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M L Kumar

Publications and source records attributed to M L Kumar.

At least 19 recordsLinked to original sources
PubMed2000

Measles vaccine immunogenicity and antibody persistence in 12 vs 15-month old infants.

HYPOTHESIS: Maternal measles immunity in the United States today is primarily vaccine induced, with corresponding lower antibody titers in infants, as compared to infants born in an earlier era to mothers with naturally acquired measles immunity. We hypothesized that, due to lower titer of passively transferred maternal measles antibody, administration of measles vaccine at 12 months of age would result in seroconversion and antibody persistence comparable to vaccination at 15 months of age. POPULATION: Children at both an urban hospital and a suburban clinic. METHODS: Informed consent was obtained from mothers for the infants to receive M-M-R(R)II vaccine at either 12 or 15 months and to have serum samples obtained before vaccination and 4 weeks post-vaccination (PV). Between 9 and 39 months PV, a third serum sample was obtained from 28% of seroconverters. A diary of adverse experiences was kept for 3 weeks PV. Sera were assayed by a microneutralization assay (NT) and an enzyme immunoassay (EIA) for measles antibody. RESULTS: Both age groups tolerated vaccination well with minor and transient side effects. Forty-four of 47 (94%) 12-month-old infants seroconverted by NT, compared to 45 of 46 (98%) 15-month-olds (p=NS). There was no statistically significant decline in median NT titers or EIA titers in nineteen 12-month-olds and thirteen 15-month olds followed for 9-39 months PV. CONCLUSION: This study showed comparable serologic responses in 12- vs 15-month-old infants born to measles vaccine-immune mothers; however, the sample size was too small to have adequate power and further study is indicated. Titers of antibody were constant in both the 12-month-old and the 15-month-old infants, over a 9-39 month period, suggesting that waning immunity over this period of time is not a problem in either age group.

Age Factors↗
PubMed1998

Immune response to measles vaccine in 6-month-old infants of measles seronegative mothers.

Determinants of measles vaccine-induced immune response in infancy include maternal immune status and the infant's age at immunization. In a previously published study, 74% of 19 6-month-old infants developed neutralizing antibody. Two of the infants were born to measles seronegative mothers. In order to (1) assess the prevalence of measles seronegativity in a population of US mothers born after 1960 and (2) assess the immunogenicity of standard titer measles vaccine in 6-month-old infants of measles seronegative mothers, mothers with healthy term (> or = 37 weeks gestation) infants attending well child care clinics at MetroHealth Medical Center were prospectively screened for measles antibody by EIA. If negative, maternal samples were retested for neutralization (NT) antibody. Fifteen of 169 women were seronegative by both assays. Six-month-old infants of 9 of these 15 seronegative mothers were enrolled in the pediatric vaccine study. Serological response of these 9 infants to monovalent measles vaccine (Attenuvax) was compared to the responses of 17 6-month-old infants of seropositive mothers and 15 15-month-old toddlers from our previous study. All 9 infants of seronegative mothers became EIA seropositive after the vaccine compared to 9 of 17 6-month-old infants born to seropositive mothers (p = 0.02). Differences in NT seroconversion rates (100% vs 70.6%) were not statistically significant. The comparison group of 15-month-old vaccinees showed 100% seroconversion by both assays. The NT geometric mean titer (GMT) was higher in the 15-month-old toddlers than in the 6-month-old infants born to seronegative mothers (87.2 vs 33.9, p < 0.01), suggesting age-related differences in humoral immune response unrelated to passively transferred maternal antibody.

Antibodies, Viral↗
PubMed1997

A comparative trial of standard or high-dose S subunit recombinant hepatitis B vaccine versus a vaccine containing S subunit, pre-S1, and pre-S2 particles for revaccination of healthy adult nonresponders.

The efficacy of 10-microg and 40-microg hepatitis B vaccines was compared with that of an investigational vaccine containing pre-S1, pre-S2, and S subunit particles (mixed particle vaccine) in inducing protective anti-hepatitis B surface antigen (anti-HBs) concentrations in 46 otherwise healthy persons who previously did not develop measurable levels of antibodies to at least one complete course of vaccine. A statistically significant difference was seen in the percentage of subjects who developed protective levels of anti-HBs (> or = 10 mIU/mL) with three 40-microg doses of S subunit vaccine versus the other groups. One hundred percent of the 40-microg dose group developed protective anti-HBs titers. No difference in adverse effects was noted.

Adult↗
PubMed1997

A long-term prospective study of varicella vaccine in healthy children.

BACKGROUND: Studies in Japan and the United States have shown that varicella vaccine is both safe and efficacious. In 1984, we undertook a 10-year prospective study using a research lot of Oka/Merck varicella vaccine to assess antibody persistence and breakthrough chickenpox rates. In 1987, we began a similar prospective study with lots made in production facilities that ended after 6 years because many children were given a second dose. The purpose of this study is to report humoral antibody persistence and breakthrough chickenpox rates after 6 to 10 years of prospective follow-up. METHODS: One hundred forty-three seronegative children received a research lot (950 plaque-forming units/dose) with 97.9% seroconversion by an assay for fluorescent antibody to membrane antigen (FAMA). One hundred thirty-eight children received production lots (1145 to 3265 plaque-forming units/dose) with 93.5% seroconversion. Yearly chickenpox exposure surveys were completed by phone, and children were seen by a study nurse whenever chickenpox was suspected. A subset in each group had serum collected every 2 years and tested for FAMA antibody. RESULTS: In the research group there have been 25 cases of chickenpox in 137 seroconverters in a period of more than 10 years (yearly rate of 1.7%). In the production lot group there have been 22 cases of chickenpox in 129 seroconverters in a 6-year period (yearly rate of 2.8%). In the research group the median titer rose from 1:16 to 1:64 between 1 and 10 years. In the production group, the median titer did not change between 1, 2, and 4 years. Median antibody titers were compared between the research and production groups at 1, 2, and 4 years and did not differ. The rate of development of modified chickenpox has not increased with time since vaccination, and neither has the case severity. Children with FAMA titers </=8 at 6-weeks' postvaccination were four times more likely to develop chickenpox than those with titers >/=64. CONCLUSIONS: 1) Modified chickenpox has occurred in approximately 2% to 3% of vaccinees per year, regardless of the vaccine lot given. 2) FAMA titers have risen between 1 and 10 years in research lot recipients and remained the same in production lot recipients. 3) The likelihood of modified chickenpox developing is inversely related to the 6-week postvaccination FAMA titer.

Adolescent↗
PubMed1996

Antibody persistence after primary measles-mumps-rubella vaccine and response to a second dose given at four to six vs. eleven to thirteen years.

BACKGROUND: Since 1989 the American Academy of Pediatrics and the ACIP have recommended a second dose of measles-mumps-rubella vaccine (M-M-R-II) at either school entry or age 11 to 13 years. Unfortunately few studies are available to compare responses to vaccine at the two ages. We performed a prospective trial to determine the persistence of antibody to measles, mumps and rubella vaccination in two age groups and the response to a second dose given at either 4 to 6 or 11 to 13 years. METHODS: Thirty-eight children 4 to 6 years old and 57 children 11 to 13 years old were given a second dose of M-M-R-II as they presented for yearly examinations. All had received the first dose at > or = 15 months of age. Measles and rubella antibody were measured by enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody (NT) assay, and mumps antibody was measured by an ELISA method only. An IgM-ELISA antibody assay for measles was used in selected children. Prevaccination and 3- to 4-week post-vaccination sera were obtained. Measles ELISA, measles-neutralizing antibody (NT) and rubella-neutralizing antibody (NT) assays were performed in all children. Seventy-nine of the 95 children had sufficient sera for repeat measles tests, as well as mumps and rubella ELISA determinations. RESULTS: Before the second dose ELISA seropositivity rates for measles and mumps were not significantly different between the two groups. Rubella ELISA seropositivity was 67% in 11- to 13-year-olds, compared with 90% in 4- to 6-year-olds (P < 0.01), suggestive of waning immunity. Rubella NT seropositivity was also lower in 11- to 13-year-olds than in 4- to 6-year-olds (63% vs. 100%, P < 0.01). After revaccination, 100% of the children become seropositive for all 3 antibodies. We performed measles IgM-ELISA testing on all 17 measles-seronegative children, as well as 15 seropositive children and 19 children who were 1 month postvaccination with the first M-M-R-II at 15 months. The purpose was to determine whether the seronegative children were primary or secondary failures. Five of the 17 children with undetectable pre-second dose antibody made IgM measles antibody after revaccination, suggesting that they were primary vaccine failures. CONCLUSIONS: Because all children became seropositive after revaccination, the age of administration can be based on the convenience of vaccine scheduling. However, in view of the apparent decline in rubella antibodies at 11 to 13 years, future studies of rubella vaccination should address the issue of whether earlier boosting leads to greater susceptibility at the time of reproductive age.

Adolescent↗
PubMed1995

Safety and cellular and humoral immune responses of a booster dose of varicella vaccine 6 years after primary immunization.

Four hundred nineteen children and adolescents immunized with live varicella vaccine 4-6 years earlier were enrolled in a study to evaluate the safety and immune response to a booster dose containing approximately 3300 pfu of virus. Of the subjects, 99% (414/419) maintained antibody to varicella zoster virus (VZV) with a geometric mean titer of 25.7 and mean stimulation index (SI) for VZV-specific lymphoproliferation response of 40.3 +/- 5.3 (SE). Some 7-10 days after the booster immunization, seropositivity rates increased to 100% (302/302), and GMT was 143.6 (anamnestic response). At 6 weeks after the booster inoculation, a subset of subjects had 100% seropositivity (74/74) with a GMT of 218.8 and an SI of 58.6. After 3 months, seropositivity was 100% (358/358), GMT was 119.0, and SI was 61.4.

Adolescent↗
PubMed1995

Acute respiratory illness in older community residents.

OBJECTIVE: To describe the 3-year incidence of acute respiratory illness in a population of noninstitutionalized elderly persons. DESIGN: Cohort analytic study with an observation period of 3 years. SETTING: Large midwestern urban community. SUBJECTS: 574 noninstitutionalized persons aged 65 years and older, of whom 349 were living independently, 110 were in congregate settings, and 115 were living independently and regularly caring for small children. METHODS: Subjects were interviewed and examined by nurse practitioners at intake and every 4 months. Acute illness and convalescent visits were made when illnesses were reported by participants. MAIN OUTCOME MEASURES: The incidence of acute respiratory illness was used to test the hypothesis that elderly persons taking care of children have the highest incidence, congregate-dwellers intermediate incidence, and those living independently the lowest incidence. RESULTS: The average incidence of acute respiratory illness was 2.5 per 100 person months, comparable to rates reported in the National Health Survey. The incidence of respiratory illness was significantly greater in subjects living in congregate settings or regularly caring for young children. Similarly, greater proportions of persons in the congregate and child-care groups reported at least one episode of illness (P < .05). A more detailed analysis of exposure shows that acute respiratory illness was significantly more common in subjects who had contact with children (P < .05). This risk was definitely present during the months November through February, and probably also during July through October, but was not observed for March through June. CONCLUSIONS: Elderly persons living in the community experience low rates of acute upper respiratory illness. Contact with children increases their risk of developing such illnesses during certain seasons of the year.

Activities of Daily Living↗
PubMed1994

Measles vaccine immunogenicity in 6- versus 15-month-old infants born to mothers in the measles vaccine era.

HYPOTHESIS: The low titer of measles antibody in infants of mothers with vaccine-induced immunity may allow immunization against measles before 15 months of age. METHODS: Six- and 15-month-old infants born to mothers < or = 30 years of age with no history of measles were recruited. Infants enrolled at 6 months of age were immunized with monovalent measles vaccine (Attenuvax), and maternal serum and infant pre- and postvaccination sera were obtained. Those enrolled for primary vaccination at 15 months of age received either Attenuvax (N = 12) or M-M-RII (N = 3). Six-month-old infants were revaccinated with M-M-RII at 15 months of age; pre- and postrevaccination sera were again obtained. Three antibody assays were used: a measles neutralizing assay (NT) and two enzyme immunoassays (EIA) for measles IgG and measles IgM. RESULTS: Among primary vaccinees, 14 of 19 infants aged 6 months (74%) developed NT antibody, as did 15 of 15 infants aged 15 months (100%). The reciprocal geometric mean titer of 6-month-old seroresponders was 23.3, significantly lower than that of the 15-month-old primary vaccinees (87.7, P < .001). Primary seroconversion rates by EIA were 53% for 6-month-old infants and 100% for those aged 15 months. Revaccination of infants who had received Attenuvax at 6 months of age resulted in 100% NT positivity; the geometric mean titer rose to equal that of the group given primary immunization at 15 months of age. Measles IgM antibody was detected in 10 of 14 infants tested 1 month after primary vaccination at 15 months, but was not detected in any of the revaccinated infants after the second dose at 15 months of age (P < .001). CONCLUSIONS: 1) Immunization with measles vaccine in infants born to vaccine-immune mothers at 6 months of age induced NT antibody in 74% of infants. 2) Revaccination of prior 6-month-old vaccinees at 15 months resulted in antibody titers equivalent to 15-month-old vaccinees. 3) Lack of an IgM response following revaccination suggests that even seronegative infants may be primed to respond on re-exposure to measles.

Adult↗
PubMed1993

Respiratory syncytial virus-specific immunoglobulins in preterm infants.

Incomplete transfer of maternal antibodies specific to respiratory syncytial virus (RSV) has been suggested as an explanation for the increased risk of RSV infections in preterm infants. Antibodies directed against the two major RSV envelope glycoproteins, F and G, are protective in vitro and in vivo. Our study was conducted to measure IgG, IgG1, IgG2, and IgG3 antibody titers against the RSV F and G glycoproteins in cord sera from infants born at different gestational ages. Titers of neutralizing antibody were measured in a subset of the subjects. The mean (+/- SEM) log2 titers of IgG antibodies directed against the RSV F and G glycoproteins were significantly lower in infants born at < or = 28 weeks of gestation (11.2 and 10.8 for F and G glycoproteins, respectively) than in term infants (12.6 and 12.8 for F and G, respectively) (p < 0.05). Preterm infants born at > or = 29 weeks had titers of antibodies against the F glycoprotein comparable to those of term infants. The highest titers of RSV-specific antibodies were in the IgG1 and IgG2 subclasses. Mean (+/- SEM) neutralizing antibody titers were lower in infants born at < or = 28 weeks (7.7 +/- 0.4) than in term infants (10.2 +/- 0.3) (p < 0.001). We conclude that (1) RSV-specific antibody titers were lower than in term infants only in the most premature infants (< or = 28 weeks) and (2) preterm infants born at > or = 29 or > or = 33 weeks of gestation had RSV-specific titers against F and G glycoproteins, respectively, that were comparable to those of term infants. Preterm infants born at < or = 28 weeks could represent a target population for passive immunoprophylaxis.

Antibodies, Viral↗
PubMed1993

Larvicidal and chemosterilant activity of Annona squamosa alkaloids against Anopheles stephensi.

Alkaloids isolated from Annona squamosa have shown larvicidal growth-regulating and chemosterilant activities against Anopheles stephensi at concentrations of 50 to 200 ppm. Adults exposed as larvae to different treatments showed reduced fecundity and fertility in females. Mortality in the larvae, pupae and adults produced about a 52-92% decrease in the laboratory experiment. The total developmental period was slightly reduced from the control. Treatment with the alkaloids had a significant effect on the mortality, emergence and reproductive physiology of An. stephensi.

Alkaloids↗
PubMed1992

Study on the physico-chemical characteristics of breeding grounds in relation to the population density of Anopheles stephensi.

The present study which was based on the quarterly sampling and estimation of various physico-chemical factors throw light on the three significant points with regard to the population build up of Anopheles stephensi. Slightly alkaline pH is essential for higher population density, lower the salinity, higher the population density and higher amount of free ammonia in the water is accounted for the higher population density of A. stephensi.

Ammonia↗
PubMed1991

Prevaccination serologic screening for measles in health care workers.

A model was developed from which the cost-effectiveness of prevaccination serologic screening for measles could be estimated, for any combination of antibody screening costs and prevalence of antibody to measles. This model was tested using sera obtained prospectively from 222 health care workers, including 181 born in or after 1957 who had no history of measles, no measles vaccine after 1980, and no documentation of immunity to measles. In addition, 41 subjects born before 1957 who had no history of measles were studied. A rapid, reliable, and inexpensive ($5 per test) commercial ELISA was used to test for antibodies to measles; its seroprevalence in the subject population was 86%. From the model, it was estimated that prevaccination serologic testing would be cost-effective if antibody screening cost less than or equal to $12.75 per test. In this subject population, prevaccination serologic screening for measles was cost-effective.

Adult↗
PubMed1991

Human parvovirus B19 and its associated diseases.

From the point of view of obstetrics and pediatrics, the importance of B19 infection lies in the potential for intraueterine infection following maternal B19 infection. Ongoing prospective studies of B19 infection in pregnant women indicate a risk of adverse pregnancy outcomes considerably lower than previous estimates from retrospective studies and case reports. The occurrence, however, of severe nonimmune hydrops or stillbirths or both in even a small percentage of progeny of B19-infected pregnant women is a concern. It thus behooves physicians caring for pregnant women and their offspring to be thoroughly familiar with B19 and issues related to B19 infection in pregnancy.

Anemia↗