Interpreteation of immunochromatographic tests with HRP-2 antigen in children under 5 years in an area of high risk of malaria transmission in Papua New Guinea

The immunochromatographic tests with HRP-2 antigen (histidine-rich protein) Vision Biotech Pf Rapid Malaria Test was performed in 291 children under 5 years presenting fever or history of fever (malaria presumptive cases) admitted to Children Out-Patient Department of the Modilon Hospital in Madang, in a high malaria risk area of Papua New Guinea. The results of the tests were compared to the results of the parasitic examination of the peripheral blood with light microscopy (thick and thin smears). The HRP-2 test showed very high sensitivity (95.4%) and specificity (94.1%) for Plasmodiumfalciparum parasitaemia and none or very low sensitivity and specificity for other malaria species. The HRP-2 test detected both asexual and sexual stages of the Plasmodium falciparum parasites. The test did not show significant changes in detection of different levels of parasitaemia. These findings enable to conclude that the HRP-2 immunochromatographic assay can be very helpful to diagnose Plasmodium falciparum malaria when microscopy examination is not available, but as qualitative tests can be difficult for interpretation especially in high malaria risk areas. Therefore it can require re-examination of blood with microscopy to confirm species and development stages of Plasmodium spp. and to assess parasite load.     

Plasmodium vivax presenting as acute glomerulonephritis in a 3-year-old child

Although acute glomerulonephritis is a rare complication of Plasmodium falciparum malaria, it has not been reported in connection with Plasmodium vivax. We report a case of complicated P. vivax malaria presenting as acute glomerulonephritis. A three-year-old boy presented with high grade fever, a seven-day history of the progressive swelling of his body and a one-day history of vomiting. An examination revealed hypertension (>95th percentile), pallor and hepatosplenomegaly. Investigations showed a platelet count 80,000/mm(3) with haematuria [20-30 red blood cells/high power field with more than 80% dysmorphic red blood cells]. A peripheral smear showed the presence of trophozoites of P. vivax. The patient was diagnosed as having P. vivax causing acute glomerulonephritis and was treated successfully with antimalarials and enalapril. With the changing epidemiological pattern of malaria, especially in endemic areas, unusual complications such as acute glomerulonephritis may sometimes present in cases of P. vivax malaria.     

The hospital- and field-based performances of the OptiMAL test,for malaria diagnosis and treatment monitoring in central India

The performance of the OptiMAL test, to detect and differentiate Plasmodium falciparum and P. vivax, was evaluated in central India. The subjects were either symptomatic patients, who presented at a referral hospital in urban Jabalpur, or the inhabitants of remote, tribal, forested villages where malaria is a major public-health problem. In each setting, the results of conventional microscopy were used as the 'gold standard'. Under hospital conditions, the test had excellent sensitivity (100%), good specificity (97%), a high positive predictive value (98%) and a high negative predictive value (100%). The corresponding values in the field-based study in the tribal villages (100%, 67%, 84% and 100%, respectively) were almost as good. The results of OptiMAL testing reveal the decline in parasitaemias (of P. falciparum or P. vivax) after drug administration. For monitoring the effectiveness of treatment, the test could therefore be a useful alternative to microscopy, particularly (1) in places where the facilities for microscopy are poor or non-existent and (2) among hospitalized patients with severe, complicated malaria (in whom parasitaemia and drug response need to be followed very carefully). Follow-up (within 28 days of diagnosis) of the 58 malaria cases detected in the field revealed that the OptiMAL test can be used to detect re-infection with a different Plasmodium sp. (sensitivity = 100%; specificity = 100%; J-index = 1) or recrudescence/re-infection with the same Plasmodium sp. (sensitivity = 83%; specificity = 100%; J-index = 0.83) accurately. The ability to use the test to distinguish P. falciparum from P. vivax, and to identify mixed infections of these two species, is of great significance in areas where the preferred and effective therapy for P. falciparum malaria differs from that for P. vivax.     

Field trial of the RTM dipstick method for the rapid diagnosis of malaria based on the detection of Plasmodium falciparum HRP-2 antigen in whole blood

The performance of the Quorum RapidTest Malaria (RTM) dipstick method that detects Plasmodium falciparum histidine-rich protein-2 (PfHRP-2) antigen in whole blood was evaluated in a malaria endemic area. Results were compared with conventional Giemsa-stained blood films. Of 306 people tested 37.9% (116/306) were found to be parasitaemic; of these 66.4% (77/116) were P. vivax and 32.8% (38/116) were P. falciparum infections. There was only one (0.9%) mixed P. falciparum plus P. vivax infection.The RTM test was positive in 35/36 patients with P. falciparum identified on blood smear examination, resulting in a sensitivity of 97.2% [95% confidence interval (CI): 91.6-102.8%]. Specificity was 96.3% (95% CI: 93.9-98.6%).The RTM test had a positive predictive value of 77.8% (95% CI: 65.7-89.9%) and a negative predictive value of 99.6% (95% CI: 98.4-100.8%). Of the 10 false positives, seven reported recent malaria episode and treatment, indicating persistence of antigenaemia. If these were assumed truly infected, the positive predictive value is increased to 93.3% (95% CI: 85.8-100.8%).The RTM test was positive in all seven P. falciparum infections with gametocytes and one mixed infection, but was negative in all falciparum gametocytes and relapsing fever cases. All but one P. vivax infection gave negative result on the RTM test.The RTM test missed one patient with parasitaemia. The test is highly sensitive and specific requiring no instrument or trained personnel. It appears to be a very useful tool for rapid diagnosis of malaria, especially in the rural health institutions with limited diagnostic facilities.     

Imported malaria in a Singapore hospital: clinical presentation and outcome.

OBJECTIVE: To evaluate the clinical presentation and outcome of imported malaria. METHODS: A retrospective chart review was conducted of patients with imported malaria admitted to the Communicable Disease Centre (CDC), Singapore (a 130-bed tertiary referral center) from January 1992 to December 1993. An imported case was defined as a smear-positive infection that was acquired in another country. RESULTS: Among 200 malaria patients hospitalized at CDC, 168 imported cases (137 males and 31 females, 131 nonresidents and 37 residents) were studied. The mean age was 31.6 6 10.5 years. The countries visited were India (49.4%), Indonesia (16.7%), and Bangladesh (13%). Five patients had chemoprophylaxis and 36 patients had experienced previous malaria infection. The predominant symptoms were fever (97.6%), chills (79.2%), and rigors (67.9%). Hepatomegaly was detected in 56 (33.3%) and splenomegaly in 49 patients (29.2%). Plasmodium vivax was present in 132 patients, Plasmodium falciparum in 29, and mixed P. vivax and P. falciparum in 7 patients. Parasitemia ranged from 0.1% to 8.0%. Of the vivax cases, 130 were treated with chloroquine, followed by primaquine in 123 patients. Quinine was given to 36 patients (29 falciparum malaria and 7 mixed infections). Median time to fever defervescence was 2 days. Complications occurred in three patients (2 with shock and 1 with pulmonary edema). According to World Health Organization gravity criteria, body temperature over 40 degrees C was detected in six patients, bilirubinemia higher than 50 mmol/L in nine, parasitemia over 5% in five, glycemia less than 2.2 mmol/L in two patients. There were five relapses. No death was recorded. CONCLUSION: Plasmodium vivax is the most common cause of imported malaria, with the majority acquired from the Indian subcontinent. Only a few patients presented with severe malaria.     

Season, fever prevalence and pyrogenic threshold for malaria disease definition in an endemic area of Mali

BACKGROUND: Modelling malaria parasitaemia as function of fever has been proposed as best alternative to estimate the attributable fraction of malaria fever and the sensitivity and specificity of different case definitions of malaria disease. OBJECTIVES: To determine the prevalence of fever and its relation to malaria parasitaemia and to establish a pyrogenic threshold for malaria disease in the area. METHODS: We conducted two cross-sectional surveys in children of 6 months to 9 years of age (2434 during the rainy season of 1993 and 2353 during the dry season of 1994) randomly selected from 21 areas of Bandiagara district, Mali. RESULTS: The relationship between fever and Plasmodium falciparum parasitaemia depends strongly on the season, thus affecting the malaria-attributable fraction of fever cases and the sensitivity and specificity of malaria case definitions. The overall proportion of fever attributable to malaria parasitaemia was 33.6% during the rainy season and 23.3% during the dry season, with the highest proportion occurring among the youngest children. The cut-off value, where the sensitivity curve crosses the specificity curve, was around 3200 pf/microl for all age categories during the rainy season and 200 pf/microl during the dry season. CONCLUSIONS: Malaria remains a main cause of fever in this area of Mali. The pyrogenic threshold of parasitaemia depends strongly on the season, and different cut-off levels of parasitaemia should be used during the two seasons to define malaria cases in this area.     

Evaluation of a rapid diagnostic test specific for Plasmodium vivax

Plasmodium vivax is the only human malaria indigenous to the Republic of Korea (ROK). A rapid and sensitive diagnostic test (RDT) that detects P. vivax is appropriate for evaluating suspected malaria patients with no travel history abroad. The RDTs, SD Malaria Antigen P.v (SD diagnostic, Kyonggi, ROK) specific for P. vivax and the well documented OptiMAL (DiaMed, Cressier, Switzerland) were compared among 282 volunteers for specificity and sensitivity of P. vivax and Plasmodium falciparum malaria infections against Giemsa-stained blood smears read by an experienced microscopist. A total of 137 volunteers were diagnosed with P. vivax, 45 cases (returned travellers from overseas) were diagnosed with P. falciparum and 100 healthy volunteers were diagnosed as negative for malaria. Correspondingly, the SD Malaria Antigen P.v test identified P. vivax infections in 128/137 malaria patients (93.4%) and 0/100 (0%) healthy volunteers. Three patients identified with P. falciparum also were interpreted as P. vivax by the SD Malaria Antigen P.v test; however, these patients were later confirmed as mixed infections of P. vivax and P. falciparum by polymerase chain reaction. OptiMAL interpreted the three mixed infections only as P. falciparum and detected 130/137 (94.9%) patients with P. vivax. The sensitivity of the SD Malaria Antigen P.v test decreased from 100% (>5000 parasite/microl) to 81.3% (1-100 parasites/microl) as parasitaemia levels declined. For the regions where P. vivax is the primary malaria parasite, the SD P. vivax-specific rapid diagnostic test may be useful for screening suspected malaria patients when sufficient material and human resources (e.g. trained microscopists) are unavailable for malaria diagnosis.     

Status febrilis mit Bewusstlosigkeit

Cerebral malaria with Plasmodium vivax is uncommon. Normally Plasmodium falciparum is the cause of cerebral malaria. We report about a 18 year old patient from Pakistan with a history of intermittent fever for several months. The patient recovered within a few days; however prognosis can be severe when cerebral malaria is complicating the course of Plasmodium vivax infection.     

Blood and bone marrow changes in malaria.

A variety of abnormalities in the number, morphology and function of blood and bone marrow cells may be found in Plasmodium falciparum and P. vivax malaria. In a non-immune individual, the nature of such abnormalities depends on the time after infection. In others it is determined by the pattern and intensity of malaria transmission in the area and the extent of host immunity. Severe anaemia may occur in children with chronic falciparum malaria and low parasitaemia as well as in patients with complicated acute falciparum malaria with high parasitaemia. However, the mechanisms underlying the anaemia in these two situations appear to be different. The possible roles of parasite products, T-cell-derived cytokines produced in response to the infection, macrophage activation and hyperplasia, macrophage-derived factors such as tumour necrosis factor-alpha, and macrophage dysfunction in the pathogenesis of the haematological abnormalities are discussed.     

Malaria dipsticks beneficial for IMCI in Cambodia

OBJECTIVES: The Integrated Management of Childhood Illness (IMCI) approach and new clinical treatment guidelines to control malaria among children less than 5 years old were introduced recently in Cambodia. This study was conducted to finalize the malaria part of the national IMCI fever chart. METHODS: A total of 323 sick children 2-59 months old were studied at rural health centres in northern Cambodia from February to April 2000. Cases with fever (by axillary temperature or history) or anaemia (by palmar pallor) were tested with dipsticks for Plasmodium falciparum and Plasmodium vivax in high and low malaria risk areas and, if positive, treated with anti-malarials. RESULTS: The draft IMCI chart identified children with malaria safely and effectively (sensitivity 14 of 15, approximately 93% and specificity 292 of 308, approximately 95%). The study confirmed the potential of malaria dipsticks as a part of IMCI case management. CONCLUSION: The Cambodian Ministry of Health will use the studied malaria chart during the Early Implementation Phase of IMCI. Dipsticks able to detect P. falciparum and P. vivax with high sensitivity and acceptable cost will be needed for this purpose. To promote the rational use of dipsticks, the National Centre for Malaria Control, Parasitology and Entomology (Centre National de Malaridogie, Parasitologie et Entomologie, CNM) should list all known malaria risk areas in the country and prepare detailed local maps guiding case management especially in transitional zones.     

Changing scenario of malaria in central India, the replacement of Plasmodium vivax by Plasmodium falciparum (1986-2000)

OBJECTIVES: Since 1986, we have been studying the changing epidemiology of malaria in a forest belt of Mandla, which has the highest number of malaria cases in central India (Madhya Pradesh) to define the epidemiological characteristics of the infection with each Plasmodium species in different seasons of the year. Our long-term objective was to determine the dynamics of Plasmodium vivax vs.P. falciparum infections. METHODS: Five villages underwent fortnightly surveillance of fever cases. Drugs were distributed within 24 h after results of blood smears became available as per Indian National Anti-Malaria Programme. Indoor resting mosquitoes were also collected fortnightly. RESULTS: The only two Plasmodium species encountered were P. vivax and P. falciparum in both children and adults. Relatively more malaria infections were recorded in children (< or =14 years) than adults (>14 years) (chi2=89.94, P<0.00001). However, there were significant falling trends in P. vivax from 1986 to 2000 in both age groups (< or =14 years from 63 to 13, P<0.0001 and >14 years from 84 to 7, P<0.0001). The indoor resting density of Anopheles culicifacies, an efficient vector resistant to both dichlorodiphenyltrichloroethane (DDT) (4%) and hexachlorocyclohexane (HCH) (0.4%), was very high throughout this period in all villages (52.35 +/- 31.8, range 5-200 per man hour). Anopheles fluviatilis was present in small numbers 0.78 +/- 1.24 (range 0-7 per man hour). CONCLUSION: Major contributors of the changing epidemiology of malaria in this area are changing drug sensitivity along with insecticide sensitivity.     

云南省西双版纳恶性疟爆发区氯喹的疗效评价

目的　对云南省使用氯喹治疗失败进行调查研究 ,为制定合理的抗疟药物使用原则提供依据。　方法　采用WHO在低、中度恶性疟流行区 2 8天氯喹疗效评价方法。患者年龄≥ 6个月 ,无疟原虫密度和体温限制 ,服药后第1、2、3、4、7、14、2 1、2 8和 35天观察患者的临床症状和疟原虫携带情况。　结果　有 6 2例患者确认为感染单纯恶性疟原虫、间日疟原虫和混合疟原虫 ,其中 5 2例单纯恶性疟患者被纳入研究对象。总治疗失败率为 40 .7% ,其中早期治疗失败率为 1.8% ,晚期治疗失败率为 38.9%。　结论　当地单纯氯喹治疗单纯恶性疟感染者失败率明显高于WHO提出的2 5 % ,应停止单用氯喹治疗恶性疟。治疗失败与疟原虫密度无关联性。     

The risk of malarial infections and disease in Papua New Guinean children

In a treatment re-infection study of 206 Papua New Guinean school children, we examined risk of reinfection and symptomatic malaria caused by different Plasmodium species. Although children acquired a similar number of polymerase chain reaction-detectable Plasmodium falciparum and P. vivax infections in six months of active follow-up (P. falciparum = 5.00, P. vivax = 5.28), they were 21 times more likely to develop symptomatic P. falciparum malaria (1.17/year) than P. vivax malaria (0.06/year). Children greater than nine years of age had a reduced risk of acquiring P. vivax infections of low-to-moderate (>150/microL) density (adjusted hazard rate [AHR] = 0.65 and 0.42), whereas similar reductions in risk with age of P. falciparum infection was only seen for parasitemias > 5,000/microL (AHR = 0.49) and symptomatic episodes (AHR = 0.51). Infection and symptomatic episodes with P. malariae and P. ovale were rare. By nine years of age, children have thus acquired almost complete clinical immunity to P. vivax characterized by a very tight control of parasite density, whereas the acquisition of immunity to symptomatic P. falciparum malaria remained incomplete. These observations suggest that different mechanisms of immunity may be important for protection from these malaria species.     

Two cases of mixed infection of malaria diagnosed by PCR method

We here reported two Japanese cases of mixed infections of plasmodium species, whose DNAs were detected using the PCR test. One case was a 31 year-old male, who presented fever and fatigue, and had a travel history to Kenya, Cameroon and Indonesia. Smear test of his peripheral blood found the presence of Plasmodium vivax, while nested-PCR diagnosis detected the DNAs both P. vivax and Plasmodium malariae. The other was a 54 year-old female suffering from general fatigue. She had been treated with chloroquine for falciparum malaria in Indonesia two weeks before. Malaria antigen test showed positive although no Plasmodium organisms were found in the smear test. The nested PCR detected the DNA of Plasmodium ovale in addition to that of Plasmodium falciparum. In conclusion, the PCR test is helpful and useful for detection of mixed infections of Plasmodium species.     

Possible role of PGD_2 in malaria infections

Objective:To preliminarily investigate the possible role of prostaglandin D_2(PGD_2) in malaria infections.Methods:Blood and urinary samples(n=120 each) were collected from Thai patients with Plasmodium falciparum(P.falciparum) with moderate(n=26) and high(n=4) parasitemia,patients with Plasmodium vivax(P.vivax)(n=30),patients with fever associated with other infections(n=30),and healthy subjects(n=30).PGD_2 concentrations in plasma and urinary samples of healthy subjects,patients with fever associated with other infections and patients with malaria were determined using Prostaglandin D2-MOX express EIA kit(Cayman Chemical,USA).Results:The possible association between PGD_2 and malaria infections is clearly demonstrated with PGD_2 concentration in urine.The urinary PGD_2 concentrations were relatively high(about 5-fold) in patients with P.falciparum with moderate parasitemia and P.vivax infections compared with other groups.Furthermore,the concentration in patients with P.falciparum with moderate parasitemia and P.vivax infection were significantly higher than that in healthy subjects and patients with fever associated with other infections.Conclusions:Urinary PGD_2 concentrations may offer a more dependable and useful tool for predicting malaria severity.Confirmation is this preliminary finding is required with a larger sample size.     

Diagnosis of imported malaria by Plasmodium lactate dehydrogenase (pLDH) and histidine-rich protein 2 (PfHRP-2)-based immunocapture assays.

This study was conducted to evaluate the performance of two rapid non-microscopic assays: Plasmodium lactate dehydrogenase (pLDH) assay (OptiMAL) and Plasmodium falciparum histidine-rich protein 2 (PfHRP-2) assay (ICT Malaria). The assays were used to detect malaria infection in 515 immigrants living in Kuwait. The performance of both assays was compared to that of microscopy of Giemsa-stained thick blood films and to each other. Of the 515 patients tested, 163 were positive for malaria parasites by microscopy of thick blood film. Of these, 87 were infected with Plasmodium vivax parasites, 63 with P. falciparum, 1 with Plasmodium malariae, and 12 had mixed infections of P. falciparum and P. vivax. The PfHRP-2 assay detected 53 P. falciparum infections and, as expected, failed to detect all but one case of P. vivax. Three cases of mixed infections were also not detected by this assay. The pLDH assay detected 56 P. falciparum cases and 77 P. vivax infections but failed to detect 4 cases of mixed infections. Compared to microscopy, the performance of both the assays to diagnose P. falciparum infection was comparable. The sensitivity for the PfHRP-2 assay was 82% with a specificity of 99.0% and for the pLDH assay the sensitivity was 89% with a specificity of 99.5%. The PfHRP-2 assay detected 4 false positive cases, 2 of which were also detected by the pLDH assay. These patients reported treatment with chloroquine in the last 2-5 weeks. Though the immunocapture diagnostic assays may be helpful in certain situations, microscopy of thick blood film is still the method of choice in diagnosing imported malaria.     

Incidences of DIC complication in Japanese patients with malaria

Fourty eight patients with falciparum malaria (14) and vivax malaria (34) were evaluated retrospectively as to whether DIC (disseminated intravascular coagulation) had been complicated or not. Serum concentration of fibrin-degradation products (FDP) was elevated in 8 cases (57%) of falciparum malaria and 3 cases (9%) of vivax malaria. Thrombocytopenia was found in 12 cases (88%) of falciparum malaria and in 30 cases (86%) of vivax malaria. Prothrombin time elongated in 4 cases (8%) and plasma concentration of fibrinogen decreased in 3 cases (17%). Only 4 patients, all of them were infected with falciparum malaria and all of three cases of cerebral malaria were included, met the criteria for the diagnosis of DIC complication and one case in vivax malaria suspected of the DIC. Abnormality grades in FDP concentration has closest association with DIC among the coagulation tests, therefore FDP test is indispensable for checking complication of DIC in malaria cases. The clinical profiles of 3 cases of cerebral malaria complicated with DIC are presented in this report.     

Tumor necrosis factor-alpha in patients with malaria

Serum concentration of Tumor Necrosis Factor-alpha (TNF-alpha) was observed in 54 parasitologically confirmed cases of malaria. Of them, 15 cases were Plasmodium falciparum with cerebral involvement, three cases with mixed infections of P. falciparum and P. vivax, 32 cases of P. vivax, three cases of P. malariae and one case of P. ovale. Five out of 15 patients of P. falciparum (33.3 per cent), one out of 54 patients with mixed infection of P. falciparum and P. malariae (1.8 per cent) and the sole case of P. ovale (1.8 per cent) had fatal outcome. The serum TNF-alpha measured by avidin-biotin sandwich ELISA, was found to be significantly raised in P. falciparum and more so in fatal infections. The degree of parasitaemia, due to single or double infection, had positive effect on cytokine production. The mean TNF-alpha concentration was statistically significantly higher (p < 0.001) in P. falciparum than in P. vivax parasites infection. The mean TNF-alpha values in P. falciparum and P. vivax were 915 and 280.6 against the values in normal healthy controls of 12.9 pcg/ml respectively (p < 0.001). The study thus showed that the serum concentration of TNF-alpha correlated well with severity of malaria and these values could be used as an important prognostic marker of the disease.