between the ages of 15 months and 5 years. Every alternate day, mothers of all children admitted with diarrhoea between 09.00 hours and 12.00 hours to one of the wards of the Department of Pediatrics and Child Health of the University Teaching Hospital (UTH) in Lusaka, Zambia, were interviewed for enrollment of their children into the study. A total of 178 children with diarrhoea were enrolled in the study. Of these 44 (25 per cent) were HIV seropositive and 134 (75 per cent) were seronegative for HIV. Out of 44 HIV-seropositive patients, 20 (45 per cent) had acute diarrhoea and 24 (55 per cent) had chronic diarrhoea. Of the 134 HIV-seronegative patients, 68 had acute diarrhoea (51 per cent) and 66 (49 per cent) had chronic diarrhoea. At least one intestinal parasite was found in 34 out of the 178 children enrolled. The commonest parasites identified were Ascaris and Cryptosporidia. No associations were identified between parasite isolation and the following: age, sex, or socio-economic status. Cryptosporidium spp. was isolated from 6 out of 44 (14 per cent) HIV-seropositive children, while 8 out of 134 (6 per cent) seronegative children had the parasite (P = 0.01). HIV-seropositive children with chronic diarrhoea had significantly higher cryptosporidium identification rates than those HIV-seropositive children with acute diarrhoea [5 out of 24 (21 per cent) patients with chronic diarrhoea compared to 1 out of 20 (5 per cent) patients with acute diarrhoea; (P > or = 0.01)].(ABSTRACT TRUNCATED AT 250 WORDS)

Helicobacter pylori, hypergastrinaemia, and recurrent abdominal pain in children

The association between Helicobacter pylori and recurrent abdominal pain (RAP) is controversial. In this cross-sectional study, the authors aim to determine whether hypergastrinaemia causes RAP in children with H pylori gastritis. In 439 children age 4 to 13 years (mean 7.3 years) attending for nongastrointestinal day-case surgery, anti-Helicobacter immunoglobulin G (IgG) was identified in serum by an enzyme-linked immunosorbent assay (ELISA) method validated in children and fasting plasma gastrin was measured. A history of RAP was sought. One hundred twenty-seven children (29%) tested seropositive for H pylori. Fiftyone seronegative children (16.3%) and 22 seropositive children (17.3%) gave a history of RAP. The mean fasting gastrin in seronegative children was 52 ng/L compared with 117 ng/L in seropositive children ( P < .001). The mean fasting gastrin in seropositive children with RAP (124 ng/L) was not significantly different from that of seropositive children without RAP (115 ng/L). The high prevalence of H pylori seropositivity in this study is at variance with other reported paediatric data from the developed world. No association between childhood H pylori gastritis, hypergastrinaemia, and RAP was found. In children with H pylori gastritis, the increase in circulating gastrin (mean 140% increase) is greater than that seen in adults (50% increase).

Serologic status and measles attack rates among vaccinated and unvaccinated children in rural Senegal

During a measles vaccine trial in a rural area of Senegal, antibody status was examined within 10 days of exposure for 228 previously vaccinated and 313 unvaccinated children more than 12 months old who were exposed to measles at home. Thirty-six percent of the children developed clinical measles, the clinical diagnosis being confirmed for 135 of the 137 children from whom 2 blood samples were collected. Vaccine efficacy was 90% (95% confidence interval, 83 to 94%). The hemagglutinin-inhibiting antibodies (HI) or plaque neutralizing antibodies (PN) assays were equally efficient in predicting susceptibility and protection against measles. Vaccinated children who had no detectable HI or PN antibodies at exposure had significant protection against measles compared with seronegative unvaccinated children (HI vaccine efficacy, 49% (95% confidence interval, 21 to 68%); PN vaccine efficacy, 43% (95% confidence interval, 12 to 62%)). The attack rate was high for children with a titer of 40 to 125 mIU) 67% (4 of 6) of those with a positive hemagglutinin-inhibiting antibody test and 36% (13 of 36) of those with a positive PN test developed measles. Attack rates among children with HI or PN titers above 125 mIU were 2% (6 of 295) and 3% (7 of 258), respectively. Because titers of < or = 120 mIU have been found to offer little protection in another study, this antibody level may be the best screening value for assessing susceptibility and protection against measles. However, it should be noted that many seronegative vaccinated children are protected against measles infection.

Increased soluble CD8 (sCD8) in human immunodeficiency virus 1-infected children in the first month and year of life.

The purpose of this study was to determine whether soluble CD8 (sCD8) in serum of perinatally human immunodeficiency virus 1 (HIV-1)-infected children during the first year of life differs from that of HIV-1-uninfected control children. Soluble CD8 concentrations in stored plasma and serum samples of children of HIV-1-infected and uninfected mothers were determined using a sandwich immune assay. In the first month of life significantly greater concentrations of sCD8 occurred in 12 HIV-1-infected infants than in 9 uninfected infants born to infected mothers (mean = 1054, SD 540 vs. 589, SD 370 units/ml, P < 0.05), although the CD8+ T cell proportions were not different (21.7 vs. 21.1, P > 0.5). The difference in sCD8 concentrations was most pronounced in 8 infants who were HIV-1 culture positive on initial testing in the first week of life compared with the remaining 4 patients when virus was first detected on subsequent analysis (mean = 1315, SD 446 vs. 529, SD 231 units/ml, P < 0.01). The concentration of sCD8 was also greater in 26 HIV-1-infected children than in either 26 uninfected children born to infected mothers or 25 seronegative children during the first year of life (mean = 1268, SD 529 vs. 630, SD 290 vs. 553, SD 315 units/ml, P < 0.05). Early and persistent elevation in sCD8 probably reflects immune activation resulting from HIV-1 infection. The occurrence of this increase in the neonatal period may reflect prenatal viral transmission, a higher viral inoculum or coinfection with other agents stimulating immune activation.

Alteration in the Proportion of CD4 T Lymphocytes in a Subgroup of Human Immunodeficiency Virus-Exposed-Uninfected Children

The age-related changes in the proportion of CD4 and CD8 lymphocytes in human immunodeficiency virus (HIV)-seronegative children born to HIV-infected mothers (seroreverters) were compared with the changes in these lymphocyte subsets in children born to seronegative women to assess a possible effect of exposure to HIV without infection. There were 146 seroreverter and 72 seronegative children. The median CD4 and CD8 percentages for each of these two groups of children were compared retrospectively at 3-month intervals from birth through 27 months and at a tenth interval for the time beyond 27 months. The weighted average of the within-subject rate of change of CD4 and CD8 percentages were also compared between the two groups. Finally, for each subject, the proportion of the subject's CD4 percentage assays which were <10th percentile of the entire study population (30%) was calculated, and the distributions of the subject-specific proportions were then compared between the seronegative and seroreverter groups using the Wilcoxon rank sum test. The proportion of CD8 assays <10th percentile (12%) or > 90th percentile (26%) were also computed for each subject, and the distributions of the proportions were compared similarly. . The median CD4 percentage of seroreverter children was lower than that for the seronegative children at every interval from birth through 27 months and for the last interval for values obtained at greater than 27 months, although the comparison was statistically significant only at the 4- to 6-month period. The weighted average of the within-subject rate of change of CD4 percentage was -0.09 and -3.0 per year (P = .04), and of CD8 percentage was 1.3 and 1.0 (P = .67), for the seroreverter and seronegative children, respectively. There were significantly more children in the seroreverter group than in the seronegative group who had repeated assays in which the CD4 percentage was < 10th percentile for age (P < .00005). In addition, there was a subset of 10 seroreverter children (6.8%) who had CD4 percentages < 30% on > 50% of their assays, as compared with only one (1.4%) seronegative child. The proportion of CD8 assays < 10th percentile or > 90th percentile were not significantly different between the two groups of children. The CD4 proportions were persistently lower in the seroreverter than in the seronegative population, although only reaching statistical significance in 1 of 10 3-month intervals. This finding may be due to a subgroup of seroreverter children who have persistently low CD4 lymphocyte percentages.

Attenuated varicella virus vaccine in children with renal transplants.

The long-term efficacy of varicella vaccine was studied in 34 children aged 2-18 years who were either on chronic dialysis (n = 17) or were renal transplant recipients (n = 17). Live attenuated virus (OKA line) was inoculated in a single 0.5-ml subcutaneous dose, without modification of the immunosuppressive therapy protocol for renal transplant recipients. The majority of children (85%) developed antibodies within the first 6 months, with IgG titres (enzyme-linked immunosorbent assay) greater than 1:40 (geometric mean 1:640). Of those children who were followed for longer than 2 years, 76% maintained their antibody titres. Reactions to the vaccine were minimal and the immunological protection was effective. Only 3 children developed a mild form of varicella in the post-vaccination period. We consider that seronegative children who are candidates for renal transplantation must be protected against varicella by attenuated varicella vaccination. When vaccination is performed after transplantation, no modification of immunosuppressive therapy is needed.

Tuberculosis and HIV infection in children in Abidjan, Côte d'Ivoire

Of 5180 consecutive outpatients diagnosed with tuberculosis in Abidjan, Côte d'Ivoire (West Africa), between July 1989 and December 1990, 289 (6%) were children aged less than 15 years. The overall prevalence of human immunodeficiency virus (HIV) 1 and/or HIV-2 infection in children with tuberculosis was 11.8% (HIV-1, 10.0%; HIV-2, 0.7%; reactivity to both viruses, 1%). The highest overall age-specific prevalence was in children aged 1–4 years (23.4%), significantly higher than the rate in attenders at a well child clinic (0.5%) (odds ratio 58.2). Of children with tuberculosis, 26% had sputum smear-positive disease (HIV seroprevalence 2.7%), 20% extrapulmonary disease (HIV seroprevalence 5.2%), and 54% were categorized as having ‘clinical tuberculosis’ (HIV seroprevalence 18.6%) based on clinical signs and chest X-ray abnormalities with negative sputum smears. Clinical tuberculosis was most frequent in seropositive children, irrespective of age, and in younger seronegative children. Extrapulmonary tuberculosis was equally distributed across age groups, and pulmonary tuberculosis was concentrated in older, seronegative children. HIV-positivity was significantly associated with other features related to the acquired immune deficiency syndrome such as wasting, chronic diarrhoea, oral candidiasis, and negative tuberculin skin tests. Tuberculosis seems to be associated with HIV infection in children in sub-Saharan Africa, but better diagnostic techniques for paediatric tuberculosis are urgently needed.

Persistence of Cell-Mediated and Humoral Immune Responses in Healthy Children Immunized with Live Attenuated Varicella Vaccine

Two hundred fourteen healthy seronegative children immunized with various doses of Oka/Merck varicella vaccine were studied for persistence of varicella-zoster virus (VZV)-specific lymphocyte proliferation and antibodies to VZV as determined by a glycoprotein (gp) ELISA. Of the 140 vaccinees tested for VZV-specific lymphocyte proliferation, 94% had positive responses, with a mean stimulation index of 8.9 (range, 3.0-44.6). Of 214 tested by gpELISA, 95% were positive for up to 6 years after immunization; the geometric mean titer was 30.2 (range, 1.3-3510.0). Of 122 individuals tested both by ELISA and for VZV-specific lymphocyte proliferation, 91% had persistence of both responses. Persistence of cellular and humoral immune responses in a large percentage of vaccinees for up to 6 years after immunization with Oka/Merck varicella vaccine suggests that protection against severe varicella is likely to be similarly long-lasting.

Detection of H. pylori in Saliva Using a Monoclonal Antibody

The presence of Helicobacter pylori in saliva specimens collected from infected children examined before and after specific therapy and from a non-infected pediatric population was detected by indirect immunofluorescence assay (IIF) using a specific monoclonal antibody. Among the 25 children with H. pylori-negative antral biopsies, 4 had in their salivas bacterial cells similar to H. pylori, but a retrospectively performed serologic test showed a positive response. No false-positive reaction was observed among non-infected and seronegative children. The observation of bacterial cells with H. pylori morphology in saliva by IIF was consistent with the presence of this bacterium in antral biopsies. A person-to-person transmission of H. pylori by saliva thus appeared to be possible.

Positive and negative titres of a new serologic test for the detection of Helicobacter pylori

Objective To determine normal ranges for positive and negative titres using a new commercially available serologic enzyme-linked immunosorbent assay for the detection of Helicobacter pylori (MALAKIT, BIOLAB, Limal, Belgium). Methods We studied 463 symptom-free children, aged 2 to 14 years (55% male and 45% female), admitted for elective minor surgery. During routine presurgery blood analysis, 1 ml of venous blood was taken for serology. Results Thirty-four children (7.3%) had a positive litre. Although we were able to observe an increase in the number of seropositive subjects with age, there was no significant increase in titre with age for both positive and negative titres. In 25 seropositive patients, a control serology and 13C-urea breath test were performed 6 to 9 months later. In all but one patient (96%), both control examinations were positive. 13C-urea breath tests were also performed in 65 randomly selected seronegative children and were all negative. Conclusions A positive 13C-urea breath test suggests that the seropositive children were infected with H. pylori. Since 13C-urea breath tests were positive in seropositive and negative in seronegative children, we validated the manufacturer's previously established cut-off values, based on 119 paediatric patients, in a significantly larger patient population. The proposed cut-off limit for children for the MALAKIT test is 0.21 optical density units at 405 nm. The significance of these ‘healthy H. pylori carriers' remains to be elucidated.