LABORATORY DIAGNOSIS OF MALARIA – RECENT REVIEW

Malaria must be recognized promptly in order to treat the patient in time and prevent further   spreading of infection in the community.   It should be considered as a potential medical emergency   and should  be treated accordingly,  delay in diagnosis and treatment is a leading  cause of death in malaria patient. Malaria can be suspected based on the patients symptoms and physical findings at  examination . However for  definitive diagnosis to be made laboratory test must be  demonstrated to confirm malaria parasites or  components . The  first symptom  of malaria   (most   often fever, chills, sweat, headaches,  muscle pains , nausea and vomiting) are   often not specific and can be found in  other diseases  ( such as  ‘Flu’  and common  viral infections ) like  wise, the physical finding are  often not specifically  elevated temperature, perspiration,   tiredness ). In
severe  malaria (caused by p falciparum ) clinical  findings (include  confusion, coma, neurologic  focal signs, severe anaemia and respiratory  difficulties ) are more  striking and may increase  the  suspicion index   for malaria.  Thus, in most cases   the early clinical findings in malaria are not typical and need to be confirmed by a laboratory test. The diagnosis of malaria is  confirmed by  the blood test and can be divided into microscopic and non-microscopic or macroscopic tests (Cheesbrough 2002)

MICROSCOPIC TEST

For nearly hundred years,  the direct  microscopic visualization of the parasite on thick  or thin blood  smears has been the accepted  method for the diagnosis  of malaria in  most setting  from of clinical hematology  laboratory to the field surveys. The careful examination of a well prepared and well  stained blood film currently  remains the  Gold  Standard for  malaria diagnosis. Microscopic test involve staining and direct visualization of  the parasite under microscope. during  staining of blood  film, hemoglobin  in the erythrocytes dissolve  (dehaemoglobinization) and is removed by water in  these staining solution leaving the parasite and the leucocytes  to be seen under the microscope 

NON-MICROSCOPIC /MACROSCOPIC TEST

This involves the test that detect parasite antigen and anti plasmodial antibodies  or the  parasite metabolic  products. Nucleic acid  probes and immune fluorescence for the  detection  plasmodia   with  the erythrocytes  get diffusion, counter immune electrophoresis, radioimmune assay and enzyme  immunoassay  for malaria antigens in the body fluids  and haemagglutination test  western  blotting for  antiplasmodia antibodies in the  serum have all been developed. The rapid diagnostic test  (RDTS ) detect species specific  circulating parasite antigens targeting  either the  Histidine Rich Protein  2 (HRP 2)  of p. falciparum it also detect parasite species. Specific lactate dehydrogenate (PLDH) enzyme and aldolase enzyme (Cheesbrought   2005). 

Although the dipstick test may enhance diagnostic   speed, microscopic examination  remain mandatory in patients with  suspected malaria because occasionally dipstick tests are negative in patients  with high parastitaemia   and their   sensitivity below  100  parasite is low.   immune chromatographic test  for malaria antigen is based on the capture  of the parasite antigens  from the peripheral blood  using   either monoclonal or polyclonal antibodies against the parasite antigen targets. 

The  histidine  rich protein  to  test for p. falciparium  is a  water soluble   protein   that is produced by the a sexual  stages and young gametocyte of  p. falciparium. It is   express to remain abandonment in the surface of the red blood cell for at least 28 days after the initiation of  antimalaria therapy. Plasmodim  aldolase is an enzyme of the parasitic  glycolytic pathway express by the blood  state of p. falciparum as well as  the  none falciparum malaria parasite. 

Parasite Lactate Dehydrogenase  (PLDH) is  a soluble glycolytic enzyme produce by sexual and asexual stages of liver parasite. Test base on polymerase chain reaction (PCR) for species.  Specific plasmodium genome are more sensitive and specific than other tests.Antibody detection has no value in diagnosis of acute malaria. It is mainly use for  epidermological studies. Therefore the simplest  and  surest rest   is the time  honoured peripheral  Smear study   for malaria parasite.

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