Schistosomiasis parasite

In 1912, however, (201) it was discovered that espundia (American mucocutaneous leishmaniasis) can be cured by tartar emetic. It was soon learned that kala-a2ar (visceral leishmaniasis) and oriental sore (a cutaneous form of the disease occurring in the Middle East) also respond to antimonial therapy, especially when compounds of pentavalent antimony are employed. Treatment of leishmaniasis with the latter type of antimonials is safe and effective in over 90% of the cases (202). In 1918, it was demonstrated that tartar emetic is of value in the treatment of schistosomiasis (203). Pentavalent antimonials proved to be less effective. The introduction of antimony compounds for the treatment of parasitic diseases is undoubtedly one of the important milestones in the history of therapeutics (see Antiparasitic agents). 

Copper has been employed as a bactericide, moUuscicide, and fungicide for a long time and is of importance in the control of schistosomiasis (see also Antiparasitic AGENTS, ANTHELMINTICS FUNGICIDES, AGRICULTURAL). Addition of copper to lake water acts as an efficient deterrent to transmittal of the disease by eliminating snails that act as hosts for the responsible parasite. Copper is commonly utilized at ca 0.1 mg/L as an algicide. In fresh water, acute toxicosis in fish is unusual if the copper concentration is below 0.025 mg/L (70) (see Poisons, economic). 

Although more people are being fed than ever before, there are also more malnourished humans than ever before. Thus, more than 1.6 billion of the 5.3 billion people living today are malnourished and do not have access to adequate supplies of food (3), Clearly, a malnourished person cannot lead a fully productive life. The plight of these people is more serious than just a lack of adequate food, for many are ill with disease and/or carry heavy loads of parasites. For example, a survey of school children in Kwale District, Kenya showed that 96% were infected with hookworms, 50% with roundworms, 95% with whipworms, and 40% with schistosomiasis... 

In some helminth infections, a migration through various body tissues is essential for maturation, as in ascarasis or schistosomiasis, whereas in other infections, the larva leaves the egg and simply matures in the intestinal tract, as in trichuriasis and enterobiasis. Host tissues involved vary depending upon the parasite. In severely immunocompromised patients, sites may be involved that are not involved in normal hosts. 

Iron-deficiency anaemia results from a discrepancy between iron availability and the amount required for production of red blood cells. The causes of acquired iron deficiency in so-called underdeveloped and developed countries must be differentiated. In underdeveloped countries, the main causes of iron deficiency are (a) the poor availability of iron in the diet due to low haem and high fibre and phytate content (D Souza et ah, 1987), and (b) chronic blood loss due to hookworm, schistosomiasis and malaria (Stoltzfus et ah, 1997 Olsen et ah, 1998 Dreyfuss et ah, 2000). Inflammation and vitamin A deficiency often interfere with the above causes of iron deficiency, causing a mixed type of anaemia. In underdeveloped countries diet improvement, iron fortification of natural foods and eradication of parasites will have a much higher impact than will refinement of diagnostic procedures and therapy of iron-deficiency anaemia. 

One likely reason for the prevalence of helminths is their undoubted ability to down-regulate the host immune system at both the antigen-specific and polyclonal levels [3], In many chronic diseases, such as schistosomiasis and lymphatic filariasis, peripheral blood T cells show dramatically impaired parasite antigen-specific responsiveness [4], as discussed in more detail below. Moreover, from early reports of immunosuppression in animal models of infection, to studies in Africa linking vaccine failure to heavy helminth infection, there is clear evidence that infections can diminish reactivity to bystander antigens, particularly with increasing intensity of... 

Our perspective is thus one of general significance to chronic infection, as well as one that will provide specific pathways to novel treatments of human schistosomiasis, and lymphatic filariasis. These two diseases represent a massive public health problem with 300 million people infected in the world today. Intervention by ablating parasite-specific Tregs in these patients will solve the specific problems of schistosomiasis and filarial diseases, while at the same time proving a principle which will be applicable to chronic infections in general. 

In an excellent review of the immunopathogenesis of schistosomiasis, Warren (W3) reported that the egg of the schistosome parasite was the prime factor responsible for the hepatosplenomegaly in the mouse furthermore, that neonatal thymectomy and antilymphocyte serum had marked immunosuppression on the granuloma formation around schistosome eggs injected into the lungs of mice, implying that cell-mediated immunity must play some role in the protection of the host against schistosome infection. 

Schistosomiasis is a parasitic disease on the increase, affecting millions of people in Africa, South America, and the Far East. A general strategy for schistosomiasis control is to remove a link in the vital cycle, i.e. the... 

Schistosomiasis. A water-borne infection, found mainly in tropical countries, in which the parasites (trematodes) develop initially in water snails and later live in the blood vessels of vertebrates. 

Many parasitic flatworms (tapeworms and flukes) attack higher organisms.124 Among them are the Schistosoma, tiny worms that are transmitted to humans through snails and which attack the blood vessels. The resulting schistosomiasis is one of the most widespread debilitating diseases on earth today, affecting 200 million people or more.125126... 

The use of new transcriptome information for discovery of novel drug candidates is desirable, as the control of schistosomiasis relies mostly on the use of a single drug, praziquantel, a heterocyclic pyrazino-isoquinolone. This drug exerts multiple effects, such as damage to the tegumental membrane, changes in calcium flux and muscular contractions in the parasite by a mechanism or mechanisms that are not... 

Carneiro-Santos, P., Martins-Filho, O., Alves-Oliveira, L.F., Silveira, A.M., Coura-Filho, P., Viana, I.R., Wilson, R.A. and Correa-Oliveira, R. (2000) Apoptosis a mechanism of immunoregulation during human Schistosomiasis mansoni. Parasite Immunology 22, 267-2 77. 

Fenwick, A., Savioli, L., Engels, D., Robert Bergquist, N. and Todd, M.H. (2003) Drugs for the control of parasitic diseases current status and development in schistosomiasis. Trends in Parasitology 1 9, 509-51 5. 

Moser, D., Doumbo, O. and Klinkert, M.Q. (1 990) The humoral response to heat shock protein 70 in human and murine Schistosomiasis mansoni. Parasite Immunology 12, 341-352. 

The only internationally used drug effective for treating schistosomiasis is praziquantel. This drug induces a rapid influx into the worms of surrounding Ca2+, a process that leads to paralysis (Martin, 1997), and changes in the surface membrane architecture that lead to the exposure of worm antigens that are normally cryptic (Brindley and Sher, 1987). Parasites affected in this way become susceptible to antibody-mediated immune attack and are killed as a result of the synergistic actions of chemotherapy and the immune response (Doenhoff et al., 1987 Brindley etal., 1989). 

Angeli, V., Faveeuw, C., Roye, O., Fontaine, J., Teissier, E., Capron, A., Wolowczuk, I., Capron, M. and Trottein, F. (2001b) Role of the parasite-derived prostaglandin D2 in the inhibition of epidermal Langerhans cell migration during schistosomiasis infection. The Journal of Experimental Medicine 193, 1135-1147. 

Predecessors to praziquantel as the preferred treatment for schistosomiasis include oxamniquine, and the related compound hycanthone (Cioli et al., 1995). These drugs act by inhibiting nucleic acid synthesis, but only after parasite-mediated biotransformation of the drug by a schistosome enzyme (Cioli et al., 1993, 1985). Until relatively recently, oxamniquine continued to be the primary drug used to treat schistosomiasis in Brazil. 

In the context of schistosomiasis, where parasites do not multiply in the mammalian host, protective immunity is primarily measured as a reduction in the adult worm burden of vaccinated animals relative to controls. Conventionally, this has been assessed by a terminal procedure involving perfusion of the portal... 

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