Performance of the OptiMAL assay for detection and identification of malaria infections in asymptomatic residents of Irian Jaya, Indonesia

The OptiMAL assay, a new immunochromatographic "dipstick" test for malaria based on detection of Plasmodium lactate dehydrogenase (pLDH), is purported to detect infections of approximately 200 parasites/microL of blood and to differentiate between Plasmodium falciparum and non-P. falciparum. We evaluated OptiMAL performance by comparing the test strip interpretations of two independent readers with consensus results obtained independently by expert malaria microscopists. Unbiased measures of sensitivity were derived by applying the OptiMAL test for detection and differentiation of light, asymptomatic infections by P. falciparum and Plasmodium vivax. OptiMAL readings were separated in time to determine whether the reaction signal was stable. Microscopy identified infections in 225 of 505 individuals screened; those with P. falciparum (n = 170) averaged 354 asexual forms/microL and P. vivax/Plasmodium malariae (n = 112) averaged 216 asexual forms/microL of blood. Concordance between OptiMAL and microscopy was 81% and 78% by the two independent readings. The assay's sensitivity for detection of any malaria species was 60.4% and 70.2% respectively and specificity was 97% and 89%. Most cases identified by microscopy as P. falciparum were graded as negative or non-falciparum by both OptiMAL readers. OptiMAL false negatives as well as misidentifications were related to low parasitemias (< 500/microL). The OptiMAL assay demonstrated 88-92% sensitivity for detecting infections of 500-1,000 parasites/microL, a range covering the mean parasitemia of primary symptomatic P. falciparum infections in malaria-na?ve Indonesian transmigrants. This device was markedly less sensitive than expert microscopy for discriminating between malaria species and is presently unsuited for use as an epidemiological screening tool. The OptiMAL assay is not approved for diagnostic use but is commercially available for research purposes only.     

Comparison of three antigen detection methods for diagnosis and therapeutic monitoring of malaria: a field study from southern Vietnam

OBJECTIVES: To compare the sensitivity, specificity and post-treatment persistence of three commonly used rapid antigen detection methods. METHOD: We studied 252 Vietnamese patients aged from 4 to 60 years, 157 with falciparum and 95 with vivax malaria and 160 healthy volunteers. An initial blood sample was taken for microscopy, and OptiMAL, immunochromatographic test (ICT) malaria P.f./P.v. and Paracheck-Pf tests. Patients with falciparum malaria were treated with an artesunate-based combination regimen and those with vivax malaria received chloroquine. Eighty-seven patients with falciparum malaria who were initially positive for one of the antigen tests and who remained blood smear-negative underwent follow-up testing over 28 days. RESULTS: Paracheck-Pf was the most sensitive test for Plasmodium falciparum (95.8% vs. 82.6% for ICT malaria P.f./P.v. and 49.7% for OptiMAL). Specificities were all 100%. For vivax malaria, OptiMAL performed better than ICT malaria P.f./P.v. (sensitivities 73.7% and 20.0%, respectively), with 100% specificity in both cases. All tests had low sensitivities (< or = 75.0%) at parasitaemias < 1000/microl regardless of malaria species. During follow-up, Paracheck-Pf remained positive in the greatest proportion of patients, especially at higher parasitaemias (> 10,000/microl). Residual OptiMAL positivity occurred only in a relatively small proportion of patients (< 10%) with parasitaemias > 10,000/microl during the first 2 weeks after treatment. CONCLUSIONS: Although microscopy remains the gold standard for malaria diagnosis, Paracheck-Pf may prove a useful adjunctive test in uncomplicated falciparum malaria in southern Vietnam. OptiMAL had the lowest sensitivity for P. falciparum but it might have a use in the diagnosis of vivax malaria and perhaps to monitor efficacy of treatment for falciparum malaria where microscopy is unavailable.     

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.     

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.     

Rapid diagnostic devices for malaria: field evaluation of a new prototype immunochromatographic assay for the detection of Plasmodium falciparum and non-falciparum Plasmodium

The NOW ICT Malaria P.f./P.v. for Whole Blood (Binax, Inc., Portland, ME) is a new malaria rapid diagnostic device that represents a technical advance over previous assays, such as ICT Malaria P.f./P.v. and ICT Malaria P.f.. We evaluated this device in March 2001 in symptomatic patients at malaria clinics in Maesod, Thailand. Microscopic examination of Giemsa-stained blood smears was the reference standard. In 246 patients, microscopy showed 32 (13.0%) infected with Plasmodium falciparum, 63 (25.6%) with P. vivax, 6 (2.4%) with mixed infections of P. falciparum and P. vivax, 5 (2.0%) with P. malariae, and 140 (56.9%) negative. Sensitivity for P. falciparum was 100% and specificity was 96.2% (200 of 208; 95% confidence interval [CI] = 92-98). For P. vivax, sensitivity was 87.3% (55 of 63; 95% CI = 77-93) and specificity was 97.7% (173 of 177; 95% CI = 95-99), but all the four false-positive results were microscopically positive for P. malariae; thus, specificity for non-falciparum Plasmodium was 100%. These results suggest improved performance over NOW ICT predecessors.     

Efficacy of a rapid test to diagnose Plasmodium vivax in symptomatic patients of Chiapas, Mexico

OBJECTIVE: To evaluate, under laboratory conditions, the sensitivity and specificity of a rapid diagnostic test (OptiMAL), based on immunoreactive strips, to detect Plasmodium vivax infection in febrile patients in Southern Chiapas, Mexico. MATERIAL AND METHODS: The presence of parasites in blood samples of 893 patients was investigated by Giemsa-stained thick blood smear microscopic examination (gold standard). A blood drop from the same sample was smeared on immunoreactive strips to investigate the presence of the parasite pLDH. Discordant results were resolved by PCR amplification of the parasite's 18S SSU rRNA, to discard infection. RESULTS: OptiMAL had an overall sensitivity of 93.3% and its specificity was 99.5%. Its positive and negative predictive values were 96.5% and 98.9%, respectively. Signal intensity in OptiMAL strips correlated well with the parasitemia density in the blood samples (r = 0.601, p = 0.0001). CONCLUSION: This rapid test had acceptable sensitivity and specificity to detect P. vivax under laboratory conditions and could be useful for malaria diagnosis in field operations in Mexico.     

快速免疫色谱测试法诊断恶性疟的初步观察

目的：评价快速免疫色谱测试法（ＩＣＴ）在我国疟区门诊疟疾的适用性。方法：以镜检结果为对照，用ＩＣＴ方法检测门诊“四热”病人中的恶性疟。结果：ＩＣＴ检测恶性疟的敏感性和特异性分别为９４．７％和９０．３％，与间日疟无交叉，检测不同性别和民族人群阳性率间的差别无显著意义。结论：ＩＣＴ较镜检诊断恶性疟更为快速且简便，更适于在疟区门诊应用。     

快速免疫色谱测试法诊断恶性疟的初步观察

目的：评价快速免疫色谱测试法（ＩＣＴ）在我国疟区门诊疟疾的适用性。方法：以镜检结果为对照，用ＩＣＴ方法检测门诊“四热”病人中的恶性疟。结果：ＩＣＴ检测恶性疟的敏感性和特异性分别为９４．７％和９０．３％，与间日疟无交叉，检测不同性别和民族人群阳性率间的差别无显著意义。结论：ＩＣＴ较镜检诊断恶性疟更为快速且简便，更适于在疟区门诊应用。     

Comparison of a rapid field immunochromatographic test to expert microscopy for the detection of Plasmodium falciparum asexual parasitemia in Thailand.

We assessed a rapid, Plasmodium falciparum histidine rich protein 2 (PfHRP2)-based immunochromatographic test (ICT Malaria Pf Test), for detection of asexual P. falciparum parasitemia in 551 subjects in three groups: (1) symptomatic patients self-referring for diagnosis, (2) villagers in a screening survey, and (3) patients recently treated for P. falciparum malaria. Expert light microscopy was the reference standard. ICT test performance was similar for diagnostic and screening modes. Four findings emerged: (1) test sensitivity correlated directly with parasite density, (2) test band intensity correlated directly with parasite density, (3) persistent test positivity after parasite clearance precludes its use for monitoring early therapeutic responses, and (4) a false negative test at 18,000 parasites/microl is unexplained. We conclude that a strong positive ICT test is highly predictive of falciparum asexual parasitemia for the diagnosis of new cases of falciparum malaria in Thailand, but a negative test result is inadequate to exclude parasitemia < 300/microl, and in some instances, even a higher parasitemia.     

Relative utility of dipsticks for diagnosis of malaria in mesoendemic area for Plasmodium falciparum and P. vivax in northeastern India

For diagnosis of malaria, popular brands of rapid test kits collectively termed as "dipsticks" were subject to field evaluation in northeastern India for their comparative sensitivity and specificity vis-à-vis conventional microscopic results. Dipsticks based on Plasmodium falciparum-specific histidine-rich protein (Pf HRP-2) antigen capture assay revealed 100% sensitivity and high specificity (94-100%); thus, they were concluded to be reliable tools for confirmed diagnosis of malarial infection. However, an advanced version of the same kit, having incorporated additional pan-malarial monoclonal antibody, was found to be less sensitive (71%) for non-falciparum infections. Besides, Pf HRP-2-based kits continued to show positive results up to day 7, even after clearance of parasitemia on account of persistent antigenemia. This very limitation seemed to have been overcome by parasite-specific lactate dehydrogenase (pLDH) enzyme-based kit. This kit was observed to have high sensitivity (81-89%) and specificity (100%) for both falciparum and non-falciparum malaria, but cannot distinguish mono-infection from mixed infections. It is concluded that the rational use of these kits would accord health benefits in terms of early detection and prompt treatment, reduce drug pressure, and possibly delay the emergence and spread of multi-drug-resistant strains of malarial parasites.     

Field evaluation of malaria rapid diagnostic tests for the diagnosis of P. falciparum and non-P. falciparum infections

The objective of this study was to evaluate various malaria rapid diagnostic tests as a tool in the detection of P. falciparum and non-P. falciparum infections in field conditions. Four field surveys were conducted in malaria-endemic areas of Palawan and Davao del Norte, Philippines to validate the various rapid diagnostic tests, namely Diamed OptiMAL 48 (DiaMed AG, Switzerland), ParaHIT f (Span Diagnostics, India), Orchid OptiMAL, and Paracheck Pf (both from Orchid Biomedical Systems, India). The results of the various rapid diagnostic tests were compared to those of microscopy. Sensitivity, specificity and detection rates according to the level of parasitemia were used as parameters to describe the performance of the various rapid diagnostic tests in the field. Practical and operational assessments were also done. The results of the study show that the sensitivity and detection rates were generally lower than previously reported, with sensitivities ranging from 4.8% to 20.6%, except for Diamed OptiMAL 48, which had sensitivities of 78.8% to 96.8%, and detection rates of 50.0% to 96.8%. The rest had detection rates ranging from 0.0% to 50.0%. All the specificities ranged from 18.2% to 100.0%. Improper conditions at the time of manufacturing, storage, transport, and utilization may affect the validity of the results. Rapid diagnostic tests for malaria provide practical means of detecting malarial infections, especially in endemic areas. However, issues regarding variability in performance must to be addressed before they can be used as mainstream diagnostic tools.     

Usefulness of the "OptiMAL Rapid Malaria test" for rapid detection of malaria imported to Poland

In this survey the use of OptiMAL test for rapid diagnosis of malaria was evaluated. It was proved that this test allowed to diagnose the Plasmodium sp. antigen in 72% of examined blood specimens, 82% for P. falciparum infection and 69% for P. vivax, whereas P. ovale was not detected at all. The test sensitivity depended on the parasitemia level. It showed a sensitivity of 100% for parasitemia density exceeded 1%, 95.4% with the parasitemia ranging from 0.1-0.99%. For lower parasite density, the test's sensitivity was of 32 and 60%. The OptiMAL test showed a 99.1% specificity thus it revealed to be significantly high.     

Performance of the OptiMAL test for malaria diagnosis among suspected malaria patients at the rural health centers

The OptiMAL test detects both Plasmodium falciparum and P. vivax malaria infections. In this study, we evaluated the performance of the OptiMAL test at the Basic Health Units (BHUs) and the District Health Quarter (DHQ) Center in rural villages of Punjab, Pakistan that provide minimal health services. Two sets of blood specimens obtained from 930 suspected malaria patients attending these BHUs were tested at BHUs and the DHQ Center by microscopy and the OptiMAL test. At the BHUs, 231 (25%) of the patients were positive by microscopy and 278 (30%) patients tested positive by the OptiMAL test. At the DHQ Center, microscopic analysis of a second set of specimens from the same patients confirmed the malaria infection in 386 (42%) patients and the OptiMAL test result was positive in 300 (32%) patients. To determine the performance of OptiMAL test at the BHUs and the DHQ Center, all data were compared with microscopy results obtained at the DHQ Center. The OptiMAL test results for P. falciparum at the BHUs were comparable to those of the OptiMAL test at the DHQ Center. However, the sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of the OptiMAL test were considerably lower for P. vivax infections than for P. falciparum infections, irrespective of whether the test was performed at the BHUs or at the DHQ Center (P. falciparum: sensitivity = 78-85%, PPV = 89-97%, NPV = 96-98%; P. vivax: sensitivity = 61-76%, PPV = 88-95%, NPV = 90-93%). The OptiMAL test also detected a number of false-positive and false-negative results at both the BHUs and the DHQ Center. The false-positive results ranged from 1% to 2%; however, the number of false-negative results was much higher (BHUs: P. falciparum = 22%, P. vivax = 39%; DHQ Center: P. falciparum = 15%, P. vivax = 24%). In conclusion, these results, when combined with other advantages of the OptiMAL test, suggest that this test can be used by relatively inexperienced persons to diagnose malaria infection in rural areas where facilities for microscopy are not available.     

The reliability of diagnostic techniques in the diagnosis and management of malaria in the absence of a gold standard

The accuracy of techniques for the diagnosis of malaria are usually compared with optical microscopy, which is considered to be a gold standard. However, microscopy is prone to error and therefore makes it difficult to assess the reliability of other diagnostic techniques. We did a systematic review to assess the specificity and sensitivity of diagnostic techniques in different settings, using a statistical method that avoided defining a gold standard. Performance varied depending on species of the malaria parasite, level of parasitaemia, and immunity. Overall, histidine-rich protein 2 (HRP2)-based dipsticks showed a high sensitivity (92.7%) and specificity (99.2%) for Plasmodium falciparum in endemic areas. The acridine orange test was more sensitive (97.1%) in detecting P falciparum in epidemiological studies, with a specificity of 97.9%. In the absence of a gold standard, HRP2 dipsticks and acridine orange could provide an alternative for detecting falciparum infections in endemic areas and epidemiological studies, respectively. Microscopy still remains more reliable in detecting non-falciparum infections.     

Evaluation of the Binax NOW ICT test versus polymerase chain reaction and microscopy for the detection of malaria in returned travelers

Microscopic detection of Plasmodium species has been the reference standard for the diagnosis of malaria for more than a century. However, maintaining a sufficient level of expertise in microscopic diagnosis can be challenging, particularly in non-endemic countries. The objective of this study was to compare a new rapid malaria diagnostic device (NOW ICT Malaria Test; Binax, Inc., Portland, ME) to polymerase chain reaction (PCR) and expert microscopy for the diagnosis of malaria in 256 febrile returned travelers. Compared with PCR, the NOW ICT test showed a sensitivity of 94% for the detection of P. falciparum malaria (96% for pure P. falciparum infection) and 84% for non-P. falciparum infections (87% for pure P. vivax infections and 62% for pure P. ovale and P. malariae infections), with an overall specificity of 99%. The Binax NOW ICT may represent a useful adjunct for the diagnosis of P. falciparum and P. vivax malaria in febrile returned travelers.     

Efficiency and specificity of the KAT-test for rapid diagnosis of falciparum malaria

A new rapid KAT Quick Malaria test for the diagnosis of falciparum malaria, which is based on the detection of a monoclonal antibody-antigen complex of malaria parasites, has been worked out by the KAT Medical CC in South Africa. The efficiency and specificity of the KAT test were compared with those of the microscopic method and with the ICT test for rapid diagnosis of P. falciparum and P. vivax. The polymerase chain reaction was used as a control test. Testing for malaria was performed on 98 blood samples from feverish patients in Vietnam and Tadjikistan and among the persons who had returned to Moscow from endemic regions. The efficiency of the KAT test for falciparum-malaria was found to be 100% versus 90.5% with ICT. The absence of cross-reactions with P. vivax and the presence of pseudopositive results of the KAT test for fever cases of non-malaria origin indicate its high specificity. There was no correlation between the rate of test line colouring and the level of parasitemia. The KAT test yielded positive results only when gametocytes were found in blood specimens.     

PCR-ELISA检测疟原虫DNA的研究

目的：介绍一种诊断疟疾的新方法ＰＣＲ－ＥＬＩＳＡ。方法：根据业已报道的疟原虫ＳＳＵｒ－ＲＮＡ基因保守序列，设计并合成一对通用于恶性疟原虫和间日疟原虫的引物，其中一引物的５’端加以生物素标记。经ＰＣＲ扩增后，携带有生物素的扩增产物与先期包被于ＥＬＩＳＡ板上的亲和素结合，再经与恶性疟原虫、间日疟原虫特异、荧光素标记的寡核苷酸探针分别杂交，底物显色等步骤，使ＰＣＲ产物得以半定量地检出。结果：对于恶性疟原虫和间日疟原虫，本法检出最低原虫密度阈值分别为４和１０个原虫／μｌ血（取血２０μｌ），本法检测两种疟原虫未发现交叉反应。结论：本试验具有较高的敏感度和特异性，可望用于疟疾流行病学调查     

Comparison of the OptiMAL rapid antigen test with field microscopy for the detection of Plasmodium vivax and P. falciparum: considerations for the application of the rapid test in Afghanistan

To establish the sensitivity and specificity of a batch of 'OptiMAL 48' rapid antigen tests procured by the World Health Organization in Afghanistan, a sample was tested, in parallel with routine, microscopical diagnosis, at basic health units (BHU) within Afghan refugee camps in Pakistan. The results of both methods of field diagnosis were compared with those of cross-checking microscopy at a reference laboratory, which were taken as the 'gold standard'. Out of 499 patients examined, 36% were diagnosed as malaria cases by field microscopy and 34% by the rapid test. For the OptiMAL 48 test, cross-checking of the corresponding smears at the reference laboratory gave a sensitivity of 79.3% and a specificity of 99.7% for Plasmodium falciparum and corresponding values of 86.1% and 98.7% for P. vivax infections. The performance of the field microscopy was better, with a sensitivity and specificity of 85.2% and 99.7% for P. falciparum, and 90.4% and 98.7% for P. vivax, respectively. These results show that the performance of OptiMAL 48 is adequate for acute- and post-emergency situations when the alternative is just clinical diagnosis. However, in the developing health system of Afghanistan, the main focus should be on the expansion of the existing network for microscopical diagnosis and quality control, to meet the needs of a stable situation. Rapid antigen tests are more suited to investigations of outbreaks in remote situations, where health services are deficient or absent.     

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.     

Evaluation of quantitative buffy coat (QBC) assay and polymerase chain reaction (PCR) for diagnosis of malaria

A prospective study was undertaken to compare the Polymerase Chain Reaction (PCR) and Quantitative Buffy Coat (QBC) assay with conventional Giemsa technique for diagnosis of malaria. A total of 104 samples were taken for the purpose. They comprised of fever cases suggestive of malaria (n=74) and control group, fever cases other than malaria (n=30). Peripheral blood smears were prepared by Giemsa staining and QBC assay was performed as per standard protocol. From the stored blood samples, parasite DNA was extracted and PCR was performed using P. falciparum and P. vivax specific sets of primers. The QBC assay was 100% in agreement with the Giemsa stain. Specificity of the PCR detection of P. falciparum parasites was 100%. However, sensitivity for detection of P. falciparum and P. vivax by PCR was 64.28% and 82.35% respectively. In mixed cases of malaria (n=2), PCR results were in 100% agreement with that of Giemsa. The lower sensitivity of PCR for P. falciparum could probably be due to inaccessibility of target DNA, presence of PCR inhibitors in samples and parasite strain variations.