Diagnosis of malaria

Background: Malaria diagnosis depending on clinical conditions is often unreliable due to the inconsistent
signs and symptoms of malaria, leading to over-diagnosis and over-treatment. Correct diagnosis is important
for effective management of malaria cases and to reduce wastage
of costly drugs.
Objective: This study was conducted to detect malaria infection in patients complaining of fever of unknown
origin, highly suspected clinically to be due to malaria. OptiMAL rapid antigen test and polymerase chain
reaction (PCR) were used in comparison with microscopy.
Subjects, Material and Methods: A total of 120 expatriate patients attending King Faisal specialized
hospital, Taif, KSA, complaining of fever of unknown origin were screened for malaria parasites by
microscopy of Giemsa-stained blood smears, OptiMAL rapid antigen test and genus specific PCR. The
diagnostic performance of these methods was statistically compared.
Results: Out of 120 clinically suspected cases, 54 (45%) were positive for Plasmodium infection by using
microscopy, and of these 45 (83.3%) were infected by P. vivax, 6 (11.1%) by P. falciparum, 1 (1.9%) by P.
malariae and 2 (3.7%) were mixed infections (P. vivax and P. falciparum). Correspondingly, OptiMAL test
and PCR detected malaria infection in 51(42.5%), and 56(46.7%) patients respectively. The differences in
detection rates of these diagnostic tests were not statistically significant (P>0.05). Using direct microscopy
as gold standard, OptiMAL test showed 5 false-positive samples that were negative by microscopy and 8
false-negative samples that were positive by microscopy. At the same time, PCR showed 3 false-positive and
one false-negative results. PCR showed a higher sensitivity (98.1%), specificity (95.5%), positive predictive
value (94.6%), negative predictive value (98.4%) and diagnostic accuracy (96.6%) than OptiMAL test
(85.1%, 92.4%, 90.1%, 88.4%, 89.1%, respectively).
Conclusion: Consideration of fever alone as a presumptive prompt diagnosis for anti-malarial treatment
would result in huge over-treatment. The use of OptiMAL test and/or PCR assay is a valuable complement
to microscopy because these methods help expand the coverage of parasite-based diagnosis and minimize
exclusive clinical diagnosis.

Malaria diagnosis is one of the greatest challenges of public health. This is usually done by the identification of the malarial parasite or its antigen or product in the blood of the patient. The present study was conducted to evaluate the efficacy of Rapid Malarial Antigen Detection test (RDT) by comparing with routine microscopy using Giemsa stained thick and thin blood films as gold standard for diagnosis. The prospective study was conducted over a period of one year with 700 patients who were selected based on clinical evaluation. Peripheral smear examination and RDT was done in these cases. 662/700 cases were malaria positive, out of which 455 were P. vivax,138 were mixed infection and 69 were P. falciparum. Overall RDT was 100% sensitive, 92.11% specific with positive predictive value (PPV) of 99.55% and negative predictive value of 100%.Even though RDTs are expensive, they definitely are an important tool in diagnosing malaria when rapid diagnosis and lack of trained personnel and infrastructure (rural areas) are present. But still it will not be able to replace microscopy which will remain the gold standard for malaria diagnosis.

Background: Malaria diagnosis depending on clinical conditions is often unreliable due to the inconsistent signs and symptoms of malaria, leading to over-diagnosis and over-treatment. Correct diagnosis is important for effective management of malaria cases and to reduce wastage of costly drugs. Objective: This study was conducted to detect malaria infection in patients complaining of fever of unknown origin, highly suspected clinically to be due to malaria. OptiMAL rapid antigen test and polymerase chain reaction (PCR) were used in comparison with microscopy. Subjects, Material and Methods: A total of 120 expatriate patients attending King Faisal specialized hospital, Taif, KSA, complaining of fever of unknown origin were screened for malaria parasites by microscopy of Giemsa-stained blood smears, OptiMAL rapid antigen test and genus specific PCR. The diagnostic performance of these methods was statistically compared. Results: Out of 120 clinically suspected cases, 54 (45%) were pos...