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

Plasmodium vivax is the most prevalent malaria infection and is an important cause of morbidity in Central and South America and Asia. P. vivax is generally sensitive to the common antimalarial drugs but high level resistance to chloroquine and/or pyrimethamine has been documented in some geographic locations. In the studies reviewed here, the therapeutic responses to antimalarial and antibacterial drugs in vivax malaria have been assessed in the Bangkok Hospital for Tropical Diseases. The evaluated drugs consisted of the eight most widely used antimalarial drugs and anti-bacterial drugs that possess antimalarial activities (tetracycline, doxycycline, clindamycin or azithromycin). The activities of these drugs in descending order of parasite clearance times were artesunate, artemether, chloroquine, mefloquine, quinine, halofantrine, primaquine, followed by the antibacterial drugs and lastly sulfadoxine-pyrimethamine. Clinical responses to sulfadoxine-pyrimethamine were also poor with evidence of high grade resistance in 42% of the patients. Of the four antibacterial drugs, clindamycin was more effective than azithromycin and can be an alternative to the tetracyclines. Except for chloroquine and mefloquine which have long plasma half lives and may therefore suppress first relapses, the cumulative cure rates for the short acting antimalarial drugs were similar. Double infection with Plasmodium falciparum was common and usually manifested 3-4 weeks following clearance of vivax malaria. The prevalence of cryptic falciparum malaria was 8-15% and was higher in patients treated with less potent antimalarial drugs. Follow-up studies have revealed that the relapse time in Thai patients with vivax malaria is on average only 3 weeks, but can be suppressed by the slowly eliminated antimalarial drugs such as chloroquine and mefloquine. For accurate comparison of relapse/recrudescence rates in vivax malaria, at least 2 month's follow-up is required. It can be concluded that in malarious areas of Thailand, double infection with P. falciparum and P. vivax is common affecting at least 25% of the patients and usually manifests as sequential illnesses. P. vivax in Thailand is sensitive to chloroquine but has acquired high grade resistance to sulfadoxine-pyrimethamine.
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PMID:Therapeutic responses to antimalarial and antibacterial drugs in vivax malaria. 1474 61

The importation of malaria into a region where it is not endemic raises many concerns, including the timely delivery of appropriate care, safety of the blood supply, and the risk of autochthonous transmission. There is presently no consensus on the best way to screen mobile populations for malaria. Between August 2000 and March 2001, 535 refugees arrived in Quebec, Canada, from Tanzanian camps. Within 4 weeks of resettlement of the first group of 224, the McGill University Centre for Tropical Diseases noted an outbreak of malaria across the province (15 cases over a 3-week period). This group (group 1) was traced and screened for malaria between 3 and 4 months after arrival in Canada. Subsequent groups of 106 and 205 refugees were screened immediately upon arrival in Canada (group 2) and immediately prior to their departure from refugee camps (group 3), respectively. A single EDTA-blood sample was obtained from 521 refugees for testing by thick and thin blood smears (groups 1 and 2), antigen detection (ICT Malaria Pf and OptiMAL; group 1 only), and nested PCR (all groups). Overall, 98 of 521 refugees were found to be infected (18.8%). The vast majority of infections (81 of 98) were caused by Plasmodium falciparum alone. Using PCR as the "gold standard," both microscopy (sensitivity, 50%; specificity, 100%) and antigen detection (ICT sensitivity, 37.5%; ICT specificity, 100%; OptiMAL sensitivity, 29.1%; OptiMAL specificity, 95.6%) performed poorly. None of the PCR-positive subjects were symptomatic at the time of testing, and only two had recently had symptoms compatible with malaria (with or without diagnosis and treatment). Active surveillance of migrants from regions of intense malaria transmission can reduce the risk of morbidity in the migrant population and mitigate against transmission to the host population. Our data demonstrate that PCR is, by far, the most powerful tool for such surveillance.
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PMID:Comparison of blood smear, antigen detection, and nested-PCR methods for screening refugees from regions where malaria is endemic after a malaria outbreak in Quebec, Canada. 1518 54

To determine if intestinal helminths and the CD23/nitric oxide pathway had an influence on liver size, we conducted a cross-sectional study on 438 patients with confirmed P. falciparum malaria admitted at the Hospital for Tropical Diseases in Bangkok. For all patients the liver size was measured as number of centimeters below the rib cage, a stool examination was conducted, and CD23 and reactive nitrogen intermediates were measured. The median liver size was smaller in helminth-infected patients than in helminth-free patients (chi2 for trend = 9.1, p = 0.003). Liver size significantly increased with the concentration of sCD23 (p < 0.0001). The median sCD23 concentration (OD) was significantly lower in helminth-infected patients than in helminth-free patients, respectively 0.33 (quartiles 0.24-0.57) and 0.45 (quartiles 0.27-0.59), (p = 0.01). There was a negative correlation between sCD23 concentrations and RNI (Spearman's rho = -0.40, p < 0.0001). All the above results remained significant after controlling for potential confounders. These results are compatible with a CD23/NO-mediated decrease in liver size in helminth-infected patients.
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PMID:Association of intestinal helminths with decreased liver size and sCD23 concentration during falciparum malaria. 1527 41

In recent years, several rapid diagnostic tests for falciparum malaria have been developed. KAT test results were compared with microscopy on 90 consecutive patients hospitalized at the Hospital for Tropical Diseases, Bangkok, Thailand. Fifty-one patients had P. falciparum infections while 49 had malaria due to other plasmodium species. For a geometric mean +/-SD (Min;Max;range) parasitemia of 11,481 +/- 5.0 (88;713,838;713,750), the sensitivity of the KAT test was 96% (95% CI = 86-99.5), the specificity was 92% (95% CI = 80-99), the accuracy was 94% and the reliability was 85%. These findings suggest that the KAT test is of potential interest in the diagnosis of falciparum malaria in Thailand.
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PMID:Evaluation of the KAT-Quick Malaria Rapid Test for rapid diagnosis of falciparum malaria in Thailand. 1527 42

Multilateral malaria research and control programs in Africa have regained prominence recently as bilateral assistance has diminished. The transnational nature of the threat and the need for inspired leadership, good coordination, and new discoveries to decrease the impact of the disease has led to the founding of the Multilateral Initiative on Malaria, the Roll Back Malaria Project, Global Fund for HIV, Tuberculosis and Malaria (Global Fund), the Medicines for Malaria Venture, and the Malaria Vaccine Initiative, among other groups. Historically, the most striking feature of malaria control and elimination activities was the connectedness and balance between malaria research and control especially, from 1892 to 1949. A combination of scientific originality, perseverance in research, integrated approaches, and social concern were the keys for success. The elimination of Anopheles gambiae from Upper Egypt in 1942 using integrated vector control methods is a prime example of malaria control during the first half of the 20th century where those factors were brought together. After 1949, there were three decades of great optimism. Four notable landmarks characterized this period: the Kampala Conference in 1950; the Global Malaria Eradication Program beginning in 1955; the primary health care strategies adopted by most African States after attaining their political independence in the 1960s, and accelerating in the 1980s; and creation of the Special Program in Training and Research in Tropical Diseases at the World Health Organization in 1975. The initial highly encouraging operational results, largely obtained in temperate or subtropical areas where transmission was unstable, engendered undue expectations for the success of identical antimalarial measures elsewhere. Many were convinced that the eradication was in sight, such that support for malaria research virtually ceased. Young, bright scientists were discouraged from seeking a career in a discipline that appeared to soon become superfluous. It took more than three decades to modify antimalarial strategies and to rehabilitate long-term control as an intermediate objective. In Africa, although multilateral malaria programs have grown over the past half century and proved the most successful, fragmentation of co-ordination remains and is a major challenge. The proliferation of malaria programs in the late 1990s has brought substantial additional funds and expertise. However, excessive funding competition and failure of different programs to collaborate has resulted in poor communication and duplication of activities. The capacities of the African nations to conduct high-quality research and to coordinate control efforts are in great jeopardy. There is an urgent need for a non-partisan umbrella organ to coordinate and facilitate the network of alliances and programs in malaria research and control in Africa.
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PMID:Are multilateral malaria research and control programs the most successful? Lessons from the past 100 years in Africa. 1533 47

The combined immuno-chromographic-malaria dipstick (ICT) for the rapid diagnosis of malaria detects both Plasmodium falciparum (P.f.)-specific, histidine-rich protein 2 (HRP-2) and a plasmodial aldolase expressed by all Plasmodium species pathogenic to humans. ICT was applied in 674 febrile returnees from malaria-endemic regions attending our Tropical Diseases Unit. Microscopy confirmed malaria in 69/674 cases, of whom 67/69 had returned from Africa or Madagascar, and 2/69 from the Caribbean. Monoparasitic P.f. infection occurred in 52/69, mixed infection was due to P.f.+ P. ovale (P.o.) in 3/69, and P.f.+P. malariae (P.m.) in 1/69 cases. Monoparasitic P. vivax (P.v.) infection occurred in 8/69 , P.o. in 3/69, and P.m. in 2/69 cases . Whereas a positive HRP-2 band on the test was a highly sensitive indicator for P.f. infection (52/52 patients; sensitivity 100%), this was not the case for a positive aldolase band (25/52 patients; sensitivity 48.1%). Sensitivity of aldolase band for non-falciparum plasmodia was even lower: aldolase was positive in only 3/8 (37.5%) of patients with vivax malaria, and in 0/5 cases with P.o.- or P.m. infection. Co-reaction of both bands occurred more frequently in patients with P.f. parasitaemia of > or =40,000/microl (20/25, 80.0%) as compared to patients with P.f. parasitaemia <40,000/microl (5/27, 18.5%; P<0.00005), and to patients with mixed infection (P.f.+ P.o., P.f.+ P.m.: 2/4, 50.0%; diff. n.s.). In our series, co-reaction of HRP-2 and aldolase indicated monoparasitic falciparum malaria with high P.f. parasitaemia, rather than mixed infection. Whereas the aldolase band is not a reliable qualitative marker for malaria, co-reaction of HRP-2 and aldolase band may have a potential for indicating high parasitaemia in falciparum malaria.
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PMID:Co-reactivity of plasmodial histidine-rich protein 2 and aldolase on a combined immuno-chromographic-malaria dipstick (ICT) as a potential semi-quantitative marker of high Plasmodium falciparum parasitaemia. 1554 88

To study the risk factors for Plasmodium vivax gametocyte carriage, the presence or absence of gametocytes was determined in 2,125 patients with P. vivax malaria participating in clinical trials at the Hospital for Tropical Diseases in Bangkok, Thailand. Stepwise logistic regression models were used to determine which variables were significantly related to gametocyte carriage. On admission, 615 patients (29%) had detectable gametocytes (before treatment). After treatment had started, an additional 245 patients (11%) developed patent gametocytemia. The variables retained by multivariate analysis were highest observed temperature (adjusted odds ratio [AOR] per degrees C increase = 0.82, 95% confidence interval [CI] = 0.71-0.94, P = 0.006), asexual parasitemia > 9,200/muL (AOR = 2.8, 95% CI = 1.9-4.2, P < 0.0001), erythrocyte counts (AOR = 0.8/million/muL increase, 95% CI = 0.67-0.95, P = 0.01), monocyte percentage (AOR = 0.93 per % increase, 95% CI = 0.89-0.96, P < 0.0001), lymphocyte percentage (AOR = 0.98 per % increase, 95% CI = 0.97-0.99, P = 0.006), albumin (AOR = 0.67 per 10 g/mL increase, 95% CI = 0.5-0.9, P = 0.007), and anion gap (AOR = 1.1 per unit increase, 95% CI = 1.02-1.14, P = 0.009). The possible significance of these observations is discussed.
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PMID:Risk factors for Plasmodium vivax gametocyte carriage in Thailand. 1564 56

Our previous study showed that in vitro susceptibility of Plasmodium vivax to chloroquine has significantly decreased in Thailand within the past two decades. Thus, the evaluation of alternative antimalarials for treatment of vivax malaria is needed. The aim of this study was to examine parasitological and clinical efficacy of an artemisinin derivative (artesunate) for the treatment of vivax malaria in patients who were admitted to the Bangkok Hospital for Tropical Diseases. We randomly allocated patients aged 12-56 years to receive 3.3mg/kg (adult dose 200 mg) on the first day, and for the next four days each patient was given 1.65 mg/kg orally (adult dose 100 mg), total dose = 600 mg. After the five-day course of artesunate, primaquine was given: a single oral dose of 15mg for 14 days. A total number of 42 patients received treatment. All participants were followed up for 28 days. In all the cases, both parasitemia and fever were resolved rapidly; the mean fever clearance time and parasite clearance time, 14.6 and 36.7 hours, respectively, showed that therapeutic response to artesunate was better than that of chloroquine. The 14-day cure rate was 100%, but reappearance of parasitemia was seen in two patients on days 21 and 25 following treatment, respectively. These two cases of failure rate should be considered as true relapse rather than recrudescence, since the relapse interval in Southeast Asian vivax malaria according to recent findings seems to be 3 weeks after start of treatment, if primaquine is not given or an inadequate amount is given. In conclusion, artesunate might be useful in treatment of vivax malaria, causing a good blood schizontocidal effect. However, to prevent emerging resistance it should never be used alone.
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PMID:Therapeutic efficacy of artesunate in Plasmodium vivax malaria in Thailand. 1568 68

The species-specific nested PCR previously described by Snounou and others, for detecting the four species of human malaria parasites, is evaluated in the current study testing 40 blood samples from malaria patients admitted during July-September, 2003, at the Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Thailand. Parasite DNA of each blood sample was extracted and purified by QIAamp. DNA mini kit. Nested PCR was performed using genus-specific primers for the first PCR cycle and species-specific primer for the second cycle. Thin and thick smears were also made, stained with Giemsa, and examined by expert microscopists. Only one of 40 samples (2.5%) was identified as Plasmodium malariae infection by both microscopy and nested PCR. Twenty blood samples (50%) were identified as Plasmodium falciparum infections by both methods. However, 19 blood samples (47.5%) were reported as Plasmodium vivax infections by microscopic methods, whereas nested PCR could detect a mixed infection of Plasmodium vivax and Plasmodium falciparum in one sample taken from a young girl with 8 ameboid trophozoites of P. vivax per 200 white blood cells. These results demonstrated that the nested PCR assay surpasses microscopy and also offers a clear advantage in the detection of mixed infections, which is important not only for successful medical treatment, but also for the study of malaria epidemiology.
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PMID:Identification of human malaria parasites and detection of mixed infection in Thai patients by nested PCR. 1590 26

A TaqMan real-time PCR system was used to detect and discriminate the 4 species of human malaria parasites in clinical blood samples. A 150-base pair (bp) region of the small subunit ribosomal RNA (SSU rRNA) gene of each malaria parasite, including species-specific sequences to be detected by TaqMan probe, was used as a target for PCR analysis. The PCR method used universal primers and species-specific TaqMan probes for Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. The detection threshold for the method, as determined with serial dilution of cultured P. falciparum-infected erythrocytes, was 5 parasite-infected erythrocytes per reaction. Fifty blood samples of falciparum malaria and a second set of 50 samples of vivax malaria, diagnosed by microscopic examination at the Hospital for Tropical Diseases, Mahidol University, Thailand, were analyzed by real-time PCR. In the 50 samples of microscopically-diagnosed falciparum malaria, 40 were regarded as P. falciparum single infection, 7 were P. falciparum and P. vivax mixed infections, and 3 were P. vivax single infection by real-time PCR. In the second set of 50 samples of microscopically diagnosed vivax malaria, all were considered P. vivax single infection by PCR. Neither P. ovale nor P. malariae infection was identified in the 100 blood samples. Real-time PCR analysis was shown to be more sensitive and accurate than routine diagnostic methods. Application and extension of the PCR method reported here will provide a powerful tool for further studies of malaria.
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PMID:Application of real-time polymerase chain reaction (PCR) analysis for detection and discrimination of malaria parasite species in Thai patients. 1590 27


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