**7.1. Materials and methods**

170 Dehydrogenases

most preferred and reliable diagnosis using two types of blood films, which is amenable to the four species of malaria parasite. These two types of films are (a) the thin blood film which is similar to the usual blood films, which allows species to be identified because they can be visualized and the appearance of the parasites are much more distorted.(b)the thick film from which an experienced microscopist can detect parasite levels or parasitemia down to levels as low as 0.0000001% of red blood cells. Diagnosis of species can be difficult because, the early trophozoites ("ring form") of all four species look identical and never possible to diagnose the species on the basis of simple ring form. The success of the method above requires well trained staff, quality equipment and supervision. The scarcity of these facilities within malaria endemic areas becomes limiting. In sub-Saharan Africa and some other areas, clinicians often have to rely on clinical signs and symptoms for diagnosis and in some areas where increasing emphasis is laid on home based management , malaria diagnosis is often equated[11] with fever. It is to be noted that such presumptive treatment without laboratory confirmation could contribute to the development of drug resistance[11]. Today, an alternative method to the blood film diagnosis approach is the rapid diagnostic test (RDTs), recommended by WHO, where reliable microscopy is not reliable or available. Rapid diagnostic tests (RDTs) are antigen detection tests, which are simple to use and interpret, although the tests also use peripheral blood. The most commonly used RDTs, is the histidinerich protein 2 (HRP 2), produced by trophozoites and young gametocytes of plasmodium falciparum. HRP 2 test has been the most widely evaluated to date test, and has shown consistently high sensitivity. The limitation of this test is that RDTs detect P. falciparum only and can remain positive for several weeks after antimalarial treatment. Besides these, a study to assess the diagnostic capabilities of three parasite lactate dehydrogenase (pan- LDH)- ,Vistapan® ,Carestat™ and Parabank® were conducted in Uganda. Similarly, a histidine- rich protein 2 (HPR 2) test, Paracheck-Pf® and a Geimsa-stained blood film were performed with pfLDH tests for outpatients. A total of 460 patients were recruited for the exercise, 248 had positive blood films and 212 with negative blood films. *Plasmodium falciparum* was present in 95% of infections. Sensitivity of the tests above 90% was shown by two pLDH tests-Carestart (96.5%) and Vistapan (91.9%) and sensitivity above 90% by Parabank (94.3%) and Carestart (91.5%). The benefits of these tests when compared with the previous gold standard for laboratory confirmation of malaria diagnosis which is a peripheral blood film examined

microscopically shows the high specificity and validity of the tests.

An alternative diagnostic method to the rapid diagnostic test (RTD), recommended by WHO, where reliable microscopy is not available. RTDs are antigen detection tests, which are simple to use and interpret and also use peripheral blood. The most commonly used RTD detects histidine -rich protein 2 (HRP2), produced by trophozoites and young gametocytes of *Plasmodium falciparum*. HRP 2 tests have been the most widely evaluated to date and show high sensitivity. However, they are limited in that they detect P. falciparum

The second type of RTD detects the malaria antigen parasite lactate dehydrogenase (pLDH), an enzyme produced in the glycolytic cycle of the asexual stage of all species of Plasmodium. Parasite lactate dehydrogenase( pLDH) are produced only by viable parasites,

only and can remain positive for several weeks after successful treatment[12,13].

The first approach is to select a site, which should be a highly malarial infested zone.
