Biomedical subjects

L S Stephenson

Publications and source records attributed to L S Stephenson.

At least 37 records · Page 2Linked to original sources

PubMed1993

Physical fitness, growth and appetite of Kenyan school boys with hookworm, Trichuris trichiura and Ascaris lumbricoides infections are improved four months after a single dose of albendazole.

We studied physical fitness with the Harvard Step Test, growth, and appetite in primary school boys infected with hookworm (96% baseline prevalence), Trichuris trichiura (98% prevalence) and Ascaris lumbricoides (41% prevalence) who received a single 600-mg dose of albendazole or an identical placebo. Boys were examined, allocated at random within pairs by descending hookworm egg count to placebo (n = 26) or albendazole (n = 27) groups, treated, and re-examined 4 mo later. Four months after treatment, the albendazole group showed highly significant improvements in fitness score, resting heart rate, and heart rates at 1, 2, 3 and 4 min after the Harvard Step Test, whereas the placebo group had not changed significantly. The albendazole group also exhibited significantly more rapid growth judged by weight gain (1.0 kg greater than the placebo group, P < 0.0002), height increment (0.6 cm more, P < 0.003), arm circumference (0.3 cm more, P < 0.0002), and triceps and subscapular skinfolds (1.0 mm more, P < 0.0002), and showed improved appetite with objective and subjective measures. We conclude that single-dose treatment with albendazole can allow improved physical fitness, growth, and appetite in school-age children in areas where these helminths and poor growth are highly prevalent.

Adolescent↗

PubMed1990

Metrifonate or praziquantel treatment improves physical fitness and appetite of Kenyan schoolboys with Schistosoma haematobium and hookworm infections.

We studied physical fitness, as determined by the Harvard Step Test (HST), and appetite, as measured by the consumption of a morning snack (maize meal porridge), in primary school boys infected with Schistosoma haematobium (100% baseline prevalence) and hookworm (94-100% prevalence) who received a single dose of metrifonate (MT, 10 mg/kg body weight) or praziquantel (PR, 40 mg/kg body weight), or a placebo (PL). Five weeks after treatment, HST scores and porridge intake increased significantly in the MT and PR groups, but the PL group did not change. At the second examination, the MT group showed a significant decrease in S. haematobium egg counts (mean = 180 vs. 14 eggs/10 ml adj, P less than 0.0002, 82% egg reduction in arithmetic means) as did the PR group (mean = 198 vs. 0.1 eggs/10 ml adj, P less than 0.0002, 99.9% reduction); the egg counts in the PL group did not change. The MT group also exhibited a significant decrease in hookworm egg counts (mean = 1,550 vs. 75 eggs per gram feces [epg], P less than 0.0005, 80% reduction). Treatment with either drug may allow improved physical fitness and appetite in areas where S. haematobium and protein-energy malnutrition are highly prevalent.

Adolescent↗

PubMed1989

The effect of iron therapy on malarial infection in Papua New Guinean schoolchildren.

The effect of iron therapy on malarial infection was investigated in Papua New Guinea, where malaria is endemic. Prepubescent schoolchildren with hemoglobin levels of 8-12 g/dl were randomly assigned to receive either 200 mg ferrous sulfate or a placebo twice daily for 16 weeks. Iron status and malarial infection were assessed at baseline, after 6 and 16 weeks of therapy, and 8 weeks after therapy was discontinued. Iron status was significantly improved by the treatment. The treatment did not significantly affect parasite rate, parasite density, or levels of anti-malarial IgG. No changes in spleen size were observed in either group. Furthermore, there was no significant difference between the groups in reported episodes of suspected malaria during the therapy. These results suggest that, in malaria endemic areas, oral treatment for iron deficiency can be carried out in semi-immune or immune schoolchildren without adverse consequences.

Anemia, Hypochromic↗

PubMed1989

Single dose metrifonate or praziquantel treatment in Kenyan children. I. Effects on Schistosoma haematobium, hookworm, hemoglobin levels, splenomegaly, and hepatomegaly.

The relationships between S. haematobium, hookworm, malaria, hemoglobin level, splenomegaly, and hepatomegaly before and 8 months after treatment with a single dose of metrifonate or praziquantel were studied in Kenyan primary schoolchildren in an area where anemia, S. haematobium, and hookworm are common and malaria is holoendemic. Children with light to moderate S. haematobium infection were examined (Exam 1), assigned at random to groups receiving placebo (PL, n = 104), metrifonate (MT, n = 103, dose 10 mg/kg body weight) or praziquantel (PR, n = 105, dose 40 mg/kg body weight), treated, and examined 8 months later (Exam 2). At Exam 2, 62% of the MT group still passed S. haematobium eggs vs. 13% in the PR group. Egg reduction rates were substantial in both groups, but greater in the PR group; geometric mean egg counts in both groups were very low. Prevalence and intensity in the PL group had not changed between exams. Hookworm egg counts were significantly reduced in the MT group (59% egg reduction rate); malarial infection had increased in all 3 groups, presumably due to the long rainy season between exams. Hookworm egg count was the most significant predictor of initial hemoglobin level, followed by S. haematobium egg count and presence of malarial infection. Treatment with a single dose of MT or PR can produce substantial decreases in S. haematobium infection 8 months later.

Adolescent↗

PubMed1989

Single dose metrifonate or praziquantel treatment in Kenyan children. II. Effects on growth in relation to Schistosoma haematobium and hookworm egg counts.

We studied the growth of comparable groups of children with light to moderate Schistosoma haematobium infections who received a single dose of metrifonate (MT, 10 mg/kg), praziquantel (PR, 40 mg/kg), or a placebo (PL). Children were re-examined 8 months later. The MT and PR groups gained significantly more than the placebo group in weight, percent weight for age, percent weight for height, arm circumference, and in triceps and subscapular skinfold thicknesses. The MT and PR groups did not differ significantly from each other. The placebo group showed statistically significant decreases or no change between exams in percent weight for age, percent weight for height, percent arm circumference, and both skinfold thicknesses; the MT and PR groups exhibited highly significant increases in these parameters (P less than 0.0002). The intensity of S. haematobium infection had decreased significantly in both the MT and PR groups, but especially in the PR group. Multiple regression analyses showed that a decrease in the intensity of S. haematobium infection was by far the most important predictor of growth rate after treatment for all 5 anthropometric measures tested; decreases in the intensity of hookworm infection was also significant for 2 of the 5 measures.

Adolescent↗

PubMed1989

Treatment with a single dose of albendazole improves growth of Kenyan schoolchildren with hookworm, Trichuris trichiura, and Ascaris lumbricoides infections.

We studied the growth of primary schoolchildren with hookworm (87%), T. trichiura (97%), and A. lumbricoides (49%) who received a single 400 mg dose of albendazole or an identical placebo. Children were allocated at random to placebo (PL, n = 72) or albendazole (A, n = 78) groups, treated, and re-examined 6 months later. The A group gained significantly more than the PL group in weight (1.3 kg), percent weight for age (4.5% age points), percent height for age (0.5% age points), percent weight for height (4.3% age points), percent arm circumference (2.9% age points), and in triceps and subscapular skinfold thicknesses (1.2 mm). The PL group showed significant decreases between exams in percent weight for age, percent height for age, percent weight for height, percent arm circumference for age, and skinfold thicknesses for age. The A group had highly significant increases (P less than 0.0002) in all of these parameters except height for age. From Exam 1 to 2, the A group exhibited decreases (P less than 0.0002) in geometric means eggs per gram of feces (epg): for hookworm, means = 1,183 epg at Exam 1 vs. 136 epg at Exam 2 (67% egg reduction); for T. trichiura, means = 2,857 epg at Exam 1 vs. 1,061 epg at Exam 2 (28% egg reduction); and for A. lumbricoides, means = 86 epg at Exam 1 vs. 2 epg at Exam 2 (91% egg reduction). The PL group had a borderline increase in geometric means hookworm egg count, no significant change in T. trichiura egg count, and a small but significant decrease in A. lumbricoides egg count. Decreases in intensities of all infections were significant predictors of growth improvement. Hookworm egg count entered the equations for all 6 measurements, and A. lumbricoides and T. trichiura entered 4/6 equations. Single dose treatment with albendazole, despite continual exposure to infection, can permit improved growth rates in areas where intestinal helminths and protein-energy malnutrition are highly prevalent.

Adolescent↗

PubMed1986

The effectiveness of metrifonate in reducing hookworm infection in Kenyan school children.

The reduction in hookworm egg counts was determined in children treated with 1 and 2 doses of metrifonate. Kenyan primary school children were allocated to receive either 10.0 mg (n = 53) or 7.5 mg (n = 53) of metrifonate per kg of body weight (mg/kg) or a placebo (n = 26). Two doses of 10.0 mg/kg reduced hookworm egg counts (from arithmetic means of 4,177 to 438 eggs per gram of feces [epg]) more than did 2 doses of 7.5 mg/kg (from 4,329 to 1,392 epg; P less than 0.01). Two doses of metrifonate reduced egg counts more than did 1 dose (P less than 0.0001). The placebo group did not show a significant change in egg counts. The single dose of 10.0 mg/kg led to a 78% reduction in hookworm egg counts (from 4,177 to 918 epg), a level unlikely to cause iron deficiency anemia. This was as effective as 2 doses of 7.5 mg/kg, and was more easily administered than 2 or 3 doses. The further reduction after a second dose of 10.0 mg/kg (to 438 epg) is probably not of practical importance. This study shows that metrifonate, even in a single dose for treatment of S. haematobium, is also useful in reducing hookworm egg counts.

Ancylostomatoidea↗

PubMed1985

Relationships of Schistosoma haematobium, hookworm and malarial infections and metrifonate treatment to growth of Kenyan school children.

Relationships of S. haematobium, hookworm and malarial infections to growth 6 months after metrifonate treatment were studied in Kenyan primary school children in an area where poor growth, S. haematobium and hookworm were common and malaria was endemic. All children with light-moderate S. haematobium infections (1-500 eggs/10 ml adj) in 4 schools were examined (Exam 1), allocated at random to either placebo (MIP, n = 198) or metrifonate treatment (MIT, n = 201) groups, treated, and examined again 6 months later (Exam 2). An additional 19 heavily infected children (HIT group greater than 500 eggs/10 ml adj) were treated immediately after Exam 1 and also followed. The MIT and HIT groups exhibited more rapid growth between Exam 1 and 2 than did the placebo group. The MIT group gained significantly (P less than 0.001) more than the MIP group in weight (0.8 kg), percent weight for age (2.3 percentage points), weight for height squared (0.04 units), arm circumference (0.4 cm), percent arm circumference for age (1.7 percentage points) and in triceps and subscapular skinfold thicknesses. In addition, the placebo group showed statistically significant decreases between exams in percentage weight for age, percent arm circumference for age, both skinfold thicknesses for age and no significant increase in percent height for age while the MIT group exhibited highly significant increases in all anthropometric parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1985

Regression of splenomegaly and hepatomegaly in children treated for Schistosoma haematobium infection.

During a study in Kenya of the relationships between Schistosoma haematobium infection and anemia and growth, evidence was found to suggest that this infection was associated with splenomegaly in children, and that both splenomegaly and hepatomegaly regressed in children treated for urinary schistosomiasis, compared with a placebo group. These results imply that S. haematobium is partially responsible for the splenomegaly and hepatomegaly found in this malarious area, and that treatment for S. haematobium may cause a significant regression of splenomegaly and hepatomegaly in children.

Adolescent↗

PubMed1985

Urinary iron loss and physical fitness of Kenyan children with urinary schistosomiasis.

Daily urinary iron loss and physical fitness were determined in Kenyan primary school children who had low-medium (16-177 eggs/10 ml adj) or high (200-1,194 eggs/10 ml adj) S. hematobium egg counts compared with a matched group of control or uninfected children before and after antischistosomal treatment with metrifonate. The 3 groups did not differ significantly before treatment in age, sex ratio, anthropometry or prevalence of other parasite infections. Before treatment, mean iron loss in the high egg count group (n = 14) was 652 micrograms/24 hr and was significantly higher than losses in the low-medium and control groups (losses = 278, 149 micrograms; n = 19, 12 respectively). Iron loss in infected children was correlated with egg count (r = 0.40) and log of egg count (r = 0.56, P less than 0.0003). After treatment iron loss decreased in the infected groups and post-treatment iron losses did not differ significantly. Physical fitness scores, measured with the Harvard Step Test, showed that the control group (score 81) was significantly more fit than the high egg count group (score 69) before treatment. Fitness scores improved significantly in both infected groups after treatment, and post-treatment fitness scores did not differ significantly between the 3 groups. This study provides evidence that relatively heavy infections of S. hematobium can cause urinary iron loss which, if it persists, is great enough to produce iron deficiency anemia and can also reduce physical fitness of children, but that both of these negative effects are reversible with treatment.

Child↗

PubMed1985

Relationships of Schistosoma hematobium, hookworm and malarial infections and metrifonate treatment to hemoglobin level in Kenyan school children.

Relationships between hemoglobin level and S. hematobium, hookworm, and malarial infection before and six months after metrifonate treatment were studied in Kenyan primary school children in an area where anemia, S. hematobium and hookworm are common (prevalences 61%, 46%, and 95%, respectively) and malaria is holoendemic. The mean hemoglobin level in children from one school, both with and without S. hematobium infection (n = 250), was significantly lower in children with higher S. hematobium egg counts, heavier hookworm infections, positive Plasmodium slides, and larger spleens. All children with light-moderate S. hematobium infection (1-500 eggs/10 ml adj) in four schools were examined (Exam 1), allocated at random to either placebo (MIP, n = 198) or metrifonate treatment (MIT, n = 202) groups, treated, and examined again six months later (Exam 2). Hemoglobin levels rose significantly in both groups between exams, but the rise in the MIT group was 30% higher than in the MIP group (1.3 vs. 1.0 g/dl, P less than 0.014). The increase in hemoglobin level in the MIT group was significantly and positively correlated with decreases between exams in S. hematobium and hookworm egg counts and with higher malarial parasite counts at Exam 1 (Pearson r's 0.21, 0.20, 0.20, respectively, P less than 0.01). A stepwise multiple regression equation using hemoglobin rise between exams as the dependent variable showed that decreases in S. hematobium and hookworm egg counts were equally important determinants of hemoglobin rise and that malarial parasite count was almost as important as the changes in intensities of the helminth infections. These results show that treatment for S. hematobium with metrifonate can increase hemoglobin levels in children in an area where S. hematobium and anemia are common. They also emphasize the importance of measuring multiple parasitic infections and using multivariate statistical techniques such as multiple regression analysis in order to define the relationships between parasitic infections and morbidity.

Adolescent↗

PubMed1984

Methods to evaluate nutritional and economic implications of Ascaris infection.

Ascaris infection has important economic implications for human populations, due to its negative effects on growth of undernourished children and its less common role in causing intestinal obstruction. The deleterious effects of Ascaris infection on growth of undernourished children have been demonstrated in studies conducted in India, Kenya and Tanzania; deworming has resulted in improved weight gains of 20-35% compared with uninfected children. However other studies in Ethiopia, Bangladesh and Guatemala have not found statistically significant improvements in growth of children after treatment for Ascaris infection, most likely due to inadequacies in choice of population, sample size, experimental design, data analysis and/or relative failure of drug treatment. Field studies which attempt to measure the magnitude of growth deficits due to Ascaris must take the following into account: (1) rapidly growing preschool age children from communities with a high prevalence of protein-energy malnutrition are the most important group to study. (2) A longitudinal design, preferably using randomly allocated treatment and placebo groups, is highly desirable. (3) A sufficient period of time for growth improvement must be allowed between the beginning of the intervention and final measurements. (4) The sample sizes necessary to test hypotheses adequately should be calculated in advance. (5) The drug chosen for treatment of Ascaris should produce high cure rates and reinfection rates should be determined. Possible effects of the drug on other diseases prevalent in the population should be considered in the data analysis. (6) Evaluation of worm loads are very important in interpretation of results. (7) The data analysis must be appropriate for the individual study and must be designed to consider confounding factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1984

Sensitivity and specificity of reagent strips in screening of Kenyan children for Schistosoma haematobium infection.

The reliability of using urinalysis reagent strips, which semi-quantitatively measure hematuria and proteinuria, to correctly select urine specimens found by microscopy to have Schistosoma haematobium eggs was studied in 359 previously unscreened Kenyan primary school children. The presence of and degree of hematuria and proteinuria were highly correlated with the presence of S. haematobium eggs and with egg counts in urine specimens. Hematuria was more strongly correlated with S. haematobium egg counts than was proteinuria. The ability of presence of hematuria or proteinuria, or both, to select all microscopically positive cases of urinary schistosomiasis for treatment was tested using sensitivity (ST) and specificity (SP) analysis. Selection of cases using 1) presence of hematuria alone, and 2) presence of either hematuria or proteinuria had the highest combined ST and SP (88% ST, 97% SP; 91% ST, 92% SP, respectively). Most of the few cases detected by microscopy but not by reagent strips had low egg counts. The presence of hematuria alone failed to detect only 12% of S. haematobium-positive cases (mostly low egg counts), and only 3% of S. haematobium-negative persons had urinary blood and would have received unnecessary treatment. Preliminary studies on the use of reagent strips to screen previously infected children 6 months after treatment, and the effects of seasonal variations in temperature and humidity on urine specimen volume, egg counts, and reagent strip results are also presented. The practical field use and cost of reagent strips in S. haematobium control programs are discussed.

Adolescent↗

PubMed1983

Parasitic infections, anaemia and nutritional status: a study of their interrelationships and the effect of prophylaxis and treatment on workers in Kwale District, Kenya.

A study was conducted between January and August 1979 on 150 male roadworkers in Kwale District in the coastal lowlands of Kenya. At the baseline examination 59% had hookworm (mean of 227 epg +/- 541), 38% had infections of Schistosoma haematobium (mean 52 +/- 82 ova per 10 ml urine), 23% had a blood film positive for malarial parasites, 47% had anaemia (Hb below 13g/dl), and 31% had a percentage weight for height below 80% of a reference value for healthy men. It was found that anaemia was significantly associated with hookworm infections and egg counts. Three interventions were evaluated. These consisted of providing pyrantel pamoate for hookworm to all men, treating the S. haematobium infections with metrifonate, and giving weekly chloroquine prophylaxis for suppression of malaria to one group of men. A final examination conducted 16 weeks later showed a significant improvement in haemoglobin levels in anaemic men treated for hookworm and in those receiving chloroquine compared with those receiving placebos. Multiple regression analyses revealed that both hookworm and S. haematobium egg counts were associated with anaemia at the baseline examinations, that factors related to the treatment of hookworm and prophylaxis for suppression of malaria were related to haemoglobin increases in anaemic men, and that successful treatment of urinary schistosomiasis was associated with weight gain. The feasibility of the interventions was good and the costs moderately low.

Adolescent↗

PubMed1983