High-throughput multiplex qPCRs for the surveillance of zoonotic species of canine hookworms

The canine hookworms Ancylostoma braziliense, Ancylostoma ceylanicum, Ancylostoma caninum and Uncinaria stenocephala are not only capable of producing morbidity and mortality in dogs but are also neglected tropical zoonoses. Each hookworm species differs considerably in its geographical distribution, life cycle, biology, pathogenic impacts on both canine and human hosts, zoonotic potential, and response to treatment with anthelminthics. Here we describe the development and validation of two Taq-Man based multiplex PCR assays capable of detecting and differentiating all four canine hookworm species in faeces of naturally infected dogs. The analytical sensitivity of both assays was assessed using 10-fold serial dilutions of synthetic gene block fragments containing individual sequence targets of each hookworm species. The sensitivity of the assays and ability to detect mixed species infections were compared to a conventional PCR-Restriction Fragment Length Polymorphism based-approach when applied to laboratory and field samples from endemic areas. The qPCRs detected at least one species of hookworms in 82.4% of PCR-RFLP-negative but microscopy-positive samples. The qPCRs detected an additional 68% mixed infections with different species of canine hookworms, and additional single species infection with A. caninum (47%), U. stenocephala (33%) and A. ceylanicum (0.02%) that were missed by PCR-RFLP. These multiplex qPCR assays will assist field based epidemiological surveillance studies towards an accurate and sensitive monitoring of canine hookworm infections in dogs, to inform their species-specific zoonotic risks to populations living in endemic areas, globally.

Anemia and its association with coffee consumption and hookworm infection among pregnant women attending antenatal care at Debre Markos Referral Hospital, Northwest Ethiopia

BACKGROUND

Anemia in pregnancy is a major public health concern worldwide, especially in developing countries. Thus, there is a need of having current information and local data on the prevalence of anemia and associated factors during pregnancy to help inform preventive programmes. The aim of this study was to assess the prevalence of anemia and associated factors among pregnant women attending antenatal care at Debre Markos Referral Hospital, Northwest Ethiopia.

METHODS

An institution based cross-sectional study was conducted at Debre Markos Referral Hospital in July and August 2016. A total of 234 randomly-selected pregnant women took part in the study. Data on sociodemographic factors, environmental and sanitation factors, reproductive factors, and nutrition related characteristics were collected using a structured questionnaire. Hemoglobin level was determined using hematological analyzer (Cell Dyn 1800) machine. The stool sample was collected to identify intestinal parasitic infections. Statistical analysis was done using logistic regression. The p value of less than 0.05 at 95% confidence interval was considered statistically significant.

RESULTS

The overall prevalence of anemia among pregnant women was 11.5% (95% CI: 8.2%- 14.9%). The result of multivariable analysis revealed that, coffee consumption [AOR = 2.91; 95% CI (1.63, 8.78)], and hookworm infection [AOR = 2.65; 95% CI (1.48, 4.72)] were factors significantly associated with anemia among pregnant women.

CONCLUSION

Anemia is of public health concern among pregnant women in the study area. All pregnant women coming to antenatal clinics should be screened and treated routinely for intestinal parasitic infection. Pregnant women should limit coffee consumption, and avoid drinking coffee with meals.

Acute major gastrointestinal bleeding caused by hookworm infection in a patient on warfarin therapy: A case report

RATIONALE

The use of anticoagulants is a contributor to gastrointestinal (GI) bleeding. Most bleeding patients on anticoagulant therapy such as warfarin commonly have basic lesions existing in their GI mucosa.

PATIENT CONCERNS

We report a case of major GI bleeding following the use of anticoagulants in a patient with hookworm infection.

DIAGNOSES

The patient was diagnosed with nephrotic syndrome with pulmonary embolism.

INTERVENTIONS

He was treated with anticoagulants and suffered from acute major GI bleeding during the treatment. Capsule endoscopy revealed many hookworms in the lumen of jejunum where fresh blood was seen coming from the mucosa.

OUTCOMES

The patient was successfully rescued and cured with albendazole.

LESSONS

Latent hookworm infection can be a cause of massive small-bowel hemorrhage in patients on anticoagulant therapy and anthelmintic treatment is the key to stop bleeding.

Multiparasitism and intensity of helminth infections in relation to symptoms and nutritional status among children: a cross-sectional study in southern Lao People's Democratic Republic

The occurrence and spatial distribution of intestinal helminth infection in children is fairly well understood. However, knowledge on how helminth infections govern intestinal morbidity is scarce. We conducted a cross-sectional study to assess and quantify the relationship between single and multiple species helminth infection with clinical and self-reported morbidity indicators and nutritional status in Champasack province, southern Lao People's Democratic Republic (Lao PDR). A random sample of 1313 children, aged 6 months to 12 years, from villages in nine rural districts were enrolled and examined for helminth infection using duplicate Kato-Katz thick smears. Morbidity was assessed by self-reported symptoms, coupled with clinical examination and appraisal of nutritional status and anaemia. Bivariate and multivariate logistic regression was employed to study associations between helminth infection and morbidity indicators and anaemia. We found considerable morbidity among the surveyed children, including hepatomegaly (13.7%), pale conjunctiva (13.2%) and abdominal pain (10.4%). Anaemia was recorded in 60.4% of the children, whilst signs of stunting and low body mass index (BMI) were observed in 49.8% and 33.3% of the surveyed children, respectively. Hookworm and Opisthorchis viverrini were the predominant helminth species with prevalences of 51.0% and 43.3%, respectively. The prevalence of Schistosoma mekongi in the surveyed children was 5.6%. Multiple species helminth infections were recorded in 40.4% of the study cohort. Morbidity was associated with specific helminth species infection (e.g. S. mekongi with hepatomegaly; adjusted odds ratio (aOR): 9.49, 95% confidence interval (CI): 2.07-43.51) and multiparasitism (e.g. two or more helminth species with abdominal pain; aOR: 2.40, 95% CI: 1.46-3.93). Anaemia was associated with hookworm infection (aOR: 1.64, 95% CI: 1.16-2.34) and multiparasitism (aOR: 1.64, 95% CI: 1.18-2.29). Low BMI was associated with O. viverrini infection (aOR: 1.68, 95% CI: 1.14-2.49) and multiparasitism (aOR: 1.42, 95% CI: 1.01-2.00). The multiple strong associations reported here between helminth infections (single or multiple species) and intestinal morbidity among children in rural parts of southern Lao PDR call for concerted efforts to control helminth infections, which in turn might improve children's health and development.

The end of the line for hookworm? An update on vaccine development

Gut-associated molecules of human hookworms have been the focus of recent interest as potential vaccine candidates.

Modeling the effects of health status and the educational infrastructure on the cognitive development of Tanzanian schoolchildren

This paper models the proximate determinants of school attendance and scores on cognitive and educational achievement tests and on school examinations of over 600 schoolchildren from the Control group of a randomized trial in Tanzania, where children in the Intervention group heavily infected with hookworm and schistosomiasis received treatment. The modeling approach used a random effects framework and incorporated the inter-relationships between school attendance and performance on various tests, controlling for children's health status, socioeconomic variables, grade level, and the educational infrastructure. The empirical results showed the importance of variables such as children's height and hemoglobin concentration for the scores, especially on educational achievement tests that are easy to implement in developing countries. Also, teacher experience and work assignments were significant predictors of the scores on educational achievement tests, and there was some evidence of multiplicative effects of children's heights and work assignments on the test scores. Lastly, some comparisons were made for changes in test scores of treated children in the Intervention group with the untreated children in the Control group.

Hookworm infection: new developments and prospects for control

PURPOSE OF REVIEW

Hookworm infection remains a major health burden in developing countries. Successful control will likely be achieved through continued advances in our understanding of the epidemiology, molecular biology and immunopathogenesis of hookworm infection. This review summarizes recent advances in each of these fields, and discusses ongoing efforts to develop vaccines against hookworm anemia and growth delay.

RECENT DEVELOPMENTS

Revised estimates indicate that hookworms afflict over 700 million persons in tropical and subtropical regions. Prevalence and intensity often vary considerably at both the regional and local levels, and may be influenced by climate, soil composition, education, and socioeconomic status. Immunoepidemiological studies suggest that hookworm infection likely induces a complex mixture of host-protective and pathological immune responses. There has been substantial progress in elucidating the molecular pathogenesis of hookworm disease, primarily through the identification of a number of parasite virulence factors. Mass chemotherapy remains a mainstay of hookworm control strategies although continued use of benzimidazole anthelminthics is perhaps contributing to the development of anthelminthic resistance. Consequently, there remains a need for innovative approaches, including the development of vaccines and new chemotherapeutic agents, in order to provide effective global control of hookworm disease.

SUMMARY

Hookworm infection and disease is a significant threat to global health. Recent advances, particularly those at the molecular level, have provided a wealth of opportunities to better understand pathogenesis. This will likely allow for the development of novel measures such as vaccines to complement existing control methods.

Heavy schistosomiasis associated with poor short-term memory and slower reaction times in Tanzanian schoolchildren

Cross-sectional studies of the relationship between helminth infection and cognitive function can be informative in ways that treatment studies cannot. However, interpretation of results of many previous studies has been complicated by the failure to control for many potentially confounding variables. We gave Tanzanian schoolchildren aged 9-14 a battery of 11 cognitive and three educational tests and assessed their level of helminth infection. We also took measurements of an extensive range of potentially confounding or mediating factors such as socioeconomic and educational factors, anthropometric and other biomedical measures. A total of 272 children were moderately or heavily infected with Schistosoma haematobium, hookworm or both helminth species and 117 were uninfected with either species. Multiple regression analyses, controlling for all confounding and mediating variables, revealed that children with a heavy S. haematobium infection had significantly lower scores than uninfected children on two tests of verbal short-term memory and two reaction time tasks. In one of these tests the effect was greatest for children with poor nutritional status. There was no association between infection and educational achievement, nor between moderate infection with either species of helminth and performance on the cognitive tests. We conclude that children with heavy worm burdens and poor nutritional status are most likely to suffer cognitive impairment, and the domains of verbal short-term memory and speed of information processing are those most likely to be affected.

Anthelmintic treatment of rural Bangladeshi children: effect on host physiology, growth, and biochemical status

BACKGROUND

The effect of helminth infestation on the nutrition, growth, and physiology of the host is still poorly understood. Anthelmintic treatment of children in developing countries has had varying success in terms of growth improvements.

OBJECTIVE

The objective of this study was to assess the effect of regular deworming on child growth, physiology, and biochemical status.

DESIGN

The study was a 12-mo longitudinal intervention in 123 Bangladeshi children aged 2-5 y. Treatment (mebendazole) or placebo tablets were administered every 2 mo for 8 mo and again at 12 mo. Weight, height, midupper arm circumference, intestinal permeability, plasma albumin, alpha(1)-antichymotrypsin, and total protein concentration were assessed every 2 mo.

RESULTS

Treatment with mebendazole reduced the prevalence of Ascaris lumbricoides from 78% to 8%, of Trichuris trichiura from 65% to 9%, and of hookworm from 4% to 0%. There was no significant difference in the growth of treated children compared with those given placebo tablets. No changes in intestinal permeability or plasma albumin were observed after deworming. Significant decreases in total protein (P<0.001) and alpha(1)-antichymotrypsin (P<0.001) were observed in the treatment group, indicating possible reductions in inflammation and immunoglobulin concentration after deworming. A significant increase in the prevalence of Giardia intestinalis (from 4% to 49%) in the treatment group was associated with a short-term reduction in weight (P = 0.02) and higher intestinal permeability (P <0.001) in infected subjects. No long-term effects of G. intestinalis on growth were observed.

CONCLUSION

Low-intensity helminth infections, predominantly of A. lumbricoides and T. trichiura, do not contribute significantly to the poor growth and biochemical status of rural Bangladeshi children.

Evidence for an association between hookworm infection and cognitive function in Indonesian school children

The association between helminth infection and cognitive and motor function was investigated in school-age children in Java, Indonesia. 432 children from 42 primary schools participated in the study. Children were stratified by age and sex into two age groups, 8-9 years and 11-13 years. Children infected with hookworm performed significantly worse than children without hookworm infection in 6 of the 14 cognitive or motor tests. After controlling for school (as a random effect) plus age, socio-economic status and parental education, sex, stunting (height-for-age < - 2sd), body mass index, haemoglobin concentration and the presence of A. lumbricoides and T. trichiura infections, infection with hookworm explained significantly lower scores on tests of Fluency (P < 0.01), Digit-Span Forwards (P < 0.01), Number Choice (P < 0.01), Picture Search (P < 0.03), Stroop Colour Word (P < 0.02) and Mazes (P < 0.001). In 4 of the 6-tests (Fluency, Number Choice, Picture Search and Mazes), there was a significant interaction between hookworm infection and age (P < 0.03), indicating that the association between hookworm and lower test scores increased with age. No associations were observed between hookworm infection and scores in tests of Digit-Span Backwards, Corsi-Block, Stroop Colour, Stroop Interference, Free Recall, Verbal Analogies, Bead Threading or the Pegboard (P > 0.05). Tests associated with helminths represented various functions of working memory. No significant associations between helminth infection and motor function were observed that could not be explained by chance. The results suggest that hookworm infection can have a significant adverse effect on children's working memory which may have consequences for a child's reasoning ability and reading comprehension. Although the results are only associational, the fact that differences in cognition were observed at baseline imply that preventing infection with helminths in school-age children could be of benefit.

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

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

Molecular pathobiology of hookworm infection

Within the past 2 years, progress has been made in the identification, isolation, and cDNA cloning of several macromolecules from hookworms. While the predicted amino acid sequences of some cDNAs resemble those from other nematodes, such as Caenorhabditis elegans, other cDNAs are unique to hookworms. Studies are under way to evaluate the function of these recombinant hookworm polypeptides with respect to the biology of hookworms in experimental animal models. The recombinant polypeptides are also under evaluation as vaccine targets and as natural products used in the treatment of human cardiovascular and autoimmune diseases.

An 18-month study of the effect of periodic anthelminthic treatment on the growth and nutritional status of pre-school children in Bangladesh

An 18-month study was conducted from February 1989 to August 1990 to examine the effect of regular deworming on child growth and nutritional status. A sample of 1402 children, from 2 to 6 years old, were divided into a treatment group and a control group. The 688 children in the treatment group received a 500 mg single dose of mebendazole, while the 714 children in the control group were given a placebo. Height, weight and mid-upper arm circumference (MUAC) were measured on monthly household visits. Growth was measured in terms of the change in height-for-age, weight-for-age, weight-for-height and MUAC over 18 months. The initial prevalence of infection was estimated from a random sample of 96 children (49 treated, 47 control). The initial overall prevalence of Ascaris lumbricoides, Trichuris trichiura and hookworm was 71, 44 and 10% respectively. The final prevalence of infection, estimated from a random sample of 265 children, was A. lumbricoides 6%, T. trichiura 6% and hookworm 2% in the mebendazole group compared with 64, 18 and 19% respectively in the placebo group. Despite the successful treatment of helminths, there was no significant improvement in the growth of treated children compared with their untreated counterparts in terms of the change in z-scores of height-for-age, weight-for-age, weight-for-height and MUAC. The factors which may have contributed to this outcome are discussed.

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.

Intestinal nematode infections in children: the pathophysiological price paid

The mechanism by which small animals such as rodents resist or eliminate nematode parasites requires mucosal inflammation as the final effector of the immune response. The resulting freedom from chronic infection may be worth the price of short-term illness. Putative vaccines which attempt to enhance the natural effect will have to take into account the inflammatory cost to the host. Human helminthiases involve a more stable equilibrium between host and parasite. The medical literature on hookworm disease and clinical ascariasis describes, for the former, some chronic inflammatory effects correlated with worm burden, but for the latter a less quantified or predictable set of detrimental effects. We describe a current, systematic study of the inflammatory response to whipworm infection, in which anaemia, growth retardation and intestinal leakiness are viewed as predictable consequences related to infection intensity. There is evidence for the absence of cell-mediated immunopathology. However, a specific, IgE-mediated local anaphylaxis may, at least partly, mediate the deleterious effects. Increased numbers of mucosal macrophages may also contribute to the chronic, systemic effects through their output of cytokines. Similar attempts to show the mechanisms of pathogenesis and quantify the effects of hookworm disease should be undertaken.

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.

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.

Pathophysiology of nematodiasis in cattle

Recent detailed studies of the physiologic changes occurring in cattle infected with some of the common gastrointestinal nematodes have shown that the weight loss and reduced carcass values resulting from these infections are a consequence of major alterations in host metabolism. Dramatic changes in protein metabolism were consistently found to involve decreased muscle synthesis and increased urinary nitrogen excretion. Because of the well-recognized loss of plasma proteins into the gut lumen and cellular damage at the mucosa occurring during nematode infections of the abomasum and duodenum, it has been assumed that protein was being lost in feces or not absorbed; however, this loss has proved not to be as significant as postabsorptive protein catabolism in these infections. Only when the colon and cecum are involved in protein-losing infections is the loss of protein into the feces significant. The mechanisms by which gastrointestinal nematode infections result in such altered host metabolic states are not known, but suggestions have been made that parasites directly or indirectly alter gut hormone levels. Gut hormone changes may also be responsible for diarrhea and anorexia. Another mechanism of altering metabolism has been proposed for chronic parasitisms that stimulate macrophages. Macrophages produce a peptide called cachectin, and cachectin is thought to mediate protein and lipid catabolism. This mechanism obviously could be contributing to weight loss and anorexia whenever nematodes cause sufficient macrophage activation, including during lungworm infections, which do not have enteric involvement.

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)

Experimental and natural infection of calves with Bunostomum phlebotomum

An experiment was conducted to determine the efficiency of a method of experimental infection of weaner beef calves with Bunostomum phlebotomum and to compare such infection with that established by natural infection. Six calves, maintained on a concrete-floored pen, were inoculated with B. phlebotomum L3 by placing the larval inocuulum, in small volume, in the outer chamber of the ear while the animal was restrained for 18 min. Inoculation doses of 20, 30, 40, 50, 60, and 80 thousand L3 were used. Six other calves were grazed on pasture known to be heavily contaminated with hookworm. All animals were killed 72 days after experimental infection and 93 days after initial exposure to pasture infection. The experimental and naturally-infected calves became patent at 55 and 66 days, respectively, after exposure to L3. Red blood cell counts and hemoglobin values were markedly depressed in both groups and lowest values coincided with onset of patency. There was difference in liveweight changes, but both groups lost weight during the prepatent period of infection and gained weight with the onset of patency. The largest number of hookworms was established at the 30000 L3 inoculation level; little or no establishment was observed at the 2 highest levels. Sizeable adult hookworm burdens were established in 4 out of 6 pastured calves. Intestinal pathology was generally more severe in experimentally-infected calves, consisting of a thickened mucosa and masses of punctate, hemorrhagic foci. Pastured calves also acquired large burdens of Ostertagia ostertagi, particularly inhibited early fourth-stage larvae. Moderate to severe abomasal pathology and elevated plasma pepsinogen were associated with ostertagiasis in the pastured calves. The experimental infection method is efficient in establishing high levels of B. phlebotomum infection in calves currently or previously infected with other gastrointestinal nematodes.

Needed research on the interactions of certain parasitic diseases and nutrition in humans

For the purpose of assigning priorities for research, each of the following parasitic disease is examined in regard to its affect on the nutritional status of the host: schistosomiasis, malaria, amebiasis, giardiasis, ascariasis, and hookworm. The epidemiology, diagnosis, immune response to, and available therapies for these diseases are discussed. It is suggested that highest priority be given to three diseases: hookworm, ascariasis, and schistosomiasis, because they can be treated successfully, diagnosed easily, and have a high prevalence.

Study of the efficacy of compound Go.9333 (Ciba-Geigy) in hookworm infestation

50 cases with hookworm infestation were studied to find out the species of the parasite, 25 of them were included for a double-blind trial of compound Go.9333 (Ciba-Geigy)/placebo. Results of the study revealed predominance of Necator americanus (96%) in and around Pondicherry, South India. Compound Go.9333 was found to very effective in the treatment of hookworm infestation. Side effects were minor and were not of much significance. The drug was well accepted and tolerated by most of the cases. On the basis of the present study, compound Go.9333 can be recommended for the treatment of hookworm infestation.

Effect of iron and protein deficiency on the expulsion of Nippostrongylus brasiliensis from the small intestine of the rat

The relationship between iron deficiency and protein deficiency and infestation of the rat with the nematode Nippostrongylus brasiliensis was investigated. There was a significant delay in the expulsion of N. brasiliensis from the small intestine of both iron deficient and protein deficient animals and those with a combined deficiency of iron and protein. Iron repletion returned the time of worm expulsion to normal and this would appear to be related to iron deficiency per se rather than to anaemia. Antibody initiated damage to worms was normal in the control animals and in animals with nutritional deficiencies. This suggests that the defect in worm expulsion occurs either in the cell-mediated immune system or in one of the other mediators of expulsion. Extrapolation to the human situation has important therapeutic implications in that iron and protein deficiency may play an important role in the perpetuation of helminth infestations. Thus, to be successful antihelminth therapy should be accompanied by iron and protein supplementation.

Small-intestinal cell turnover in patients with parasitic infections

Small-intestinal deoxyribonucleic acid (DNA) loss rates were measured in six patients with Strongyloides stercoralis hyperinfestation, in four patients with hookworm disease, and in eight normal controls. In the four patients with strongyloidiasis having weight loss, hypoproteinaemia, and oedema the mean DNA loss rates were 73.9, 51.6, 58.0, and 62.2 ng atoms DNA-P/min respectively, which was significantly higher than that of patients with hookworm disease (mean 17.3, S.D. 6.6) or in eight control subjects (mean 14.5, S.D. 7.5). In two of three patients with strongyloidiasis the high DNA loss rates fell to normal after treatment, and in two others investigated only after treatment the rates were normal. It is suggested that the high epithelial cell turnover in these patients may result in excessive loss of endogenous substances and that this may be an important mechanism in causing malnutrition and hypoproteinaemia in patients with S. stercoralis hyperinfestation.

Immune reactions in mucous membranes. I. Intestinal mast cell response during helminth expulsion in the rat

Measurement of the mast cell response in the jejunal mucosae of rats infected with Nippostrongylus brasiliensis was carried out at the time of worm expulsion (self-cure). Just prior to the start of self-cure, a new mast cell population differentiated from cells with large nuclei and prominent nucleoli. Beginning on the 10th day of infection, mast cell numbers increased in an exponential fashion and reached a peak in the middle of the self-cure reaction 14 days after infection. At first the cells had few granules but their granule content subsequently increased and by day 14 some of them appeared to be mature. Mitoses were observed in granulated cells at all stages of the population expansion.

Differential counts showed that an increasing proportion of the mast cell population migrated intraepithelially to become globule leucocytes so that by day 14 the ratio of globule leucocytes to mast cells was 1/1. On subsequent days of infection, this ratio and the total population of granulated cells gradually diminished.

The results suggest that cell differentiation and division are responsible for the population increase. The high globule leucocyte/mast cell ratio points to an extensive release of amines from the granules during self-cure. The significance of this reaction in relation to antibody release from the mucosa and to worm expulsion is discussed.

On the mechanism of expulsion of helminths

In rats infected with larvae of the nematode Nippostrongylus brasiliensis, treatment from day 9 to day 19 with the chemical histamine-liberator, compound 48/80, produces a clear delay in worm expulsion. However, the number of mast cells in the epithelium of the jejunum is not markedly decreased by this treatment.

Relationship of anaemia and hypoproteinaemia to the functional and structural changes in the small bowel in hookworm disease

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Functional and structural changes in the small intestine in children with hookworm infection

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