Hookworm and S. haematobium infections, unlike Afebrile P. falciparum Malaria, do not Impair Intestinal Iron Absorption.

Objectives: In sub-Saharan Africa, parasitic diseases and low intake of bioavailable iron are the main causes of anemia. Anemia is further increased by inflammation during malarial infections blocking iron recycling and decreasing iron absorption. The influence of hookworm and Schistosoma infections on iron absorption and recycling is not known. Our objectives were to compare the influence of malaria, hookworm, and Schistosoma infections on inflammation, iron absorption and iron incorporation. Methods: Ivorian adolescents (12-17 years) presenting with a single infection of afebrile P. falciparum, hookworm or S. haematobium consumed 200 mL of test syrup containing 3 mg iron as ferrous sulfate labeled with 57Fe. Fractional absorption of the stable iron isotope was measured during infection and two weeks after treatment when subjects were free of infection. Erythrocyte incorporation of intravenous iron labeled with 58Fe and inflammation biomarkers were also measured. Results: Geometric mean iron absorption was 12.1% (95% CI: 9.2 - 18.0) during afebrile P. falciparum infection and increased to 23.6% (95% CI: 19.6 - 28.5) (P < 0.05) after treatment. Inflammation biomarkers were elevated during malarial infection and decreased after treatment. Light to moderate hookworm and S. haematobium infections did not increase inflammation and did not influence iron absorption (P > 0.05). Erythrocyte incorporation of intravenous iron was not affected by P. falciparum, hookworm or S. haematobium infections (P > 0.05). Conclusions: Unlike afebrile P. falciparum infection, light to moderate hookworm and S. haematobium infections do not lead to low-grade inflammation, and do not decrease iron absorption.

Ultrastructural Alterations of Adult Schistosoma haematobium Harbored in Mice Following Artemether Administration / 中国寄生虫学与寄生虫病杂志

Objective To perform a temporal examination of ultrastructural alterations in adult Schistosoma haematobium due to artemether Methods Eight mice infected with 100-120 S. haematobium cercariae for 81 days were treated intragastrically with 400 mg/kg artemether. At 24 hours, 3, 7 and 14 days post-treatment, groups of 2 mice were sacrificed and schistosomes collected by the perfusion technique. Worm samples were fixed and examined by transmission electron microscopy. Schistosomes were also obtained from 2 untreated mice that served as control.Results Typical ultrastructural alterations included swelling, lysis and vacuolization of the tegumental matrix, and disappearance of basal membrane. In sensory organelles and tubercles, there was extensive or local lysis of internal structure. In the musculature, parenchymal tissues, syncytium and gut epithelial cells, focal or extensive lysis, decrease in granular endoplasmic reticulum, vacuolization and degeneration of mitochondria were observed. These alterations became apparent both in male and female worms 24 hours post-treatment. In female worms, severe damage to the vitelline cells was also observed, resulting in the emergence of vacuoles, a decrease in granular endoplasmic reticulum,fusion of vitelline balls or even collapse of damaged vitelline cells. The most extensive tegumental alterations were observed 3-7 days post-treatment. Whilst 14 days post-treatment ultrastructural damage was still apparent, the tegument of some worms showed similar features to those recovered from untreated control mice. Conclusion Administration of artemether to mice infected with adult S. haematobium results in extensive damage to the ultrastructure in the tegument and subtegument tissues of the worms, confirming previous results with other schistosome species.

Effect of Artemether on the Tegument of Adult Schistosoma haematobium Recovered from Mice / 中国寄生虫学与寄生虫病杂志

Objective To assess the effect of artemether on the tegument of adult Schistosoma haematobium harbored in mice. Methods Ten mice were infected subcutaneously with 100-120 S. haematobium cercariae each. At day 81 post-infection, 8 mice were treated orally with 400 mg/kg artemether. Mice were sacrificed at 1, 3, 7 and 14 days post-treatment, and schistosomes were collected by the perfusion technique, fixed and examined under a scanning electron microscope. Schistosomes obtained from the 2 untreated mice served as a control. Results Twenty-four hours post-treatment, tubercles on the tegument of male worms showed lesions, characterized by enlargement, collapse and partial peeling off from the border with the tegument. In both male and female worms, the tegument showed focal or extensive swelling, fusion, vacuolization, erosion, peeling, and destruction of sensory structures. Three days post-treatment,tegumental alterations further aggravated; particularly severe damage was the swelling or collapse of the oral sucker observed in both sexes. In addition, extensive swelling, erosion and peeling of tegumental ridges and destruction of discoidlike sensory structures were seen in female worms. Seven to 14 days post-treatment, moderate-to-severe damage was still evident in some worms, whereas other worms surviving the treatment showed apparent recovery in most parts of their tegument. Conclusion Artemether causes extensive and severe tegumental damage in adult S. haematobium.

Ultrastructural alterations in adult Schistosoma mansoni caused by artemether

Progress has been made over the last decade with the development and clinical use of artemether as an agent against major human schistosome parasites. The tegument has been identified as a key target of artemether, implying detailed studies on ultrastructural damage induced by this compound. We performed a temporal examination, employing a transmission electron microscope to assess the pattern and extent of ultrastructural alterations in adult Schistosoma mansoni harboured in mice treated with a single dose of 400 mg/kg artemether. Eight hours post-treatment, damage to the tegument and subtegumental structures was seen. Tegumental alterations reached a peak 3 days after treatment and were characterized by swelling, fusion of distal cytoplasma, focal lysis of the tegumental matrix and vacuolisation. Tubercles and sensory organelles frequently degenerated or collapsed. Typical features of subtegumental alterations, including muscle fibres, syncytium and parenchyma tissues, were focal or extensive lysis, vacuolisation and degeneration of mitochondria. Severe alterations were also observed in gut epithelial cells and vitelline cells of female worms. Our findings of artemether-induced ultrastructural alterations in adult S. mansoni confirm previous results obtained with juvenile S. mansoni and S. japonicum of different ages

Evaluation of chemical and physical-morphological factors as potencial determinants of Biomphalaria pfeifferi (Krauss, 1848) distribution

This study was carried out in five sites along a small perennial river system in south-central Tanzania, which had been identified as the focus for transmission of intestinal schistosomiasis in the area. Malacological surveys preceding the study showed a focal distribution of Biomphalaria pfeifferi, intermediate host snail of Schistosoma mansoni, the snail being present in three sites but absent from the other two sites. The objective of this study was to evaluate to what extent chemical and/or physical-morphological factors determine the distribution of B. pfeifferi between these five sites. It was found that none of the chemical constituents in the waters examined were outside the tolerance range of B. pfeifferi snails. Moreover, the composition of water from B. pfeifferi-free sites was not different from that in those sites where snails occurred. Furthermore, none of the physical-morphological constituents seemed likely to be determinant for the absence of B. pfeifferi. In view of these findings, and those of previous studies, it is concluded that the focal distribuition of B. pfeifferi cannot be associated with a single environmental factor and is rather the result of more complex interactions of habitat factors.