| Abstract|| |
Background and Objectives : The incidence of malaria worldwide is estimated to be 300 - 500 million cases each year, and in India about 1.5 - 2 million cases have been reported annually. This study has been conducted to identify the present scenario of malaria in the Davangere district of Karnataka, India, from April 2007 to April 2008, and to compare the available diagnostic tests for malaria. Materials and Methods: The present study was conducted at the Department of Microbiology, J. J. M. Medical College, Davangere, from April 2007 to April 2008. A total of 202 malaria suspected cases were examined. All the cases were screened by blood smear examination, both by Leishman's staining and JSB (Jaswant Singh Bhattacharji) staining, and also by the antigen detection method. Results: In our study, a total of 22 cases out of 202 suspected cases were positive for malaria, with an incidence of 10.9%. Out of them 15 (68.2%) were positive for Plasmodium falciparum, four (18.2%) were positive for Plasmodium vivax, and three (13.6%) were positive for both Plasmodium falciparum and Plasmodium vivax. The Malarigen kit detected 20 positive cases compared to the blood smear study, which detected 16 cases. Fourteen cases were detected both by the Malarigen kit and blood smear study. Six cases were positive by the Malarigen kit, but not by the blood smear study. Two cases detected to be positive by the blood smear study were found to be negative by the Malarigen kit. One hundred and eighty cases were negative both by the Malarigen kit and the blood smear study. Conclusion: The incidence of malaria in the present study is 10.9%, which is low when compared to other studies. Malaria more commonly affects the pediatric age group and males, rather than females. Light microscopy is the gold standard, but it requires considerable expertise and time for examination. In comparison, the sensitivity of Malarigen is very close to microscopy and it does not require highly skilled personnel to perform or interpret results. Therefore, Malarigen is a simple, sensitive, and effective diagnostic test for P. falciparum and P. vivax malaria.
Keywords: Blood smear, Malaria, Malarigen (pLDH)
|How to cite this article:|
Prabhu K, Lava R, Usha M G. Study of hospital based malaria cases in Davangere district of Karnataka, India. Ann Trop Med Public Health 2010;3:19-22
|How to cite this URL:|
Prabhu K, Lava R, Usha M G. Study of hospital based malaria cases in Davangere district of Karnataka, India. Ann Trop Med Public Health [serial online] 2010 [cited 2018 Aug 15];3:19-22. Available from: http://www.atmph.org/text.asp?2010/3/1/19/76179
| Introduction|| |
Malaria is a major public health problem in India. The national Vector Borne Diseases Control Program (NVBDCP) reported about 1.67 million cases of malaria (including 0.75 million P. falciparum cases) and 1487 deaths in the country, in 2006.  Malaria kills about one million children, under five years of age, each year, worldwide. 
Rapid diagnosis is a prerequisite for the initiation of effective treatment and to reduce the mortality and morbidity of malaria. Microscopic examination of blood smears remains the gold standard for the diagnosis of malaria, but it is time-consuming and requires skilled operators.  In addition, in patients with Plasmodium falciparum malaria, sometimes the parasites can be sequestered and are not present in the peripheral blood. Thus, a Plasmodium falciparum infection can be missed due to the absence of parasites in the blood smear.  A majority of malaria cases occur in rural areas where there is little or no access to reference laboratories, and in many areas where microscopy is not available.  Several methods have been developed to supplement and replace the conventional microscopic method. The most promising new malaria diagnostics are the serological dipstick tests. 
Therefore, this study was carried out to recognize the present scenario of malaria in the Davangere district of Karnataka, from April 2007 to April 2008, and to compare available diagnostic tests for malaria.
| Materials and Methods|| |
The present study was conducted at the Department of Microbiology, J. J. M. Medical College, Davangere, from April 2007 to April 2008. The suspected cases of malaria, attending the Outpatient Department and admitted as inpatients in the Chigateri General Hospital and Bapuji Hospital were included in this study. The specimens were collected from all febrile cases, clinically suspected of malaria, before starting any treatment. A total of 202 samples were examined.
Oral consent was taken from the patients prior to the collection of specimens. With all aseptic precautions, 2 ml of venous blood was collected with a sterile syringe and needle and was transferred into a sterile bottle containing EDTA (ethylene diamine tetraacetate).
- Microscopy: Thick and thin smears were prepared from the collected blood samples using the standard method. The smears were stained with (1) Leishman's stain and (2) JSB (Jaswant Singh Bhattacharji) stain. The stained smears were examined under the oil immersion field using a light microscope.
- Subsequently, the blood sample was subjected to antigen detection by using the Malarigen kit (pLDH assay) according to the manufactuer's instructions.
Detailed medical records of all those who were positive for the malarial parasite were maintained. The species of the parasite as also the stages in which the parasite were seen, were also noted. The results were tabulated and analyzed statistically.
| Results|| |
A total of 202 blood samples were tested for malaria parasites. Twenty-two cases were positive for malaria, with an incidence of 10.9%. The distribution of malaria cases among the total cases studied is shown in [Table 1]. Age-wise and sex-wise distributions of positive cases are shown in Graphs 1 and 2. The seasonal distribution of malaria positive cases is reported in [Table 2].
The Malarigen kit detected 20 positive cases compared to the blood smear study, which detected 16 cases [Table 3] and [Table 4]. Fourteen cases were detected both by the Malarigen kit and the blood smear study. Six cases were positive by the Malarigen kit, but not by the blood smear study. Two cases detected to be positive by the blood smear study were found to be negative by the Malarigen kit. One hundred and eighty cases were negative both by the Malarigen kit and the blood smear study [Table 5]. There were three cases of mixed Plasmodium falciparum and Plasmodium vivax infection detected by the blood smear study [Table 3]. In these cases the Malarigen kit gave the result as Plasmodium falciparum.
|Table 5 :Comparison of the results of the blood smear examination and the Malarigen kit|
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| Discussion|| |
The incidence of malaria worldwide is estimated to be 300 - 500 million cases each year. In India there is a consistently declining trend in the annual incidence since 1997. About 1.5 - million cases have been reported annually in India, with the majority being P. vivax cases. In this study the incidence of malaria is 10.9%, with a predominance of P. falciparum (68.2%). This is low when compared to other studies. 
Malaria affects all age groups. In our study, the highest number of positive cases is in the age group of 1 - 10 years followed by 11 - 20 years, which shows that malaria more commonly affects the pediatric age group. These findings are consistent with the previous studies.  Among 22 positive cases, 17 were males with a percentage of 77.3% as compared to females (22.7%). This can be explained by the fact that males are more frequently exposed to the risk of acquiring malaria than females, because of the outdoor life they lead.
In our study, the cases were more during August (36.4%) and July (18.2%) and was comparable to other studies.  This shows the association of malaria with rainfall. Rain in general provides opportunities for the breeding of mosquitoes and it also increases atmospheric humidity, which is necessary for the survival of mosquitoes.
Rapid diagnosis is a prerequisite for the initiation of effective treatment and to reduce the mortality and morbidity of malaria. Several methods have been developed to supplement and replace the conventional microscopic method. Most new technology for the diagnosis malaria incorporates immunochromatographic capture procedures with conjugated monoclonal antibodies. In this study we used the Malarigen rapid test and compared it with the conventional blood smear examination. Two staining methods were employed in the study - the Leishman's stain and the JSB stain. Both were found to be equally good.
In this present study, the blood smear study detected 16 positive cases. However, 20 cases were detected by the Malarigen kit. Two cases detected by the blood smear examination were not detected by the Malarigen kit. This could be explained by the fact that increased awareness of malaria among the general public has led to the rampant misuse of antimalarial drugs, in inadequate doses, empirically, for any fever. As the Malarigen kit detected pLDH, which was produced only by living parasites, the blood samples judged negative by the Malarigen kit could have been due to dead parasites that had not yet been cleared from the host.  This could also be due to insufficient enzyme production, which occurred during early malarial infection, or the patient blood samples contained parasites at concentrations below the Malarigen detection level.  Six cases identified by the Malarigen kit, were not detected by the blood smear examination. Out of the six cases four cases were Plasmodium falciparum. This could be explained by the fact that P. falciparum could sometimes sequester and might not be present in the circulating blood.  Two cases were Plasmodium vivax; those were mostly false positive cases, due to the presence of cross reacting autoantibodies like the rheumatoid factor.  There were three cases of mixed Plasmodium falciparum and Plasmodium vivax, detected by the blood smear study. In these cases, the Malarigen kit gave the result as Plasmodium falciparum. This could be expected from the configuration of the test, where Plasmodium falciparum could react with both monoclonal antibodies on the strip and this might potentially mask another species in a mixed infection. However, this represented a clinical advantage, as it avoided missing Plasmodium falciparum.
In this study the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic efficiency of the Malarigen kit, when compared to microscopy, were 87.5, 96.8,70, 98.9, and 96%, respectively. These findings were consistent with other studies. ,,
This evaluation has shown that Malarigen is a simple, sensitive, and effective diagnostic test for Plasmodium falciparum and Plasmodium vivax. Light microscopy is the gold standard, but it requires considerable expertise and time for examination, especially in patients with low parasitemia. In comparison, the sensitivity of Malarigen is very close to the microscopic examination of blood smears, but does not require highly skilled personnel to perform or interpret results. Therefore, it is a good alternative to microscopy for malaria diagnosis. The disadvantage of Malarigen is its high cost, which may not be affordable by many. However, it is a valuable adjunct at the time of emergency, for a rapid diagnosis, although microscopy still remains the mainstay for the diagnosis of malaria, for routine use, in countries like India.
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Department of Microbiology, Yenepoya Medical College, Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]