Impact of intestinal helminth infection on anemia and iron status during pregnancy: a community based study in Indonesia

A cohort study was carried out in Purworejo District, Central Java, Indonesia to investigate prevalence of anemia and low iron stores during pregnancy in relation to intestinal helminth infection. 442 pregnant women were followed until 5-10 weeks postpartum, during the period of April 1996 - August 1998. Information on intestinal helminths, hemoglobin and serum ferritin was collected each trimester. Highest prevalence of anemia in pregnancy (37.1%) was found in the second trimester, while the highest prevalence of low iron stores (49.5%) was found in the third trimester. Most pregnant women (69.7%) were infected with at least one species of pathogenic intestinal helminths. The most common helminth detected was Trichuris trichiura followed by Necator americanus (hookworm) and Ascaris lumbricoides. A significant negative association was found between hookworm infection and serum ferritin at the first trimester (p = 0.010). It is concluded that hookworm infection can interfere iron stores. Other causes of anemia among pregnant women should be considered. Anthelminthic therapy could be given to infected women before conception as public health strategy to improve iron status.     

Search for protective antigens of hookworms

Hookworms are very important blood sucking nematode parasites of humans and domestic animals. The host with a heavy infection can lose almost a cup of blood per day. This may contribute to anemia which is associated with many physical and mental developmental insults. The works on obtaining an effective hookworm vaccine have been lasting for about eighty years. Recent identifications of a number of bioactive molecules produced by larval and adult stages of Ancylostomatidae are very helpful for selecting of nematode proteins crucial for host-parasite interactions and promising vaccine antigens. Many of these molecules are involved in host skin penetration by infective larvae, intestinal tissue invasion and digestion of haemoglobin and/or other macromolecular substrates. However, the results of many vaccination trials using recombinant forms of these proteins showed no sufficient protection against experimental hookworm infections.     

Vitamin B12 and Folic Acid Metabolism in Hookworm-Infected Patients

Studies on the metabolism of B₁₂ and folic acid were performed inpatients with heavy hookworm infection and severe iron deficiency anemia,and in patients with light infection, noninfected patients and normal subjects.

Patients with heavy hookworm infection showed a marked decrease ofthe serum B₁₂ as compared with normal subjects. Eight of 21 cases studiedshowed values of serum B₁₂ below 100 µµg./ml.

Twelve of 13 patients with severe hookworm infection showed impairmentof the pteroylglutamic acid intestinal absorption; however, none of themexhibited megaloblastic proliferation in the bone marrow. They all recoveredwith iron therapy alone. The patients with light infection and the noninfected patients with iron deficiency anemia did not demonstrate significantdifferences from the normal subjects studied.

Submitted on January 19, 1959 Accepted on May 10, 1959     

Moderate- and low-intensity co-infections by intestinal helminths and Schistosoma mansoni, dietary iron intake, and anemia in Brazilian children

To determine the role of moderate- and low-intensity infections with Schistosoma mansoni and intestinal helminths (hookworm, Trichuris trichiura, Ascaris lumbricoides) on the prevalence of anemia and their relationship to iron consumption, a cross-section of 1,709 children in rural Brazil was studied. All participants were selected for infection with one or multiple helminthic parasites, and demographic, anthropometric, and dietary intake were surveyed. The prevalence and intensity were as follows: hookworm infection, 15.7% and 8.6 eggs/g; T. trichiura, 74.8% and 190.5 eggs/g; A. lumbricoides, 63% and 1,905.5 eggs/g; S. mansoni, 44.5% and 60.3 eggs/g. There was no increase in odds ratio for anemia with any combination of intestinal helminths without S. mansoni infection. By logistic regression, the odds ratio for having anemia when infected with S. mansoni and two intestinal helminths was 1.7 (95% CI, 1.1-2.5) and for S. mansoni and three intestinal helminths was 2.4 (95% CI, 1.2-4.6) compared with children with a single parasite species. Children with an adequate intake of iron had no increased odds of anemia independent of the combination of parasite infections.     

Parasitological, hematologic, and immunologic responses in acute and chronic infections of dogs with Ancylostoma ceylanicum: a model of human hookworm infection

A model of human hookworm infection has been defined with a strain of Ancylostoma ceylanicum that is known to be infective for humans. In the first experiment, dogs were infected with between 150 and 12,150 filariform larvae and followed up for six weeks. A direct relation was found between the size of infecting dose, fecal egg excretion, intestinal adult worm burden, and worm distribution in the bowel. Dogs with heavy infection developed bloody diarrhea and iron-deficient anemia. In the second experiment, dogs infected with 2,000 larvae excreted ova until autopsy 36 weeks after infection. Normocytic anemia and blood eosinophilia coincided with maximal egg excretion. Transitory lymphocyte stimulation was seen with adult worm antigen. The specific IgM antibody response was transient, but IgG antibodies persisted indefinitely. Marked skin immediate hypersensitivity and Arthus (but no delayed) hypersensitivity reactions were seen to injected larval and adult antigens. Thus, dogs develop both hookworm disease and chronic infections similar to those seen in humans.     

Excess Hemolysis in Subjects with Severe Iron Deficiency Anemia Associated and Nonassociated with Hookworm Infection

An excess hemolysis was found in subjects with iron deficiency anemia associated with hookworm infection. Red cell survival, measured with Cr⁵¹ andDFP³² in the subjects before deworming, showed a marked disproportionbetween the decrease of the survival and the amount of daily intestinal bloodloss in most cases. Excess of hemolysis was still present after more than 90 percent of the parasites were removed. Red cell survival became normal aftercorrection of anemia through iron treatment. Excess of hemolysis was alsopresent in noninfected subjects with iron deficiency anemia due to othercauses.

The reduction in the survival of the erythrocytes from infected subjectstransfused into normal recipients shows that the hemolytic process is due toan intrinsic defect of the red cells. The low values of hemoglobinemia andthe presence of haptoglobins in the plasma indicate that hemoglobin has notbeen liberated in excess intravascularly. Finally, the fact that the red cellsfrom an infected patient taken after deworming survived normally in splenectomized recipients indicates that the spleen is probably the principal siteof the red cell destruction. The clinical and autopsy findings suggest thatsplenic function is not pathologically increased, but rather that this organ isacting physiologically at a more rapid rate, "culling" the abnormal circulatingred cells and thus leading to a decrease in red cell survival.

The studies presented here also indicate that the hookworm infection perse does not induce hemolysis.

Submitted on January 13, 1964 Accepted on April 24, 1964     

Hookworm vaccines.

Hookworm infection caused by the soil-transmitted nematodes Necator americanus and Ancylostoma duodenale is one of the most common parasitic infections worldwide. Although not directly responsible for substantial mortality, it causes significant morbidity in the form of chronic anemia and protein malnutrition. Current global control efforts based on periodic mass anthelmintic administration are unsustainable, and new control strategies must be developed. This review describes progress in the development of vaccines against hookworm infection, including the preclinical and initial clinical testing of the N. americanus Ancylostoma Secreted Protein-2 Hookworm Vaccine. Plans call for eventual development of a vaccine that will combine at least 2 hookworm antigens--one targeting the larval stage of the life cycle and another targeting the adult worm living in the gastrointestinal tract.     

Mitigation of hookworm disease by immunization with soluble extracts of Ancylostoma ceylanicum

Hookworms are a leading cause of anemia in developing countries, and a strategy aimed at reducing pathology caused by blood-feeding adult parasites would be a valuable addition to global control efforts. This article describes experiments designed to induce resistance to the major clinical sequelae (weight loss and anemia) of Ancylostoma ceylanicum hookworm infection in Syrian golden hamsters of the outbred LVG strain. Previously infected animals acquired long-lived resistance to weight loss and anemia caused by a secondary hookworm infection. Furthermore, transfer of pooled serum from twice-infected hamsters to animals undergoing a primary infection was associated with partial resistance to growth delay and anemia. Active vaccination of hamsters with soluble adult hookworm antigens emulsified in alum led to partial protection from hookworm-associated pathology in the absence of reductions in adult worm burden. This intriguing result may have important implications for human vaccine development.     

Selective primary health care: strategies for control of disease in the developing world. XVII. Hookworm infection and anemia

Approximately one-quarter of the world's population is infected with either Ancylostoma duodenale or Necator americanus. Humans transmit the hookworm by fecal contamination of the soil. The eggs hatch and the larvae may survive several months in warm, damp soil. Humans are infected when the larvae penetrate the skin and migrate through the body to the intestines, where the median survival time of the hookworm is one year. The loss of red blood cells into the gut is proportional to the worm load. Symptoms result from iron deficiency anemia and protein loss caused by a heavy worm burden. The peak age-specific prevalence of infection occurs in adult life, but only a small proportion of those infected ever become symptomatic. Possible control measures include chemotherapy to reduce the intensity of infection and the transmission potential and sanitation.     

Anemia, iron deficiency, meat consumption, and hookworm infection in women of reproductive age in northwest Vietnam

Iron deficiency anemia poses an important public health problem for women of reproductive age living in developing countries. We assessed the prevalence of iron deficiency and anemia and associated risk factors in a community-based sample of women living in a rural province of northwest Vietnam. A cross-sectional survey, comprised of written questionnaires and laboratory analysis of hemoglobin (Hb), ferritin, transferrin receptor, and stool hookworm egg count, was undertaken, and the soluble transferrin receptor/log ferritin index was calculated. Of 349 non-pregnant women, 37.53% were anemic (Hb < 12 g/dL), and 23.10% were iron deficient (ferritin < 15 ng/L). Hookworm infection was present in 78.15% of women, although heavy infection was uncommon (6.29%). Iron deficiency was more prevalent in anemic than non-anemic women (38.21% versus 14.08%, P < 0.001). Consumption of meat at least three times a week was more common in non-anemic women (51.15% versus 66.67%, P = 0.042). Mean ferritin was lower in anemic women (18.99 versus 35.66 ng/mL, P < 0.001). There was no evidence of a difference in prevalence (15.20% versus 17.23%, P = 0.629) or intensity (171.07 versus 129.93 eggs/g, P = 0.412) of hookworm infection between anemic and non-anemic women. Although intensity of hookworm infection and meat consumption were associated with indices of iron deficiency in a multiple regression model, their relationship with hemoglobin was not significant. Anemia, iron deficiency, and hookworm infection were prevalent in this population. Intake of meat was more clearly associated with hemoglobin and iron indices than hookworm. An approach to addressing iron deficiency in this population should emphasize both iron supplementation and deworming.     

Reversal of hemochromatosis by apotransferrin in non-transfused and transfused Hbbth3/+ (heterozygous b1/b2 globin gene deletion) mice

Intermediate beta-thalassemia has a broad spectrum of sequelae and affected subjects may require occasional blood transfusions over their lifetime to correct anemia. Iron overload in intermediate beta-thalassemia results from a paradoxical intestinal absorption, iron release from macrophages and hepatocytes, and sporadic transfusions. Pathological iron accumulation in parenchyma is caused by chronic exposure to non-transferrin bound iron in plasma. The iron scavenger and transport protein transferrin is a potential treatment being studied for correction of anemia. However, transferrin may also function to prevent or reduce iron loading of tissues when exposure to non-transferrin bound iron increases. Here we evaluate the effects of apotransferrin administration on tissue iron loading and early tissue pathology in non-transfused and transfused Hbb^th3/+ mice. Mice with the Hbb^th3/+ phenotype have mild to moderate anemia and consistent tissue iron accumulation in the spleen, liver, kidneys and myocardium. Chronic apotransferrin administration resulted in normalization of the anemia. Furthermore, it normalized tissue iron content in the liver, kidney and heart and attenuated early tissue changes in non-transfused Hbb^th3/+ mice. Apotransferrin treatment was also found to attenuate transfusion-mediated increases in plasma non-transferrin bound iron and associated excess tissue iron loading. These therapeutic effects were associated with normalization of transferrin saturation and suppressed plasma non-transferrin bound iron. Apotransferrin treatment modulated a fundamental iron regulatory pathway, as evidenced by decreased erythroid Fam132b gene (erythroferrone) expression, increased liver hepcidin gene expression and plasma hepcidin-25 levels and consequently reduced intestinal ferroportin-1 in apotransferrin-treated thalassemic mice.     

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 hookworm platelet inhibitor: functional blockade of integrins GPIIb/IIIa (alphaIIbbeta3) and GPIa/IIa (alpha2beta1) inhibits platelet aggregation and adhesion in vitro

Hookworms, aggressive, blood-feeding, intestinal nematodes, are currently a leading cause of iron deficiency anemia in the developing world. An inhibitor of platelet aggregation and adhesion has been partially purified and characterized from soluble protein extracts of adult Ancylostoma caninum hookworms. This protein, named the hookworm platelet inhibitor, has an estimated molecular mass of 15 kDa as determined by size-exclusion chromatography. In addition to blocking platelet aggregation in response to a variety of agonists, the partially purified inhibitor also prevents adhesion of resting platelets to immobilized fibrinogen and collagen. Inhibitory monoclonal antibodies were used to identify specific blockade of cell surface integrins GPIIb/IIIa (alphaIIbbeta3) and GPIa/IIa (alpha2beta1), the platelet receptors for fibrinogen and collagen, respectively. This broad-spectrum anti-platelet activity is also present in excretory and secretory products of adult worms, suggesting a biologic role for the hookworm platelet inhibitor in vivo.     

Hepcidin和铁稳态

铁代谢紊乱引起的疾患是人类最常见的疾病。生理条件下，人体主要通过调控小肠铁吸收保持机体铁稳态。最近关于hepcidin的研究显示，这种肝脏合成的已知具有抗菌功能的多肽是控制小肠铁吸收，以及调节机体铁稳态的铁调节激素。肝脏hepcidin高表达可能是许多贫血包括炎症和慢性疾病性贫血的根本原因，而hepcidin表达障碍可能是许多铁过负荷类疾病的起因。     

Morbidity indicators of Schistosoma mansoni: relationship between infection and anemia in Ugandan schoolchildren before and after praziquantel and albendazole chemotherapy

The potential relationship between Schistosoma mansoni and anemia was examined using data obtained by the Schistosomiasis Control Initiative (SCI) before (baseline) and 1 year after (follow-up) a chemotherapeutic treatment program in Uganda. Changes in hemoglobin (Hb) levels in 2,788 children in relation to their schistosomiasis and/or hookworm infection intensity category and baseline anemia status were analyzed. At baseline, significant predictors of childhood anemia were intensities of S. mansoni and hookworm infection. At follow-up, moderate or heavy hookworm as well as heavy S. mansoni infections were important. Children heavily infected with S. mansoni or hookworm had significantly lower Hb counts at baseline compared with those not infected. Among anemic children at the baseline survey, a significant increase in Hb counts of 0.834 g/dL after treatment was found. Our results suggest that anemia is associated with schistosomiasis and hookworm in Ugandan children and that such anemia shows a significant improvement after chemotherapy.     

Helicobacter pylori infection is associated with severe anemia of pregnancy on Pemba Island, Zanzibar

Helicobacter pylori infection has recently been associated with iron deficiency and anemia in developed countries. To determine the association of H. pylori and anemia in a tropical region, we measured hemoglobin concentration (Hb) and H. pylori infection by the 13C urea breath test among 857 pregnant women attending antenatal care clinics. Parasitology, anthropometry, obstetric history, sociodemographic and dietary variables were also assessed. Logistic regression showed an odds ratio of 7.63 (95% confidence interval=1.73-33.55) for H. pylori infection comparing women with and without severe anemia (Hb<7 g/dL), controlling for hookworm infection, body mass index and parity, but only among women with a diet low in foods containing heme iron. Infection with H. pylori with low bacterial load was associated with lower Hb concentration while high bacterial load was associated with higher Hb concentration. Further research is needed to establish causality because high worldwide prevalence means that even a small associated risk would be of public health significance.     

Hepcidin,a putative mediator of anemia of inflammation,is a type II acute-phase protein

Hepcidin is a liver-made peptide proposed to be a central regulator of intestinal iron absorption and iron recycling by macrophages. In animal models, hepcidin is induced by inflammation and iron loading, but its regulation in humans has not been studied. We report that urinary excretion of hepcidin was greatly increased in patients with iron overload, infections, or inflammatory diseases. Hepcidin excretion correlated well with serum ferritin levels, which are regulated by similar pathologic stimuli. In vitro iron loading of primary human hepatocytes, however, unexpectedly down-regulated hepcidin mRNA, suggesting that in vivo regulation of hepcidin expression by iron stores involves complex indirect effects. Hepcidin mRNA was dramatically induced by interleukin-6 (IL-6) in vitro, but not by IL-1 or tumor necrosis factor alpha (TNF-alpha), demonstrating that human hepcidin is a type II acute-phase reactant. The linkage of hepcidin induction to inflammation in humans supports its proposed role as a key mediator of anemia of inflammation.     

Iron deficiency anemia in celiac disease

Iron is an important micronutrient that may be depleted in celiac disease. Iron deficiency and anemia may complicate well-established celiac disease, but may also be the presenting clinical feature in the absence of diarrhea or weight loss. If iron deficiency anemia occurs, it should be thoroughly evaluated, even if celiac disease has been defined since other superimposed causes of iron deficiency anemia may be present. Most often, impaired duodenal mucosal uptake of iron is evident since surface absorptive area in the duodenum is reduced, in large part, because celiac disease is an immune-mediated disorder largely focused in the proximal small intestinal mucosa. Some studies have also suggested that blood loss may occur in celiac disease, sometimes from superimposed small intestinal disorders, including ulceration or neoplastic diseases, particularly lymphoma. In addition, other associated gastric or colonic disorders may be responsible for blood loss. Rarely, an immune-mediated hemolytic disorder with increased urine iron loss may occur that may respond to a gluten-free diet. Reduced expression of different regulatory proteins critical in iron uptake has also been defined in the presence and absence of anemia. Finally, other rare causes of microcytic anemia may occur in celiac disease, including a sideroblastic form of anemia reported to have responded to a gluten-free diet.     

Platelet parameters in subjects infected with hookworm

Hookworm is an important intestinal parasite infection with high prevalence in tropical countries. In addition to iron deficiency anaemia, the human hookworm appears to have evolved a number of complementary strategies to overcome the host's haemostatic processes. These include the inhibition of blood coagulation, platelet aggregation and mediator release, and the secretion of fibrinogenolytic enzymes. In this work, we studied the platelets in the subjects with detection of hookworm infection from screening stool examination comparing to those without. One hundred subjects were included, studied for stool parasite and platelet parameters. Of our 100 subjects, hookworms were identified in stools of six cases, giving an infection rate equal to 6%. The platelet parameters of the subjects showed a statistically significant lowering of mean platelet volume (MPV) in the subjects with hookworm infection. Also, we detected a non-significant lower platelet count in subjects with hookworm infections. Of interest, the alteration in platelet size, identified by platelet parameters, has never been documented in the literature. This observation might be a pathological process or might be an accidental finding in our study.     

Hookworm vaccines: past, present, and future

Hookworms are gastrointestinal nematodes that infect almost 1 billion people in developing countries. The main clinical symptom of human hookworm infections is iron-deficiency anaemia, a direct consequence of the intestinal blood loss resulting from the parasite's feeding behaviour. Although treatment is available and currently used for the periodic removal of adult hookworms from patients, this approach has not effectively controlled hookworm in areas of rural poverty. Furthermore, treated individuals remain susceptible to reinfection following exposure to third-stage infective hookworm larvae in the soil as early as 4-12 months after drug treatment. Therefore, a prophylactic vaccine against hookworm infection would provide an attractive additional tool for the public-health control of this disease. The feasibility of developing a vaccine is based on the previous success of an attenuated larval vaccine against canine hookworm. Several laboratory and field studies have explored the development of a human anti-hookworm vaccine, describing potential protective mechanisms and identifying candidate antigens, one of which is now in clinical trials. The current roadmap that investigators have conceived has been influenced by vaccine development for blood-feeding nematodes of livestock and companion animals; however, recombinant vaccines have yet to be developed for nematodes that parasitise animals or human beings. The roadmap also addresses the obstacles facing development of a vaccine for developing countries, where there is no commercial market.