Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The prevalence of different haemoglobins and their interaction with malaria have been studied in Garki, Kano State, Nigeria. Sickle cell trait was present in 24% of newborn and 29% of those aged over five years. Hb.AC was present in 0.7%. Frequency of both haemoglobin variants was greater in Hausa than Fulani. Sickle cell anaemia was almost invariably fatal in early childhood. The distribution curve of percentage of Hb.S in sickle cell trait subjects was normal, and did not demonstrate any high frequency of a gene for alpha-thalassaemia. The presence of beta-thalassaemia minor could not be tested, but Hb.S/beta-thalassaemia was not detected. Hb.S gene frequency appears to have been maintained by a fitness in heterozygotes of 21% over normal homozygotes; increased fertility and high mutation rate did not make any apparent contribution. Hb.AS subjects had on average lower frequency and considerably lower densities of Plasmodium falciparum trophozoites than Hb.AA from the age of 30 to 59 weeks; density was less in sickle cell trait up to age three years in the dry season only. It is suggested that the survival advantage and hence the prevalence of sickle cell trait may be greatest in some hyperendemic areas and less where malaria transmission is extremely high or when it is high and unvaried.
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PMID:Abnormal haemoglobins in the Sudan savanna of Nigeria. I. Prevalence of haemoglobins and relationships between sickle cell trait, malaria and survival. 31 11

The prevalence of malaria and the frequency of gene S were surveyed in two different regions of Benin, savana and coastal lacustrine regions. In both regions, prevalence of malaria was not significantly different between Hb AA people and Hb AS people. Gene S prevalence was not modified by age, excepted for Hb SS which was not found in people upper than 25 years. In holoendemic area, i.e. lacustrine region, means of P. falciparum parasitaemia were significantly lower in Hb AS children than in Hb AA children. Sickle cell trait did not reduce the prevalence of malaria but seemed to decrease the level of parasitaemia.
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PMID:[Plasmodium falciparum or P. malariae parasitemia in carriers of sickle cell trait in various Benin biotypes]. 146 31

Haematological indices, malarial parasitaemia, serum and red cell folate (SFA, RCF), serum vitamin B12 and haemoglobin (Hb) electrophoretic patterns were studied in 228 non-elite young Hausa primigravidae at less than 24 weeks of gestation. The study was conducted in the guinea savanna of Nigeria, where malaria is hyperendemic. Ninety-nine (43%) were anaemic (Hb less than 11.0 g dl-1). The commonest cause of anaemia was malaria, in 28% of all and 40% of anaemic subjects. Plasmodium falciparum was predominant; P. malariae was seen in 1.3% and P. ovale was not recorded. Parasitaemia was more frequent and more dense in the wet than the dry season. Iron deficiency was diagnosed in 18% of all and 25% of anaemic women; 14% of all patients were folate-deficient; high MCV and MCH correlated with anaemia, and low SFA was associated weakly with anaemia and malaria. Serum vitamin B12 was normal or high in all 145 in whom it was measured; 3% had congenital elliptocytosis, but this did not contribute to the anaemia. Sickle-cell trait was present in 26% and Hb-AC in less than 1%. Hb-AS was associated with significantly lower frequency and density of P. falciparum; this has not been demonstrated in pregnancy in Africa previously. However, the parasitological advantage was not reflected in any haematological advantage. The roles of malaria, folate-deficiency and iron-deficiency in the causation of anaemia in Hausa primigravidae will be defined further by a double-blind trial of antimalarial prophylactics, iron supplements and folic acid supplements.
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PMID:Anaemia in young primigravidae in the guinea savanna of Nigeria: sickle-cell trait gives partial protection against malaria. 638 38

In regions highly endemic for Plasmodium falciparum malaria, red cell polymorphisms that confer resistance to severe disease are widespread. Sickle cell trait, alpha-thalassemia, glucose-6-phosphate dehydrogenase deficiency, and blood groups were determined in 100 children from Gabon with severe malaria who were matched with 100 children with mild malaria and followed up for evaluation of reinfections. The sickle cell trait was significantly associated with mild malaria and blood group A with severe malaria. During follow-up, the original severe cases had significantly higher rates of reinfection than the original mild cases, with higher parasitemia and lower hematocrit values. Incidence rates did not differ in the context of erythrocyte polymorphisms, but patients with sickle cell trait presented with markedly lower levels of parasitemia than those without. Thus, the severity of malaria is partly determined by the presence of blood group A and the sickle cell trait. The different presentation of reinfections in severe versus mild cases probably reflects different susceptibility to malaria.
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PMID:The role of red blood cell polymorphisms in resistance and susceptibility to malaria. 1082 41

Plasmodium ovale is a common malaria parasite in Africa, but the epidemiology of P. ovale malaria is poorly known. Exposure to malaria, parasitemia, and morbidity were monitored for 6 years among the residents of a village in Senegal. The relationship between the level of P. ovale parasitemia and fever risk were analyzed, and diagnostic criteria for clinical P. ovale malaria were established. Then the relationships between the occurrence of P. ovale clinical malaria and a series of entomological, epidemiological, and genetic factors were investigated. There was no increased risk of fever when the P. ovale parasite count was <800 parasites/microL of blood. Of 6621 episodes of illness, 114 (1.7%) were attributable to P. ovale. Although most clinical episodes occurred during early childhood, a low incidence of the disease persisted among adults. Sickle cell trait carriers had increased susceptibility to the disease.
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PMID:Diagnostic criteria and risk factors for Plasmodium ovale malaria. 1219 57

The role of the sickle cell hemoglobin type as a determinant of treatment outcome with sulfadoxine-pyrimethamine was retrospectively studied in young children with uncomplicated falciparum malaria who lived in an area with intense perennial malaria transmission. Between 1993 and 1997, 2795 treatments involving 813 children were monitored. Sickle cell trait (HbAS) was present in 17.7% of the children. Two-and-a-half percent of the children experienced early clinical treatment failure by day 2-3, and 17.3% of the children were parasitemic on day 7. Treatments in HbAS children were less likely than those in HbAA children to result in persistence of parasitemia by day 3 (relative risk [RR], 0.66; 95% confidence interval [CI], 0.47-0.93; P=.02) or in parasitologic treatment failure on day 7 (RR, 0.51; 95% CI, 0.36-0.71; P<.0001). These results suggest that the HbAS phenotype should be included among factors that determine sulfadoxine-pyrimethamine treatment outcome.
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PMID:Increased efficacy of sulfadoxine-pyrimethamine in the treatment of uncomplicated falciparum malaria among children with sickle cell trait in Western Kenya. 1244 44

To assess the frequency of asymptomatic plasmodial infections in young children living in an area of hyperendemicity, a cohort of 200 children in Gabon was investigated longitudinally. Of 660 cases of Plasmodium falciparum infection, 77% were symptomatic at the time they were identified and only 7% were preceded by an asymptomatic phase of >4 days. Sickle cell trait, glucose-6-phosphate dehydrogenase deficiency, and mutation in the promoter region of tumor necrosis factor (TNF(-376A/-238A)) were significantly associated with asymptomatic P. falciparum infection (P=.03, P=.009, and P<.001, respectively). We conclude that true asymptomatic cases of P. falciparum infection are uncommon in young children and that single measurements or measurements made at long time intervals will lead to a strong underestimation of the incidence of malaria.
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PMID:Uncommon asymptomatic Plasmodium falciparum infections in Gabonese children. 1271 18

Haptoglobin (Hp) levels were investigated in relation to host genotype in a malaria-endemic area in Gabon. A cross-sectional study of 1-12-year-old children was conducted in the rainy season, a period of high malaria transmission, to examine this relationship. Variables that influenced Hp levels were Hp genotype, location, and age interacting with parasite density. At low parasite densities, there was a negative correlation between Hp levels and age. At higher densities, there was a positive correlation with age. This suggests that in the presence of greater parasite-induced hemolysis, older children are capable of increased production of Hp. Sickle cell trait and ABO blood group was not associated with Hp levels in this population.
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PMID:Association of haptoglobin levels with age, parasite density, and haptoglobin genotype in a malaria-endemic area of Gabon. 1640 42

Although variable clinicopathological entities have been documented in sickle cell trait in pregnancy, such information is absent in this environment. This study therefore was aimed at examining the outcome of pregnancy in a population of Nigerian women with sickle cell trait. A prospective analytical study was carried at Ile-Ife, Nigeria comparing morbidities and mortalities between 210 pregnant women with sickle cell trait and 210 women with HbAA. Data were processed using SPSS 11.0 and PEPI packages, and the p value was set at =0.05. There were no significant differences between mothers with sickle cell trait and HbAA in terms of sociodemographic characteristics, the course of labour, deliveries and morbidity patterns. However, mothers with sickle cell trait had significantly fewer attacks of malaria in pregnancy (25.7% compared with 34.8%) and faster recovery of their newborn from birth asphyxia at 1 min (0.9% compared with 4.9%). Sickle cell trait may confer greater resistance to malaria in pregnancy and carries no extra risk to the outcome of pregnancy.
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PMID:Outcome of pregnancy in a population of Nigerian women with sickle cell trait. 1648 70

Treatment efficacy is related to the interaction of three parameters: drug, parasites, and human factors. The role of human factors in treatment outcome has been poorly documented to date, although human genetic factors and specific immunity have been related to protection against malaria. This study aimed to evaluate a possible cooperation between drug efficacy and host factors in treatment success. The contribution of host factors to treatment efficacy was studied in Gabonese children with a non-severe malaria attack. Children (n=232) aged under 10 years were treated with either sulfadoxine-pyrimethamine or amodiaquine. The influence of erythrocyte-related genetic factors and humoral immune responses (IgG and subclasses) against MSP1(19) on anti-malarial treatment outcome during a 28-day follow-up was studied. Sickle-cell trait carriage and anti-MSP1(19) IgG3 levels were related to lower parasite densities at enrolment (multiple linear regression analysis, P<or=0.005). Strikingly, early failures after AQ or SP treatment were associated with decreased anti-MSP1(19) IgG, IgG1 and IgG3 levels at enrolment. However, this finding was achieved in a low number of children presenting with an early failure. Kinetics of anti-MSP1(19) IgG and subclasses between Days 0 and 28 were also related to treatment efficacy, as the most effective treatment (sulfadoxine-pyrimethamine) was characterised by a higher elevation of antibody titres by Day 28. No effect of erythrocyte-related genetic factors on treatment outcome was shown, although the protective role of sickle-cell trait against higher parasitaemias was confirmed at enrolment. Our data suggest that anti-MSP1(19) IgG1 may have a supportive role during the first days of treatment to prevent early failures. The interference between drug efficacy, immunity and human genetic factors needs further investigation to be elucidated.
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PMID:Correlations between treatment outcome and both anti-MSP119 antibody response and erythrocyte-related genetic factors in Plasmodium falciparum malaria. 1689 Apr 98


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