Showing papers on "Malaria published in 1977"

An effective immunization of experimental monkeys against a human malaria parasite, Plasmodium falciparum

Abstract: This is the first report of successful immunization of experimental monkeys against a human malaria parasite, Plasmodium falciparum. Of the five owl monkeys (Aotus trivirgatus) used in this pilot study, two served as controls and the other three were immunized with P. falciparum antigen consisting primarily of mature segmenters containing fully developed merozoites. Two injections of antigen emulsified with Freund's complete adjuvant were administered intramuscularly 3 weeks apart. Three weeks after the second vaccination, all monkeys were challenged with the homologous strain of P. falciparum. The control monkeys died with high levels of parasitemia within 2 weeks of challenge. The three immunized monkeys survived and showed strong protection against P. falciparum. These results are encouraging for the possible future development of an effective vaccine against human malaria.

Malaria and hereditary ovalocytosis

Abstract: Hereditary ovalocytosis in Papua New Guinea is restricted to areas of endemic malaria and may confer increased resistance to the disease The incidence of malaria was investigated in 1616 Melanesians of known red cell morphology and severity of infection determined in a smaller subsample Ovalocytics tended to be more resistant to severe malarial infections than normocytics The ratio of parasitaemia in 112 ovalocytics compared with 741 normocytic children was 105 for P falciparum; 090 for Pvivax; 054 for P malariae, and 091 for infection with any species The difficulties in conclusively demonstrating any selective advantage of the condition are discussed

The Duffy blood group and malaria prevalence in Gambian West Africans.

Abstract: Erythrocytes from 1,168 donors, comprising almost the entire populations of two rural Gambian villages, have been tested for Duffy blood group antigens using antisera to both Fya and Fyb. All tests were negative. Blood film examination of the same samples showed complete absence of Plasmodium vivax parasitaemia, but infections with P. falciparum,P. malariae and P. ovale were observed. The findings are consistent with the view that the Duffy-negative phenotype, FyFy, constitutes the basis of innate resistance towards infection with P. vivax but not towards infection with the other plasmodial species.

The natural decline of Wuchereria bancrofti infection in a vector control situation in the Solomon Islands

Abstract: In a situation where filariasis and malaria are transmitted by the same vector, as seen here in the Solomon Islands, the Malaria Eradication Programme aimed at controlling the vector, was found to have an effect on both diseases. In an area of Choiseul island first surveyed by the author in 1970, three follow-up surveys were conducted—in 1974, 1975 and 1976. These showed a progressive decrease in persons infected. When the densities, especially the median microfilarial counts, were expressed as percentage values of the pre-spray survey, there was found to be a proportional decrease over eight years. It is possible that the Anopheline vector needs to be reduced less for the cessation of transmission of filariasis than for malaria. A theoretical ratio was calculated and supporting field evidence presented.

Sequential treatment with quinine and mefloquine or quinine and pyrimethamine-sulfadoxine for falciparum malaria.

Abstract: Patients with falciparum malaria were studied in Thailand, an area of known chloroquine resistance. The patients were unselected and some had severe malaria, and they were randomly assigned to one of two sequential regimes. A short course of quinine (average 4 doses, equivalent to 2 g base) followed by a single dose of pyrimethamine-sulfadoxine (Fansidar) cured 92% of patients (36 out of 39), while a short course of quinine followed by a single 1-5-dose of mefloquine cured all of the 35 patients who could be followed up. Gastrointestinal side effects were minimal if at least 12 hours elapsed between the last dose of quinine and the mefloquine. Sequential quinine and mefloquine is the most effective treatment for patients with chloroquine-resistant falciparum malaria, including those with severe or complicated disease. Mefloquine, however, is not commercially available, and the similar regimen using Fansidar is almost as effective.

Lymphocyte changes in acute malaria.

Abstract: Lymphocyte sub-populations were studied in children with acute malaria. Depletion of T cells was found associated with an increased proportion of null cells. K cell activity for chicken red cells was also increased and it is likely that some of the increased number of null cells were K cells. An increase in K cell activity in acute malaria could be part of a protective immune response.

Specific and non-specific immunity to haemoprotozoa.

Abstract: Immunity to haemoprotozoa is complex, involving several components that interact in ways that vary from one host-parasite combination to another. In recent years, most attention has been given to antibody formation, which is relatively easily measured. It has been suggested that antibodies interfere with the penetration of merozoites into erythrocytes, or opsonize parasites or parasitized erythrocytes for phagocytosis by macrophages. Our observations on human and rodent malaria and Babesia infections show that other factors must also be borne in mind. Erythrocytes themselves differ in susceptibility to infection, and some of the factors underlying these differences are known, as will shortly be summarized. These differences are specific for each parasite, even though they do not depend upon acquired responses of immunocompetent cells. That both T- and B-lymphocytes respond to parasite antigens is, nevertheless, clear. Cells of the B-lymphocyte lineage produce antibodies to the parasites, and ways of detecting responses to T-lymphocytes are considered later.

The treatment of severe falciparum malaria.

Abstract: In severe falciparum malaria there is a pathophysiological cascade beginning with changes in the parasitized red blood cells which induce intermediate effects, in turn contributing to dysfunction of several organs. A low serum albumin is a common but often unrecognized finding which may contribute to oedema especially in the lung and brain. The only irreversible complication in falciparum malaria is the acute respiratory distress syndrome, manifested by cyanosis and rapid breathing, basically distinct from acute pulmonary oedema caused by therapeutic overhydration. The pathophysiology of falciparum malaria may be complex but the treatment is simple. Drugs, other than antimalarials, are rarely needed. Guidelines for cholorquine or quinine dosage in severe disease are proposed; each drug is given at a dose of 5 to 10 mg/kg in 10 ml/kg of fluid as an intravenous infusion in four hours at a frequency of dosing every 12 to 24 hours. When the disease has been brought under control the treatment should be changed from the intravenous to the oral route.

Malaria and the political economy of public health.

Abstract: After more than a decade when the disease was under increasing control, malaria has been making a dramatic resurgence in the 1970s. Even more troubling has been the inadequacy of government respons...

Malaria antigen-specific T-cell responsiveness during infection with Plasmodium falciparum.

Abstract: Protective immunity against Plasmodium falciparum develops only after several years of repeated exposure to the malarial parasite. We therefore investigated the possibility that acute malaria was associated with malarial antigen-specific immunosuppression. Peripheral lymphocytes of West Africans with and without P. falciparum infections were tested for their in vitro proliferative responses to a preparation of P. falciparum antigen. There was no significant difference between the magnitude of the proliferative response of lymphocytes from infected as compared to normal Africans, although the responses from both African groups were significantly higher than responses from a group of European controls. Furthermore, no soluble inhibitor of antigen-specific proliferation was present in plasma of infected patients. These observations strongly suggest that if the sluggish development of protective immunity in malaria is based upon infection-related immunosuppression, this occurs without affecting the proliferative responsiveness of specific sensitized, circulating T cells. Preliminary observations also indicate that Europeans residing in Africa and taking malaria prophylaxis may acquire sensitized T cells without experiencing clinically apparent infections.

Effect of insecticide spraying for malaria control on the incidence of sandfly fever in Athens, Greece.

Abstract: Sera from 637 Athens residents of various age groups were examined by plaque reduction neutralization test for antibodies against Naples and Sicilian Phlebotomus fever viruses. A marked change in the prevalence of antibodies to both agents was observed in persons born after 1946, when residual insecticide spraying for malaria control was initiated in Greece. The prevalence of Naples and Sicilian neutralizing antibodies among residents greater than or equal to 30 years of age was 36% and 13%, respectively. In contrast, only 4% of persons less than or equal to 29 years of age had Naples antibodies and all were negative to Sicilian. These serologic data confirm previous clinical observations that sandfly fever becam uncommon in Athens after initiation of the insecticide spraying program. Presumedly the spraying program was effective in reducing the Phlebotomus population to levels where virus transmission was minimal. New information on the specificity and duration of Phlebotomus fever neutralizing antibodies is also presented.

Morphologic Variants of Anopheles Albimanus and Susceptibility to Plasmodium Vivax and P. Falciparum

Abstract: Three morphologically different, true-breeding phenotypes have been isolated from a strain of Anopheles albimanus from Lake Apastepeque, El Salvador. Studies with coindigenous strains of Plasmodium vivax and P. falciparum show that these phenotypes differ significantly in their susceptibility to malaria parasites. This difference is apparent both in the number of mosquitoes that become infected and the level of infection obtained. Variations in malaria susceptibility are markedly greater with P. vivax than with P. falciparum. The significance of genetic variants within a local vector population with respect to the epidemiology of malaria is discussed.

Merozoite vaccination of rhesus monkeys against Plasmodium knowlesi malaria; immunity to sporozoite (mosquito-transmitted) challenge.

Abstract: Five normal rhesus monkeys were infected with Plasmodium knowlesi sporozoites (A-strain); two developed rapidly fatal malaria and three chrinic relapsing infections. Vaccination with P. knowlesi (W-strain) merozoites (unmodified or formol-treated and freeze-dried) in Freund's complete adjuvant (FCA) did not inhibit pre-erythrocytic parasite development after challenge with A-strain sporozoites. However, the subsequent blood-stage infection was terminated in nine out of ten vaccinated monkeys even though the challenge strain was different form that used for vaccination. The degree of parasitaemia (0·01–0·70 %) and brevity of infection (1–12 days) in six animals vaccinated with untreated merzoites was similar to that observed after direct challenge with blood-stage parasites. Monkeys were equally resistant to sporozoite challenge given as the post-vaccination infection or administered 6 months after blood challenge. These results are discussed in relation to the development of a human malaria vaccine.

Congenital Malaria: A Rare Cause of Splenomegaly and Anemia in an American Infant

Abstract: A 38-day-old infant had fever, jaundice, hepatosplenomegaly, and a hemolytic anemia. A peripheral blood smear demonstrated intraerythrocytic malarial parasites identified as Plasmodium vivax. Maternal and infant sera contained antibodies to this species. A directed history revealed the mother had suffered several febrile illnesses in Mexico during her pregnancy. Malaria had not been diagnosed nor was it considered at the time of her delivery at this hospital. Review of this and six other cases of congenital malaria reported in this country since 1950 indicates clinical manifestations seldom appear before 3 weeks of age. Although these signs are more frequently associated with other transplacental infections, their occurrence in an infant whose mother is from or who has traveled in an endemic area should prompt consideration of the diagnosis of congenital malaria.

Malaria eradication in Portugal.

Abstract: Research on malaria, which was endemic in several parts of Portugal at the beginning of this century, was intensified in the 1940's and led to the development of better control methods, especially in the rice-growing areas of the country. In the 1950's residual DDT spraying was introduced and followed by extensive detection of cases of malaria and their treatment. Plans for eradication of the disease were made, and by 1958 the transmission of the infection was interrupted in nearly all areas of European Portugal. The country was placed in the maintenance phase of malaria eradication and the certification of malaria eradication was confirmed by the WHO in 1973. The political and military events of the past five years greatly increased the number of cases of malaria imported into Portugal from tropical Africa and indicated the need for much vigilance to prevent the resumption of transmission by the local vectors. It appears that the measures put into action have succeeded in this respect. This was due to the high degree of effective surveillance and also to the fact that Anopheles atroparvus does not readily transmit the exotic strains of Plasmodium falciparum and P. vivax. However, further vigilance must be maintained and intensified.

Further studies of space-time clustering of Burkitt's lymphoma in Uganda.

Abstract: All hospital-treated cases of Burkitt's lymphoma (BL), with onset of symptoms in the period 1963-68 and resident in the Lango and Acholi districts of Uganda, were identified. The average annual incidence of BL in the 6-year period was 1-87 X 10(-5), similar to that in the adjacent West Nile district. Contrary to findings in other areas of Uganda, there was no evidence of seasonal variation in the onset of cases, nor of space-time clustering, nor of a decline in the incidence of BL in the study period. An inverse relationship was noted between the median age at onset of BL and the incidence of the disease in different areas of Uganda, a finding consistent with intense malarial infection being a precipitating factor for BL. The variable observations with respect to space-time clustering of BL and seasonal variation in incidence in different areas remains unexplained, but it is suggested that a closer study of the patterns of malarial infection in these areas may help to account for the findings.

The practical and therapeutic implications of chloroquine-induced itching in tropical Africa.

Abstract: Attention has once again been directed to the very uncomfortable itching following chloroquine chemotherapy of malaria in about 8% of the Nigeria population. Six typical case reports are presented. We have been able to identify three stages in the course of the itching and in the second stage, four phases have been outlined. The major implications of the pruritus are briefly discussed in respect to its effect on malaria treatment. Its possible link with more serious adverse effects and variations in drug metabolism are also mentioned. The treatment outlined is directed towards minimizing the intensity and duration of the itching reaction.