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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The occurrence of enlarged spleens and its age distribution has long been used as a crude measure to estimate malaria endemicity in cross-sectional surveys. Spleen size, however, is influenced by several variables that should be considered if they are observed in a population under study. We hypothesized that spleen indices are dependent on distinct red blood cell polymorphisms. Accordingly, we expected a lower prevalence of splenomegaly among patients with the sickle-cell trait (HbAS), HbAC trait and G6PD deficiency than in patients without red cell disorders, possibly due to the lower incidence of malaria attacks in these individuals. In our survey, however, spleen rates and sizes did not differ significantly between HbAA-, HbAS- and HbAC-positive individuals. Furthermore, enlargement of spleens was found at similar frequencies in persons with and without glucose-6-phosphate-dehydrogenase (G6PD)-deficiency (G6PD-A(-)).
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PMID:Spleen size determined by ultrasound in patients with sickle cell trait, HbAC trait and glucose-6-phosphate-dehydrogenase deficiency in a malaria hyperendemic area (Ashanti Region, Ghana). 1160 86

In many parts of the world malaria still is a major medical problem. Heavy international and transcontinental traveling carries malaria to non-endemic areas. Practicing physicians must be aware of the common, but also the rare and severe complications of malaria. During malaria changes in splenic structure can result in asymptomatic enlargement or complications such as hematoma formation, rupture, hypersplenism, ectopic spleen, torsion, or cyst formation. An abnormal immunological response may result in massive splenic enlargement. Spontaneous rupture of the spleen is an important and life threatening complication of Plasmodium vivax infection, but is rarely seen in Plasmodium falciparum malaria. The ability to properly diagnose and manage these complications is important. Spleen-conserving procedures should be the standard whenever possible especially in patients with a high likelihood of future exposure to malaria.
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PMID:Nonoperative treatment of splenic rupture in malaria tropica: review of literature and case report. 1190 97

Malaria endemicity in lower Myanmar has been studied to identify the causes for the prevalence of malaria in Yeasitkan village of lower Myanmar. Vector mosquitoes were collected by mosquito net in cattlesheds and in human dwellings (indoor and outdoor) by biting and catching procedure for the identification of species, insecticide susceptibility test and sporozoites detection. Larvae of mosquitoes were also collected in and around the village for vector identification and for breeding sources. Malaria infection in humans was examined by blood examination and blood antibody detection by ELISA method. Results showed that malaria infection was 43.2% in children under 10 years of age and An. dirus and An. minimus were found as main vectors. Total parasite positive rate was found to be 41.28% and in this 78.87% were P. falciparum infections and remaining 18.31% were of P. vivax. Spleen positive rate has been found very high in children between 2 and 9 years (52.94%). Study indicates that villages near to dam areas are more prone to malaria infection.
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PMID:Study of malaria in a village of lower Myanmar. 1468 17

We compared malaria indicators among sympatric groups to study human heterogeneities in the response to Plasmodium falciparum malaria infection. Four cross-sectional surveys and two longitudinal surveys in two sympatric ethnic groups (Dogon and Fulani) in Mali were carried out from 1998 to 2000. Spleen and parasite rates were evaluated during the cross-sectional surveys and disease incidence was assessed during longitudinal surveys. In spite of similar sociocultural factors and entomologic inoculation rates between ethnic groups, the Fulani had a significantly higher spleen enlargement rate, lower parasite rate, and were less affected by the disease than the Dogon group, whose frequency of hemoglobin C was higher than that recorded among the Fulani group. The Fulani group had significantly higher levels of IgG and IgE against crude malaria antigen than the Dogon group, suggesting a role of anti-malaria antibodies in the immune protection seen in this group.
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PMID:Difference in susceptibility to malaria between two sympatric ethnic groups in Mali. 1577 14

The high resistance to malaria in the nomadic Fulani population needs further understanding. The ability to cope with multiclonal Plasmodium falciparum infections was assessed in a cross-sectional survey in the Fulani and the Dogon, their sympatric ethnic group in Mali. The Fulani had lower parasite prevalence and densities and more prominent spleen enlargement. Spleen rates in children aged 2-9 years were 75% in the Fulani and 44% in the Dogon (P<0.001). There was no difference in number of P. falciparum genotypes, defined by merozoite surface protein 2 polymorphism, with mean values of 2.25 and 2.11 (P=0.503) in the Dogon and Fulani, respectively. Spleen rate increased with parasite prevalence, density and number of co-infecting clones in asymptomatic Dogon. Moreover, splenomegaly was increased in individuals with clinical malaria in the Dogon, odds ratio 3.67 (95% CI 1.65-8.15, P=0.003), but not found in the Fulani, 1.36 (95% CI 0.53-3.48, P=0.633). The more susceptible Dogon population thus appear to respond with pronounced spleen enlargement to asymptomatic multiclonal infections and acute disease whereas the Fulani have generally enlarged spleens already functional for protection. The results emphasize the importance of spleen function in protective immunity to the polymorphic malaria parasite.
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PMID:Spleen enlargement and genetic diversity of Plasmodium falciparum infection in two ethnic groups with different malaria susceptibility in Mali, West Africa. 1629 5

We examined a potential role of gammadelta T cells in protective immunity to blood-stage Plasmodium berghei XAT infection. Plasmodium berghei XAT is an attenuated variant of the lethal strain P. berghei NK65 and its infection is self-resolving in immune competent mice. To determine whether gammadelta T cells are essential for the resolution of P. berghei XAT malaria, mice were depleted of gammadelta T cells with anti-TCRgammadelta antibody treatment. Although mice that had received control antibody resolved infections, mice received anti-TCRgammadelta antibody could not control their infections and eventually died. Spleen cells from infected mice produced IFN-gamma and nitric oxide (NO) within the first week of infection, however, levels of IFN-gamma and NO in gammadelta T cell-depleted mice were significantly lower than in control mice. To examine whether gammadelta T cells are involved in the antibody production, malarial-specific antibodies of the various isotypes were measured in the sera of gammadelta T cell-depleted mice and control mice. Serum levels of IgG2a, which was known to be a protective antibody in P. berghei XAT malaria, were significantly lower in gammadelta T cell-depleted mice than in control mice, whereas levels of IgG1 were comparable to those in control mice. Our results indicated that the presence of the gammadelta T cell subset was essential for resolution of blood-stage P. berghei XAT malaria and played a modulatory role in the development of Th1 response and host defense against this malarial parasites.
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PMID:Plasmodium berghei XAT: contribution of gammadelta T cells to host defense against infection with blood-stage nonlethal malaria parasite. 1760 62

Endemic malaria still exists in the Republic of Vanuatu, an 80-island archipelago that sits astride the southeast margin of the Southeast Asian-Melanesian malaria band (Buxton Line 170 degrees E, 20 degrees S). The annual parasite incidence has decreased dramatically over the past decade, which has been attributed to an intensive insecticide-treated bednet distribution program and implementation of a revised Plasmodium falciparum treatment policy that employs combination chloroquine + sulfadoxinelpyrimethamine as a first-line therapy. Standard malariometric surveys were conducted at 10 locations in 2 provinces, screening 2351 adults and children towards the end of the peak transmission season. Spleen rates were consistent with mesoendemic malaria. Examination of blood slides revealed a mean slide-positive rate of 22% (range 4% to 33%). P. falciparum predominated, accounting for 73% of infections, followed by P. vivax (25%). Among 396 individuals with P. falciparum, the gametocyte rate was 54%, with 37% presenting gametocytes alone without asexual stages. Only 8% and 4% of persons with asexual stage P. falciparum and P. vivax parasitaemia, respectively, were symptomatic. These data suggest that malaria transmission has increased in some locations in Vanuatu over the past decade and this report underscores the importance of appropriate bednet use and vector control in this setting as well as the impact of adding sulfadoxine/pyrimethamine and removing primaquine from the national malaria treatment formulary.
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PMID:Cross-sectional characterization of malaria in Sanma and Shefa Provinces, Republic of Vanuatu: malaria control implications. 1839 9

Persons living for long periods of time in malaria hyper-endemic areas may suffer from hyper-reactive malarial splenomegaly (HMS), a frequent cause of splenomegaly in such areas. Splenomegaly and sub-microscopic P. falciparum parasitaemia are hallmarks of HMS. Spleen has been suggested to play a protective antimalarial role and splenectomy may trigger symptomatic malaria attacks. Other causes of immune suppression may possibly reactivate latent malaria parasites. We report the case of an Italian 60-year-old male, who had spent 33 years in sub-Saharan Africa, who experienced a P. falciparum malaria attack 12 months after his return to Italy, concomitantly with a diagnosis of lung carcinoma possibly impairing his immune system.
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PMID:P. falciparum malaria recrudescence in a cancer patient. 1935 23

An epidemiological cross-sectional study was undertaken to determine the endemicity of malaria among the Orang Asli population of Raub, Pahang. Malaria endemicity was measured in terms of the prevalence of parasitaemia and splenomegaly. A total of 520 Orang Asli were examined. The point prevalence of malaria was 24.2% (95% CI 20.7-25.1), with Plasmodium falciparum (67.5%) being the predominant species. Children < 12 years were at least 3.7 times more likely to be parasitaemic compared to those older. The prevalence of malaria among children 2-<10 years was 38.1% (95% CI 31.6-50.0). Spleen rate among children 2-<10 years old was 22.3% (95% CI 17.1-28.3). The average enlarged spleen size was 1.2. These findings classify the study area as being mesoendemic. Malaria control activities among the Orang Asli should focus on protecting vulnerable subgroups like young children. Measuring the level of malaria endemicity at regular intervals is fundamental in evaluating the effectiveness of malaria control programs.
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PMID:Malaria endemicity in an Orang Asli community in Pahang, Malaysia. 1969 28

Spleen rates (SR) have been traditionally used to estimate the burden of malaria transmission. Results are presented from 51 surveys, which measured SR and parasite rates (PR) in 29,962 individuals in the archipelago of Vanuatu. Indices for spleen size computed with multivariate statistical tools outperformed the WHO average spleen index and showed that spleen sizes in a population can track shifts in malaria transmission. In general, a positive linear relationship between Plasmodium spp. PR and SR was found for the archipelago. In the context of malaria elimination and for the specific setting of this study we found that spleen examination is a useful tool in post-malaria elimination surveillance. Finally, results highlight the value of measuring spleen sizes to rapidly assess the impact of intervention packages aimed at malaria elimination or control.
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PMID:Spleen rates in children: an old and new surveillance tool for malaria elimination initiatives in island settings. 2136 41


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