Evaluation of the polymerase chain reaction analysis for diagnosis of falciparum malaria in Delhi, India

Abstract

Plasmodium falciparum infections are frequently fatal if untreated and hence need to be diagnosed and treated early. Malaria diagnosis, with conventional Giemsa staining as a gold standard, has had several limitations. New rapid and accurate methods are needed for diagnosis. In this study, polymerase chain reaction (PCR) analysis specific for diagnosis of P. falciparum was evaluated. For the study, blood samples were collected from 310 patients suspected of having malaria. PCR analysis for P. falciparum from venous blood and at the same time Giemsa staining of thick and thin blood smears was done. A total of 160 (51.6 %) samples were positive for malarial parasite of which 63 (39.4 %) were positive for P. falciparum by Giemsa staining while 61 (38.1 %) were positive for P. falciparum by PCR analysis. Giemsa staining was time consuming, laborious and may give poor results in cases with low parasitaemia. The PCR analysis for P. falciparum was able to detect 3 cases of low parasitaemia missed initially on Giemsa staining, was 96.8 % sensitive, 100% specific but was very costly, needed a lot of practice and standardization and was time consuming. PCR analysis can be used to supplement the conventional Giemsa staining for reliable diagnosis of falciparum malaria especially in cases with low parasitaemia.

A comparative laboratory diagnosis of malaria: microscopy versus rapid diagnostic test kits

“…The introduction of high-cost antimalarial drugs such as ACT is encouraging in malariaendemic countries in sub-Saharan Africa to reassess diagnostic practices [3] . This drive to have rapid and accurate method of malaria diagnosis led Nandwani et al [2] to carry out a comparative malaria detection between polymerase chain (PCR) reaction and microscopy on 100 Indian patients. They found the PCR method to be 96.8% sensitive but took about [10][11] h to complete whereas microscopy took an average of 40-45 min.…”

“…In capable hands it is very sensitive for parasitaemia 曑50/毺L (0.001%) [2] and it can give important information to the clinician like species, parasites stages and parasite density. However, good quality of microscopy is difficult to implement and maintain.…”

“…Of all the human malaria parasites Plasmodium falciparum (P. falciparum) is the most pathogenic and is frequently fatal if untreated in time [2] . In India, according to Nandwani [2] a total of 1.82 million cases of malaria and 0.89 million cases of P. falciparum cases with 902 death were reported in the year 2002. Traditional practice for outpatients has been to treat presumptively for malaria based on a history of fever but, a significant proportion of those treated may not have parasites (over 50% in many settings) and hence waste a considerable amount of drugs [3] . This old clinical based practice is still relevant today especially, in infants where time spent on getting a confirmatory laboratory diagnosis could lead to increased fatality.…”

“…Thus microscopy in Africa is generally, limited to larger clinics/tertiary centers. This conventional staining of peripheral blood smears/microscopy however still remains the gold standard in laboratory diagnosis of malaria [2] .…”

Rapid Diagnosis of Malaria by Antigen Detection

“…3 Several laboratory procedures such as different types of microscopy, immunological methods for antigen and antibody detection, polymerase chain reaction, species-specific DNA probe and ribosomal RNA probe have been developed. 4 Among the methods, fluorescence microscopy and molecular techniques are highly sensitive (99.5%) and specific (100%) but needs considerable amount of practice with costly equipments. 4,5 The most widely used approach to confirmatory diagnosis of malaria is demonstration of Plasmodium species by microscopic examination of thick and thin films.…”