Lani S. Stephenson

Improvements in physical fitness of Kenyan schoolboys infected with hookworm, Trichuris trichiura and Ascaris lumbricoides following a single dose of albendazole

We studied physical fitness with the Harvard step test (HST), in primary schoolboys infected with hookworm (91% baseline prevalence), Trichuris trichiura (94%) and Ascaris lumbricoides (39-40%) who received a single 400 mg dose of albendazole or an identical placebo. Boys were examined, allocated at random to placebo or albendazole groups, treated, and re-examined 7 weeks later. The 2 groups did not differ significantly before treatment in age, anthropometry, haemoglobin levels, prevalence or intensity of the 3 helminth infections, or in initial HST fitness scores and heart rates. Seven weeks after treatment, the albendazole group (n = 18) exhibited significant improvements in fitness scores and heart rates at 1, 2, 3, and 4 min after the HST while in the placebo group (n = 15) these quantities had not changed significantly. After treatment, the albendazole group had significant decreases in the logarithmic egg counts for hookworm (80% reduction in arithmetic means) and A. lumbricoides (100% reduction); T. trichiura egg counts did not change significantly. The placebo group showed a borderline increase in the logarithms of hookworm egg counts and no significant change in T. trichiura and A. lumbricoides egg counts. Multiple regression analysis showed that the significant linear predictors of increase in HST score after treatment were decrease in resting heart rate after treatment, and decreases in hookworm egg counts and logarithms of A. lumbricoides egg counts after treatment. We conclude that single dose treatment with albendazole, despite continual exposure to reinfection, can allow improved physical fitness in schoolboys in areas where soil-transmitted helminths and protein-energy malnutrition are highly prevalent.

Ascaris suum: Nutrient absorption, growth, and intestinal pathology in young pigs experimentally infected with 15-day-old larvae

Abstract Three-week-old pigs on high (HP) or low (LP) protein diets were infected with 15-day-old Ascaris suum larvae (W). Including noninfected pigs (C), the experimental groups were HPW, LPW, HPC, and LPC. After 8 weeks, worm burden in the intestine averaged 42 in LPW and 31 in HPW. Nitrogen balance during Week 4 showed nonsignificantly less nitrogen absorption and retention in LPW compared to LPC. A similar, nonsignificant decrease in fat absorption was recorded in LPW vs LPC and in HPW vs HPC. The weight of the small intestine was significantly greater in W than C pigs but did not differ because of protein level. The weight correlated positively to worm burden and the increase was due mainly to hypertrophy of the tunica muscularis (muscle layers).

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.

False-positive Ascaris suum egg counts in pigs.

False-positive Ascaris suum egg counts in pig faeces are frequently observed under both experimental and natural conditions. Data from 12 experiments with A. suum infections in pigs were summarized and showed that the percentage of false-positive faecal samples ranged from 4 to 36%. False-positive egg count values varied greatly between pigs and experiments (range 20-1060 eggs per gram faeces). Indoor experiments with pigs housed groupwise in pens generally produced more and higher false-positive egg counts, which may reflect differences in surface area and hence exposure to infective eggs, compared with pasture experiments. The positive predictive value (the number of pigs diagnosed positive by faecal sample that actually harboured worms) was low for indoor experiments (45%) compared with pasture experiments (89%). Differences in design for indoor experiments, such as floor type and use of bedding material, did not influence the positive predictive value (44-47%). A positive correlation was found (r = 0.56, P < 0.05) between faecal egg counts of true-positive and false-positive pigs that were penned together. The results of this survey strongly support previous suggestions that false-positive A. suum egg counts in pigs are the result of coprophagia in indoor experiments and coprophagia/geophagia in pasture experiments. False-positive A. suum egg counts in pig faeces may vary greatly in prevalence and magnitude, and depend in part on management/housing factors.

Intestinal parasitic infections of men in four regions of rural Kenya

Faecal samples were obtained from 906 men living in four different regions of rural Kenya: the cool Highlands, the humid coastal lowlands, the equatorial Lake Victoria basin and the arid marginal highlands. The prevalence of intestinal parasitic infections is reported and compared, contrasted and discussed in terms of the typical environmental conditions in each region. Almost 70% of men appeared to be infected with intestinal helminths; hookworm was most common. The regional prevalence of hookworm infections appeared to be related to relative humidity.

Optimising the benefits of anthelmintic treatment in children.

Optimal use of anthelmintics in children is of major public health importance because the parasites involved probably infect over 2 billion persons, and most are especially common and debilitating in children. Well targeted drug delivery, particularly via community chemotherapy, can substantially decrease aggregate morbidity and mortality and also improve growth rates, physical fitness and activity, cognitive and school performance, and social well-being.The drugs discussed here include the benzimidazoles (albendazole, levamisole and mebendazole), pyrantel, praziquantel, oxamniquine, ivermectin, diethylcarbamazine and some traditional medicines. The parasitic infections discussed are hookworm, ascariasis, trichuriasis, strongyloidiasis, schistosomiasis and lymphatic filariasis; onchocerciasis and loiasis are also mentioned briefly. Dosage regimens and effectiveness, including combination treatment, are discussed. Mechanisms by which parasites may cause or aggravate malnutrition and retard development are shown, along with examples of nutritional and functional improvement at various ages due to antiparasitic treatment.Improvement in appetite is likely to be the single most important mechanism through which a variety of physiological improvements occur. We recommend community treatment of girls and women of childbearing age in areas with widespread hookworm and anaemia, because effective treatment can reduce the incidence of low birthweight, mortality in infancy and pregnancy, and stunted growth and morbidity in children and adults. Treatment of moderate-to-severe anaemia improves appetite, growth and cognitive and school performance in children, and also improves work and social capacity and productivity in children and adults. Since treatment for helminth infections may also decrease both the probability of contracting HIV infection and the rate of viral replication in those infected with both types of organisms, large-scale treatment and control of helminths and treatment of individual cases when diagnosed are now truly urgent.

Iron status of middle-aged women in five counties of rural China

Objective: To determine the relationships of dietary iron sources, other dietary factors, and lifestyle to iron status among premenopausal and recently postmenopausal Chinese women with widely varying regional dietary patterns.Design: Cross-sectional. Subjects were interviewed, blood samples were drawn, and dietary intakes were measured by a 3-day dietary survey for subjects in the five survey counties.Setting: Rural ChinaSubjects: About 80 randomly selected subjects per county among women aged 32–66 y.Main outcome measures: Blood hemoglobin, plasma ferritin, and plasma iron.Results: Total iron intake was relatively high (15–29 mg/d) compared to developed counties. Heme iron intake was negligible in two of the study counties. Overall levels of iron deficiency anemia were relatively low in these generally iron-stressed women. There was no clear statistical relationship between iron intake and physiological iron status. Although several measures of dietary intake (heme iron, dietary calcium, animal protein) were correlated with several measures of iron status before adjusting for survey county, only dietary animal protein was significantly positively correlated with plasma ferritin after adjusting for the possibly confounding factor of the survey county (r=0.15, P=0.009). Intakes of potential inhibitors of iron absorption, such as tea, even in very high amounts, were not correlated to iron status. Plasma ferritin was positively correlated with plasma retinol (P=0.024) and cholesterol (P=0.007). Systemic inflammatory response, as indicated by high plasma C-reactive protein levels, was shown to be raised in a group of subjects with apparently contradictory high levels of ferritin and low levels of hemoglobin (P=0.03).Conclusions: Iron nutriture in these areas of rural China seemed more related to physiological factors such as inflammatory response, menses, plasma vitamin A and cholesterol, than to dietary factors.Sponsors: NIH grant 5RO1 CA33638, Kellogg Co., Northeast Dairy Foods Research Center, American Institute for Cancer Research

A comparative study of the nutritional status, parasitic infections and health of male roadworkers in four areas of Kenya.

The nutritional status, parasitic infections and general health of 801 male roadworkers living in four different areas of Kenya, namely, the highlands, coastal lowlands, Lake Victoria basin and the semiarid north-west, were investigated. Undernutrition was common in all areas but was most marked among men in the semi-arid area. Anaemia was most prevalent in the coastal lowlands where 41% of men had a haemoglobin level less than 13.0 g/dl. Hookworm eggs were seen in the faeces of 40% of all men and in 69% of samples collected in the coastal lowlands. The Lake Victoria basin was a significant focus of infection with Schistosoma mansoni, 51% of faecal samples containing its eggs; S. haematobium also occurred but was most common in the coastal lowlands. Stages of Plasmodium spp. were most commonly observed in blood smears collected from men near Lake Victoria and the coast, two significant foci of malaria. An analysis of variance was used to examine the relationship between variables and indicated that the most significant association was between hookworm infections and low haemoglobin levels.

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)

Evaluation of a four year project to control Ascaris infection in children in two Kenyan villages.

The major aims of the Ascaris Control Project were to assess the feasibility effectiveness and cost of controlling Ascaris infection in Kenyan children over a 4-year period using mass treatment with the drug levamisole. The project took place in 2 adjacent rural communities and used a village-based delivery system to administer the drug. The control method chosen was mass treatment 3 times per year of all enrolled children and stools were collected 7 times to monitor changes in the prevalence of Ascaris infection. In order to estimate the worm burden in children mothers of Ascaris-infected preschool children were twice asked to collect the worms passed by their children after treatment. The 1st collection was in 1976; the mean number of worms per infected child was 10.1. The mean number in 1978 at the 2nd collection was 4.2. The prevalence of infection during the same 2 years was reduced from 16% to 8%. The total cost per village per year was estimated at US