Malaria endemicity in an Orang Asli community in Pahang, Malaysia

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.

[Case report: two Plasmodium vivax malaria cases in the Van Province]

Malaria is an important parasitic infection which is endemic in the Eastern Mediterranean and Southeastern Anatolia regions and sporadic in other regions of Turkey, while Plasmodium vivax is the most common cause. Two patients who were admitted to our hospital in October with complaints of high fever, chills, nausea-vomiting, generalized body pain and fatigue and diagnosed as P. Vivax malaria are presented, because they were two brothers with no history of travel outside of Van city.

[Malaria in Moscow (2006-2007): monitoring of the situation and assessment of antimalaria measures]

The malaria situation in Moscow in 2007 versus 2006 improved--the cases of malaria reduced by 16.3%. A total of 30 new cases of malaria were notified (46 cases in 2006), of them there were 34 imported cases and 4 secondary cases to imported ones. In 2007, the proportion of tertian malaria cases reduced to 55.3% versus 60.9% in 2006. As compared with 2005, in 2007 the cases of locally transmitted malaria decreased by 5 times--from 20 to 4, only 1 case of infection occurred in Moscow (Central Administrative District) and 3 cases took place in the Moscow Region (Ramensky, Stupinsky, and Dmitrovsky districts). Cases of malaria were notified in all administrative districts, with their largest number in the South-Western Administrative District of Moscow due to the detection of ill students from the Russian University of People's Friendship who had come to study from African countries. In accordance to the performed certification of water reservoirs in 2007, a total of 722 Moscow water reservoirs of an area of 1569 ha were registered at the Administration of the Russian Agency for Consumer Surveillance. The examination frequency of all water reservoirs was about 13 per season, including 20 anopheles-containing ones. The larvae of bloodsucking mosquitoes inhabited 541 (75%) water reservoirs, including 461 (63%) water reservoirs occupied by the malaria vector. As compared with 2006, the area of treatments increased by 351 ha. In the summer, a total of 2133.3 ha ofwater reservoirs were treated, including 2009.5 ha against larvae of malaria mosquitoes. The bulk of water reservoirs were exposed to triple-quadruple treatments.

The Chesson strain of plasmodium vivax in humans and different species of Aotus monkeys

Comparison was made between the parasitemia of Chesson strain Plasmodium vivax in humans and in splenectomized Aotus lemurinus griseimembra, A. nancymaae, A. vociferans, and A. azarae boliviensis monkeys. In the monkeys, 56.3% of the animals had maximum counts > 25,000/muL and in humans 59.6% were above this peak parasitemia. In humans, it took an average of 9.3 days to reach the maximum parasite count. In monkeys with no previous infections, it took an average of 18.9 days to reach the maximum parasite count; for those with previous infections, it took an average of 15 days. Human and nonhuman primate data on this parasite suggest that splenectomized Aotus monkeys, particularly A. lemurinus griseimembra, and to a somewhat lesser extent A. vociferans, can mimic the course of Chesson malaria in humans regarding parasitemia and mosquito infection.

Southeast Asian ovalocytosis is associated with increased expression of Duffy antigen receptor for chemokines (DARC)

The Duffy antigen receptor for chemokines (DARC or Fy glycoprotein) carries antigens that are important in blood transfusion and is the main receptor used by Plasmodium vivax to invade reticulocytes. Southeast Asian ovalocytosis (SAO) results from an alteration in RBC membrane protein band 3 and is thought to mitigate susceptibility to falciparum malaria. Expression of some RBC antigens is suppressed by SAO, and we hypothesized that SAO may also reduce Fy expression, potentiallyleading to reduced susceptibility to vivax malaria. Blood samples were collected from individuals living in the Madang Province of Papua New Guinea. Samples were assayed using a flow cytometry assay for expression of Fy on the surface of RBC and reticulocytes by measuring the attachment of a phycoerythrin-labeled Fy6 antibody. Reticulocytes were detected using thiazole orange. The presence of the SAO mutation was confirmed by PCR. There was a small (approximately 10%) but statistically significant (p=0.049, Mann-Whitney U test) increase in Fy expression on SAO RBC compared with RBC from individuals without this polymorphism: mean Fy expression (mean fluorescence intensity [MFI]) was 10.12 +/- 1.22 for SAO heterozygotes versus an MFI of 8.95 +/- 1.1 for individuals without SAO. For reticulocytes the MFI values were 27.61 +/- 19.12 for SAO heterozygotes and 16.47 +/- 3.81 for controls. SAO is associated with increased and not decreased Fy6 expression so that susceptibility to P. vivax infection is unlikely to be affected.

[Primary evaluation on the application of nested/multiplex PCR in malaria diagnosis and surveillance]

OBJECTIVE

To compare the usefulness of Tag-primer nested/multiplex PCR (UT-PCR) method with microscopy in malaria diagnosis and surveillance.

METHODS

400 blood smears and blood samples on filter paper were taken from febrile patients which were initially diagnosed as malaria or suspected malaria during surveillance in mixed endemic areas of Plasmodium falciparum (Pf) and P. vivax (Pv) in Hainan and Yunnan provinces and a malaria-controlled area in Guangxi Zhuang Autonomous Region. The initial test results of both UT-PCR and microscopy for the 400 samples were compared under double blind condition. Blood smears with discrepant results between the two methods were retested by an experienced microscopist, and also repeated by UT-PCR for 2-3 times. The sensitivity and specificity of the two methods were evaluated following the Tjitra's method.

RESULTS

Among the 400 blood samples, 234 were found plasmodium-positive by microscopy with 125 Pf and 109 Pv; 235 were positive by UT-PCR including 124 Pf, 109 Pv and 2 mixed infection. Altogether, the coincidence between the two methods stood for 92.5 % (370/400), including 154 negatives and 216 positives (Pv 117, Pf 99). 25 samples with discrepancy from the initial detections were retested, which covered 11 microscopy negative and PCR positive, 10 microscopy positive and PCR negative, 3 microscopy Pf positive and PCR Pv positive, 1 microscopy Pv positive but PCR mixed infection. 15 of the 25 samples showed same UT-PCR results, 7 "false positives" and 3 "false negatives" . Therefore, the sensitivity and specificity of UT-PCR was 99.6% and 98.8% respectively.

CONCLUSION

As a diagnosis method, UT-PCR is useful for confirmation of malaria diagnosis and differentiation of Plasmodium species, also for improving the effectiveness and quality of malaria surveillance.

[Plasmodium vivax malaria in the Brazilian Amazon: some aspects of its epidemiology, clinical spectrum and naturally induced immune responses]

Malaria was a nationwide problem in Brazil in the 1940's. However during the late fifties a national and successful campaign gained strength in the country decreasing malaria to its lowest level by 1960, when only 36,9 thousand cases were registered. Although the Malaria Eradication Program of the Ministry of Health in Brazil succeeded by the late 60's in freeing the majority of the country from malaria transmission, it was unable to contain the rapid spread of the disease in the Amazon Basin. In the 1970's the Amazon region witnessed a huge transformation. Colonization programs sponsored by the government, mining exploration, massive migration and the construction of roads and dams brought a new reality for which the area was not prepared. The last data available show that in 2007, the Amazon registered around 450 thousand cases, 99.9% of the national cases. P. vivax has been reported as representing around 80% of all malaria cases. P. vivax is thought to cause little mortality but like P. falciparum, P. vivax accounts for vast amounts of morbidity and for huge burdens on the prosperity of endemic communities. However, in the last few years a pattern of unusual clinical complications with fatal cases associated with it have been reported in Brazil and is a matter of tremendous concern in the Brazilian community of malariologists. In addition, the emergence of P. vivax strains resistant to chloroquine and primaquine in some reports needs to be further investigated. In contrast, asymptomatic infections by P. falciparum and P. vivax were detected in epidemiological studies in the states of Rondonia and Amazonas. Seropidemiological studies investigating the type of immune responses elicited in naturally exposed populations to several malaria vaccine candidates in Brazilian populations have also been providing important information on whether immune responses specific to those antigens are generated in natural infections and their immunogenic potential as vaccine candidates. In fact ultimate test of a malaria vaccine will be determined in field trials under natural conditions of parasite exposure.

[Gestational malaria: HELLP syndrome mistaken diagnosis]

Malaria is one of the most important parasitic infections in Mexico and Latin America. Here we report a case of a 21 year-old female with 38.4 weeks of pregnancy and previous hospitalization due to malaria. Showing a thick drop negative test she was referred to Mexico City Hospital de la Mujer with presumptive diagnosis of preeclampsia and HELLP syndrome. During her stay in ICU she developed malarial paroxysm and Plasmodium vivax was identified, conducting to specific therapy.

Congenital malaria in neonates: two case reports and review of the literature

Congenital malaria is uncommon in nonendemic countries. We describe two cases involving neonates hospitalized with fever, anaemia and thrombocytopaenia. Thick and thin blood smears were positive for Plasmodium vivax (P. vivax) and P. ovale, respectively. These two cases were discussed regarding the literature and potential implications of HIV coinfection in the mother.

CONCLUSION

Consistent data in the literature suggest that peripheral blood films should be performed in HIV-positive women who travelled to an endemic area or with a history of malaria prior to gestation. With today's travelling patterns, congenital malaria should be considered as an important differential diagnosis of neonatal sepsis.

Malaria mortality in Venezuela: focus on deaths due to Plasmodium vivax in children

Morbidity and mortality burden of malaria in the childhood represents a public health threat not only in countries with high levels of transmission, but also in those, such as Venezuela and others in Latin America, with moderate to low transmission. Usually its mortality has been attributed just to Plasmodium falciparum malaria, but the changing patterns of increase in Plasmodium vivax malaria morbidity and mortality are now causing concern. We studied malaria mortality by analyzing different epidemiological variables during a 10-year period in Venezuela, finding mortality rates ranging 0.10-0.36 deaths/100,000 population, with almost a third of deaths in children (<10 years old), corresponding 270 deaths to P. falciparum cases and 30 to P. vivax; but along the period with a decrease trend for P. falciparum and an increase trend for P. vivax.

Comparison of the diagnosis of malaria by microscopy, immunochromatography and PCR in endemic areas of Venezuela

Whole blood samples (N = 295) were obtained from different locations in Amazonas and Sucre States, in Venezuela. Malaria was diagnosed by microscopy, OptiMAL and polymerase chain reaction (PCR), with Plasmodium vivax, P. falciparum, and P. malariae being detected when possible. We identified 93 infections, 66 of which were caused by P. vivax, 26 by P. falciparum, and 1 was a mixed infection. No infection caused by P. malariae was detected. The sensitivity and specificity of each diagnostic method were high: 95.7 and 97.9% for microscopy, 87.0 and 97.9% for OptiMAL, and 98.0 and 100% for PCR, respectively. Most samples (72.2%) showed more than 5000 parasites/microL blood. The sensitivity of the diagnosis by microscopy and OptiMAL decreased with lower parasitemia. All samples showing disagreement among the methods were reevaluated, but the first result was used for the calculations. Parasites were detected in the 6 false-negative samples by microscopy after the second examination. The mixed infection was only detected by PCR, while the other methods diagnosed it as P. falciparum (microscopy) or P. vivax (OptiMAL) infection. Most of the false results obtained with the OptiMAL strip were related to the P. falciparum-specific band, including 3 species misdiagnoses, which could be related to the test itself or to genetic variation of the Venezuelan strains. The use of the microscopic method for malaria detection is recommended for its low cost but is very difficult to implement in large scale, population-based studies; thus, we report here more efficient methods suitable for this purpose.

Microscopic detection of mixed malarial infections: improvement by saponin hemolysis

OBJECTIVE

The objective of the present study was to determine whether saponin hemolysis could improve microscopic detection of malaria parasites in human blood, since it has been previously reported that the technique has been used to enrich Plasmodium falciparum culture to >or=90% parasitemia.

MATERIAL AND METHODS

Blood samples from suspected malaria cases were first examined in routine thick and thin smears under the microscope. The sample (1 ml) was then hemolyzed with 0.015% saponin in saline and centrifuged, the separated pellet was stained with Giemsa stain and examined microscopically, using PCR to confirm species identification.

RESULTS

With P. falciparum in vitro culture, the proportions of infected erythrocytes were approximately 0.7-2% before and 65-97% after saponin hemolysis, confirming published reports. In contrast, there was little or no increase in the proportions of intact infected erythrocytes after saponin hemolysis of clinical blood specimens. However, 20-600 hemolyzed parasites were detected per field under the microscope after saponin hemolysis of patients' blood samples that contained only 1-15 parasites per field in conventional thick smears. In addition, more P. falciparum gametocytes were detected after saponin hemolysis.

CONCLUSION

Saponin hemolysis concentrated the parasites in large volumes of blood into a small volume that could be smeared on a slide. This concentration method made it easy to detect malaria parasites and reduced the time needed for microscopy. In the present study, the method was comparable to PCR for the identification of P. vivax and P. falciparum mixed infections.

Prevalence of imported malaria in Parma during 2005-2006

BACKGROUND AND AIM OF THE WORK

Malaria is a protozoan infection caused by parasites of the genus Plasmodium (P. falciparum, P. ovale, P. vivax, P. malariae) that is transmitted from one human to another by female Anopheles mosquitoes. It can be considered a reemerging imported disease in our area because of increasing of movements from endemic countries, and nowadays it is the most common imported infection in Italy. This study describes the occurrence of imported malaria in our area between January 2005 and May 2006.

METHODS

During 17 months we analysed 170 blood samples belonging to 139 patients (95 foreigners and 44 Italians) with the clinical suspect of malaria. Samples were used to prepare orange acridine and Giemsa stained thin blood films for microscopic observation and to perform an immunochromatographic assay for the detection of specific plasmodia antigens. Molecular assays (nested-PCR and Real-time PCR) were also performed in order to confirm the diagnosis.

RESULTS

Thirty-six cases of malaria were diagnosed: 35 in foreigners coming from Africa and only one in an Italian who lived in Chad. Thirty-three patients were infected by P. falciparum, 1 by P. ovale, 1 by P. vivax, and a mixed infection by P. falciparum, P. ovale and P. malariae was also found.

CONCLUSIONS

Malaria is usually associated with travels within areas where the infection is endemic and our data demonstrated that imported malaria in our area has a prevalence of 25.89%.

Antigen capture immuno-chromatographic strip format in detecting parasite-specific lactate dehydrogenase to diagnose malaria in nonimmune patients

Several rapid diagnostic test devices (RDT) based on detection of malaria antigen in the whole blood were developed. OptiMal test the presence of parasite-specific lactate dehydrogenase (LDH) enzyme using three monoclonal antibodies was used. Two monoclonal antibodies were pan-specific and recognized all malaria species. The third one was specific only for Plasmodium falciparum. The parasite antigens were detected using an antigen-capture immunochromatographic strip format. One hundred-nine malaria positive and 730 malaria negative cases diagnosed by microscopy were included. 75/109 were P. falciparum 26 as P. vivax, 3 P. malariae and 5 mixed infection of P. falciparum & P. vivax. The RDT showed a low sensitivity (85%, 95% Confidence Interval [CI], 79-92%) with a much lower sensitivity in detecting species other than P. falciparum as well as in mixed infections. The sensitivity was 50% for less than 200 parasites/micro. The sensitivity of OptiMal for P. falciparum was 87% (95% CI, 79-94), 81% (95% CI, 66-96) for P. vivax, and failed with P. malariae. Mixed infections were misdiagnosed as Pfalciparum. The sensitivity of OptiMal was quite good in detecting both P. falciparum & P. vivax (98%; 95% CI, 97-99 & 100%; 95% CI, 100-100 respectively) and 99% (95% CI, 98-99) for all species. The positive and negative ratio for all malaria species was: (+LR = 62.3, -LR = 0.01); for P. falciparum (+LR = 38.9, -LR = 0.01) and for P. vivax (+LR = 0.8077/0, -LR = 0.2). The test value to assess drug resistance in post treatment days was discussed.

Two cases of Plasmodium vivax Malaria with the clinical picture resembling toxic shock

Fatal complications of Plasmodium falciparum malaria have been reported. However, complicated P. vivax malaria is rare. We observed two unusual cases of P. vivax malaria who presented with clinical pictures of toxic shock. Both showed disseminated intravascular coagulation with marked thrombocytopenia, oliguric renal failure, and pulmonary edema. Examination of initial blood smears showed a P. vivax parasitemia of 2,352/microL and 12,376/microL, respectively. The patients were treated with hydroxychloroquine and primaquine without an antibacterial agent. These cases emphasize the importance of considering the possibility of P. vivax malarial infection in patients with a clinical picture resembling toxic shock if they have a travel history to malaria-endemic areas.

Polymerase chain reaction detection of Plasmodium vivax and Plasmodium falciparum DNA from stored serum samples: implications for retrospective diagnosis of malaria

Polymerase chain reaction (PCR) detection of Plasmodium DNA is highly sensitive in diagnosing malaria. The specimen of choice for this assay has been whole blood samples from malaria patients. To retrospectively determine malaria infection rates in populations or cohorts for whom stored serum samples are available, we determined the ability of a nested PCR assay to detect Plasmodium DNA in stored serum samples. The PCR result was positive in 20 of 23 serum samples from patients with microscopy-confirmed malaria and negative in 8 of 8 healthy controls, resulting in a sensitivity of 87% and specificity of 100%. In all positive samples, species were correctly identified by PCR except for one case where a mixed infection was detected. The PCR is able to detect Plasmodium DNA in serum samples frozen up to 2.5 years and has the potential for the retrospective identification of malaria parasitemia in patient cohorts to determine potential interactions of malaria and other diseases such as human immunodeficiency virus/acquired immunodeficiency syndrome.

Comparison of artemether-lumefantrine with sulfadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria in eastern Nepal

Because available data suggest that resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine (SP) is increasing in Nepal, an open-label, parallel-group efficacy/safety study was conducted in 99 Nepalese patients with uncomplicated falciparum malaria randomized 2:1 to artemetherlumefantrine (AL) or SP. Efficacy was assessed from clinical and microscopic evidence of treatment failure. Four SP-treated patients (12.1%; 95% CI, 4.0-29.1%) redeveloped parasitemia during the 28-day follow-up versus 0% (95% CI, 0-6.9%) in the AL group (P = 0.011), a difference that was confirmed by polymerase chain reaction (PCR) analysis of parasite DNA. PCR detected an additional six patients (two SP and four AL) with sub-microscopic gametocytemia or breakthrough parasitemia between Days 14 and 28, suggesting that AL efficacy was lower than estimated by microscopy. Dhfr and dhps mutations were not associated with outcome. AL is more effective than SP for uncomplicated malaria in Nepal, but regular monitoring of its efficacy should be carried out if this combination therapy is introduced.

Improving case definitions for severe malaria

The authors discuss a study by Philip Bejon et al. that adopted a new approach to balancing the sensitivity and specificity of criteria for defining severe malaria.

Real-time PCR versus conventional PCR for malaria parasite detection in low-grade parasitemia

We have optimized a faster and cheaper real-time PCR and developed a conventional genus specific PCR based on 18S rRNA gene to detect malaria parasites in low-grade parasitemias. Additionally, we compared these PCRs to the OptiMAL-IT test. Since there is no consensus on choice of standard quantitative curve in real-time assays, we decided to investigate the performance of parasite DNA from three different sources: "genome", amplicon and plasmid. The amplicon curve showed the best efficiency in quantifying parasites. Both PCR assays detected 100% of the clinical samples tested; the sensitivity threshold was 0.5 parasite/mul and no PCR positive reaction occurred when malaria parasites were not present. Conversely, if OptiMAL-IT were employed for malaria diagnosis, 30% of false-negative results could be expected. We conclude that PCR assays have potential for detecting malaria parasites in asymptomatic infections, in evaluation of malaria vaccine molecule candidates, for screening blood donors, especially in endemic areas, or even in monitoring malaria therapy.

[Evaluation of the Optimal-IT and ICT P.f./P.v. rapid dipstick tests for diagnosing malaria within primary healthcare in the municipality of Manaus, Amazonas]

Malaria is routinely diagnosed using the thick blood smear test. However, this technique requires the training of microscopists and may be time-consuming. A concordance study was conducted on two dipstick tests (Optimal-IT and ICT P.f./P.v.) and the thick blood smear test, within primary healthcare in Manaus.

Concurrent salmonella bacteremia in P. vivax infection--a report of 2 cases at the Hospital for Tropical Diseases, Thailand

Malaria and concurrent bacteremia has been described in many reports, most of them with P. falciparum. Concurrent bacteremia with P. vivax infected patients is very rare. We reported 2 cases of salmonella bacteremia with P. vivax infection. Both patients presented with fever and the diagnosis of P. vivax was confirmed microscopically. The first patient presented with fever, jaundice, shock and renal failure which rarely occurs with P. vivax infection. The second patient had no clinical response after receiving standard antimalarial drugs. Hemoculture was positive for Salmonella spp in both cases. They recovered completely after appropriate antibiotics and antimalarial treatment.

Concurrent dengue and malaria due to Plasmodium falciparum and P. vivax

Concurrent infections of dengue and malaria are rare. We report a case of dengue fever with acute malaria due to Plasmodium falciparum and P. vivax in which the presence of mixed infection with P. vivax was overlooked and confirmed later on during recurrence of the fever that had initially responded to conventional antimalarial treatment and symptomatic treatment for dengue fever. We suggest that in concurrent infections of dengue and malaria, possibility of mixed infection with various Plasmodium species should be excluded to ensure a better treatment outcome.

Symmetric peripheral gangrene with mixed malaria

Symmetric peripheral gangrene (SPG) in a case of mixed malaria (P. falciparum and P. vivax) is a rare and relatively unknown complication of malaria. We report a case of 10-yr-old female with mixed malaria infection and SPG (Symmetric Peripheral Gangrene) of foot, which is most likely due to interaction between parasite factors (P. Falciparum and P. viavx) and host factors.

Cross sectional study reveals a high percentage of asymptomatic Plasmodium vivax infection in the Amazon Rio Negro area, Brazil

A parasitological, clinical, serological and molecular cross-sectional study carried out in a highly endemic malaria area of Rio Negro in the Amazon State, Brazil, revealed a high prevalence of asymptomatic Plasmodium vivax infection. A total of 109 persons from 25 families were studied in five villages. Ninety-nine inhabitants (90.8%) had at least one previous episode of malaria. Serology showed 85.7% and 46.9% of positivity when P. falciparum antigens and P. vivax MSP-1, respectively, were used. Twenty blood samples were PCR positive for P. vivax (20.4%) and no P. falciparum infection was evidenced by this technique. No individual presenting positive PCR reaction had clinical malaria during the survey neither in the six months before nor after, confirming that they were cases of asymptomatic infection. Only one 12 year old girl presented a positive thick blood smear for P. vivax. This is the first description of asymptomatic Plasmodium infection in this area studied.

[Sensitivity, specificity and stability of the Tag-primer nested/multiplex PCR for malaria diagnosis]

OBJECTIVE

To improve the sensitivity, specificity and stability of the Tag-primer nested/multiplex PCR for malaria diagnosis.

METHODS

Filter paper blood samples were collected from 30 non-malaria fever patients and 20 infectious disease patients (common cold, influenza, typhoid, hepatitis, etc.). Four ml blood each taken from one falciparum malaria patient and one vivax malaria patient was serially diluted. Healthy blood sample was used as negative control. Improved direct heating method was used to prepare DNA template. The cytochrome oxidase gene (coxI) located in mitochondrion was selected as target gene. Relevant web resources and software (PUBMED, NCBI-BLAST, Mfold server and Primer Premier 5.0) were employed to design and optimize Tag-primer nested/multiplex PCR (UT-PCR) which was used to test all blood samples.

RESULTS

A 611 bp band and a 255 bp band were seen in serially diluted infected blood samples (1,000, 100, 10 and 1 parasite/microl) from P.f and P.v patient tested by UT-PCR. The detection limit of either P. falciparum or P. vivax reached 1 parasite/microl, and the tested blood samples of non-malaria fever patients, patients with other infectious diseases and healthy persons were all negative. Consistent results of each sample in more than 3 duplicated tests were obtained.

CONCLUSION

The optimized Tag-primer nested/multiplex PCR shows high sensitivity, specificity and stability in malaria diagnosis.

Clinical spectrum of uncomplicated malaria in semi-immune Amazonians: beyond the " symptomatic " vs " asymptomatic " dichotomy

We analyzed prospectively 326 laboratory-confirmed, uncomplicated malarial infections (46.3% due to Plasmodium vivax, 35.3% due to P. falciparum, and 18.4% mixed-species infections) diagnosed in 162 rural Amazonians aged 5-73 years. Thirteen symptoms (fever, chills, sweating, headache, myalgia, arthralgia, abdominal pain, nausea, vomiting, dizziness, cough, dyspnea, and diarrhea) were scored using a structured questionnaire. Headache (59.8%), fever (57.1%), and myalgia (48.4%) were the most frequent symptoms. Ninety-six (29.4%) episodes, all of them diagnosed during cross-sectional surveys of the whole study population (96.9% by molecular technique only), were asymptomatic. Of 93 symptom-less infections left untreated, only 10 became symptomatic over the next two months following diagnosis. Fever was perceived as " intense " in 52.6% of 230 symptomatic malaria episodes, with no fever reported in 19.1% episodes although other symptoms were present. We found significant differences in the prevalence and perceived intensity of fever and other clinical symptoms in relation to parasite load at the time of diagnosis and patient's age, cumulative exposure to malaria, recent malaria morbidity, and species of malaria parasite. These factors are all likely to affect the effectiveness of malaria control strategies based on active or passive detection of febrile subjects in semi-immune populations.

Congenital malaria, an important differential diagnosis to consider when evaluating febrile infants of immigrant mothers

Congenital malaria is reported rarely in the United States and almost exclusively affects infants of immigrant mothers. Because of its nonspecific presentation with fever during the first 3 months of life, it is an important differential diagnosis when evaluating such infants with fever in the pediatric emergency department. A complete and accurate travel and residency history on the infant's family should be sought during evaluation. As intercontinental travel and immigration increases, emergency department physicians should be alert to the diagnosis of malaria in ill neonates and young infants. We discuss a case of congenital malaria in a 26-day-old infant and review the clinical features of previously reported cases in the United States.

Impact of competitive inhibition and sequence variation upon the sensitivity of malaria PCR

Real-time PCR assays for Plasmodium species utilizing universal and species-specific primers were compared to investigate variables influencing decreased assay sensitivity. Sequence variation in oligomer targets and competitive inhibition of dual-species templates in universal-primer mixes were found to decrease assay sensitivity.

Congenital malaria with atypical presentation: a case report from low transmission area in India

BACKGROUND

Malaria during first few months of life may be due to transplacental transfer of parasitized maternal erythrocytes. Although IgG and IgM antimalarial antibodies can be detected in maternal blood, only IgG antibodies are present in the infant's blood. These antibodies can delay and modify the onset of clinical manifestations.

CASE PRESENTATION

An infant is described who presented with irritability and feeding problems. Clinical examination and investigations revealed that the infant was afebrile, had jaundice, hepatosplenomegaly and haemolytic anaemia. Peripheral smear demonstrated Plasmodium vivax. While the mother had significant levels of immunoglobulin G (IgG), the infant was found negative for IgG and had low immunoglobulin M (IgM) levels. The mother had a history of febrile illness during pregnancy and her peripheral smear was also positive for P. vivax. Both were successfully treated with chloroquine in the dose of 25 mg/kg/day over three days.

CONCLUSION

The case emphasizes the importance of considering the diagnosis of malaria even in infants in low transmission area, who may not present with typical symptoms of malaria, such as fever, but have other clinical manifestations like jaundice and haemolytic anaemia.

High prevalence of malaria infection in Amazonas state, Venezuela

This study was carried out to determine the incidence of malaria in an endemic region of Amazonas State, Venezuela. For this, 200 random samples were collected from symptomatic and asymptomatic individuals from San Fernando de Atabapo and Santa Barbara. Epidemiological factors were related to malaria infection, which was diagnosed by microscopy observation and amplification of the 18S rDNA sequence by PCR. Malaria prevalence in these populations was 28.5%, whilst P. vivax and P. falciparum prevalences were 12 and 17%, respectively. No infection by P. malariae was found. A mixed infection was found on an asymptomatic individual. Prevalence patterns differed between age groups depending on the Plasmodium species. We found that 34.8% of the P. vivax and 15.2% of the P. falciparum infections were asymptomatic. The use of nets was helpful to prevent P. vivax infection, but did not protect against P. falciparum infection. The results suggest the presence of more than one mosquito vector in the area, displaying a differential pattern of infection for each Plasmodium species. There appear to be risk factors associated with malaria infections in some individuals. The population based approach and PCR diagnosis improved the accuracy of the statistical analysis in the study.

Supportive presumptive diagnosis of Plasmodium vivax malaria. Thrombocytopenia and red cell distribution width

OBJECTIVE

To evaluate hemoglobin, leukocyte, platelet counts and red cell distribution width values during acute vivax malaria.

METHODS

This study, which comprises 90 symptomatic vivax malaria patients compared with 52 healthy controls, investigated hemoglobin, leukocyte, platelet counts and red cell distribution width values during acute disease prior to the treatment in vivax malaria, from May 2002 to December 2004 in Adana, Cukurova region, located in the southern part of Turkey, along the Mediterranean coast.

RESULTS

Mean values for hemoglobin, leukocyte and platelet counts in the vivax malaria group in our study were found to be significantly lower in comparison to the control group. Anemia and thrombocytopenia were also observed in the malaria group while not in the control group (p<0.05, p<0.0001). Mean red cell distribution width values were found to be significantly higher in the malaria group (p<0.0001).

CONCLUSION

Our findings indicated that routinely used laboratory findings such as low hemoglobin, leukocyte or platelet counts and especially high red cell distribution width values could present a more supportive clue in the diagnosis of vivax malaria in endemic areas.

Urban malaria in the Brazilian Western Amazon Region I: high prevalence of asymptomatic carriers in an urban riverside district is associated with a high level of clinical malaria

Cross sectional studies on malaria prevalence was performed in 2001, 2002, and 2004 in Vila Candelária, an urban riverside area of Porto Velho, Rondônia, in the Brazilian Western Amazon, followed by longitudinal surveys on malaria incidence. Vila Candelária is a working class district, provided with electricity, water supply, and basic sanitation. Previous preliminary surveys indicated high malaria incidence in this community. At the end of year 2000 regular diagnostic and treatment measures for malaria were introduced, with active search of febrile cases among residents. Despite of both rapid treatment of cases and relative good sanitary and housing conditions, the malaria incidence persisted at high levels during the following years with an annual parasite index of 150 to 300/1000 inhabitants. Parasite surveys in 2001, 2002, and 2004 achieved through microscopy and polymerase chain reaction to diagnose malaria showed a constant high prevalence of asymptomatic carriers for both Plasmodium falciparum and P. vivax parasites. It was concluded that asymptomatic carriers represent an important reservoirs of parasites and that the carriers might contribute to maintaining the high level of transmission. Comparing our findings to similar geo-demographic situations found in other important urban communities of the Brazilian Amazon, we propose that asymptomatic carriers could explain malaria's outbreaks like the one recently observed in Manaus.

Decreased glutathione-S-transferase activity: Diagnostic and protective role in vivax malaria

OBJECTIVES

The study was undertaken to establish data on the comparative status of antioxidant enzyme GST activity, levels of lipid peroxidation and catalase activity during pathology of Plasmodium vivax malaria in Indian population. We investigated whether serum and plasma glutathione-S-transferase activity in vivax patients are unique to the disease or act as one of the important antioxidant marker for diagnostic potential and candidate for chemoprevention.

METHODS

We measured activity of antioxidant enzyme GST, levels of lipid peroxidation and catalase activity during vivax infection.

RESULTS

Mean activity of antioxidant enzyme GST in patients serum and plasma were less (6.43 and 5.65 IU/L respectively) than healthy subjects (11.65 and 10.09 IU/L respectively). Lipid peroxidation level and catalase activity of patients (1.77 micromol/L and 29.64 U/mL) with vivax malaria were higher than those of healthy subjects (1.03 micromol/L and 10.87 U/mL). GST activity in serum and plasma was inversely correlated with age in case of vivax patient and were found significant (R2=0.1907 and 0.1605 and p<0.0007 and p<0.01).

CONCLUSIONS

In view of the present findings we suggest that GST, lipid peroxidation and catalase evaluation may be considered to be reliable biochemical markers and possess promising rational for diagnostic and therapeutic potential in vivax malaria. Decreasing GST activity and elevated activity of lipid peroxidation and catalase may play important roles in host defence mechanisms against vivax infection by up-regulating oxidative defence mechanisms.

Molecular screening of Plasmodium sp. asymptomatic carriers among transfusion centers from Brazilian Amazon region

The transmission of malaria in Brazil is heterogeneous throughout endemic areas and the presence of asymptomatic Plasmodium sp. carriers (APCs) in the Brazilian Amazon has already been demonstrated. Malaria screening in blood banks is based on the selection of donors in respect to possible risks associated with travel or residence, clinical evidence and/or inaccurate diagnostic methods thereby increasing the probability of transfusion-transmitted infection. We evaluated the frequency of APCs in four blood services in distinct areas of the Brazilian Amazon region. DNA was obtained from 400 human blood samples for testing using the phenol-chloroform method followed by a nested-PCR protocol with species-specific primers. The positivity rate varied from 1 to 3% of blood donors from the four areas with an average of 2.3%. All positive individuals had mixed infections for Plasmodium vivax and Plasmodium falciparum. No significant differences in the results were detected among these areas; the majority of cases originated from the transfusion centres of Porto Velho, Rondônia State and Macapá, Amapá State. Although it is still unclear whether APC individuals may act as reservoirs of the parasite, efficient screening of APCs and malaria patients in Brazilian blood services from endemic areas needs to be improved.

High rate of detection of mixed infections of Plasmodium vivax and Plasmodium falciparum in South-East of Iran, using nested PCR

Sistan and Baluchestan province, South-East of Iran, has been reported as an endemic area of malaria [Sadrizadeh B. Malaria in the world, in the eastern Mediterranean region and in Iran: Review article. WHO/EMRO Report 2001: 1-13.]. The main objective of this research was to perform rapid and correct diagnoses of malaria infection. Blood specimens were collected from 140 suspected volunteers. The Giemsa-stained slides examination and nested PCR for amplification of the Plasmodium small subunit ribosomal genes (ssrRNA) were utilized. The results demonstrated 118 out of 140 cases (84.3%) positive for malaria parasites, including 60.7%, 20.7% and 2.9% as having Plasmodium vivax (P.v), Plasmodium falciparum (P.f) and mixed infections (P.v+P.f), respectively by microscopy. The nested PCR detected malaria parasites in 134 samples (94.3%), consisting of 51.4% P.v, 12.6% P.f and 29.3% mixed infections. The PCR analysis detected 37 cases of mixed infections more than that of the routine microscopy. These results suggested that there are a considerable number of cases with mixed infections in the study area that mainly remain undiagnosed by microscopy. It is also concluded that the nested PCR is a suitable complement to microscopy for accurate specific diagnosis of malaria species in field.

Comparison of PCR and microscopy for the detection of asymptomatic malaria in a Plasmodium falciparum/vivax endemic area in Thailand

OBJECTIVE

The main objective of this study was to compare the performance of nested PCR with expert microscopy as a means of detecting Plasmodium parasites during active malaria surveillance in western Thailand.

METHODS

The study was performed from May 2000 to April 2002 in the village of Kong Mong Tha, located in western Thailand. Plasmodium vivax (PV) and Plasmodium falciparum (PF) are the predominant parasite species in this village, followed by Plasmodium malariae (PM) and Plasmodium ovale (PO). Each month, fingerprick blood samples were taken from each participating individual and used to prepare thick and thin blood films and for PCR analysis.

RESULTS

PCR was sensitive (96%) and specific (98%) for malaria at parasite densities > or = 500/microl; however, only 18% (47/269) of P. falciparum- and 5% (20/390) of P. vivax-positive films had parasite densities this high. Performance of PCR decreased markedly at parasite densities <500/microl, with sensitivity of only 20% for P. falciparum and 24% for P. vivax at densities <100 parasites/microl.

CONCLUSION

Although PCR performance appeared poor when compared to microscopy, data indicated that the discrepancy between the two methods resulted from poor performance of microscopy at low parasite densities rather than poor performance of PCR. These data are not unusual when the diagnostic method being evaluated is more sensitive than the reference method. PCR appears to be a useful method for detecting Plasmodium parasites during active malaria surveillance in Thailand.

Evaluation of a real-time PCR assay for malaria diagnosis in patients from Vietnam and in returned travellers

Real-time PCR diagnosis of malaria has advantages over traditional microscopic methods, especially when parasitaemia is low and when dealing with mixed infections. We have developed a new real-time PCR with specific genes in each Plasmodium species present only in one copy to identify the four pathogenic Plasmodium spp. for humans. The sensitivity was less than 25 parasites/microl. No cross-hybridisation was observed with human DNA or among the four Plasmodium spp. Using LightCycler PCR and conventional microscopy, we compared the diagnosis of malaria in patients from Vietnam and in returned European travellers with suspicion of malaria. In patients from Vietnam with suspicion of malaria, one mixed infection was observed by PCR only; the remaining data (54 of 55 patients) correlated with microscopy. In 79 patients without symptoms, low parasitaemia was detected in 7 samples by microscopy and in 16 samples by PCR. In returned travellers, PCR results were correlated with microscopy for all four species in 48 of 56 samples. The eight discrepant results were resolved in favour of real-time PCR diagnosis. This new real-time PCR is a rapid, accurate and efficient method for malaria diagnosis in returned travellers as well as for epidemiological studies or antimalarial efficiency trials in the field.

Evaluation of three rapid tests for diagnosis of P. falciparum and P. vivax malaria in Colombia

The diagnostic capacity of three malaria rapid diagnostic tests (RDTs), NOW-Malaria-ICT, OptiMAL-IT, and Paracheck-Pf, was evaluated against expert microscopy in Colombia. We tested 896 patients, of whom microscopy confirmed 139 P. falciparum, 279 P. vivax, and 13 mixed P.f/P.v infections and 465 negatives. Paracheck-Pf and NOW-malaria-ICT were more accurate in detecting P. falciparum (sensitivities 90.8% and 90.1%, respectively) in comparison with Optimal-IT (83.6%). NOW showed an acceptable Pf detection rate at low densities (< 500/microL), but resulted in a higher proportion of false positives. For P. vivax diagnosis, Optimal-IT had a higher sensitivity than NOW (91.0% and 81.4%, respectively). The choice between the two Pf/Pv detecting RDTs balances P. falciparum and P. vivax detection rates. Considering some degree of P. falciparum overtreatment and failure to detect all P. vivax cases as more acceptable than missing some cases of P. falciparum, we recommend careful implementation of NOW-malaria-ICT in areas where microscopy is lacking. The price is however still a constraint.

Cutaneous and presumed visceral leishmaniasis in a soldier deployed to Afghanistan

Leishmaniasis has been frequently diagnosed in US military personnel returning from duty in Southwest Asia. The majority of cases have demonstrated cutaneous disease, although a few cases of visceral disease have been documented. We present the case of an immunocompetent, HIV-negative, US Army soldier who suffered both visceral and cutaneous manifestations of leishmaniasis after returning from deployment in Afghanistan. Overlap of cutaneous and visceral involvement is rare and has not been reported in our cohort. Latent Plasmodium vivax infection may have been an exacerbating cofactor. We discuss this case and present a review of the literature.

Development of an automated malaria discriminant factor using VCS technology

Malaria diagnosis presents a challenge to all laboratories. There is a need for rapid, sensitive, and cost-effective screening on all samples, particularly in areas where malaria is endemic. Response to malaria infection involves an increased monocyte count and production of large activated monocytes. These changes can be detected by volume, conductivity, and scatter (VCS) technology on certain automated blood cell counters (Beckman Coulter, Miami, FL). The SD of the volume of lymphocytes and monocytes demonstrates a significant difference from normal when malaria is present. By using a calculation derived from the SD volume of the lymphocytes and monocytes, herein termed the malaria factor, sensitivity of 98% and specificity 94% were demonstrated for the detection of malaria. Based on this derived discriminant, VCS technology should become a useful tool in the detection of malaria. A flag to indicate the potential presence of malaria could then be generated by the instrument if the user or manufacturer chose to do so.

A case of autochthonous Plasmodium vivax malaria, Corsica, August 2006

A case of Plasmodium vivax malaria was diagnosed in Corsica in August 2006. This is the first case of autochthonous transmission of malaria to be reported in the region since 1972