Showing papers on "Malaria published in 1982"

Demonstration of Hypnozoites in Sporozoite-Transmitted Plasmodium vivax Infection*

Abstract: . Hypnozoites of two strains of the human relapsing malaria parasite, Plasmodium vivax, have been detected among maturing 7- and 10-day pre-erythrocytic schizonts in liver biopsies of chimpanzees infected by intravenous inoculation of sporozoites obtained from dissected salivary glands of heavily infected anopheline mosquitoes. As in the simian relapsing species, P. cynomolgi, the hypnozoites of P. vivax at 7 and 10 days are uninucleate forms of approximately 4–5 µm diameter, lying within the cytoplasm of individual hepatocytes. Their presence in this relapsing human species is added support for the hypnozoite theory of malarial relapse.

Monoclonal antibodies to circumsporozoite proteins identify the species of malaria parasite in infected mosquitoes

Abstract: An understanding of the epidemiology of malaria depends on the accurate identification of the portion of the mosquito vector population carrying infectious sporozoites This is usually determined by laborious dissection and examination of individual mosquitoes, often in areas where less than 1 per 1,000 mosquitoes contain sporozoites1 Moreover, it is impossible to identify the species of malaria parasite in the invertebrate host by morphological criteria Here we describe two sensitive immunoradiometric assays which use monoclonal antibodies to detect circumsporozoite (CS) protein antigens These tests can detect, identify and quantify sporozoites in individual or pools of mosquitoes; minimal effort is required and testing can be performed long after mosquito collection at sites removed from endemic areas

An evaluation of five regimens for the outpatient therapy of falciparum malaria in Thailand 1980-81.

Abstract: Five regimens for the radical treatment of falciparum malaria were compared in five geographically separate areas of Thailand. The cure rate for sulfadoxine-pyrimethamine was found to be low in the area of the Kampuchean border and in the northeastern and western parts of the country. This distribution may be related to the spread of resistant parasites through the migration of labourers. A 7-day course of quinine was found to be uniformly effective, with an overall cure rate of 90% in these primary infections with comparatively low parasitaemia.

Observations on early and late post-sporozoite tissue stages in primate malaria. II. The hypnozoite of Plasmodium cynomolgi bastianellii from 3 to 105 days after infection, and detection of 36- to 40-hour pre-erythrocytic forms.

Abstract: Confirmation of the existence of a persistent, uninucleate, dormant pre-erythrocytic stage, the hypnozoite, of the relapsing simian malaria parasite, Plasmodium cynomolgi bastianellii, has been obtained by means of experiments involving the intravenous injection into susceptible monkeys of 48 to 85 × 106 sporozoites derived from mosquitoes of a different species and source than employed previously. The development of these hypnozoites was traced from 3 days until 105 days after sporozoite inoculation, employing a sensitive immunofluorescence technique followed by restaining with Giemsa. From an average mean diameter of 4 µm at 3 and 5 days, uninucleate hypnozoites grow to 5 µm at 7 days, then persist with little change until at least 105 days after infection. Strong evidence for the viability of these persistent forms was obtained by treatment of a host monkey with primaquine, which eliminated all trace of hypnozoites present 2 weeks before. Examination of hepatic tissue from a monkey injected with sporozoites 36 and 40 hours earlier revealed rare uninucleate pre-erythrocytic forms of 2.5-µm diameter. These early forms were present in hepatocytes in a density only approximately 1/30th of that expected on the basis of numbers of pre-erythrocytic stages found in the same animal's liver 7 days after infection. Nevertheless, subinoculation experiments appeared to rule out the circulation as a vehicle for dissemination of any putative early intermediate hepatotropic forms from another site.

Alterations in the surface membrane of red blood cells during malaria.

Abstract: There are three basic approaches to the global control of malaria: interruption of mosquito-dependent transmission of the disease through destruction of mosquito habitats and use of insecticides and larvicides; chemoprophylaxis or symptomatic treatment of the disease with drugs; and the development of a malaria vaccine. Recent resurgences in the incidence of malaria have been due partly to the emergence of insecticide and larvicide-resistant mosquitos, and drug-resistant strains of the asexual malaria parasite. As a consequence, several strategies to vaccine development are being actively pursued. In this review we will describe in detail only one approach; the identification of alterations in the surface components of malaria-infected erythrocytes which might constitute targets for host-protective (i.e., parasiticidal) immune responses. In addition to vaccine development, exploration of erythrocyte membrane changes during malaria infection is also prompted by the profound anemia accompanying this disease. The destruction of red blood cells (RBCs) during malaria infection far exceeds that expected on the basis of parasite growth alone (reviewed in Zuckerman 1966), and may reflect host elemination of uninfected RBCs due to parasite-induced antigenic alterations.

Malaria: Nutritional Implications

Abstract: Epidemiologic and immunologic factors determine the impact of malaria on the demography and economics of human communities. Where malaria is epidemiologically stable, its effects are most obvious in young children; adults, because of acquired immunity, are much less affected and remain an economically viable workforce. Where the disease is unstable, it affects all age groups and may incapacitate adults enough to impede food production seriously. Three areas are identified in which malaria may adversely affect host nutrition: low birth weight, the development of protein energy malnutrition, and the pathogenesis of anemia. The influence of host nutrition on malarial infections is considered. The view is expressed that, although deficiencies of some dietary factors may potentiate the resistance to malaria conferred by some genetic traits, there is as yet little convincing evidence that malnutritional states in humans materially enhance the severity or lethality of plasmodial infections.

Conditions Favoring Gametocytogenesis in the Continuous Culture of Plasmodium falciparum

Abstract: . Gametocyte formation was observed in six isolates of Plasmodium falciparum in continuous culture. Optimal conditions include constant temperature and addition of caffeine at 2.0 mM. Depletion of glucose in the medium and treatment with cAMP did not consistently trigger the formation of gametocytes.

Suggested importance of monokines in pathophysiology of endotoxin shock and malaria

Abstract: There are many similarities in the pathophysiology of gram-negative infections and in acute falciparum malaria. Particularly, noteworthy is the detection of circulating inflammatory mediators in animals receiving endotoxin and in animals infected with malarial parasites. These observations have lead to the notion that macrophage derived mediators may be responsible, at least in part, for the pathology observed in malaria.

Correlation between susceptibility to malaria and babesia parasites and to endotoxicity

Abstract: Adult (185g) rats are about twice as sensitive to the harmful effects of injected endotoxin as are younger (65g) rats. This relationship correlates with an earlier report on the densities of Plasmodium berghei at which deaths occur in rats of these two age groups. Similarly lizards, which withstand very high parasitaemias of malaria parasites, are refractory to very large doses of endotoxin. This correlation appears to hold for malaria and babesiosis in all host species for which information is available, with man, for instance, very sensitive to these infections and to injected endotoxin. It is now realized that endotoxicity is not caused by the direct effects of endotoxin, but is the consequence of the release of a range of harmful soluble mediators, mainly from macrophages. Since the susceptibility of a host species to endotoxicity and to malaria and babesiosis correlate, and the illness produced in each case is very similar, these harmful mediators which cause endotoxicity are likely candidates for the origins of much of the pathology of malaria and babesiosis. This concept may also explain the relationship between parasite density and illness in these infections in man.

Mitogenic activity of extracts from continuous cultures of Plasmodium falciparum.

Abstract: Studies were initiated to determine whether or not transformation of lymphocytes isolated from individuals functionally immune to malaria would be a useful tool for the identification of protective antigens derived from continuous cultures of Plasmodium falciparum. Soluble antigen preparations stimulated lymphoproliferative responses in cells isolated from immune and nonimmune individuals. To rule out the possibility that those nonspecific responses were mixed lymphocyte reactions or other, undefined stimuli due to the heterologous nature of the lymphocyte culture system, subsequent experiments were conducted using extracts from parasites cultured in erythrocytes obtained from the same donors whose lymphocytes were tested. Soluble parasite extracts from continuously cultured P. falciparum produce nonspecific lymphocyte blast transformation responses in immunologically naive individuals. Such mitogens should be identified and removed from antigen preparations before a vaccine against malaria can be developed.

Estimates of malaria vectorial capacity for Anopheles culicifacies and Anopheles stephensi in rural Punjab province Pakistan.

Abstract: During the monsoon malaria-transmission season of 1978, infrequent feeding on humans coupled with reduced anopheline life expectancy contributed to low estimates of malaria vectorial capacity (number of infections distributed per case per day) for Anopheles culicifacies (<1.01 × 10−2 for Plasmodium vivax and <6.43 × 10−3 for P. falciparum ) and An. stephensi (<1.29 × 10−4 for P. vivax and <1.09 × 10−5 for P. falciparum ) at a previously malarious village in rural Punjab Province, Pakistan. Cattle and buffaloes interspersed throughout the village may have diverted host-seeking females from human hosts. The present range of vectorial capacity values may be representative for unstable malaria in rural Punjab during a nonepidemic year. Alterations in the degree of human feeding, longevity or population size would presumably have to occur before vectorial capacity would attain levels suitable for the occurrence of a malaria outbreak.

Sulfadoxine-pyrimethamine for the treatment of acute malaria in children in Papua New Guinea. I. Plasmodium falciparum.

Abstract: Chloroquine-resistant Plasmodium falciparum malaria is increasing in prevalence in Papua New Guinea and alternative therapies for acute malaria are being sought. A trial of sulfadoxine-pyrimethamine for the treatment of acute falciparum malaria in children has been carried out in Madang Papua New Guinea. 85 children were treated with sulfadoxine-pyrimethamine either alone or in combination with a single 10 mg/kg dose of chloroquine. Of 78 children completing 28 days follow-up treatment failures occurred in 15 (19.2%) and of these 8 (10.3%) are believed to be sulfadoxine-pyrimethamine resistant; the others remain equivocal. There was no advantage in this study in combining a single dose of chloroquine with sulfadoxine-pyrimethamine; indeed this combination was associated with an increased incidence of vomiting. It is argued that this treatment should not become the standard presumptive treatment for acute malaria in Papua New Guinea. (authors)

Anaemia, malaria and sickle cell disease.

Abstract: Serious defects in the living conditions of the vast majority of people in the tropics, rather than racial factors, are the underlying reasons why anaemia is common, why malaria is rampant and why the complications of sickle cell disease are so serious. Mass illiteracy, poor environmental hygiene and widespread poverty with all their implications explain why malaria eradication programmes have so far failed in tropical Africa and why basic health-care schemes have been difficult to establish. Pregnant women are very vulnerable to the effects of anaemia, malaria and sickle cell disease. However, appropriate use of folic acid and iron supplements as well as malarial chemosuppression succeeds in maintaining haemoglobin concentrations at reasonable levels during pregnancy. If, for whatever reason, the haemoglobin level falls to under 4.4 g/dl or the haematocrit value is 0.14 or less, anaemia becomes an obstetric emergency. Both maternal and fetal mortality rise sharply, maternal death being due to anaemic heart failure, fulminating bacterial infection and shock from even small loss at delivery or abortion. With the haemoglobin concentration as low as 4.4 g/dl, blood transfusion greatly improves maternal but not necessarily fetal prognosis. Additional cause of morbidity in sickle cell disease is painful crises, the control of which remains largely unsatisfactory. Now that sickle cell disease can be diagnosed early in intrauterine life the idea of aborting the affected fetuses as a means of controlling or reducing sickle cell disease is well within the means of developed countries, but it is a line of approach which developing countries cannot afford at present.

Congenital malaria due to Plasmodium vivax: a case report from Sri Lanka

Abstract: A case of Plasmodium vivax malaria in an eight-week-old infant in Colombo is documented, with epidemiological and circumstantial evidence which strongly supports a transplacental route of infection. The malarial antibody levels detected by the indirect fluorescent antibody technique in both mother and child are discussed in terms of the present epidemiological pattern of malaria in the country. We also comment on the species incidence of congenital malaria, this case being the first caused by P. vivax in Sri Lanka, despite this species being more prevalent than P. falciparum which has been reported in six previous cases of congenital malaria in Sri Lanka.

Parasitic Disease as a Cause of Immunosuppression

Abstract: Parasitic infections, whether induced by protozoa (as in malaria and trypanosomiasis) or by helminths (as in schistosomiasis and filariasis) are among the most widespread and severe diseases of man...