Prevalence Of Hookworm Research Articles

Uncinaria hamiltoni (Nematoda: Ancylostomatidae) in South American sea lions, Otaria flavescens, from northern Patagonia, Argentina.

Thirty-one South American sea lion pups (Otaria flavescens) found dead in Punta León, Argentina, during the summer of 2002, were examined for hookworms (Uncinaria hamiltoni). Parasite parameters were analyzed in 2 locations of the rookery, i.e., a traditional, well-structured breeding area and an expanding area with juveniles and a lax social structure. Prevalence of hookworms was 50% in both localities, and no difference was observed in prevalence between pup sexes (P > 0.05). Hookworms were concentrated in the small intestine. Transmammary transmission is assumed because only adult hookworms were found in the pups. The mean intensity of hookworms per pup was 135; the mean intensity in females (92.78) was significantly different (P < 0.05) from that of males (230.25). No difference (P > 0.05) in intensity was found between the 2 breeding areas, although prevalence was higher in the traditional breeding area than in the other area. Location was the only factor affecting hookworm prevalence (P log-linear model: 0.9552; chi2: 1.5629). No apparent trend between body condition and intensity of hookworms was observed.

Application of a species-specific PCR-RFLP to identify Ancylostoma eggs directly from canine faeces

Apart from their veterinary importance, the hookworms Ancylostoma caninum, Ancylostoma braziliense and Ancylostoma caninum are also capable of causing zoonotic disease in humans. A highly sensitive and species-specific PCR-RFLP technique was utilised to detect and differentiate the various canine Ancylostoma spp directly from eggs in faeces. This technique was utilised to screen 101 canine faecal samples from parasite endemic tea growing communities in Assam, India, as part as an ongoing epidemiological investigation into canine parasitic zoonoses. The prevalence of hookworms in dogs was found to be 98% using a combination of PCR and conventional microscopy. Overall, 36% of dogs were found positive for single hookworm infections with A. caninum, 24% positive for single infections with A. braziliense and 38% had mixed infections with both A. caninum and A. braziliense. No dogs were found positive for A. ceylanicum in the community under study. The high prevalence of A. caninum and A. braziliense in dogs in this community may account for the high incidence of cutaneous larva migrans (CLM) observed among the human population residing at the tea estates. The PCR-RFLP technique described herein allows epidemiological screening of canine hookworms to be conducted rapidly, with ease and accuracy, and has the potential to be applied to a number of different clinical, pharmacological and epidemiological situations.

Anemia and malaria at different altitudes in the western highlands of Kenya

Malaria associated severe anemia in children is the most important complication of Plasmodium falciparum infection in sub-Saharan Africa. To evaluate anemia and malaria in an area with recurrent malaria epidemics in the western highlands of Kenya, we conducted cross-sectional surveys in four “lowland” (1440–1660 m) and two “highland” (1960 and 2040 m) villages in 2002. Among 1314 subjects randomly selected from all age groups, the overall prevalence of anemia (hemoglobin, Hb<11 g/dl) was 14% and P. falciparum infection 17%. In children ≤5 years, anemia prevalence ranged from 57% at 1440 m to 11% at 2040 m and correlated with altitude ( r=−0.88, P<0.05). Similarly, P. falciparum prevalence ranged from 31 to 0% and correlated with altitude ( r=−0.93, P<0.01). Malnutrition defined by a body mass index <15th percentile characterized 39% of the population and the hookworm prevalence was 3.9%. In the lowland villages, anemia was most common in children ≤5 years of age (34%) followed by women of childbearing age (16%). A similar pattern was also observed in the highland villages. In these vulnerable populations, hemoglobin concentration was significantly associated with malaria infection, but not with malnutrition or hookworm infestation and comparisons of anemia prevalence between highland and lowland villages revealed that two-thirds of anemia could be attributed to malaria infection. The prevalence of severe anemia (Hb<8 g/dl) was 1.5%; of these, 90% resided in lowland villages, 70% were under-fives, while 20% were women of childbearing age. In severely anemic subjects, the Hb concentration decreased further with malnutrition ( P<0.05). Anemia was more prevalent in the lowland villages characterized by high prevalence of P. falciparum infection. We conclude that malaria may also be the main cause of anemia in the highland fringe areas of sub-Saharan Africa. Measures that reduce the prevalence of malaria will consequently reduce anemia in both, young children and adult women and the need for blood transfusions associated with the risk of HIV-transmission.

The prevalence, intensities and risk factors associated with geohelminth infection in tea-growing communities of Assam, India.

To determine the prevalence, intensity and associated risk factors for infection with Ascaris, hookworms and Trichuris in three tea-growing communities in Assam, India. Single faecal samples were collected from 328 individuals and subjected to centrifugal flotation and the Kato Katz quantitation technique and prevalence and intensities of infection with each parasite calculated. Associations between parasite prevalence, intensity and host and environmental factors were then made using both univariate and multivariate analysis. The overall prevalence of Ascaris was 38% [95% confidence interval (CI): 33, 43], and the individual prevalence of hookworm and Trichuris was 43% (95% CI: 38, 49). The strongest predictors for the intensity of one or more geohelminths using multiple regression (P < or = 0.10) were socioeconomic status, age, household crowding, level of education, religion, use of footwear when outdoors, defecation practices, pig ownership and water source. A universal blanket treatment with broad-spectrum anthelmintics together with promotion of scholastic and health education and improvements in sanitation is recommended for helminth control in the communities under study.

Hookworm (Necator americanus) transmission in inland areas of sandy soils in KwaZulu-Natal, South Africa.

This study extended the association between hookworm transmission in KwaZulu-Natal and the sandy coastal plain by investigating the parasite's occurrence in isolated areas of sandy soils further inland. A school-based prevalence survey was carried out in selected inland sandy areas and in surrounding areas dominated by clay soils within a narrow altitudinal range of between 500 and 700 m to reduce the effect of altitude on climate-related factors (rainfall and temperature). Sandy areas situated on the coastal plain were included in the analysis for comparative purposes. Soil samples (0-50 mm depth) were collected from each locality to assess their nematode loadings and to analyse selected physical and chemical properties. Significant differences were found between the moderate prevalence of hookworm infection among children living in inland areas with sandy soils (17.3%) and the low prevalence in surrounding non-sandy areas (5.3%, P < 0.001), and between infection among children living in all inland areas (9.3%) and the high prevalence on the coastal plain (62.5%, P < 0.001). Amounts of fine and medium sand were highest in both the coastal plain soils and in inland sandy areas and these fractions showed a significant positive correlation with hookworm prevalence and nematode loadings. Clay, coarse sand and organic matter contents were highest in surrounding non-sandy soils and showed a significant negative correlation with the nematode variables. No statistically significant correlations were found with soil pH at study localities. We conclude that properties of inland sandy soils, particularly particle size distribution, correlate well with hookworm prevalence and nematode loadings and therefore provide a more suitable habitat for nematodes than surrounding non-sandy areas. These results suggest that particle size distribution of sand fractions, organic matter and clay content in the soil influence the survival of hookworm larvae and hence the parasite's transmission.

Prevalence of intestinal parasitic infections in northern Vietnam.

We surveyed the prevalence of parasitic infections in the mountainous province of Hoa Binh, north-west Vietnam, involving 526 households of six ethnic groups: Muong, Kinh, Dao, Thai, Tay and Hmong. Eggs or cysts of at least one parasite species were detected in 88% of stool samples (n = 2522). Prevalences of nematodes were high among all ethnic groups: hookworm (52%), Trichuris trichiura (50%) and Ascaris lumbricoides (45%). Ascaris infection appeared to be lower in households owning a latrine, was highest among children and decreased with age. Prevalence of hookworm rose during childhood, remained high until old age, was highest among adult women, but was not linked to anaemia. Eggs of Chlonorchis spp. were found in 126 (5%) individuals (of the Muong, Kinh or Thai groups only). Chlonorchiasis increased with age and was highest among adult men. Taenia eggs were found in three individuals (0.1%). Giardia lamblia was found in all districts and among all groups and the prevalence of infection was estimated at 3%.

The effect of soil type and climate on hookworm (Necator americanus) distribution in KwaZulu-Natal, South Africa.

We investigated environmental factors influencing the distribution of hookworm infection in KwaZulu-Natal, South Africa. Prevalence data were sourced from previous studies and additional surveys carried out to supplement the database. When geo-referenced the data revealed that higher prevalences are limited to areas below 150 m above sea level, and low prevalences to areas above this altitude. Using univariate analysis we investigated the differences in environmental factors in the two areas. The relationship between hookworm prevalence, altitude and climate-derived variables was assessed using Pearson correlation coefficient, and that of soil type using the t-test. Multivariate analysis was used to determine environmental factors that combine best to provide favourable conditions for hookworm distribution. The results revealed that areas <or=150 m above sea level, i.e. the coastal plain, supported high prevalences (x = 45, n = 51), and were characterized by sandy soils with a clay content of less than 15%, warm temperatures and relatively high rainfall. Areas >150 m above sea level, i.e. inland, supported low mean hookworm prevalences (x = 6, n = 21), and were characterized by soils with a clay content of more than 45%, variable temperatures and moderate rainfall. Hookworm prevalence also decreased southwards as temperatures became slightly cooler, rainfall remained more-or-less constant and the coastal plain narrowed. In the multivariate model prevalence was most significantly correlated with the mean daily minimum temperature for January followed by the mean number of rainy days for January. This indicates the importance of summer conditions in the transmission of hookworm infection in KwaZulu-Natal and suggests that transmission may be seasonal.

'Intervenir et représenter': campagnes sanitaires et élaboration des cartographies de l'ankylostomiase

This paper compares anti-hookworm campaigns conducted in the early twentieth century in France, Germany, Brazil and West India. The populations that suffer from hookworm are not identical in the North and in the South. In tropical and semi-tropical regions hookworm is mainly found among poor peasants and is related to lack of hygiene, while in temperate climates hookworm was a professional disease of miners, a highly organized professional segment. Nevertheless, major disparities in the pattern of hookworm control did not reflect the North-South divide, but a difference between campaigns. These aimed at the eradication of hookworm infection (Germany and West-India) and at alleviating the effects of this infection on populations (France and Brazil). Maps that represented the prevalence of hookworm mirrored the aims of the sanitary campaign in which they were used: eradication of parasitic worms versus the reduction of the handicap induced by these worms. In public health as well, representing is intervening. And vice versa: patterns of intervention shape representations.

First nationwide survey of the health of schoolchildren in Chad.

Survey data are presented from a nationwide survey of the health of schoolchildren in Chad. The country was stratified into distinct ecological zones based on satellite sensor environmental data. Twenty schools were visited and 1024 children aged between 6 and 15 years were included in the study. The overall prevalence of stunting, underweight, anaemia and goitre was 18.7, 16.5, 25.1 and 23.3%, respectively. Schistosoma haematobium, Schistosoma mansoni and hookworm were the only helminth species found with prevalences of 13.2, 1 and 32.7%, respectively. A greater proportion of boys were stunted, underweight, anaemic and infected with S. haematobium and hookworm than girls. Older children were more stunted, underweight and infected with S. haematobium and hookworm than younger children, but less anaemic. The prevalence of infection showed marked geographical heterogeneity, with hookworm prevalence being highest in the Sudanian and tropical zone, and S. haematobium being most prevalent in the Sahelian zone and the Logone and Chari basins in the west of the country. These data show that there is a high prevalence of helminth infection in Chad, but that treatment for S. haematobium and hookworm should be targeted to different geographical areas.

Epidemiology of Necator americanus hookworm infections in Xiulongkan Village, Hainan Province, China: high prevalence and intensity among middle-aged and elderly residents.

Hookworm is highly endemic to Hainan Province, an island located in the South China Sea. To investigate the prevalence and intensity of infection in the area, the village of Xiulongkan was surveyed between April and July 1998. A cross-sectional study was conducted in which fecal samples of 80% of the village residents (631 individuals) were tested for the presence of helminth eggs. Hookworm was the predominant intestinal helminth in Xiulongkan, where it was determined that 60% of those tested were infected. Necator americanus was the predominant species of hookworm in this population. The prevalence of hookworm increased with age, and then leveled to a plateau for ages 41 yr and up. This observation was in contrast to infections with Ascaris lumbricoides, where the highest prevalences occurred among school-aged children. Women had a significantly higher prevalence of hookworm than men and this difference emerged in early adulthood. The intensity of hookworm infection also significantly increased with age, with the highest intensity infections occurring among middle-aged and elderly residents. Females were more likely to have moderate or heavy infections, whereas males were more likely to have light infections. The rates of hookworm transmission are particularly high among the middle-aged and elderly residents of Xiulongkan.

Lower hookworm incidence, prevalence, and intensity of infection in children with a Bacillus Calmette-Guérin vaccination scar.

Bacillus Calmette-Guérin (BCG), the most common vaccine worldwide, has broad effects on the immune system. Hookworm infections are a major source of morbidity. In response to a preliminary report of BCG vaccination protection against nematodes in human immunodeficiency virus-infected adults, data from an ongoing prospective study were analyzed to determine the intensity (eggs per gram of stool), prevalence, and incidence of different helminths in children with and without a BCG vaccination scar. Adjusted prevalence and incidence ratios were estimated by using logistic regression. Children with a BCG vaccination scar were found to have statistically significantly lower hookworm prevalence (41%), incidence (37%), and mean egg counts (39%), after controlling for age, sex, and socioeconomic factors. There was no BCG association with incidence, prevalence, or intensity of infection with Schistosoma mansoni, Ascaris lumbricoides, or Trichuris trichiura. Such protection would have implications for public health and for research on mechanisms behind human immunological responses to hookworm.

Hookworms, Malaria and Vitamin A Deficiency Contribute to Anemia and Iron Deficiency among Pregnant Women in the Plains of Nepal

Anemia and iron deficiency during pregnancy are prevalent in developing countries, but their causes are not always known. We assessed the prevalence and severity of anemia and iron deficiency and their association with helminths, malaria and vitamin A deficiency in a community-based sample of 336 pregnant women in the plains of Nepal. Hemoglobin, erythrocyte protoporphyrin (EP) and serum ferritin were assessed in venous blood samples. Overall, 72.6% of women were anemic (hemoglobin < 110 g/L), 19.9% had moderate to severe anemia (hemoglobin < 90 g/L) and 80.6% had iron deficiency (EP > 70 micromol/mol heme or serum ferritin < 10 microg/L). Eighty-eight percent of cases of anemia were associated with iron deficiency. More than half of the women (54.2%) had a low serum retinol concentration (<1.05 micromol/L), 74.2% were infected with hookworms and 19.8% had Plasmodium vivax malaria parasitemia. Hemoglobin, EP and serum ferritin concentrations were significantly worse and the prevalence of anemia, elevated EP and low serum ferritin was increased with increasing intensity of hookworm infection. Hookworm infection intensity was the strongest predictor of iron status, especially of depleted iron stores. Low serum retinol was most strongly associated with mild anemia, whereas P. vivax malaria and hookworm infection intensity were stronger predictors of moderate to severe anemia. These findings reinforce the need for programs to consider reducing the prevalence of hookworm, malaria infection and vitamin A deficiency where indicated, in addition to providing iron supplements to effectively control anemia.

The Effect of Repeated Four Monthly Treatments on the Prevalence and Worm Burden of Ascaris, Trichuris and Hookworm Infections in an Endemic Area.

The effect of repeated 4 monthly treatment of single dose of 400 mg albendazole on the prevalence and worm burden of Ascaris, Trichuris and hookworm was studied in an endemic area. Repeated 4 monthly treatment, had significant effect in reducing the worm burden of Ascaris and not the prevalence. As for hookworm infection repeated 4 monthly treatment had significant impact in reducing both prevalence and worm burden in the community. However, repeated 4 monthly treatments had no significant impact in reducing the prevalence and worm burden of Trichuris infection in the community. Trichuris infection should be considered as a continuing infection rather than reinfection because of poor cure rate of albendazole at the onset of the study. Significant and strong predisposition (p < 0.0001) were detected after single and repeated 4 monthly treatment in Ascaris and Trichuris infection but not in hookworm infection. Stratification of data indicated that significant and strong predisposition was also seen in gender. This study concludes that changes in mean egg count per gram (mean EPG) is a sensitive indicator in measuring effect of treatment in an endemic area, and repeated 4 monthly treatments has successfully reduced the worm burden of Ascaris and hookworm infection. Subjects remained predisposed to Ascaris infection over 2 reinfection periods, and for hookworm infection evidence of predisposition was seen only over 1 reinfection period.

Epidemiology of human hookworm infections among adult villagers in Hejiang and Santai Counties, Sichuan Province, China

Hookworm infection as well as other intestinal nematodiases are endemic to Sichuan Province in China. In order to research the prevalence and intensity of these infections we visited two villages in Hejiang County (southern Sichuan Province) and Santai County (northwestern Sichuan Province) between July and October of 1997. Fecal examinations were performed on adult villagers over the age of 15 years (currently children under this age are dewormed annually with anthelmintic drugs). Among 310 residents of Lugao Village (Hejiang County), 87, 63 and 60% were infected with hookworm, Ascaris or Trichuris, respectively. The prevalence of hookworm determined to rise linearly with age ( r=0.97). High intensity infections with hookworm still occur in this region as 22% of the residents have over 3000 eggs per gram (PEG) of feces as determined by quantitative egg counts. The majority of these individuals harbored mixed infection with Necator americanus and Ancylostoma duodenale, although the former predominated when adult hookworms were collected from 30 village residents treated with pyrantel pamoate. In contrast, among the 334 Xinjian villagers examined (Santai County) the majority harbored predominantly light hookworm infections—66.1% of the residents has less than 400 EPG by quantitative fecal examination and only 3.7% exhibited greater than 3000 EPG. Again, N. americanus was the predominant hookworm seen after worm expulsion. We have round that despite economic development which is occurring in some parts of China, significant hookworm infections and clinical hookworm anemia still exist in areas of Sichuan Province. In Hejiang County we found that the intensity of hookworm infection has actually risen within the last 10 years. Hookworm is a medical problem among the elderly in Sichuan.

The prevalence of intestinal parasitism in native villages of the Tembé tribe, the Brazilian eastern Amazon

To determine the prevalence of intestinal parasitism in the Tembé settlements, parasitological examination was performed in December 1996 in the entire population (93 Indians). Hookworms were found in 29.0%, A. lumbricoides in 34.4%, E. histolytica in 12.9%, and G. lamblia in 4.3% of the individuals. The Turé-Mariquita settlement had the highest prevalence of hookworms and A. lumbricoides, while Acará-Mirim had the highest prevalence of E. histolytica and G. lamblia. No differences in mean age were found between Indians with parasites and Indians without parasites. The association between intestinal parasites and sex was nonsignificant, except for the prevalence of hookworms, which was very high in males (38.6%) compared to females (20.4%). The study showed a high prevalence of some intestinal parasites in the Tembé settlements, indicating that primary and secondary health measures should taken immediately for the prevention of intestinal parasitoses.

The population biology and epidemiology of schistosome and geohelminth infections among schoolchildren in Tanzania

A study of helminth infections was undertaken among 3244 schoolchildren from 28 schools in Morogoro Rural District, Tanzania. Schistosoma haematobium was the most common infection, followed by hookworms, Ascaris lumbricoides, S. mansoni, and Trichuris trichiura. Infection prevalence of each species varied among schools and age groups, but not between sexes. There was no relationship between the prevalences of different infections among schools, except for a strong negative correlation between the prevalence of hookworm and S. mansoni infections. Within each age group, there was little excess overlap in the distribution of each infection; thus the number of multiple infections was low whereas the number of individuals harbouring at least one infection was relatively high. More children than expected carried infections of A. lumbricoides and S. mansoni, and the clustering effect increased with age. Only 2 schools had high overall infection prevalences of both geohelminths and schistosomes. Logistic regression analysis of morbidity and parasitological data indicated that individuals with multiple species infections were not at increased risk of morbidity (on a multiplicative scale) compared to individuals with single species infections. This was attributed in part to the low egg counts observed for each parasite species. The results implied little interaction between schistosome and geohelminth infections in the region, both in parasitological terms and in the context of their combined effects on health. Implications for the feasibility and benefits of combined control of geohelminths and schistosomes are discussed.

The proportion of helminth infections in a community in western Kenya which would be treated by mass chemotherapy of schoolchildren

The present study used data from a community-based epidemiological survey of 752 persons in 3 villages in Kisumu District, western Kenya, to examine the proportion of infected persons who would be treated, as well as the effect on helminth egg production, if anthelmintics were provided to schoolchildren. Overall prevalences of hookworm, Ascaris lumbricoides, Trichuris trichiura and Schistosoma mansoni infections were 63%, 16%, 24% and 24% respectively, and intensities were low for all infections. Only 79% of the schoolaged children were enrolled. For all 4 infections, a school-based programme would treat between 76% and 86% of infected school-age children and would theoretically eliminate between 83% and 92% of the number of eggs excreted by this age group. Of the total population, school-based programmes would treat only between 31% and 50% of the infected persons and eliminate only 15%, 46%, 29% and 27% of the total number of hookworm, Ascaris, Trichuris and S. mansoni eggs excreted, respectively. Provided that school attendance rates were high in the study area, school-based programmes would be efficient in improving the helminth infection status of school-aged children. On the other hand, adults, non-enrolled school-aged children and preschool children not offered treatment represented more than half of the helminth-infected persons and they excreted between half and 85% of the total burden of helminth eggs in the area. Hence, mass chemotherapy of schoolchildren would be less effective in the control of at least hookworm and S. mansoni infections in this specific community. There should therefore be a communitybased approach to helminth control in combination with a school-based programme.

Factors affecting high and low human IgE responses to schistosome worm antigens in an area of Brazil endemic for Schistosoma mansoni and hookworm.

We have previously examined the antibody isotype responses to schistosome worm and egg antigens in human populations living in areas of Kenya and the Philippines endemic for Schistosoma mansoni and S. japonicum, respectively. Here, we have analyzed antibody isotype responses to S. mansoni adult worm (AW) antigen and soluble egg antigen (SEA) in more than 500 Brazilian individuals, and found similar relationships with age and sex as in the Kenyan and Filipino populations. Isotype responses to AW antigen broadly increased with age whereas isotype responses to SEA decreased, and a higher proportion of males than females had detectable IgE against AW antigen. Most isotype responses to AW antigen and SEA correlated positively with intensity of infection with S. mansoni except AW antigen-specific IgG2, which correlated negatively. The overall prevalence of infection with S. mansoni in this area was relatively low at only 39.5%; hookworm prevalence was higher at 57.4%. The majority of those infected with S. mansoni were also infected with hookworm (76%). Those individuals with high IgE responses to AW antigen were matched for sex, age, and total IgG to AW antigen as closely as possible with individuals with low levels of AW antigen-specific IgE. The two groups were compared for factors potentially influential in IgE production. No difference was found between the high and low IgE responders for 1) intensity or prevalence of infection with S. mansoni, 2) relative exposure to S. mansoni, 3) number of previous treatments for schistosomiasis, or 4) prevalence of infection with hookworm, but differences were found in other isotype responses to S. mansoni. The high IgE responders had higher IgA and IgG4 against both AW antigen and SEA but lower IgG3 responses to AW antigen than the low IgE responders. The IgE responses to three S. mansoni antigens (paramyosin, Sm22.6, and a 12-kD AW antigen band) were detected in individuals with IgE against AW antigen only.

Time series analysis of the prevalence of endoparasitic infections in cats and dogs presented to a veterinary teaching hospital

The apparent prevalence of endoparasitic infections of cats and dogs presented to the small animal Veterinary Hospital of the University of Pennsylvania was measured between 1984 and 1991. Two thousand feline and 8077 canine fecal samples were examined along with 6830 canine blood samples. The overall mean monthly prevalence of feline infections was 16% for ascarids, 0.9% for hookworms, 4.0% for tapeworms, 2.4% for Giardia spp. and 4.2% for coccidia. The overall mean monthly prevalence of canine infections was 5.7% for ascarids, 9.7% for hookworms, 9.7% for whipworms. 1.8% for tapeworms, 4.7% for Giardia spp. and 3.1% for coccidia. There was a significant downward trend in the prevalence of hookworms and heartworms in dogs ( P<0.001 in both cases). There was a significant upward trend in the prevalence of tapeworms in cats ( P<0.05). There were no significant long-term trends in any of the other time series. The smoothed data were analyzed for seasonal trends. None of the autocorrelation analyses gave incontrovertible evidence of seasonality. The repeated peaks at the 6, 12 and 24 month lags in the case of ascarid infections were suggestive of a 12 month seasonality with a peak prevalence in December, but the results were not statistically significant at the 5% level. Hookworms and whipworms in dogs occurred together more than would be expected by chance in 4 out of the 6 years for which data were available.

The distribution of intestinal helminth infections in a rural village in Guatemala.

Fecal egg count scores were used to investigate the distribution and abundance of intestinal helminths in the population of a rural village. Prevalences of the major helminths were 41% with Ascaris lumbricoides, 60% with Trichuris trichiura and 50% with Necator americanus. All three parasites showed a highly aggregated distribution among hosts. Age/prevalence and age/intensity profiles were typical for both A. lumbricoides and T. trichiura with the highest worm burdens in the 5-10 year old children. For hookworm both prevalence and intensity curves were convex in shape with maximum infection levels in the 30-40 year old age class. Infected females had higher burdens of T. trichiura than infected males in all age classes of the population; there were no other effects of host gender. Analysis of associations between parasites within hosts revealed strong correlations between A. lumbricoides and T. trichiura. Individuals with heavy infections of A. lumbricoides and T. trichiura showed highly significant aggregation within households. Associations between a variety of household features and heavy infections with A. lumbricoides and T. trichiura are described.