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Biomedical subjects

R J Stoltzfus

Publications and source records attributed to R J Stoltzfus.

At least 37 records · Page 2Linked to original sources
PubMed1998

Implications of the Institute of Medicine weight gain recommendations for preventing adverse pregnancy outcomes in black and white women.

OBJECTIVES: This study examined the relation between gestational weight gain and risk of delivering a small-for-gestational-age or large-for-gestational-age infant by race, along with the implications of gaining weight according to the Institute of Medicine guidelines. METHODS: Logistic regression methods were used to identify risk factors for small- and large-for-gestational-age births among 2617 Black and 1253 White women delivering at the Johns Hopkins Hospital between 1987 and 1989. RESULTS: Rate of total weight gain was related to risk of small- and large-for-gestational-age births; the relationship differed according to maternal body mass index but not race. No differences in outcome by race were evident for women with low body mass indexes; among those with average or high indexes, however, Black women were at higher risk of small-for-gestational-age births and at lower risk of large-for-gestational-age births. CONCLUSIONS: Having Black women gain at the upper end of the recommended range is unlikely to produce measurable reductions in small-for-gestational-age births. Some beneficial reductions in the risk of large-for-gestational-age births may occur if weight gain recommendations are lowered for average-weight and overweight White women.

Adolescent↗
PubMed1998

Ancylostoma duodenale is responsible for hookworm infections among pregnant women in the rural plains of Nepal.

Fecal specimens from 292 pregnant women (ages 15-40 yr) and 129 infants (ages 10-20 wk) were examined for helminth eggs by the Kato-Katz method and cultured for helminth larvae identification using a modified Harada Mori method. These specimens were collected from June 1995 through July 1996 in Sarlahi District in the southern rural plains of Nepal. Among pregnant women, the prevalence of helminth infection by the Kato-Katz method was 78.8%, 56.2%, and 7.9% for hookworm, Ascaris lumbricoides, and Trichuris trichiura, respectively. Using the modified Harada-Mori method, 66.1% and 2.0% of women's fecal cultures were positive for hookworm and Strongyloides stercoralis, respectively. All of the cultured hookworm larvae were identified as Ancylostoma duodenale. Among infants, 1 specimen was positive for hookworm and 1 for A. lumbricoides using the Kato-Katz method. The modified Harada Mori method detected no larvae in specimens from infants. There was 81.8% agreement between the 2 methods for the detection of hookworm infection. Ancylostoma duodenale is endemic in this study population and highly prevalent in pregnant women.

Adolescent↗
PubMed1997

Epidemiology of iron deficiency anemia in Zanzibari schoolchildren: the importance of hookworms.

Anemia is estimated to affect one-half of school-age children in developing countries. The school years are an opportune time to intervene, and interventions must be based on sound epidemiologic understanding of the problem in this age group. We report on the distribution of iron deficiency and anemia across age, sex, anthropometric indexes, and parasitic infections in a representative sample of 3595 schoolchildren from Pemba Island, Zanzibar. Iron status was assessed by hemoglobin, erythrocyte protoporphyrin (EP), and serum ferritin concentrations from a venous blood sample. Overall, 62.3% of children were anemic (hemoglobin < 110 g/L), and 82.7% of anemia was associated with iron deficiency. The overall prevalence of iron-deficient erythropoiesis (EP > 90 mumol/mol heme) was 48.5%, and the prevalence of exhausted iron stores (serum ferritin < 12 micrograms/L) was 41.3%. In bivariate analyses, iron status was slightly better in girls than in boys, and was better in children aged 7-11 y than in those older or younger. Hemoglobin but not EP or serum ferritin concentrations were lower in stunted children. Infection with malaria, Trichuris trichiura, Ascaris lumbricoides, and hookworms were all associated with worse iron status; the association with hookworms was strongest by far. In multivariate analyses, hookworm infection intensity was the strongest explanatory variable for hemoglobin, EP, and serum ferritin. Sex, malarial parasitemia, A. lumbricoides infection, and stunting were also retained in the multivariate model for hemoglobin. Twenty-five percent of all anemia, 35% of iron deficiency anemia, and 73% of severe anemia were attributable to hookworm infection; < 10% of anemia was attributable to A. lumbricoides, malaria infection, or stunting. We conclude that anthelminthic therapy is an essential component of anemia control in schoolchildren in whom hookworms are endemic, and should be complemented with school-based iron supplementation.

Adolescent↗
PubMed1997

School-based deworming program yields small improvement in growth of Zanzibari school children after one year.

Efficacy trials of antihelminthic therapies conducted in Africa have reported improvements in children's growth, but nutritional evaluations of large-scale deworming programs are lacking. We evaluated the first-year effect on growth of a school-based deworming program in Zanzibar, where growth retardation occurs in school children. Children in four primary schools were given thrice-yearly mebendazole (500 mg) and compared with children in four schools that received twice-yearly mebendazole and children in four non-program schools. Evaluation schools were randomly selected and allocated to control, twice-yearly or thrice-yearly deworming. Approximately 1000 children in each program group completed the 1-y follow-up. Children <10 y old gained 0.27 kg more weight (P < 0.05) and 0.13 cm more height (P = 0.20) in the twice-yearly group, and 0. 20 kg more weight (P = 0.07) and 0.30 cm more height (P < 0.01) in the thrice-yearly group, compared with the control group. Children <10 y old with higher heights-for-age at baseline had higher weight and height gains in response to deworming. In children >/=10 y old, overall program effects on height or weight gains were not significant. But in this age range, younger boys had significant improvements in height gain with thrice-yearly deworming, and children with higher heights-for-age had greater improvements in weight gain with deworming. We conclude that the deworming program improved the growth of school children, especially children who were younger and less stunted, but the improvements were small. More effective antihelminthic regimens or additional dietary or disease control interventions may be needed to substantially improve the growth of school children in areas such as Zanzibar.

Animals↗
PubMed1997

Serum ferritin, erythrocyte protoporphyrin and hemoglobin are valid indicators of iron status of school children in a malaria-holoendemic population.

In many African populations, the prevalences of both iron deficiency and malarial infection exceed 50%. The control of iron deficiency anemia is of urgent public health importance, but assessment of iron status in these contexts has been controversial because of the effects of malarial disease on common iron status indicators. We assessed iron status in 3605 school children in Zanzibar by measuring hemoglobin, erythrocyte protoporphyrin (EP) and serum ferritin concentrations. Malaria parasitemia was quantified by counting against leukocytes. Iron deficiency was highly prevalent: 62.4% of hemoglobin concentrations were <110 g/L, 59.7% of EP values were >80 micromol/mol heme, and 41.5% of ferritin concentrations were <12 microg/L. Prevalence of Plasmodium falciparum parasitemia was 60.6%, but <1% of children had densities above 5000 parasites/microL blood. Neither hemoglobin nor EP concentration was associated with malaria parasite density, but prevalence of abnormal values increased by < or = 25% with parasite density. Erythrocyte protoporphyrin and hemoglobin were strongly inversely related regardless of parasite density. The relationship of EP to hemoglobin was slightly attenuated when parasite density exceeded 1000 parasites/microL blood. Ferritin rose by 1.5 microg/L per 1000 parasites/microL for parasite densities >1000 parasites/microL, but the relationship of ferritin to hemoglobin or EP was strong even when parasite densities exceeded this cutoff. The population prevalences of iron deficiency were not significantly biased by malarial infection. In this population of school children, iron status assessment using these indicators was not seriously influenced by malarial infection. We hypothesize that these indicators perform reliably in populations in which malarial infection is infrequently associated with disease; namely older children and adults in holoendemic environments.

Adolescent↗
PubMed1997

Linear growth retardation in Zanzibari school children.

This paper describes the longitudinal changes in height and weight of children in school grades 1-3 on Pemba Island, Zanzibar, a poor rural population in which parasitic infections and anemia are highly prevalent. Heights and weights of children were measured at base line, and 6 and 12 mo later, and were compared with U.S. reference data. At base line, the prevalence of height-for-age Z-score < -2 rose from 14% in 7-y-old children to 83% in 13-y-old children. Prevalence of weight-for-age Z-score < -2 in children < 10 y was approximately 10% or less. Median 6-mo height increments for Pembian boys were around the 5th percentile at age 8 and around the 10th percentile from age 9 to 13 y. Height increments for girls improved from below the 25th percentile to above the median in this age range. Based on the longitudinal yearly gains observed, boys accumulate a height deficit of 11.9 cm and girls 8.5 cm, relative to the reference population. In multivariate analyses, a small part of the variability in growth increments was explained by ascariasis and anemia (for weight gain) and schistosomiasis (for height gain). A review of other growth data from rural African Bantu populations provides supporting evidence that stunting occurs in older as well as younger children. It has been controversial whether school-based health and nutrition interventions could induce catch-up growth in already stunted children. Our results suggest that appropriate interventions might actually prevent stunting in late childhood.

Adolescent↗
PubMed1997

Hookworm control as a strategy to prevent iron deficiency.

The hookworms Necator americanus and Ancylostoma duodenale infect approximately 1 billion people worldwide. The prevalence of hookworm infection increases with age in children, typically reaching a plateau in late adolescence, whereas the intensity of infection may continue to increase throughout adulthood. Hookworms cause intestinal blood loss in amounts proportional to the number of adult worms in the gut. The relationship between hookworm infection intensity and hemoglobin concentration is evident in epidemiologic studies, but may be apparent only above a threshold worm burden that is related to the iron stores of the population. Current hookworm control efforts are focused on reducing infection load and transmission potential through periodic anthelminthic chemotherapy. Several controlled trials have demonstrated a positive impact of anthelminthic treatment on hemoglobin levels, with best results obtained in settings where iron intakes were also increased. Evidence suggests that anthelminthic programs will have modest impacts on iron deficiency anemia in the short term, with greater impacts on more severe anemia. Hookworms are an important cause of anemia in women, who are often overlooked by current helminth control programs. Current WHO recommendations for use of anthelminthics in schoolchildren and women are reviewed. There is a need to clarify whether hookworms are an important etiology of iron deficiency anemia in preschool children.

Adolescent↗
PubMed1996

Determinants of gestational weight gain outside the recommended ranges among black and white women.

OBJECTIVES: To identify factors influencing risk of gaining outside the Institute of Medicine recommendations for pregnancy weight gain, and to determine whether these factors differ by race. METHODS: Multivariate methods were used to identify risk factors for under- and over-gain among 2617 black and 1253 white women delivering at the Johns Hopkins Hospital during 1987-1989. RESULTS: Only 28.2% of black women and 32.5% of white women gained the recommended amounts of weight during pregnancy. Maternal pre-pregnancy body mass index (BMI), height, parity, education, smoking, hypertension, duration of pregnancy, and fetal sex influenced risk for under-gain or over-gain. Black women were 1.51 (95% confidence interval [CI] 1.23-1.85) times more likely to under-gain, but 0.89 (95% CI 0.74-1.08) times less likely to over-gain than white women. No interactions were found between any factor examined and BMI or race. CONCLUSION: Only about one-third of women are gaining the recommended amounts of weight during pregnancy. Black women are at increased risk for gaining less weight than recommended, and selected maternal characteristics associated with race do not explain this difference. Further, risk factors for under-or over-gain do not differ between black and white women.

Adult↗
PubMed1996

Hemoquant determination of hookworm-related blood loss and its role in iron deficiency in African children.

Iron deficiency remains the most prevalent form of human malnutrition, and current interventions to control it have not decreased the global prevalence. Hookworm control activities are becoming more widely implemented, but the importance of these efforts to prevent anemia in populations is not well-defined. We studied the relationships among hookworm infection, intestinal blood loss, and iron status of 203 Zanzibari school children. Helminth infection intensity was quantified by fecal egg counts, and iron deficiency anemia was defined by low hemoglobin and serum ferritin concentrations. Intestinal blood loss was quantified by measuring fecal heme and heme breakdown products as porphyrin, a noninvasive method that has not been used previously to assess hookworm blood loss. Intestinal blood loss was strongly and linearly related to hookworm egg counts. The degree of degradation of fecal heme indicated that blood loss occurred in the upper gastrointestinal tract, compatible with the behavior of hookworms. Trichuris trichiura and Ascaris lumbricoides infections were also common, but did not contribute significantly to intestinal blood loss in this population. The prevalence of iron deficiency anemia increased steadily as hookworm infection intensity and intestinal blood loss increased. In the context of a poor diet, as exists in Zanzibar and many tropical countries, hookworm-related blood loss contributes dramatically to anemia. In such contexts, hookworm control is a feasible and essential component of anemia control. Determination of fecal heme is relatively simple and noninvasive and may be a useful tool for measuring the impact of hookworm control activities.

Anemia, Iron-Deficiency↗
PubMed1995

Influence of maternal anthropometric status and birth weight on the risk of cesarean delivery.

OBJECTIVE: To determine whether greater weight gain during pregnancy is associated with an increased risk of cesarean delivery, and, if so, whether this effect is explained by the positive influence of weight gain on birth weight and if there is a threshold of pregnancy weight gain above which the risk of cesarean delivery is increased differentially. METHODS: We analyzed live births at Johns Hopkins Hospital for the period 1987-1989. A multiple logistic regression model was used to evaluate the risk of cesarean delivery, recorded in the hospital's perinatal data base. RESULTS: The study sample contained 4346 patients, 1086 of whom delivered by cesarean. Associated independently with an increased risk of cesarean delivery were the following: 1) greater weight gain during pregnancy, 2) older maternal age, 3) greater maternal prepregnant body mass index, 4) maternal height of 1.57 m or less, 5) the diagnosis of preeclampsia during current pregnancy, and 6) carrying a fetus weighing more than 3591 g at birth. An additional risk factor for cesarean delivery was a fetus less than 2847 g at birth, with the risk more marked the lower the gestational age. Maternal height of 1.73 m or more and a history of at least one previous viable pregnancy were associated independently with a decreased risk of cesarean delivery. CONCLUSION: The risk of cesarean delivery increases linearly with pregnancy weight gain, independent of birth weight. No specific threshold of weight gain can be determined above which the cesarean risk climbs more rapidly.

Adult↗
PubMed1995

Breast-milk vitamin A as an indicator of the vitamin A status of women and infants.

This article reviews the evidence for using breast-milk vitamin A as an indicator of vitamin A status and provides technical information for researchers who want to use this indicator to assess the vitamin A status of women and breast-fed children. Breast-milk vitamin A is a unique indicator for assessing the vitamin A status of lactating women and their breast-fed infants, and has recently been recommended by WHO for use in monitoring global elimination of vitamin A deficiency. Assessing breast-milk vitamin A is less invasive than alternative approaches for assessing a mother's vitamin A status and not at all invasive for her infant. Collection of milk samples in the field is generally feasible and acceptable. Breast-milk vitamin A appears to be an especially good indicator for measuring the impact of vitamin A interventions on women and infants, and for this purpose, it is more responsive than other indicators.

Feasibility Studies↗
PubMed1993

Growth monitoring.

Explore the source record for details and available documents.

Anthropometry↗
PubMed1993

Conjunctival impression cytology as an indicator of vitamin A status in lactating Indonesian women.

Conjunctival impression cytology (CIC) has been used to assess the vitamin A status of children but not women. We used CIC in a randomized controlled trial of high-dose vitamin A supplementation in Indonesian women. We report its association with biochemical indicators and evaluate its usefulness for several assessment functions, using two definitions for abnormal CIC. Serum retinol concentrations of all women and milk vitamin A concentrations of unsupplemented women decreased with worsening CIC category. CIC indicated risk of low milk vitamin A and low infant serum retinol with low sensitivity and high specificity. CIC did not identify women who benefited from supplementation. The usefulness of CIC to measure response to supplementation was limited by the low prevalence of abnormal status in these women. CIC may be a useful indicator of vitamin A deficiency in women or their breast-fed infants, or to measure response to supplementation, when a more sensitive cutoff point for abnormal status is used.

Conjunctiva↗
PubMed1993

Evaluation of indicators for use in vitamin A intervention trials targeted at women.

This paper examines the ability of three indicators to detect changes in women's vitamin A status. Serum retinol concentration, milk vitamin A concentration, and milk vitamin A per gram milk fat were used to assess the vitamin A status of mildly deficient Indonesian women before and after supplementation in a randomized intervention trial. Choice of indicator made a fourfold difference in the sample size required to measure a statistically significant change in vitamin A status. Milk vitamin A per gram milk fat was the best indicator of response, milk vitamin A concentration was intermediate, and serum retinol concentration performed most poorly. Serum retinol concentration was equally responsive across the range of vitamin A status in this population. The milk indicators were more responsive among women of lower status than women of higher status. Milk vitamin A is an efficient indicator for monitoring the effects of vitamin A interventions in women.

Adult↗
PubMed1993

High dose vitamin A supplementation of breast-feeding Indonesian mothers: effects on the vitamin A status of mother and infant.

For regions where vitamin A deficiency is common, high dose vitamin A supplementation of lactating mothers is currently recommended, but the effects of this intervention have not been carefully evaluated. We conducted a randomized, double-blind trial in which 153 Indonesian mothers 1-3 wk postpartum received either a capsule containing 312 mumol of vitamin A as retinyl palmitate or a placebo. Mothers' serum retinol concentrations in the vitamin A group tended to be lower than in the placebo group at baseline but higher at 3 mo postpartum (1.39 vs. 1.24 mumol/L, P = 0.03) and 6 mo postpartum (1.23 vs. 1.08 mumol/L, P < 0.01). The milk retinol concentrations of the vitamin A group were higher than those of the placebo group by 0.48 to 1.18 mumol/L at 1-8 mo postpartum (P < 0.05). Among the infants at 6 mo of age, the prevalences of low serum retinol concentration (< 0.52 mumol/L) were 36 and 15% in the placebo and vitamin A groups, respectively (P < 0.005), and the prevalences of low vitamin A stores (assessed by relative dose response) were 23 and 10%, respectively (P < 0.03). High dose vitamin A supplementation of lactating mothers is an efficacious way to improve the vitamin A status of both mother and breast-fed infant.

Adolescent↗