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PubMed2005

Seasonal prevalence and intensity of hookworms (Uncinaria spp.) in California sea lion (Zalophus californianus) pups born in 2002 on San Miguel Island, California.

Intestines of California sea lion (Zalophus californianus) pups (n= 204), born in 2002 on San Miguel Island, California, were examined for hookworms (Uncinaria spp.) as part of a seasonal mortality study from June through December 2002 and January 2003. The investigation was planned to coincide with most of the previously established hookworm infection period of the pups. Prevalence of hookworms in dead pups was 100% for each month of the study. The geometric mean intensity of infections per month was: 94.03 (n=30) for June, 629.09 (n=50) for July, 319.90 (n=31) for August, 159.90 (n=30) for October, 109.03 (n=30) for November, 37.84 (n=24) for December 2002 and 11.05 (n=9) for January 2003. In addition to the temporal pattern, the infection intensity was higher for pups in good condition and for male pups. An inter-year comparison of hookworm counts from dead pups collected in July of 1996, 2000, and 2002 also demonstrated higher intensity in pups in better condition but sex-differences in intensity were inconsistent across years. The inter-year comparison also demonstrated higher intensities in dead pups collected from portions of the rookery with sandy substrate versus rocky substrate. No annual differences in intensity were found after adjusting for substrate and condition.

Ancylostomatoidea↗

PubMedDate not supplied

Age-dependency in predisposition to hookworm infection in the Burma valley area of Zimbabwe.

We examined hookworm re-infection intensities (measured as faecal egg count by the Kato technique) following anthelmintic treatment of farm workers resident on 15 large-scale commercial farms in Zimbabwe. All individuals examined were treated with albendazole (400 mg). Hookworm reinfection intensities of individuals examined, treated and reexamined were compared with the intensities of infection before treatment. Adults had higher than average infection intensities both before and after reinfection. Predisposition to hookworm infection was marked in adults, and absent from younger, less heavily infected hosts. The observations suggest that acquired immunity is unlikely to be an important determinant of hookworm infection and that behaviour may play a major role in determining the observed infection patterns in this community.

Adolescent↗

PubMedDate not supplied

Diagnosis of Strongyloides and hookworm infections: comparison of faecal and duodenal fluid microscopy.

Faecal microscopical diagnosis of Strongyloides and hookworm infections is insensitive. We have therefore compared duodenal fluid and faecal microscopy for detection of these parasites in a group of 292 patients being investigated for gastrointestinal symptoms who were examined by both techniques. Thirty-three of these patients (8%) were infected with Strongyloides stercoralis and 88 (30%) had hookworm infections. Microscopical examination of up to 3 faecal specimens detected only 33% and 65% of patients with Strongyloides and hookworm infections, respectively. Microscopical examination of a single specimen of duodenal fluid was more sensitive for detection of strongyloidiasis, identifying 76% of patients; the parasite was found exclusively in duodenal fluid (and not in faeces) in 67% of patients. For hookworm, the diagnostic sensitivity was similar with both techniques but duodenal fluid microscopy detected some patients (35%) who had not been identified by faecal microscopy. This study confirms previous work indicating the insensitivity of faecal microscopy in these infections and emphasizes the need to consider routine examination of duodenal fluid to exclude chronic strongyloidiasis. This may have particular relevance for south-east Asian war veterans and immunocompromised patients.

Ancylostomatoidea↗

PubMedDate not supplied

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.

Albendazole↗

PubMed2006

New technologies for the control of human hookworm infection.

Since the 1990s, the major approach to hookworm control has been morbidity reduction in school-aged children by periodic deworming with benzimidazoles. Now, efforts are underway to determine the feasibility of integrating deworming with control programs that target other neglected tropical diseases. However, the sustainability of benzimidazole deworming for hookworm is of concern because of the variable efficacy of mebendazole, high rates of post-treatment reinfection and possible development of drug resistance. This requires parallel efforts to develop new and complementary hookworm control tools, such as new anthelmintic drugs (e.g. tribendimidine) and a recombinant hookworm vaccine. It is hoped that, ultimately, anthelmintic vaccination will be linked to deworming as part of an expanded control package.

Ancylostomatoidea↗

PubMed1998

Efficacy of albendazole against Giardia and hookworm in a remote Aboriginal community in the north of Western Australia.

The parasitological, clinical efficacy and tolerability of albendazole in the treatment for both giardiasis and hookworm infection in a remote Aboriginal population was investigated. Albendazole at a dose rate of 400 mg daily for 5 days was highly effective in reducing hookworm egg numbers and both Giardia antigen and cysts. The 36.6% prevalence of Giardia prior to treatment fell to 12% between days 6 and 9, 15% for days 10-17 and rose to 28% between days 18 and 30. Tolerability and clinical efficacy were excellent. The effect of albendazole on hookworm was longer lasting than that on Giardia, reducing percent infection from over 76-2% on days 6-9 and zero by day 18-30 despite conditions highly conducive to rapid re-infection. We conclude that albendazole is highly efficacious against both parasites when used as described but that long term community benefit may require additional education programmes to avoid re-infection with Giardia although treatment strategies would seem appropriate for hookworm.

Adolescent↗

PubMedDate not supplied

Predictors for the risk of hookworm infection: experience from endemic villages in southern Thailand.

To assess the role of defaecation pattern in predicting the level of risk for hookworm infection in southern Thailand, 4 villages in different geographical settings in endemic areas were studied. Close observation and stool examinations for hookworm were carried out. The first village was used for exploring the risk factors for hookworm infection. The resultant statistical model was then tested using the other 3 villages. Only 23-40% of the sample regularly defaecated in a latrine. The pattern of defaecation did not differ between the sexes, but was associated with age and site of residence. In the first village, the following variables were not statistically significant: sex, age, level of past education, household income, having neighbouring houses within 20 m, latrine availability, site of defaecation. The only statistically significant protective factor was shoe wearing, which showed an exposure-outcome severity relationship. Similar results were obtained in the other 3 villages. These results refute the protective effect of latrine use on the individual user, who may still get infection from the faeces of other community members. Promotion of shoe-wearing, which provides individual protection, should be an important supplementary strategy for hookworm control programmes in such areas.

Adolescent↗

PubMed2003

The influence of sampling effort and the performance of the Kato-Katz technique in diagnosing Schistosoma mansoni and hookworm co-infections in rural Côte d'Ivoire.

The Klato-Katz method is widely used for diagnosing helminth infections in epidemiological surveys, but is known to have a low sensitivity. In the case of Schistosoma mansoni, statistical methods have been developed to compensate for the poor sensitivity, but the same is not true of any other helminth parasite, or infections with multiple-helminth species. We screened 101 schoolchildren from a rural area of Côte d'Ivoire over 5 consecutive days and made 5 Kato-Katz readings from each stool specimen. We estimated single and dual-species infections with S. mansoni and hookworm based on raw egg count data and after developing a latent-class model. The cumulative prevalence of co-infections was estimated at 9.9% after reading slides on the first day, and 57.0% after reading all 25 slides per person. The latent class model yielded a co-infection prevalence estimate of 79.6%, with marginal prevalence estimates for hookworm and S. mansoni infections of 83.9% and 91.6% respectively. The sensitivities of a single Kato-Katz thick smear for detection of S. mansoni alone, hookworms alone, or S. mansoni plus hookworms were 22.4%, 8.0% and 17.7%, respectively. In the current setting this could be attributable to low infection intensities of both parasites, combined with intra-specimen and day-to-day variation in egg output. If confirmed in other settings, these findings have implications for estimating the prevalence of multiple species helminth infections, and hence the design and implementation of efficacious and cost-effective control programmes.

Ancylostomatoidea↗

PubMed2006

Distribution and clustering of Oesophagostomum bifurcum and hookworm infections in northern Ghana.

Human Oesophagostomum infections are locally common in northern Ghana. The present study describes the results of a cross-sectional survey involving 1011 subjects, selected by a compound-based random sampling method from 1227 compounds in 24 villages. Selected persons were examined by both Kato and coproculture methods. Hookworm-like eggs, representing ova of Oesophagostomum bifurcum and hookworm were detected in 87.5% of the Kato smears. The geometric mean egg count of the infected subjects was 1018. Upon coproculture, third-stage larvae of O. bifurcum and hookworm were detected in 53.0% and 86.9% of subjects respectively. Oesophagostomum infections were clustered but no clear explanation for aggregation of infections could be found as yet. Subjects infected with hookworm had a 5-fold higher risk of being infected with O. bifurcum. Infection rates in adult women were higher than in adult men. No association was found with family size, level of hygiene or with the presence of animals in the compounds. Representatives of the Bimoba-tribe were significantly more infected than those of the other tribes. It appears, however, that this tribal association is a geographical phenomenon: Bimoba are mostly living in villages with the highest infection rates.

Adolescent↗

PubMedDate not supplied

The immunoepidemiology of human hookworm infection.

Advances in hookworm immunoepidemiology are reviewed. Recent studies demonstrate a mixed Th1/Th2 response in human hookworm infection, with immunosuppression of specific and nonspecific IFN-gamma responses. There is increasing evidence for protective immunity in human hookworm infection, including anti-larval IL-5- and IgE-dependent mechanisms, and for immunological interactions between hookworm infection and other diseases.

Ancylostoma↗

PubMed2006

Contrasting effects of heterozygosity on survival and hookworm resistance in California sea lion pups.

Low genetic heterozygosity is associated with loss of fitness in many natural populations. However, it remains unclear whether the mechanism is related to general (i.e. inbreeding) or local effects, in particular from a subset of loci lying close to genes under balancing selection. Here we analyse involving heterozygosity-fitness correlations on neonatal survival of California sea lions and on susceptibility to hookworm (Uncinaria spp.) infection, the single most important cause of pup mortality. We show that regardless of differences in hookworm burden, homozygosity is a key predictor of hookworm-related lesions, with no single locus contributing disproportionately. Conversely, the subsequent occurrence of anaemia due to blood loss in infected pups is overwhelmingly associated with homozygosity at one particular locus, all other loci showing no pattern. Our results suggest contrasting genetic mechanisms underlying two pathologies related to the same pathogen. First, relatively inbred pups are less able to expel hookworms and prevent their attachment to the intestinal mucosa, possibly due to a weakened immune response. In contrast, infected pups that are homozygous for a gene near to microsatellite Hg4.2 are strongly predisposed to anaemia. As yet, this gene is unknown, but could plausibly be involved in the blood-coagulation cascade. Taken together, these results suggest that pathogenic burden alone may not be the main factor regulating pathogen-related mortality in natural populations. Our study could have important implications for the conservation of small, isolated or threatened populations, particularly when they are at a risk of facing pathogenic challenges.

Ancylostomatoidea↗

PubMed2006

Comparative immunology of human and animal models of hookworm infection.

Hookworm infection is a major cause of disease burden for animals and humans. Over the past years, the use of animal models in hookworm infections has been driven by the search of new anthelminthic therapies and, especially, vaccine development. These studies also contributed to the advance of knowledge on immunity to hookworms, offering new insights to understand the nature of this parasitic infection. In this article, we will summarize the essential features of the immune response in the two major animal models of hookworm infections (dog and hamster) and then consider its implication for the human immune response.

Ancylostoma↗

PubMed2006

A double-blind randomized controlled trial of antenatal mebendazole to reduce low birthweight in a hookworm-endemic area of Peru.

OBJECTIVE: To assess the effect on birthweight of antenatal mebendazole plus iron vs. placebo plus iron in a highly hookworm-endemic area. METHODS: Double-blind, randomized controlled trial set in rural and peri-urban communities in the Peruvian Amazon region. A total of 1042 second trimester pregnant women between the ages of 18 and 44 years were recruited from April to November 2003, and followed to July 2004. Women were randomly assigned to receive either mebendazole (500 mg single dose) plus iron supplements (60 mg elemental iron daily) or placebo plus iron supplements. The primary outcome was mean infant birthweight and secondary measures included proportion of low birthweight babies and maternal anaemia. RESULTS: The prevalence of hookworm infection was 47.5%. There were no differences between intervention groups in mean birthweight (3104 g vs. 3090 g, P = 0.629), proportion of low birthweight (<2500 g; 8.1%vs. 8.7%, P = 0.755) or maternal anaemia in the third trimester [33.0% (158/479) vs. 32.3% (152/471), P = 0.815]. However, the proportion of very low birthweight (<1500 g) was significantly lower in the mebendazole group [0% (0/479) vs. 1.5% (7/471), P = 0.007]. CONCLUSIONS: This trial provides additional evidence for the use of anthelmintics, over and above iron supplementation, within antenatal care programmes in hookworm-endemic areas. Benefits of de-worming may be higher in countries not having an antenatal iron supplementation programme or where intensity of hookworm infections is higher.

Adult↗

PubMed1988

Role of specific immunoglobulin E to excretory-secretory antigen in diagnosis and prognosis of hookworm infection.

Total immunoglobulin E (IgE) and specific IgE were assayed by a radioimmunosorbent test and a reverse enzyme immunoassay in patients with hookworm infections before and after treatment. A total of 77 subjects (30 patients with hookworm infections and 47 subjects as controls) were studied. Both specific and total IgE levels in serum and jejunal juice were raised in hookworm patients. There was a significant decrease in IgE levels after therapy. Total IgE levels were raised in other nematode infections, but specific IgE levels were low. The reverse enzyme immunoassay for specific IgE was highly specific (96%) and sensitive (100%) and may be used in the serodiagnosis of hookworm infections.

Adolescent↗

PubMed1971

Pyrantel embonate in treatment of hookworm infestation.

The efficacy of pyrantel embonate (1,4,5,6-tetrahydro-1-methyl-2-(trans-2-(2-thienyl)-vinyl)-pyrimidine embonic acid salt; Combantrin) was evaluated in 60 cases of hookworm infestation. They were divided into six groups of 10 cases. Pyrantel embonate was administered orally, in dosage schedules (randomized) of 100, 75, 50, 20, 15, and 10 mg/kg of body weight. The stool examination for hookworm ova and coproculture were positive in each case. The predominant species was Ancylostoma duodenale (in 58 patients). After treatment with pyrantel embonate the stool examination for hookworm ova and coproculture were negative on the 10th and 15th days in each group. The blood levels of the drug were significantly higher in patients receiving 100 and 75 mg/kg body weight. In groups A and B one patient experienced nausea and vomiting on the day of administration of drug. There were no abnormal changes in liver function tests or blood urea levels in any of the groups. Hence the optimum single dose of the drug effective against hookworm infestation is 10 mg/kg body weight, and further studies are required to evaluate the minimum effective dose of pyrantel embonate.

Administration, Oral↗

PubMed2006

The co-distribution of Plasmodium falciparum and hookworm among African schoolchildren.

BACKGROUND: Surprisingly little is known about the geographical overlap between malaria and other tropical diseases, including helminth infections. This is despite the potential public health importance of co-infection and synergistic opportunities for control. METHODS: Statistical models are presented that predict the large-scale distribution of hookworm in sub-Saharan Africa (SSA), based on the relationship between prevalence of infection among schoolchildren and remotely sensed environmental variables. Using a climate-based spatial model of the transmission potential for Plasmodium falciparum malaria, adjusted for urbanization, the spatial congruence of populations at coincident risk of infection is determined. RESULTS: The model of hookworm indicates that the infection is widespread throughout Africa and that, of the 179.3 million school-aged children who live on the continent, 50.0 (95% CI: 48.9-51.1) million (27.9% of total population) are infected with hookworm and 45.1 (95% CI: 43.9-46) million are estimated to be at risk of coincident infection. CONCLUSION: Malaria and hookworm infection are widespread throughout SSA and over a quarter of school-aged children in sub-Saharan Africa appear to be at risk of coincident infection and thus at enhanced risk of clinical disease. The results suggest that the control of parasitic helminths and of malaria in school children could be viewed as essential co-contributors to promoting the health of schoolchildren.

Africa South of the Sahara↗

PubMedDate not supplied

Epidemiology of hookworm infection in Itagua, Paraguay: a cross sectional study.

A cross-sectional study in Itagua, Paraguay tested 192 people for the presence, intensity and species of hookworm infection. Fifty-nine percent of these individuals were found to be infected. Intensity of infection was determined on 92% of infected individuals by quantitative egg counts. The high intensity hookworm infections, which cause the greatest morbidity, were clustered between the ages of five and 14 years. No differences were seen between genders. The species of hookworm was determined for parasites reared from 72% of infected individuals. Both Necator americanus and Ancylostoma duodenale were identified, although the former species predominated. We conclude that hookworm infection continues to be a public health problem in Paraguay, particularly among children and adolescents who suffer from high intensity infections. A. duodenale continues to persist in the Western Hemisphere and has not been completely displaced by N. americanus.

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↗