**2. Measurement of parasite lactate dehydrogenase (pLDH) activity of plasmodium falciparum**

Malaria is the most lethal parasitic disease in the world, annually affecting approximately 500 million people and resulting in 800,000 deaths, mostly in Africa and Sub-Saharan countries [1]. Some countries, for example Brazil registered more than 306,000 deaths in 2009, most of which were in the Amazonian region [2]. In Africa, the figures may be higher due to endemic nature of the infection. Transmission occurs through the bite of the female anopheles mosquitoes infected with the parasite of which there are five species affecting humans. Plasmodium falciparum is the most pathogenic species and may cause severe malaria and death in non-immune individuals, especially children under five years [3].Drug resistant malaria parasites have emerged and has resulted in treatment failures. This resistance might be as a result of mutation at the active sites of drug targets or from biochemical changes in the drug receptors [4].

Plasmodium falciparum is a significant cause of morbidity and mortality in travelers to areas where the parasite is endemic. Non –specific manifestations may equally result in failure to recognize malaria until autopsy, when it is often too late to obtain blood for microscopic evaluation, which has been in use for years for the diagnosis of malarial parasitemia. The Plasmodium falciparum lactate enzyme (pLDH) has been considered, a potential molecular target for antimalarials. This is an enzyme assay for the detection of Plasmodium falciparum, employed in the assessment of malarial parasitism. The enzyme assay is based on the observation that Lactate dehydrogenase(LDH) enzyme of *P. falciparum* has the ability to rapidly use 3-acetylpyridine dinucleotide(APAD) as a co-enzyme instead of NAD in the reaction leading to the formation of pyruvate from lactate. Human red blood cells' LDH carries out this reaction at very low rate in the presence of APAD. The measured development of APADH leads to the formation of a product that could establish the basis of an assay that detects the presence of *P. falciparum* from *in vitro* cultures at parasitemic levels of 0.02 %. Lactate dehydrogenase is the most abundant enzyme expressed by *P. falciparum.*

A correlation between levels of parasitemia and the activity of parasite LDH from patients with malaria is worthwhile. The serum assay for PLDH is followed up to monitor the level of PLDH in a patient with cerebral malaria prior to antimalarial therapy and also during recovery period. It is evident that measurement of pLDH has a strong correlation with malarial parasitemia and can follow a method that can be developed into a simple test for the detection of *Plasmodium falciparum* as an assessment of plasmodium parasitemia. In malarial falciparum parasitemia, LDH does not persist in blood, but clears about the time as the parasite, following successful treatment. The lack of antigen persistence after treatment makes the pLDH test useful in predicting treatment failure. In this respect, pLDH is similar to pGluDH. LDH for *P.vivax*, *P.ovale*, and *P. malariae* exhibit 90-92% identity to pLDH *from P. falciparum.*

166 Dehydrogenases

**plasmodium falciparum** 

biochemical changes in the drug receptors [4].

Type composition Location

LDH1 HHHH Found in the heart and red blood cells

LDH2 HHHM Found in the heart and red blood cells

LDH4 HMMM Found in a variety of organs and is 3%-

LDH5 MMMM Found in liver and skeletal muscles and

**2. Measurement of parasite lactate dehydrogenase (pLDH) activity of** 

Malaria is the most lethal parasitic disease in the world, annually affecting approximately 500 million people and resulting in 800,000 deaths, mostly in Africa and Sub-Saharan countries [1]. Some countries, for example Brazil registered more than 306,000 deaths in 2009, most of which were in the Amazonian region [2]. In Africa, the figures may be higher due to endemic nature of the infection. Transmission occurs through the bite of the female anopheles mosquitoes infected with the parasite of which there are five species affecting humans. Plasmodium falciparum is the most pathogenic species and may cause severe malaria and death in non-immune individuals, especially children under five years [3].Drug resistant malaria parasites have emerged and has resulted in treatment failures. This resistance might be as a result of mutation at the active sites of drug targets or from

Plasmodium falciparum is a significant cause of morbidity and mortality in travelers to areas where the parasite is endemic. Non –specific manifestations may equally result in failure to recognize malaria until autopsy, when it is often too late to obtain blood for microscopic evaluation, which has been in use for years for the diagnosis of malarial parasitemia. The Plasmodium falciparum lactate enzyme (pLDH) has been considered, a potential molecular target for antimalarials. This is an enzyme assay for the detection of Plasmodium falciparum, employed in the assessment of malarial parasitism. The enzyme assay is based on the observation that Lactate dehydrogenase(LDH) enzyme of *P. falciparum* has the ability to rapidly use 3-acetylpyridine dinucleotide(APAD) as a co-enzyme instead of NAD in the reaction leading to the formation of pyruvate from lactate. Human red blood cells' LDH carries out this reaction at very low rate in the presence of APAD. The measured development of APADH leads to the formation of a product that could establish the basis of an assay that detects the presence of *P. falciparum* from *in vitro* cultures at parasitemic levels of 0.02 %. Lactate dehydrogenase is the most abundant enzyme expressed by *P. falciparum.*

**Table 1.** Subunit compositions and major locations of Lactate Dehydrogease Isoforms

LDH3 HHMM Found in a variety of organs and is

level.

and Is 17%-27% of the normal serum

and 27%-37% of the normal serum level

18%-25% of the normal serum level.

is 0%-5% Of the normal serum level.

8% of the normal serum level.
