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Showing papers in "Advances in Parasitology in 1968"


Book ChapterDOI
TL;DR: American trypanosomiasis shows a very peculiar pathology of homeostasis of the human organism, and represents even today a new realm in pathology, which becomes understandable through Cannon's law of denervation.
Abstract: Publisher Summary Chagas' disease-like all really great and important discoveries-has its own and very peculiar history, called by Magalhaes , a “tragicomedy, which embittered and destroyed the life of one of our greatest compatriots”. In this history it is useful to distinguish the following six periods. Chagas in 1908 discovered in the intestine of the blood-sucking triatomas that were common in the primitive huts of the Brazilian hinterland, an unknown trypanosome, which was named by “Schizotrypanum cruzi.” The presence of this parasite in bugs suggested to him the possible existence of an infectious disease in animals and man. Soon afterwards Chagas also found the parasites in the blood of domestic animals (dogs and cats) and in the blood of a sick child with a high temperature. The discovery of American trypanosomiasis by Carlos Chagas represents one of the most fascinating events in the history of medicine. It is almost incredible that such severe pathological manifestations, which represent the “causa mortis” of one third of our autopsy material, would have been overlooked or unknown before Chagas' unique discovery. American trypanosomiasis shows a very peculiar pathology of homeostasis of the human organism, and represents even today a new realm in pathology, which becomes understandable through Cannon's law of denervation.

518 citations


Book ChapterDOI
TL;DR: This chapter deals with more recent knowledge of the morphology and biology, pathology and laboratory diagnosis of T. vuginalis, with clinical aspects of trichomoniasis in women, men and children, and with the epidemiology and treatment of this infection.
Abstract: Publisher Summary This chapter deals with more recent knowledge of the morphology and biology, pathology and laboratory diagnosis of T. vuginalis, with clinical aspects of trichomoniasis in women, men and children, and with the epidemiology and treatment of this infection. Trichomonas vaginalis is known as a ‘harmless commensal of the human vagina. “Trichomonadenkolpitis = trichomoniasis” of women whose vaginae contained many of these flagellates. The concept of T. raginalis as a primary pathogenic parasite was only gradually accepted. Without a doubt, T. iuginalis is the commonest of the human trichomonads and “Trichomonadenkolpitis” does exist despite the sceptical adverse views of some prominent older gynaecologists. Serological and immunobiological investigations have been only of theoretical interest until the present, because the finding of T. vaginalis by cultivation or direct microscopical examination is easier and more reliable. In mostly symptomless trichomoniasis of man, however, such investigations could be important. It seems that the divergences reported by different authors, may be due to the antigenic structure of the individual T. vaginalis strains.

176 citations


Book ChapterDOI
TL;DR: In mice experimentally infected with Schistosoma mansoni, praziquantel (2-cyclohexylcarbonyl-1,3,4,6,7,11b-hexahydro-2H-pyrazino[2,1-a]isoquinoline-4-one), administered orally at the levels of 100 and 50 mg/kg, for 5 consecutive days, produced oogram changes in all animals and a pronounced hepatic shift
Abstract: In mice experimentally infected with Schistosoma mansoni, praziquantel (2-cyclohexylcarbonyl-1,3,4,6,7,11b-hexahydro-2H-pyrazino[2,1-a]isoquinoline-4-one), administered orally at the levels of 100 and 50 mg/kg, for 5 consecutive days, produced oogram changes in all animals and a pronounced hepatic shift of schistosomes (97.1 and 89.1, respectively). At lowest levels (12.5 and 6.3 mg/kg), alterations in the oogram could still be detected, although hepatic shift of schistosomes was no more evident. After a single intramuscular injection, the results obtained paralleled those observed with a single-dose oral treatment. The hepatic shift was only moderate at 200 and 100 mg/kg and the percentages of worms retained in the liver, after perfusion, were particularly low. When nasal route in a 1-day regimen was used, the results obtained were slightly less evident as compared with those observed by oral route (5-day schedule).

150 citations


Book ChapterDOI
TL;DR: This chapter covers recent work on the physiology of development of early parasitic stages from the infective stage, which may lead to a more general understanding of the relationship of the parasite to its host and help to explain the phenomenon of parasitism.
Abstract: Publisher Summary This chapter covers recent work on the physiology of development of early parasitic stages from the infective stage. There is now much evidence to support the view that the infective stage (in nematodes which infect the host per os) must receive from the host a stimulus which induces early developmental changes. It is presumed that the stimulus acts on a “receptor” of the infective stage and leads to possible neuro-endocrine activity which directly or indirectly affects target areas concerned in development. This area of research is of special interest because it may lead to a more general understanding of the relationship of the parasite to its host and help to explain the phenomenon of parasitism. Moreover, the early development from the infective stage may provide a useful model for the study of the control of differentiation. The concept of a “receptor” in this context is a broad one. It could be a discrete structure (e.g. a chemical sensory organ) or, more likely, it could refer to a compound or group of compounds distributed more widely in certain cells (e.g. some neurones or the nuclei of some cells) in the organism.

56 citations


Book ChapterDOI
TL;DR: The confusion surrounding the epidemiology of amoebiasis has arisen from a failure to appreciate the nuances in the host-parasite relationship, and in part from faulty diagnosis, not only of the parasite, but also of the host's reaction to infection.
Abstract: Publisher Summary The didactic meaning of amoebiasis implies a host inhabited by an amoeba, whether it be Entamoeba histolytica, E . coli, E . gingivalis, Iodamoeba biitschlii, Endolimax nana, or any other, including those species of Hartmanella which have been shown to invade man. Current practice has confined the term to hosts harbouring E . histolytica. but some authors have further restricted the meaning to those with disease. As the information sought is some concept of the distribution of the parasite and its effects, a way must be found around this. No parasite is more often wrongly labeled than has E. hisrolyrica , and too few organisms has such a wide gamut of clinical presentations been attributed. The confusion surrounding the epidemiology of amoebiasis has arisen in part from a failure to appreciate the nuances in the host-parasite relationship, and in part from faulty diagnosis, not only of the parasite, but also of the host's reaction to infection. It has been shown that available data-either parasitological or clinicalgive but little information on the distribution of amoebiasis. The most reliable is that based on the occurrence of amoebic liver abscess, though this too is clouded by differing outlooks on the condition. In general, amoebiasis is no exception to the rule that uncritical adherence to the dicta of the great is apt to mislead. In malaria the story of the direct entry of the sporozoite into a red blood cell retarded progress for many years, and the false concept took a lot of destroying.

50 citations


Book ChapterDOI
TL;DR: This chapter concerns mainly with pathogenesis reactions in simian and to some extent in human and rodent malarias and the processes involved in P .
Abstract: Publisher Summary This chapter concerns mainly with pathogenesis reactions in simian and to some extent in human and rodent malarias. The pathological and physiological disturbances in malaria vary considerably in severity and duration according to the infecting Plasmodium and the host. The processes involved have so far been most carefully studied in P . knowlesi infections in rhesus monkeys (Macaca mulatta). Discussion of the pathogenesis of the liver lesions in malaria must take into account all mechanisms that are responsible for functional and structural disturbances in the organ arising from non-specific reactions, and those that can be attributable more directly to the infection itself. The effects of the latter are frequently also non-specific because a given tissue can react in only a limited number of ways. An example of the first type of reaction in the liver in malaria is the response to the hyperactivity of the sympathetic nervous system initiated by the infection The second type of reaction is exemplified by the histotoxic activity of certain factors, to be discussed later, circulating in the blood of the infected host which cause fatty degeneration of parenchymal cells and inhibit mitochondria1 oxidative phosphorylation.

13 citations


Book ChapterDOI
TL;DR: This chapter supplements the more extensive earlier experimental research on avian malaria and tentative conclusions indicated that the genera Aedes and Armigeres reflect their systematic propinquity by their susceptibility to P. gallinaceum.
Abstract: Publisher Summary This chapter supplements the more extensive earlier experimental research on avian malaria Two symposia have been published on malaria since the earlier review Although these reports included work on many phases of malaria, a considerable portion of them dealt with avian malaria In this period of time the most comprehensive book yet published on the non-medical aspects of malaria appeared A review by Huff (1965) attempted to collect all published experimental results on the susceptibility of mosquitoes to avian malaria up to 1964 Tentative conclusions indicated—namely, (1) that the genera Aedes and Armigeres reflect their systematic propinquity by their susceptibility to P gallinaceum, (2) that a close relationship of the species P fallax, P gallinaceum and P lophurae is indicated by their capability of infecting species of Aedes, and (3) that a similar close relationship between P relictum and P cathemerium is reflected in their infectivity to Culex Previous workers have shown that, regardless of the species of parasite or its host, splenectomy resulted in a decrease in immunity, which resulted in relapse and recrudescence of the infection One area in which studies on avian malaria in immunological studies hold an advantage over the mammalian malarial paragites is thy ease witb which their exoerythrocytic stages can be cultivated

13 citations


Book ChapterDOI
TL;DR: A new species of Eimeria has been described and the life cycles and pathogenicity of others have been re-examined, and work in progress includes further studies on the roles of the thymus and the leucocytes, particularly lymphocytes, in the development of immunity to coccidiosis.
Abstract: Publisher Summary A new species of Eimeria has been described and the life cycles and pathogenicity of others have been re-examined. Species of Eimeria have been cultivated in the allantoic membranes of the developing chick embryo and some progress has been made in the cultivation of Eimeriu species in tissue cultures. More work ha5 been published on factors affecting reproduction and pathogenicity of Eimeria and on acquired immunity to Eimeria infections in the fowl. The endogenous stages of E. acervulina and E. mivatiare similar; the average sizes and timing of the schizont generations of both species, given in a table in the chapter. Species of Eimeria usually have a marked predilection for a given site and, in the fowl, have not been found in sites other than the intestines. Work in progress includes further studies on the roles of the thymus and the leucocytes, particularly lymphocytes, in the development of immunity to coccidiosis.

12 citations