Showing papers in "Annals of Tropical Medicine and Parasitology in 1991"
TL;DR: The pattern of results was consistent with the hypothesis that parasitic infections combine with nutritional deficits to impair the efficiency of cognitive processes, and an index weighted for estimated pathogenicity was found to give the best estimate.
Abstract: Two studies were carried out in the Nyuswa area of Natal to investigate the effects of parasitic infection on cognitive function in children. In the first study, children infected with intestinal helminths were given tests of information processing and perceptual speed before and after treatment with a single 500 mg dose of Mebendazole. The pattern of results was consistent with the hypothesis that parasitic infections combine with nutritional deficits to impair the efficiency of cognitive processes. There was, however, some confounding of variables, and the single drug treatment reduced but did not eliminate the parasites. The second study removed the confounding effects due to age and nutrition and employed a more comprehensive drug-treatment programme. A memory task and a test of sustained attention were administered. Poor performance on the attention task showed a significant association with parasite status, but no association was observed with educational attainment or memory function. The study also examined various ways of assessing parasite load, and an index weighted for estimated pathogenicity was found to give the best estimate. The results provide evidence of the effects of parasitic infection on attentional processes.
151 citations
TL;DR: The plant alkaloid, berberine sulphate, inhibited the growth of Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis in BI-S-33 medium, and induced morphological changes in the parasites, demonstrating that, in vitro, this drug was effective against the three parasites.
Abstract: The plant alkaloid, berberine sulphate, inhibited the growth of Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis in BI-S-33 medium, and induced morphological changes in the parasites. Exposure of E. histolytica to berberine caused a clumping of chromatin in the nucleus, and the formation of autophagic vacuoles and aggregates of small vacuoles in the cytoplasm. In berberine-treated G. lamblia, an irregularly-shaped vacuole appeared in the cytoplasm and gradually enlarged during culture. The trophozoites became swollen and deposits of glycogen were seen in the cytoplasm. Trichomonas vaginalis was also affected by the berberine; autophagic vacuoles increased in number soon after exposure, and one large vacuole, which was characteristic of treated cells, appeared. These observations demonstrate that, in vitro, this drug was effective against E. histolytica, G. lamblia and T. vaginalis. Another alkaloid, coptisine, was inactive against the three parasites.
100 citations
TL;DR: This is the largest recorded histopathological study of enterobiasis in man and suggests that the worm, carried to the lung as an embolus, impacted in a pulmonary arteriole.
Abstract: Enterobius worms or their eggs, or both, are present in preserved tissue sections or tissue specimens of 259 patients whose medical records are on file at the Armed Forces Institute of Pathology, Washington D.C., U.S.A. The most common site of infection (86.5%) was found to be the lumen of the appendix, where the worms provoke no reaction. Of the 259 patients 11 (4.2%) had worms and/or eggs in granulomas of the abdominal and pelvic peritoneum, and an equal number had granulomas on the peritoneum of the salphinx or on the surface of the ovary. There were also ectopic worms and/or eggs in granulomas on the peritoneum of the small and large intestines (2.7%). These Enterobius granulomas form around degenerating adult worms, around discrete eggs, around clusters of eggs, and, we believe, also around the tracks of migrating worms. Three patients (1.2%) had worms in perianal abscesses. A necrotic granuloma, removed from the lung of one patient, surrounded a degenerating adult worm. This suggests that the worm, carried to the lung as an embolus, impacted in a pulmonary arteriole. A stool specimen of one patient contains eggs of Enterobius, and that of another patient contains an adult Enterobius. This is the largest recorded histopathological study of enterobiasis in man.
55 citations
TL;DR: It is concluded that insulin administration may be useful in reversing haemodynamic changes and pulmonary oedema in victims of scorpion stings.
Abstract: The efficacy of insulin administration in reversing haemodynamic changes in pulmonary oedema in victims of poisonous scorpion sting is assessed by a study based on animal experiments in which insulin administration reversed metabolic and electrocardiographic changes induced by scorpion envenomation. Six previously healthy children aged 18 months to 11 years were admitted to hospital five to 17 hours after scorpion sting. Frusemide for raised central venous pressure and pulmonary oedema, crystalloid infusion for reduced central venous pressure, and hydrocortisone and dopamine for hypotension were used as standard therapy. Insulin (0.3 units g-1 of glucose) was administered when the standard therapy failed to produce an improvement, and at the earliest sign of haemodynamic instability. Reversal of pulmonary oedema and haemodynamic changes, and attainment or normal respiratory rate, blood pressure and central venous pressure, were observed. It is concluded that insulin administration may be useful in reversing haemodynamic changes and pulmonary oedema in victims of scorpion stings.
54 citations
TL;DR: The aqueous extract of the plant Enantia chlorantha was found effective in suppressing Plasmodium yoelii infection in mice if given orally in drinking fluid at 0.2-150 mg ml-1, but not if given by oral cannulation or subcutaneously.
Abstract: The aqueous extract of the plant Enantia chlorantha was found effective in suppressing Plasmodium yoelii infection in mice if given orally in drinking fluid at 0.2-150 mg ml-1, but not if given by oral cannulation or subcutaneously. The animals given the extract in their drinking fluid survived for over 60 days. The ethanolic extract also was found to be effective in eliminating the parasites when administered subcutaneously in doses of 0.05-0.5 mg g-1. The chemoprophylactic action of the aqueous extract given in drinks prior to infection gave protection for almost 96 hours, but the ethanolic extract administered parenterally gave no such protection. The aqueous and ethanolic extracts have ED50 values of 6.9 mg g-1 and 0.34 mg g-1, respectively, and are schizonticidal in action. Phytochemical analysis of the plant extracts revealed the presence of alkaloids, saponins and simple sugars.
51 citations
TL;DR: In four provinces of north-western Argentina, between March 1976 and March 1990, 514 ticks were found on humans, and most of the ticks were from the phytogeographical region of Chaco, one was from an ecotone between the Chaco and the Andean Patagonia region, and the remainder was from the Amazon region.
Abstract: In four provinces of north-western Argentina (Catamarca, Jujuy, Salta and Tucuman), between March 1976 and March 1990, 514 ticks were found on humans. They were identified as Rhipicephalus sanguine...
51 citations
TL;DR: The authors have defined the real gametocyte reservoir in the native population, followed the fluctuations of gametocytaemia throughout the transmission period, and measured the infectiousness of malarious individuals to mosquitoes.
Abstract: For a better understanding of the epidemiology of Plasmodium falciparum in an African savanna area, the authors have: (a) defined the real gametocyte reservoir in the native population; (b) followe...
39 citations
TL;DR: Sera of patients infected with Schistosoma japonicum, S. mansoni or S. haematobium were tested in an indirect haemagglutination assay (IHA), finding that reactions were best, in terms of titres and sensitivity, in homologous systems.
Abstract: Sera of patients infected with Schistosoma japonicum, S. mansoni or S. haematobium were tested in an indirect haemagglutination assay (IHA) using soluble S. japonicum egg antigen (SjSEA) and soluble S. mansoni adult antigen prepared either from a Puerto Rican strain (SmAWA) or an Egyptian strain (SmBW; Cellognost-Schistosomiasis Kit). Reactions were best, in terms of titres and sensitivity, in homologous systems. Heterologous systems were less reliable, particularly those using sera from urinary schistosomiasis patients. It is suggested that IHA is a suitable test to detect Schistosoma infections, especially when homologous systems are used.
38 citations
35 citations
TL;DR: Western blotting on leishmanial membranes showed that common antigens with values of 26,000 and 70-84,000 were recognized by all infected dog sera, regardless of the serum titre, and ELISAs are preferred to IFA for the rapid diagnosis of canine visceral leish maniasis because of their greater simplicity.
Abstract: Sera collected in Portugal from 43 dogs were screened for specific antibodies to Leishmania donovani antigens. Three different techniques were compared: an indirect immunofluorescence assay (IFA), a direct enzyme-linked immunosorbent assay (ELISA) and a competitive-ELISA (C-ELISA) using two species-specific monoclonal antibodies, D2 and D13. By IFA, 22 of the sera examined showed positive reactions, compared with 26 by ELISA or 27 by C-ELISA. There was no direct correlation observed between the serum titre by IFA and the strength of the reaction in ELISA or inhibition in C-ELISA. However, a good correlation was observed between sera identified as positive (95·5%) by all three techniques. Western blotting on leishmanial membranes showed that common antigens with Mr of 26 000 and 70–84 000 were recognized by all infected dog sera, regardless of the serum titre. In large scale studies, ELISAs are preferred to IFA for the rapid diagnosis of canine visceral leishmaniasis because of their greater simplicity.
34 citations
TL;DR: In a 48-hour microtest, phaeanthine at antimalarial concentrations showed no cytotoxicity to mammalian (KB) cells in vitro, and Isobolograms constructed from experiments with chloroquine/phaeanthines combinations showed antagonism in T9-96 and an additive effect in K1.
Abstract: Phaeanthine, a bisbenzylisoquinoline alkaloid which occurs naturally in Triclisia species, was extracted from Triclisia patens (Menispermaceae) obtained from Sierra Leone (West Africa). In vitro, p...
TL;DR: The development of eflornithine (DFMO) for the treatment of gambiense sleeping sickness is a major breakthrough in view of its safety compared with current treatment alternatives, and it has been nicknamed the 'resurrection drug'.
Abstract: African trypanosomiasis affects both man and his domestic animals, and is fatal if untreated. The risk of epidemics makes the disease a major public health problem in 36 sub-Saharan African countri...
TL;DR: A process is described by which trapping technology is being taught to a rural community which has been affected continuously by an epidemic of sleeping sickness for over a decade through a systematic health education programme.
Abstract: A process is described by which trapping technology is being taught to a rural community which has been affected continuously by an epidemic of sleeping sickness for over a decade. Through a systematic health education programme, people are actively involved in making and setting traps and in learning about the general characteristics of the tsetse fly and the disease. A mono-screen trap has been developed for community use and is being used to trap flies. This is the first time that this kind of community participation has been attempted in tsetse control--and this approach is discussed in relation to other approaches.
TL;DR: It is demonstrated that, in this population newly exposed to P. falciparum infections, almost all sporozoite inoculations lead to blood parasite infection requiring treatment, and this study demonstrates that there is an important increase in both morbidity and mortality in the population.
Abstract: The recent reappearance of Plasmodium falciparum in the central highland plateaux of Madagascar has led to an important increase in both morbidity and mortality in the population. To understand the phenomena that originated this outbreak, and to evaluate the clinical and biological reactions of the population, we conducted entomological surveys during the whole malaria transmission season of 1988. In parallel, 41 individuals presenting with a malaria attack in January were given a curative antimalarial treatment and were followed weekly for 20 weeks, until the end of the transmission season, in June. During the follow-up, individuals presenting with a clinical malaria attack or with a parasite density above 5000 per mm3 of blood were again given antimalarial treatment. Overall, individuals presented with an average of 5.6 thick blood smears positive for P. falciparum, and 1.4 malaria attacks requiring treatment. Plasmodium falciparum prevalence rates gradually increased to 53.8% in April, one to two months after the observed peak of transmission, then decreased to 15.4% at the end of follow-up. The proportion of P. falciparum infections with clinical symptoms did not follow a similar temporal evolution and was significantly lower than at enrollment. Splenic rates gradually decreased from 29.3-2.6%, while anti-P. falciparum and anti-Pfl55/RESA antibodies increased. For the whole transmission season individuals experienced a mean 1.5 infective bites; the malaria vectors were Anopheles gambiae s. 1 and An. funestus. This study demonstrates that, in this population newly exposed to P. falciparum infections, almost all sporozoite inoculations lead to blood parasite infection requiring treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Neither verapamil nor cyproheptadine, which reverse chloroquine resistance in P. falciparum and in rodent malaria parasites, reverse resistance to mefloquine (MEF) in the MEF-resistant NS/1100 line of P. yoelii ssp.
Abstract: Multiple drug resistance in Plasmodium falciparum is already showing evidence of extending to mefloquine, which at present is one of the few alternative antimalarials for the prevention or treatment of infection with such parasites. Neither verapamil nor cyproheptadine, which reverse chloroquine (CQ) resistance in P. falciparum and in rodent malaria parasites, reverse resistance to mefloquine (MEF) in the MEF-resistant NS/1100 line of P. yoelii ssp. NS. On the other hand, such resistance is clearly reversed when mefloquine is administered to infected mice together with penfluridol.
TL;DR: P. loveni occurs in the upper reaches of rivers on the highlands of western Kenya and eastern Uganda and its replacement by other species, principally P. niloticus, at lower altitudes is probably determined by the temperature range of the water.
Abstract: Potamonautes loveni (Colosi) is the valid name for the species also described as P. granviki, P. harvardi and P. loveni longimerus, and incorrectly identified as P. berardi berardi. Potamonautes jeanelli and P. idjwiensis may be allied to P. loveni, but are geographically separated and show sufficient morphological distinction not to be considered conspecific. Potamonautes loveni occurs in the upper reaches of rivers on the highlands of western Kenya and eastern Uganda. Its replacement by other species, principally P. niloticus, at lower altitudes is probably determined by the temperature range of the water. Potamonautes loveni has been observed to coexist with P. niloticus within the range of altitude 1280-1950 m. Distinct forms of P. loveni, differing in colour, size and the expression of the post-frontal crest, occur on the western side of Mt. Elgon and in the former ochocerciasis foci of Kenya. Hybridization is evident in populations from between these areas. Morphological divergence within P. loveni may be the result of past climatic change. Periods of generally lower temperature have been accompanied by increased aridity and reduction of forest cover. It is suggested that these conditions are such as to promote a disjunct distribution of P. loveni, and in particular the isolation of the Mt. Elgon population.
TL;DR: It remains to be seen whether mosquitoes can produce a specific protective response to infection with eukaryotic organisms such as filaria that is distinctive from that mobilized against bacteria.
Abstract: A brief review is presented of the literature relating to factors which limit the capacity of filariae to develop in mosquitoes, with particular emphasis on immune mechanisms. Most insects respond ...
TL;DR: In this article, the sexual development of Taenia solium in hamsters was studied and the results showed that the animals were able to develop sexual relations with other hamsters.
Abstract: (1991). Sexual development of Taenia solium in hamsters. Annals of Tropical Medicine & Parasitology: Vol. 85, No. 5, pp. 573-576.
TL;DR: A marked monthly variation is revealed both in natural infections with Leishmania and in biting activity of sandflies in the endemic area, demonstrating a high transmission rate during the period from the early rainy season to the early or mid dry season (February to July).
Abstract: In order to collect information on the role of Lutzomyia ayacuchensis in the transmission of leishmaniasis in a newly discovered Andean endemic focus in Ecuador, a longitudinal field study was carried out over 13 months. Monthly dissections were made of a minimum of 200 anthropophilic sandflies, collected at night during the month. A total of 2600 flies was separated from a small number of Lu. osornoi, another anthropophilic species in the area, and dissected; 95 (3·65%) were naturally infected with Leishmania mexicana promastigotes. The parasites were always located in the sandfly midgut. The current study revealed a marked monthly variation both in natural infections with Leishmania and in biting activity of sandflies in the endemic area, demonstrating a high transmission rate during the period from the early rainy season to the early or mid dry season (February to July).
TL;DR: A year-long study of the vector and the clinical manifestations of the disease in a forest-savannah mosaic area on the Oji river found microfilaraemia was found in 76% of the population, and nodules in 62%; there were no significant differences between male and female prevalence rates.
Abstract: Reports on onchocerciasis in Nigeria have been scanty, despite the size of the country and of the problem. A survey of the prevalence and transmission of the disease in the south-eastern communities of Nigeria was commenced, with a year-long study of the vector and the clinical manifestations of the disease in a forest-savannah mosaic area on the Oji river. Microfilaraemia was found in 76% of the population, and nodules in 62%; there were no significant differences between male and female prevalence rates. Skin and ocular lesions of onchocerciasis, including 'Sowda', were common. Flies of the Simulium damnosum complex were found breeding along the entire length of the Oji river and tributaries. Biting occurred all the year round, but peaked in the months of March, April and May.
TL;DR: Anticysticercus antibody titre levels were measured in the sera of 1352 school children from two rural areas of Transkei with different climatic conditions, in the southeastern seaboard of South Africa, and well-nourished children from the Cofimvaba area were significantly the most likely to be seropositive.
Abstract: Anticysticercus antibody titre levels were measured in the sera of 1352 school children from two rural areas of Transkei with different climatic conditions, in the southeastern seaboard of South Africa The overall seropositivity rate was 55%, while the rates for children with good and poor nutritional status were 73% and 33% respectively The rates for the two geographical areas did not differ However, the mean antibody titre level in the 'dry' area (Cofimvaba) with extreme temperature regimes was higher than that in the 'wet' area (Umtata), and well-nourished children from the Cofimvaba area were significantly the most likely to be seropositive On the other hand, undernourished children from Cofimvaba, and undernourished male children generally, were more likely to be seronegative (Odds Ratio 278 and 362 respectively) The implications of the findings for the treatment and control of cysticercosis are discussed
TL;DR: Onchocerca dukei was found to develop to infective third-stage larvae in Simulium flies and the implications of these findings for the epidemiology of human onchocerciasis are discussed.
Abstract: Neonate Simulium females from an endemic area of human and bovine onchocerciasis in North-Cameroon were injected in one set of experiments with microfilariae (mff) of Onchocerca dukei and in anothe...
TL;DR: In vitro study showed that cyproheptadine and azatadine may be promising candidates for potentiating chloroquine against resistant malaria parasites.
Abstract: Tricyclic antihistaminics have relatively few side-effects compared to other agents that enhance the susceptibility to chloroquine of chloroquine-resistant strains of Plasmodium falciparum. Their efficacy was tested in vitro against resistant and sensitive culture-adapted strains of P. falciparum. Isobologram analysis showed that both cyproheptadine and azatadine exert a marked synergistic action on chloroquine against chloroquine-resistant, but not against chloroquine-sensitive, strains of parasites. Cyproheptadine was about twice as effective as azatadine in reversing chloroquine resistance. Loratadine had no effect on chloroquine against both resistant and sensitive strains of parasites. Our in vitro study showed that cyproheptadine and azatadine may be promising candidates for potentiating chloroquine against resistant malaria parasites.
TL;DR: In this paper, the authors discuss the history, the life cycle, and the history of the human onchocerciasis, and present a review of the current state of the art.
Abstract: (1991). Human onchocerciasis: notes on the history, the parasite and the life cycle. Annals of Tropical Medicine & Parasitology: Vol. 85, No. 1, pp. 83-95.
TL;DR: In all cases the mycobacterium infection was found within or close to the anatomical confines of the echinococcal disease, as determined clinically, radiologically or histologically, which suggested a saprophytic-supportive role of the hydatid cyst for theMycobacterial infection to survive.
Abstract: The clinical and radiological features of five patients with echinococcal disease in whom mycobacterial infection was also present are described. Three had clinically significant disease due to Mycobacterium tuberculosis (two patients) and M. fortuitum-chelonae (one patient), whilst in two others secondary infection with M. gordonae had occurred. In all cases the mycobacterium infection was found within or close to the anatomical confines of the echinococcal disease, as determined clinically, radiologically or histologically, which suggested a saprophytic-supportive role of the hydatid cyst for the mycobacterium to survive. Mycobacterial disease should be borne in mind in patients with echinococcal disease who remain unwell despite apparently effective treatment for the hydatid cyst.
TL;DR: A low-cost mono-screen trap for Glossina fuscipes fusciped suitable for use by a rural community in Uganda is described and the differences in trap catches between the mono- screen, biconical, pyramidal and vavoua traps were highly significant.
Abstract: A low-cost mono-screen trap for Glossina fuscipes fuscipes suitable for use by a rural community in Uganda is described. The trap has a single blue/black screen and a cone made from mosquito netting. The supporting framework is made from indigenous plant materials. The differences in trap catches between the mono-screen, biconical, pyramidal and vavoua traps were highly significant (P< 0·001). Taking the standard biconical trap as control, the mono-screen trap was 1·25 times as efficient and the pyramidal trap was 0·04 times as efficient. The cost of one mono-screen trap is estimated as 1800 Uganda shillings (= U.S.$14·7), about half the cost of a pyramidal trap and one-quarter the cost of a biconical trap. The prospects for the use of the mono-screen trap by the community are discussed.
TL;DR: Western blot analyses with cyst antigens showed that CSF antibodies from confirmed NCC patients consistently recognized a protein in the region of 64-68 kDa, which showed a high degree of sensitivity and specificity.
Abstract: Enzyme linked immunosorbent assay (ELISA), dot immunobinding assay (DIA) and passive haemagglutination assay (PHA) were evaluated for the detection of anticysticercal antibodies in cerebrospinal fluids (CSF) from neurocysticercosis (NCC) patients. Results from the three tests were similar. Higher titres of antibodies were observed to the antigens in porcine whole-cyst sonicate than to those in vesicular fluid or scolex or membrane sonicates. Affinity purified parasitic antigens showed a higher degree of specificity and sensitivity in PHA than in ELISA or DIA. Western blot analyses with cyst antigens showed that CSF antibodies from confirmed NCC patients consistently recognized a protein in the region of 64-68 kDa. Other proteins, of 110, 94-97, 80, 72-75, 52, 45, 26-28 and 16-18 kDa, showed heterogenous reactivity, whereas the partially purified antigen of 64-68 kDa showed a high degree of sensitivity and specificity.
TL;DR: The likely course of the early development of O. volvulus in the vertebrate host is discussed, based on analogy with O. lienalis in cattle; and some of the factors to be taken into account when pursuing the search for O.volvulus immatures are described.
Abstract: Knowledge of the morphology, migrations and development rates of the L3, L4 and prepubertal L5 stages of Onchocerca volvulus in the vertebrate host is an essential prerequisite to work vaccine development of chemoprophylaxis. After a brief review of the scanty literature available on this subject a description is given of two immature worms, one male and one female, found in an O. volvulus nodule from Guatemala. The male, which measured 12 mm x 40 micron(s), had fine regular transverse cuticular annulations, two prominent spicules, and an undifferentiated testis. The female, which measured 20 mm x 40 micron(s), had not yet developed cuticular ridges but showed a vulva, gut, and two rudimentary genital tracts. It is thought that these worms may have been six to 12 weeks old. The likely course of the early development of O. volvulus in the vertebrate host is discussed, based on analogy with O. lienalis in cattle; and some of the factors to be taken into account when pursuing the search for O. volvulus immatures are described.