Acquired hookworm immunity in the golden hamster (Mesocricetus auratus) elicited by living Necator americanus third-stage infective larvae.

The aim of the study is to demonstrate and understand the acquired immunity in golden hamsters (Mesocricetus auratus) elicited by primary Necator americanus infective third-stage larvae (L3) infection. Hamsters infected with 150 L3 for 1, 2, 3, 6 and 10 weeks, were challenged with the same number of L3 and sacrificed 25 days post challenge. The primarily infected hamsters exhibited 99-100% protection against subsequent L3 challenge compared to un-infected naive hamsters. The acquired immunity was developed as early as 1 week post L3 infection and lasted up to 10 weeks. Similar protective immunity was obtained in hamsters infected with N. americanus L3 and then treated orally with a single of 100mg/kg albendazole, followed by challenge with N. americanus L3 4 and 8 weeks post-treatment. The infected hamsters exhibited a rise in IgG antibodies against L3 and juvenile adult worm antigens. Histological examination showed that challenging L3 were trapped in the skin of primarily infected hamsters and surrounded or infiltrated by different inflammatory cells. The trapped L3 were damaged and dead followed by the formation of granulomas encasing dead worms. The results demonstrate that hamsters primarily infected with N. americanus L3 develop acquired immunity against re-infection.

A case of severe anemia by Necator americanus infection in Korea.

This report describes clinical and parasitological findings of an 82-yr-old female patient who lived in a local rural village and suffered from severe chronic anemia for several years. She was transferred to the National Police Hospital in Seoul for management of severe dyspnea and dizziness. At admission, she showed symptoms or signs of severe anemia. Gastroduodenoscopy observed hyperemic mucosa of the duodenum and discovered numerous moving roundworms on the mucosa. Endoscopy isolated seven of them, which were identified as Necator americanus by characteristic morphology of cutting plates in the buccal cavity. The patient was treated with albendazole and supportive measures for anemia, and her physical condition much improved. This case suggests the possibility that hookworm N. americanus is still transmitted in a remote local mountainous area in Korea.

Coinfections with Schistosoma haematobium, Necator americanus, and Entamoeba histolytica/Entamoeba dispar in children: chemokine and cytokine responses and changes after antiparasite treatment.

The effect of polyparasite infections on cytokine and chemokine responses as well as the effect of antiparasite treatment was studied in children without parasite infection (the G0 group), in children singly infected with Schistosoma haematobium (the G1 group), and in children multiply infected with S. haematobium/Schistosoma mansoni, Entamoeba histolytica/Entamoeba dispar, and Necator americanus (the G3+ group). Linear regression analysis disclosed a significant risk for coinfection with hookworm and Schistosoma species. Polyparasite infections detected in 23% of children before treatment were present in 5% at 15 months after treatment. Chemokine responses to S. mansoni adult worm antigen (SmAg) diminished after treatment for macrophage inflammatory chemokine (MIP)-1alpha/chemokine (C-C motif) ligand (CCL)-3 (among G3+ children, by a factor of 200 [95% confidence interval {CI}, 33-1111]) and for MIP-1beta/CCL-4 (among G3+ children, by a factor of 26 [95% CI, 6-117]) but were enhanced for thymus- and activation-regulated chemokine/CCL-17 (among G3+ children, by a factor of 10 [95% CI, 3-32]) (P < .001 for all). In response to E. histolytica antigen, interleukin (IL)-13 levels increased after treatment among G1 children by a factor of 138 (95% CI, 12-1569) and among G3+ children by a factor of 21 (95% CI, 7-64) (P < .001 for both). Cellular production of interferon (IFN)-gamma in response to SmAg decreased 4 weeks after treatment among G3+ children, whereas T helper cell type 2 (Th2) IL-13 production was enhanced among G1 and G3+ children. In summary, polyparasite infections with S. haematobium/S. mansoni, E. histolytica/E. dispar, and N. americanus generated prominent proinflammatory cytokine and chemokine responses, and, after antihelminth treatment, the inflammatory chemokine response lessened as the Th2 responsiveness in coinfected children increased.

Cellular responses and cytokine production in post-treatment hookworm patients from an endemic area in Brazil.

Human hookworm infections are distributed widely in tropical areas and have a significant impact on host morbidity and human health. In the present study, we investigated the cellular responsiveness and cytokine production in peripheral blood mononuclear cells (PBMC) from Necator americanus-infected schoolchildren who had recently received chemotherapy, and compared them with non-infected endemic controls. Hookworm patients and treated, egg-negative individuals showed a lower cellular reactivity against phytohaemagglutinin (PHA) and hookworm antigen when compared with egg-negative endemic controls. The baseline production of proinflammatory tumour necrosis factor-alpha (TNF-alpha) in PBMC from infected patients and treated, egg-negative individuals was elevated. On the other hand, PHA- or hookworm antigen-induced interleukin (IL)-12 and interferon (IFN)-gamma secretion was higher in endemic controls than in hookworm patients, who either continued egg-positive or were egg-negative after treatment. Also, PBMC from endemic controls secreted more IL-5 and IL-13 than the other patient groups. Opposite to that, the spontaneous as well as the antigen-driven IL-10 secretion was lower in endemic controls when compared with the other groups. In summary, patently hookworm-infected as well as egg-negative treated patients disclosed an elevated spontaneous cellular secretion of proinflammatory TNF-alpha, a prominent secretion of regulatory Th2-type IL-10 and an impaired production of IL-12, IFN-gamma, IL-5 and IL-13.

Effects of the Zanzibar school-based deworming program on iron status of children.

We evaluated the effects of the Zanzibar school-based deworming program on the iron status of primary school children. Parasitologic and nutritional assessments were carried out at baseline, 6 mo, and 12 mo in 4 nonprogram schools (n = 1002), 4 schools in which students received twice-yearly deworming (n = 952), and 4 schools in which students received thrice-yearly deworming (n = 970) with 500 mg generic mebendazole. Schools were randomly selected for evaluation and allocated to program groups. Relative to no treatment, thrice-yearly deworming caused significant decreases in protoporphyrin concentrations and both deworming regimens caused marginally significant increases in serum ferritin concentrations. The average annual changes in protoporphyrin concentrations were -5.9 and -23.5 micromol/mol heme in the control and thrice-yearly deworming groups, respectively (P < 0.001). The average changes in ferritin concentration were 2.8 and 4.5 microg/L, respectively (P = 0.07). Deworming had no effect on annual hemoglobin change or prevalence of anemia. However, the relative risk of severe anemia (hemoglobin < 70 g/L) was 0.77 (95% confidence limits: 0.39, 1.51) in the twice-yearly deworming group and 0.45 (0.19, 1.08) in the thrice-yearly deworming group. The effects on prevalence of high protoporphyrin values and incidence of moderate-to-severe anemia (hemoglobin < 90 g/L) were significantly greater in children with > 2000 hookworm eggs/g feces at baseline. We estimate that this deworming program prevented 1260 cases of moderate-to-severe anemia and 276 cases of severe anemia in a population of 30,000 schoolchildren in 1 y. Where hookworm is heavily endemic, deworming programs can improve iron status and prevent moderate and severe anemia, but deworming may be needed at least twice yearly.

Hookworm control as a strategy to prevent iron deficiency.

The hookworms Necator americanus and Ancylostoma duodenale infect approximately 1 billion people worldwide. The prevalence of hookworm infection increases with age in children, typically reaching a plateau in late adolescence, whereas the intensity of infection may continue to increase throughout adulthood. Hookworms cause intestinal blood loss in amounts proportional to the number of adult worms in the gut. The relationship between hookworm infection intensity and hemoglobin concentration is evident in epidemiologic studies, but may be apparent only above a threshold worm burden that is related to the iron stores of the population. Current hookworm control efforts are focused on reducing infection load and transmission potential through periodic anthelminthic chemotherapy. Several controlled trials have demonstrated a positive impact of anthelminthic treatment on hemoglobin levels, with best results obtained in settings where iron intakes were also increased. Evidence suggests that anthelminthic programs will have modest impacts on iron deficiency anemia in the short term, with greater impacts on more severe anemia. Hookworms are an important cause of anemia in women, who are often overlooked by current helminth control programs. Current WHO recommendations for use of anthelminthics in schoolchildren and women are reviewed. There is a need to clarify whether hookworms are an important etiology of iron deficiency anemia in preschool children.

Evaluation of albendazole, pyrantel, bephenium, pyrantel-praziquantel and pyrantel-bephenium for single-dose mass treatment of necatoriasis.

An effective drug for single-dose mass treatment of necatoriasis was sought by testing three drugs and two drug combinations in Ethiopian immigrants to Israel found to have light infections. The drugs tested sequentially in single-doses were pyrantel pamoate (20 mg kg-1, 81 subjects); bephenium hydroxynaphthoate (2.5-5 g, 65 subjects); combined pyrantel and bephenium (25 subjects); combined pyrantel (20 mg kg-1) and praziquantel (40 mg kg-1) (16 subjects); and albendazole (400 mg, 77 subjects). Follow-up under conditions without likelihood of reinfection was by one stool examination. Cure rates with albendazole, pyrantel-bephenium and pyrantel-praziquantel were 84, 80 and 81% respectively; these rates were significantly higher than the 49% found for bephenium and the 51% for pyrantel (P less than 0.05). Egg reductions in those not cured were pyrantel (22%), bephenium (6%), pyrantel-bephenium (34%), pyrantel-praziquantel (3%) and albendazole (6%). Albendazole was the most promising single drug treatment; unexpected was the high effectiveness of pyrantel-praziquantel in combination.

Dosis única antihelmíntica: estudio comparativo con dosis única, entre oxantel/pirantel y albendazol en ascariasis, tricocefalosis y uncinarias / Single antihelminthic dosage: comparative study with single doses between oxantel/pirantel and albendazole in ascariasis, trichocephaliasis and uncinarias

Se presentan los resultados de un estudio comparativo entre el oxantel-pirantel y el albendazol, en un grupo de 60 años parasitados por alguno de los siguientes helmintos transmitidos por el suelo: áscaris, tricocéfalos y uncinarias. Los medicamentos fueron administrados en dosis única: el oxantel-pirantel a razón de 20 miligramos-/kilogramo de peso, y el albendazol en dosis total de 400 milígramos. Se observaron excelentes resultados con ambos medicamentos en el tratamiento de la ascariasis. En la curación parasitológica de la uncinariasis el oxantel-pirantel exhibió superioridad (85.7%) de los casos tratados) sobre el albendazol (66.7% de los casos tratados); y, en lo que respecta a la reducción en el número de huevecillos, ambas drogas demostraron ser de utilidad. En las tricocefalosis de grados, I, II y III la curación obtenida con oxantel-pirantel fué superior. En relación a la disminución de huevecillos en las heces, existió una ligera superioridad por parte del oxantel-pirantel. En el grado IV de tricocefalosis, el efecto terapéutico de ambos medicamentos mostró muy poca utilidad cuando son suministrados en dosis única. Se propone una escala de los grados de parasitosis para ser utilizada en la evaluación de drogas antihelmínticas

Eficacia a los seis meses de diferentes esquemas terapeuticos de mebendazol en las infecciones por A. lumbricoides, ancylostomidae SP y T. trichiura en niños de edad escolar / Efficacy after 6 months of different therapeutic schedules of mebendazole in infections by A. lumbricoides, Ancylostomidae sp and T. trichiura in school children

En una investigación prospectiva con grupo control llevada a cabo en 386 escolares de un barrio periférico de la ciudad de Santa Cruz, se evidenció la eficacia del mebendazol sobre la reducción a los seis meses de las cargas parasitarias para Ancylostomidae sp. y T. trichiura, mientras que no se observó tal efecto para A. lumbricoides. El resultado fue similar entre el esquema clásico (3 x 2 tab. de 100 mg) y el de la dosis única de 300 mg. (3 tab.)

The relationship of hookworm infection, anaemia and iron status in a Papua New Guinea highland population and the response to treatment with iron and mebendazole.

In 345 apparently healthy Papua New Guinea male subjects, predominantly highlanders, 89% of whom were infected with hookworm (Necator americanus), there was a statistically significant inverse correlation of hookworm egg count with haemoglobin and serum ferritin level, but no significant correlation with serum albumin, folate or B12 values. A sub-group of 128 was chosen for a six-month study on the effect of treatment with the anthelmintic mebendazole and/or parenteral iron on haemoglobin and serum ferritin levels. Mebendazole-treated subjects remained worm-free and the hookworm egg counts of the controls decreased during the study period. Parenteral iron treatment had the expected effect of raising haemoglobin to a normal level. There was a statistically significant improvement in haemoglobin level in all treated groups but not in the control. Serum ferritin levels decreased significantly in all groups, but more in the control than in the treated groups, although treatment groups were not significantly different. Although probable inadequate uptake of iron by the subjects and blood donation by some subjects was apparently more detrimental to iron status than hookworm infection, the results of this study support the view that hookworm infection in this country contributes to lowered haemoglobin levels and iron status.