Dr. S.A. Krishna*, Dr. A.K. Jaiswal**, Dr. Anil Kumar***
HOD, Dept of Pediatrics, NMCH, Patna.*, Asso. Professor , Dept of Pediatrics, NMCH, Patna.**, Senior Resident
Dept of Pediatrics, NMCH, Patna.***
|Malaria is an acute and chronic illness characterized by paroxysm of fever, chills, sweating, fatigue, anemia and splenomegaly.|
|Malaria is caused by intracellular Plasmodium protozoa, transmitted to human by female Anopheles mosquitoes. Four species of Plasmodium cause malaria in human beings :
- P. Falciparum
- P. Ovale
- P. Vivax
Malaria also can be transmitted by blood transfusion, use of contaminated needles, by vertical transmission from a pregnant women to her fetus.
At present about hundred countries in the world are considered malarious,almost half of which is Sub-Sahara Africa.
During 2003, about 1.65 million cases were reported with 943 deaths. Malaria has been a serious problem in North-eastern states mainly Assam, Nagaland, Tripura and West Bengal. Contributes 8.5 to 11% of total malaria cases and 13 to 15 percentage of mortality.
|Sexual form: In female Anopheles
Asexual form: In human beings
|LABORATORY DIAGNOSIS OF MALARIA|
|Various method for diagnosis of malaria can be classified as under:
- CONVENTIONAL METHODS
- NEWER TECHNIQUES
- Peripheral blood film
It is an oldest method. Two types of smear (thick and thin) are prepared from peripheral blood:
- Thick film.
- Thick smears have more quantity of blood in small area.
- Chances of detection of malaria parasites are more in thick smear.
- Since morphology of the parasite is not clear, so species identification can not be done.
- Malarial pigment is easily detected in thick film.
- The thick film concentrates the parasites up to 40-times.
- So it increases the sensitivity of diagnosis.
- Thin film.
- Level of parasitaemia and malarial species can be detected.
- Count number of RBC containing asexual parasites per 1000 RBC.
- Mild -1 to 10%.
- Serious - 10 to 20%.
- Grave - 20 to 30%.
- Exceptionally Grave - more than 30%.
- In severe malaria, stages of parasite development can be detected.
- Neutrophils containing malarial pigment can be counted.
- It provides prognostic information.
- Parasite count
- Parasite count denotes their concentration in blood at a particular point of time.
- A rough estimate of parasite concentration is as follows:
+ - 1 to 10 parasites/100 thick film field.
++ - 11 to 100 parasites/100 thick film field.
+++ - 1 to 10 parasites/thick film field.
++++ - more than 10/thick film field.
- Complete blood count
- WBC - count
- Normal or low WBC count. Elevated in severe infection.
- RBC count
- Low RBC count with decreasing Hemoglobin % Normocytic, Normochromic anemia is the rule.
- Platelets counts
- Platelet count is almost always decreased-Thrombocytopenia.
- Plasma viscosity
In severe infection - PT, PTT prolonged, thrombocytopenia is severe. CRP, CSF pressure, protein level is usually normal or elevated.
- Electrolyte level
- mild cases.
- In severe cases
- Lactic acidosis.
- Decreased plasma concentration
- Glucose, Na, HCO3, Calcium, Phosphate.
- Increased concentration
- Lactate, Blood urea nitrogen,Creatinine, Urate etc.
- FLUORESCENT MICROSCOPY
Fluorescent dye binds to parasite nucleic acids. Methods used are:
- Direct Acridine Orange staining.
- Acridine Orange stains cytoplasm orange and DNA green.
- Quantitative Buffy Coat (QBC) Technique
- In this method, due stains DNA green and RNA orange.
- BPC(Benzothiocarboxypurine) method.
- IMMUNOLOGICAL METHODS
- Antibody detection
- Immunofluorescent Antibody absorption test (IFAT) - The main method for routine diagnosis.
- ELISA Test.
- Latex agglutination test.
- Solid phase dipstick and membrane dot blot.
- Antigen detection
- Based on the detection of circulating antigen specific for P. Falciparum in whole blood.
- PfHRP-II deep stick or ICT, Immunochromatographic card test
- This test utilizes affinity to purified sheep polyclonal antibody specific for P. Falciparum circulating antigen PfHRP-II.
- A drop of blood is placed on stick 01 card.
- Monoclonal antibodies captures the parasite antigen and read out as a colored band.
- Rapid, sensitivity is 0.001% parasitemia.
- Plasmodium LDH dipstick or card test
- A drop of blood is placed on stick or card.
- Monoclonal antibodies capture the parasite and read out a colored bands.
- Two bands-one band is genus specific and other is specific for P. Falciparum.
- Rapid, sensitivity similar to thick film up to 0.001% parasitemia.
- MOLECULAR BIOLOGICAL DETECTION TESTS
- Genetic probes.
- Two types of probes used are based on hybridization of probe DNA with genomic DNA or ribosomal RNA of parasites.
- In severe cases
- Lactic acidosis.
- Gene amplification technique or polymerase chain reaction (PCR).
- This technique is based on amplification of gene by PCR.
- More sensitive and specific than genetic probing.
- PCR is capable of detecting parasitemia of < 0.00002%.
|How to Cite URL :|
|Krishna S D, Jaiswal A D, Kumar A D.. Available From : http://www.pediatriconcall.com/fordoctor/ Conference_abstracts/report.aspx?reportid=116|