Hepatitis A foci in children's collectives studied by using clinico-biochemical, virological and serological diagnostic methods

In 4 foci of hepatitis A (HA) at children's institutions in Moscow 218 children and 30 staff members were examined. Simultaneously with clinico-biochemical studies, specific IgM and IgG in the blood and hepatitis A virus (HAV) antigen in feces were determined by radioimmunoassay. Different forms of HA were detected in 29.1% of children in kindergartens, 19.4% of school children and 3.3% of adults, which was due to great differences in the size of the immune stratum among them (IgG to HAV was detected in 8-10% of children aged 3-6 years and in 83% of adults). In 2/3 of children with HA in the foci the disease was not accompanied by jaundice, 1/5 of them having the inapparent form of this infection. In 45% of the patients HAV antigen was detected in feces, irrespective of the form of HA, 5-14 days before the appearance of hyperfermentemia, and in 2/3 of them this antigen was also detected during the first 6 days after that. Simultaneously with an increase in aminotransferase activity, all of the HA patients showed the presence of specific IgM in their blood.     

Characteristics of the manifest and latent components of the hepatitis A epidemic process in cities of Russia

Seroepidemiological study of hepatitis A (HA) morbidity was carried out in three Russian cities, with different levels of HA morbidity. The study included the analysis of HA morbidity for 22 years, the determination of antibodies to HA virus (anti-HAV) in 2,958 healthy persons aged 0-12 months to 40 years and older. In one of the cities 7 isolates of HA virus were obtained from unrelated sources and the genotypes of the virus were determined. The study revealed that the frequency of seropositive cases among persons of different ages correlated with the level and prolonged dynamics of HA morbidity. According to the occurrence of anti-HAV, such cities as St. Petersburg, Rostov-on-Don and Yakutsk may be at present classified as territories, moderately endemic in HA. At the same time in the 90 s the epidemic situation in HA was more favorable in Rostov-on-Don than in two other cities. The suggestion was made that a high proportion of seropositive persons among the population of St. Perersburg was linked with an almost twofold rise in HA morbidity in 1993-1995 caused by genotype 1 of the virus. Seroepidemiological studies in HA during the period of a drop in morbidity acquire special importance in the surveillance and control system of this infection.     

Antigenic anachronism of the influenza A(H2N2) viruses in Leningrad in 1980. I. The epidemiological and serological characteristics of the influenzal infection caused by A/Leningrad/80 (H2N2) viruses

In April-May 1980 a number of unrelated outbreaks of influenza-like diseases were registered in Leningrad in an infant home (50 out of 68 children under observation, aged 3 months to 2 years, were affected) and among the pupils of a boarding school (13 out of 50 adolescents under observation, aged 15-17 years, were affected). 5 strains of influenza A virus were isolated from 3 sick children and 1 clinically healthy child. A similar virus was isolated from a sick adolescent in a boarding school, as well as from a female patient aged 24 years at a domiciliary focus of infection (a sporadic case). In the subsequent laboratory investigation all these 7 strains were identified as viruses A/H2N2. Isolated cases of seroconversion to hemagglutinin H2 were definitely registered in 6 patients during February--May 1980. In 3 cases, including the 24-year old female patient with an acute respiratory disease, seroconversion to hemagglutinin H2 was observed in combination with the release of influenza viruses A/H2N2 from these patients. 2 influenza virus strains with this antigenic characteristic were isolated from a young female patient at an interval of 3 days. Among the patients admitted to the clinics of the Research Institute of Influenza in Leningrad on account of acute respiratory diseases isolated cases of diagnostically significant seroconversion to hemagglutinin H2 constituted 3.5% among children and 4.5% among adults. The study of the level of antihemagglutinins in the population revealed that in 1980 persons aged 18-50 years showed a high level of antihemagglutinins.(ABSTRACT TRUNCATED AT 250 WORDS)     

Data on the study of the epidemiology of rotavirus infection in Leningrad

The results obtained in the study of rotavirus infection in Leningrad in 1984-1987 are presented. Enzyme immunoassay techniques were used for the examination of 4,715 children aged 0-14 years and 1,162 adults with diagnosed acute enteral infection of unknown etiology, as well as the control group of 556 of healthy children aged 0-6 years and 77 healthy adults. The rotavirus antigen was detected in 1.210 sick children (25.7%) and 133 sick adults (11.4%), as well as in 6 healthy children (1.1%), but not detected in healthy adults. The following epidemiological regularities of rotavirus infection were established: the highest sick rate among children aged 0-2 years and a low level of rotavirus carriership among healthy persons; the seasonal character of rotavirus infection, its outbreaks occurring in winter and the epidemic periods varying in their character and duration in different years; the prevailing role of rotaviruses in the development of winter rises of acute enteral infection of unknown etiology in the city among children aged 0-2 years. The problem of the respiratory syndrome in rotavirus diarrhea is discussed. The rotavirus antigen was detected in 39 out of 144 children (27%) with diagnosed acute respiratory virus diseases and in 4 out of 99 nasopharyngeal washings (4%) from diarrhea patients. Adenoviruses were shown to play an insignificant role in the etiology of diarrhea (10% of cases).     

Risk factors for severe acute lower respiratory tract infection in Bogota, 2001

Severity of acute respiratory infection is higher in developing countries, especially among the socioeconomically underprivileged. Viral pneumonias are more common, especially among children. A prospective hospital-based case control study was undertaken in Bogota between November 2000 and August 2001, aimed to identify factors related to severe low acute respiratory infection (SLARI). Cases were limited to children aged between 2 months and 5 years who filled WHO criteria for SLARI. Controls were children at the same hospital with ARI in a similar age range, but without symptoms of chest drawing. A total of 638 children (277 cases and 361 controls) were included. The most important risk factors included the following: living in borrowed houses (odds ratio (OR) = 2.7; 95% Confidence Interval (CI): 1.06-7.07), sharing the bed (OR = 1.88, CI: 1.0-3.7), living with more than 9 people (OR = 1.82, CI: 1.0-3.51), and living with smokers (OR = 1.4, CI: 1.0-2.05). Of the 114 samples collected (from children at third day after beginning of symptoms), 98 had viruses, sincitial respiratory virus was the most frequently identified virus (41.8%), followed by influenza A virus (3.1%) and influenza B virus (1%). All positive isolates for influenza A and B were sent to the United States Center for Disease Control (CDC) in Atlanta, where they were classified as influenza A/PANAMA/2007/99-like and influenza B/SICHUAN/379/99-like, respectively.     

西安市2010-2015年0-5岁儿童HBV感染状况的流行病学研究

摘要 目的：总结西安市2010-2015年 0-5岁儿童乙肝病毒感染的发病趋势和流行病学特征,寻找高危人群。通过随访研究获取HBV感染儿童疾病转归及乙肝监测系统存在的问题,为乙肝监测系统完善及制定防治策略提供科学依据。方法：采用描述性流行病学方法对西安市2010-2015年的0-5岁儿童乙肝患者进行三间分布描述分析;采用前瞻性队列研究方法,检测母亲及儿童的外周血HBV病毒学情况,获得母亲感染状况和患儿转归。结果：6年间,西安市0-5岁儿童共上报乙肝病例175例,年均HBV感染率为6.05/10万,2013年最高,为9.73/10万,以散发为主;0-1岁为高发年龄段,男童发病多于女童;未央区、雁塔区为高发地区。截止2016年8月,随访HBV感染学龄前儿童139例,仅17例完成流行病学调查和体检检测,失访率高达87.7%,17例HBV感染儿童中HBsAg慢性化高达88.2%,其中14例(82.3%)母亲为HBsAg阳性者。结论：西安市0-5岁儿童HBV感染的高危人群为HBsAg阳性母亲的儿童,与宫内感染/母婴传播有关。0-5岁HBV感染儿童转归结局不良,建议加强HBV宫内阻断,并对高危新生儿进行乙肝抗体监测。     

Prevalence of hepatitis-B surface antigen among blood donors and human immunodeficiency virus-infected patients in Jos, Nigeria

Information is very scarce on the prevalence of hepatitis-B virus (HBV) infection among blood donors and patients with human immunodeficiency virus (HIV) infection in Nigeria. Hepatitis-B surface antigen (HBsAg) ELISA was used to determined the prevalence of HBsAg among 175 blood donors (aged 20-40 years) and 490 HIV-infected patients (aged 17-60 years) in Jos, Nigeria. Twenty-five (14.3%) of the blood donors and 127 (25.9%) of the HIV-infected individuals were HBsAg seropositive, indicating a higher HBV infection among HIV-infected persons than among healthy blood donors. A slightly higher HBsAg seroprevalence was recorded in the males (14.6%) than females (12.9%) of the blood donors. Among the HIV-infected patients, the males had considerably higher HBsAg seroprevalence than the females (31.8 vs 22.1%) with the highest prevalence of HBsAg occurring in the 51-60 years age group (44%), followed by those of 31-40 years (28.2%). Results confirmed the high endemicity of HBV infection in Jos, Nigeria and the significantly greater prevalence of HBV infection among HIV-infected patients than among blood donors.     

Viral hepatitis in different population groups of Republic of Sakha (Iakutia)

A survey for the presence of markers of viral hepatitis B, delta, C and E among different groups of the population of the arctic and agricultural zones of the Republic of Sakha (Yakutia), as well as in Yakutsk, was carried out. The survey revealed that viral hepatitides with the parenteral mechanism of the transmission of infective agents were widely spread among the population. In the arctic zone HBsAg was detected in persons aged 20 years and older in 10.8-17.1% of cases. On the average, in the arctic zone antibodies to virus delta were detected in 2.4% of cases. In different regions of the agricultural zone the detection rate of HBsAg was also high (10.4-23.8%). In the Namsk and Vilyui regions delta infection was registered among adolescents (15-19 years of age) in 8.7 and 22.4% of cases respectively. In the Mountainous region anti-delta antibodies were detected among persons aged 20 years and older in 31% of cases. The survey showed the presence of considerable differences in the detection rate of the markers of hepatitis B, depending on the ethnic origin of the examined patients. Similar tendencies were found to exist with respect to delta infection.     

Monoclonal antibodies detect different forms of influenza virus hemagglutinin during viral penetration and biosynthesis.

Monoclonal antibodies specific for the influenza virus A/PR/8/34 hemagglutinin (HA) were used to examine the structure of the HA glycoprotein by immunofluorescence techniques during infection of MDCK cells. One antibody (Y8-10C2), shown previously to detect conformational alterations in the HA coinciding with the acid induction of viral fusion activity, bound to internalized virus but not to virus adsorbed to the cell surface. The binding of Y8-10C2 was completely inhibited by ammonium chloride treatment of the cells. These findings are consistent with the idea that Y8-10C2 detects conformational changes in the HA which accompany the acid-induced fusion of viral and endosomal membranes. The same antibody also bound to newly synthesized HA but not to later forms of cytoplasmic HA or to HA incorporated into the cell membrane during virus maturation. A possible common denominator of the antigenic changes detected by antibody Y8-10C2 during virus entry and replication may be alterations in the structural relationship among the three HA monomers which form the mature HA molecule.     

Estimates of Dengue Force of Infection in Children in Colombo,Sri Lanka

Dengue is the most important vector-borne viral disease worldwide and a major cause of childhood fever burden in Sri Lanka, which has experienced a number of large epidemics in the past decade. Despite this, data on the burden and transmission of dengue virus in the Indian Subcontinent are lacking. As part of a longitudinal fever surveillance study, we conducted a dengue seroprevalence survey among children aged <12 years in Colombo, Sri Lanka. We used a catalytic model to estimate the risk of primary infection among seronegative children. Over 50% of children had IgG antibodies to dengue virus and seroprevalence increased with age. The risk of primary infection was 14.1% per year (95% CI: 12.7%–15.6%), indicating that among initially seronegative children, approximately 1 in 7 experience their first infection within 12 months. There was weak evidence to suggest that the force of primary infection could be lower for children aged 6 years and above. We estimate that there are approximately 30 primary dengue infections among children <12 years in the community for every case notified to national surveillance, although this ratio is closer to 100∶1 among infants. Dengue represents a considerable infection burden among children in urban Sri Lanka, with levels of transmission comparable to those in the more established epidemics of Southeast Asia.     

Mathematical model of influenza A virus production in large-scale microcarrier culture

A mathematical model that describes the replication of influenza A virus in animal cells in large-scale microcarrier culture is presented. The virus is produced in a two-step process, which begins with the growth of adherent Madin-Darby canine kidney (MDCK) cells. After several washing steps serum-free virus maintenance medium is added, and the cells are infected with equine influenza virus (A/Equi 2 (H3N8), Newmarket 1/93). A time-delayed model is considered that has three state variables: the number of uninfected cells, infected cells, and free virus particles. It is assumed that uninfected cells adsorb the virus added at the time of infection. The infection rate is proportional to the number of uninfected cells and free virions. Depending on multiplicity of infection (MOI), not necessarily all cells are infected by this first step leading to the production of free virions. Newly produced viruses can infect the remaining uninfected cells in a chain reaction. To follow the time course of virus replication, infected cells were stained with fluorescent antibodies. Quantitation of influenza viruses by a hemagglutination assay (HA) enabled the estimation of the total number of new virions produced, which is relevant for the production of inactivated influenza vaccines. It takes about 4-6 h before visibly infected cells can be identified on the microcarriers followed by a strong increase in HA titers after 15-16 h in the medium. Maximum virus yield Vmax was about 1x10(10) virions/mL (2.4 log HA units/100 microL), which corresponds to a burst size ratio of about 18,755 virus particles produced per cell. The model tracks the time course of uninfected and infected cells as well as virus production. It suggests that small variations (<10%) in initial values and specific rates do not have a significant influence on Vmax. The main parameters relevant for the optimization of virus antigen yields are specific virus replication rate and specific cell death rate due to infection. Simulation studies indicate that a mathematical model that neglects the delay between virus infection and the release of new virions gives similar results with respect to overall virus dynamics compared with a time delayed model.     

Seroepidemiological characterization of virus hepatitis in the Republic of Armenia

The survey of the population immunological structure with respect to parenteral hepatitis showed awide circulation of hepatitis B (HB) and hepatitis C (HC) viruses among the adult population of Armenia. During the 5 year period of observation the number of persons having antibodies to HC virus increased 2.7-fold. High occurrence of antibodies to HBsAg of HB virus among the healthy population in 2002 (12.0%) in comparison with 1997 (5.4%) reflected a decreased infection rate with HB virus as well. Antibodies to hepatitis A (HA) virus were isolated, on the average, in 64 % of persons. Simultaneously with a decrease in the proportion of HA cases an increased number of HC patients was registered. No circulation of hepatitis E virus was detected. A high percentage of hepatitis cases of mixed etiology was established, as well as an increased number of combined parenteral hepatitis cases was registered (57.1%).     

Total immunization of children against influenza decreases morbidity in a number of diseases among elderly persons during influenza epidemic

Immunization of children aged 3-6 years in kindergartens and school children aged 7-17 years against influenza with inactivated influenza vaccine was carried out in two districts of the Moscow region. The comparison of morbidity in influenza-like diseases among the immunized children with that among nonimmunized children in control districts revealed that the effectiveness of immunization was 60.9% in kindergartens and 68.8% in schools. The analysis of morbidity in a number of diseases among 158,451 elderly persons not immunized against influenza demonstrated that, in comparison with the control districts, in those districts where mass immunization of children was carried out morbidity in influenza-like diseases among elderly persons was 3.4 times lower and, out of other 10 diseases under study, morbidity in 8 diseases was 1.5-2.6 times lower. As indicated by the data obtained in this study, total anti-influenza immunization of children in organized groups not only essentially decreased influenza morbidity among children, but also greatly decreased morbidity in influenza and a number of diseases, appearing as complications of influenza infection, among nonimmunized elderly persons during influenza epidemic.     

Urinary schistosomiasis in southern Ghana: 1. Prevalence and morbidity assessment in three (defined) rural areas drained by the Densu river

Epidemiological studies on urinary schistosomiasis were carried out in eight villages in the Ga and Akuapem South districts in Ghana. Single urine samples were collected from individuals aged 5 years and above between 10.00 and 14.00 h. The samples were examined for the presence of Schistosoma haematobium eggs using a filtration technique. Indirect morbidity was determined as the presence of microhaematuria and proteinuria using reagent strips, and macrohaematuria was recorded with the naked eye. Out of the study population of 3912 subjects, 2562 (65.5%) submitted urine samples. The prevalence of a Schistosoma haematobium infection ranged between 54.8 and 60.0%. Infection rates increased by age with a peak in the 10-19 years category, and decreased with increasing age. Disease prevalence was higher in males aged 15 years and above in Areas 2 (Ntoaso and Sansami Amanfro) and 3 (Dom Faase, Papase, Chento and Gidi Kope), whereas it was higher among males aged 10 years and above in Area 1 (Ayikai Doblo and Akramaman). The intensity of infection was highest among children aged 10-14 years in most of the villages. More than half of egg-positive children in this age group had a heavy infection (100 eggs and above in 10 ml of urine). Although both egg-positive and egg-negative individuals manifested variable degrees of macro- or micro-haematuria, microhaematuria was more prevalent among egg-positives (chi(2)=918.5, d.f.=1, P<0.01). The degree of microhaematuria and proteinuria were significantly associated with the intensity of the infection. These results indicate a high transmission of disease in the study area.     

High Incidence of Multiple Viral Infections Identified in Upper Respiratory Tract Infected Children under Three Years of Age in Shanghai, China

Background

Upper respiratory tract infection (URTI) is a major reason for hospitalization in childhood. More than 80% of URTIs are viral. Etiological diagnosis of URTIs is important to make correct clinical decisions on treatment methods. However, data for viral spectrum of URTIs are very limited in Shanghai children.

Methods

Nasopharyngeal swabs were collected from a group of 164 children aged below 3 years who were hospitalized due to acute respiratory infection from May 2009 to July 2010 in Shanghai. A VRDAL multiplex PCR for 10 common respiratory viruses was performed on collected specimens compared with the Seeplex® RV15 ACE Detection kit for 15 respiratory viruses.

Results

Viruses were detected in 84 (51.2%) patients by VRDAL multiplex PCR, and 8 (4.9%) of cases were mixed infections. Using the Seeplex® RV15 ACE Detection kit, viruses were detected in 129 (78.7%) patients, 49 (29.9%) were co-infected cases. Identified viruses included 37 of human rhinovirus (22.6% of cases), 32 of influenza A virus (19.5%), 30 of parainfluenzavirus-2 (18.3%), 23 of parainfluenzavirus-3 (14.0%), 15 of human enterovirus (9.1%), 14 each of parainfluenzavirus-1, respiratory syncytial virus B and adenovirus (8.5%), 8 of coronavirus 229E/NL63 (4.9%), 6 of human bocavirus (3.7%), 5 each of influenza B virus and respiratory syncytial virus A (3.0%), 3 of parainfluenzavirus-4 (1.8%), 2 of coronavirus OC43/HKU1 (1.2%), and 1 human metapneumovirus (0.6%).

Conclusions

A high frequency of respiratory infections (78.7%) and co-infections (29.9%) was detected in children with acute respiratory infection symptoms in Shanghai. The Seeplex® RV15 ACE detection method was found to be a more reliable high throughput tool than VRDAL method to simultaneously detect multiple respiratory viruses.     

Intracellular Cleavage of Human Influenza A Virus Hemagglutinin and Its Inhibition

Replication of human influenza A viruses and proteolytic cleavage of the viral glycoprotein HA0 HA1/2 were studied in passaged cultures of epithelial cells of the serous membrane of human large intestine (CACO-2 line), dog kidney cells (MDCK), and monkey kidney cells (CV-1). Cleavage of the viral glycoprotein HA0, synthesis of activated virions, multicycle virus infection, and effective production of viral foci under an agarose overlayer were found in CACO-2 cells. By pulse–chase labeling of viral glycoproteins, testing the sensitivity to endoglycosidase-H of the viral glycoproteins HA0 and HA1/2 synthesized, and inhibiting the HA0 proteolysis with brefeldin A, the HA0 HA1/2 proteolysis was established to occur in the late stages of intracellular transport in the trans-Golgi and plasma membrane areas of the cells. Proteolysis of the viral glycoprotein HA0 in CACO-2 cells was suppressed by aprotinin, a natural inhibitor of serine proteinases. Unlike MDCK and CV-1 cells resistant to apoptosis induced by influenza virus, CACO-2 cells retained their viability for 2-3 days after infection with human influenza A virus.     

Influenza A virus neuraminidase limits viral superinfection

Enveloped viruses use multiple mechanisms to inhibit infection of a target cell by more than one virion. These mechanisms may be of particular importance for the evolution of segmented viruses, because superinfection exclusion may limit the frequency of reassortment of viral genes. Here, we show that cellular expression of influenza A virus neuraminidase (NA), but not hemagglutinin (HA) or the M2 proton pump, inhibits entry of HA-pseudotyped retroviruses. Cells infected with H1N1 or H3N2 influenza A virus were similarly refractory to HA-mediated infection and to superinfection with a second influenza A virus. Both HA-mediated entry and viral superinfection were rescued by the neuraminidase inhibitors oseltamivir carboxylate and zanamivir. These inhibitors also prevented the removal of alpha-2,3- and alpha-2,6-linked sialic acid observed in cells expressing NA or infected with influenza A viruses. Our data indicate that NA alone among viral proteins limits influenza A virus superinfection.     

Haemoglobin variants and Plasmodium falciparum malaria in children under five years of age living in a high and seasonal malaria transmission area of Burkina Faso

ABSTRACT: BACKGROUND: Genetic factors play a key role in determining resistance/susceptibility to infectious disease. Susceptibility of the human host to malaria infection has been reported to be influenced by genetic factors, which could be confounders if not taken into account in the assessment of the efficacy of interventions against malaria. This study aimed to assess the relationship between haemoglobin genotypes and malaria in children under five years in a site being characterized for future malaria vaccine trials. METHODS: The study population consisted of 452 children living in four rural villages. Hb genotype was determined at enrolment. Clinical malaria incidence was evaluated over a one-year period using combined active and passive surveillance. Prevalence of infection was evaluated via bi-annual cross-sectional surveys. At each follow-up visit, children received a brief clinical examination and thick and thin blood films were prepared for malaria diagnosis. A clinical malaria was defined as Plasmodium falciparum parasitaemia >2,500 parasites/ul and axillary temperature [greater than or equal to]37.5degreesC or reported fever over the previous 24 hours. RESULTS: Frequencies of Hb genotypes were 73.2% AA; 15.0% AC; 8.2% AS; 2.2% CC; 1.1% CS and 0.2% SS. Prevalence of infection at enrolment ranged from 61.9%-54.1% among AA, AC and AS children. After one year follow-up, clinical malaria incidence (95% CI) (episodes per person-year) was 1.9 (1.7-2.0) in AA, 1.6 (1.4-2.1) in AC, and 1.7 (1.4-2.0) in AS children. AC genotype was associated with lower incidence of clinical malaria relative to AA genotype among children aged 1-2 years [rate ratio (95% CI) 0.66 (0.42-1.05)] and 2-3 years [rate ratio (95% CI) 0.37 (0.18-0.75)]; an association of opposite direction was however apparent among children aged 3-4 years. AS genotype was associated with lower incidence of clinical malaria relative to AA genotype among children aged 2-3 years [rate ratio (95% CI) 0.63 (0.40-1.01)]. CONCLUSIONS: In this cohort of children, AC or AS genotype was associated with lower risk of clinical malaria relative to AA genotype only among children aged one to three years. It would be advisable for clinical studies of malaria in endemic regions to consider haemoglobin gene differences as a potentially important confounder, particularly among younger children.     

Frequency of finding hepatitis B viral markers in young children born of mothers carrying the HBs-antigen

The present communication deals with the results of investigations on the frequency of HBsAg-carriership among expectant mothers in Fergana (the Uzbek SSR) and on the risk for their children to be infected with hepatitis B virus. To detect the markers of hepatitis B virus, the passive hemagglutination test, the enzyme immunoassay, and the radioimmunoassay were used. The incidence rate of HBsAg-carriership among expectant mothers was rather high (5.1 +/- 0.52%) in comparison with the control group (3.5 +/- 0.70%). The detection of HBsAg in children 3 months after their birth, i.e. at the term corresponding to the possible incubation period of hepatitis B, suggested that the children were infected at birth. As noted in the course of this investigation, the risk for a newborn to be infected was directly related to the titer of HBsAg, as well as to the presence of HBeAg, in the blood of the carrier mother. A high detection rate of HBsAg was registered among children born to HBsAg-carrier mothers, which makes it possible to consider these children as a high risk group with respect to hepatitis B virus infection and necessitates the development of the system of antiepidemic and prophylactic measures for preventing newborns to be infected with hepatitis B.     

Evaluation of the immune response to hepatitis B vaccination in children aged 1-3 years in Malatya, Turkey

By the end of 1998, Turkey had launched the routine vaccination of infants against hepatitis B. The purpose of the study is to evaluate the immune response in a sample of vaccinated children aged 1-3 years in the city of Malatya. A total of 210 vaccinated children 12 to 48 months old were selected for the study with 30 cluster sampling in the city of Malatya, Turkey. The children were visited at their homes during January-April 2002. The information on demographic characteristics, family's and child's medical history was gathered, childrens' weight and height were measured and blood samples were taken. Anti-HBs, HbsAg and anti-HBc titers were assayed by micro-ELIZA from the sera. The mean age of the children was 26.3 months, 100 (47.6%) were male and 110 (52.4%) were female. Overall, 203 (96.7%) children had protective anti-HBs levels (> or = 10 IU/l), 0.5% showed evidence of natural infection (with positive anti-HBc and anti-HBs titers), 0.5% had acute or chronic infection (with positive HbsAg and anti-HBc titers) and 2.3% were seronegative. Geometric mean titer of anti-HBs among vaccinated children except those who had positive anti-HBc titers was 138.7 mIU/ml (95% CI:124.7-154.2) and seroconversion rates did not differ by age, sex, anthropometric measurements, time after third dose and place of vaccine administered (P > 0.05). The high seroprotection rate over 95% showed that routine infant vaccination program for hepatitis B was successfully carried out in the city Malatya.