On March 23, 2018, the Ministry of Health and Family Welfare, Government of India, has, in public interest, prohibited the use of the Antibody Detecting Rapid Diagnostic Tests (ADRDT) for routine diagnosis of malaria with immediate effect. Through a gazette notification S.O. 1352(E), the ministry has informed, in exercise of the powers conferred by section 26A of the Drugs and Cosmetic Act, 1940 (23 of 1940), the Central Government prohibits the manufacture for sale, sale and distribution of the test kits used in 'Antibody Detecting Rapid Diagnostic Tests for routine diagnosis of malaria' with immediate effect.
Earlier, the matter was examined by an Expert Committee appointed by the Central Government, which recommended that the said drug was found to have no therapeutic justification. Now the Central Government is satisfied that it is necessary and expedient in public interest, to prohibit the use of the ADRDTs for routine diagnosis of malaria; therefore, it prohibits the manufacture for sale, sale and distribution of the test kits used in 'Antibody Detecting Rapid Diagnostic Tests for routine diagnosis of malaria'. It has been found that there is a rampant use of Antibody Detecting Rapid Diagnostic Tests due to low cost and free availability of these tests. But this test raises the rate of, false positive tests very high in the endemic areas, as patients with fever due to other reasons, who test negative by antigen detection, test positive by ADRDTs.
The ministry has also indicated that the use of ADRDTs is not the solution to diagnose malaria. This is because serological testing is not practical for routine diagnosis of an acute parasite infectious disease going by the time required for development of antibody. The reason to issue the guidance banning the use of ADRDTs is the persistence of antibodies even after clearance of an active infection. The government's expert committee sees that serology does not detect current infection but measures past exposure. Malaria antibody detection is performed using the indirect fluorescent antibody test for a patient who is infected with plasmodium. Because of the time required for development of antibody and, also the persistence of antibodies, serological testing is not practical for routine diagnosis of acute malaria, stated the government vide notification issued on March 23, 20188.
The notification also states that the only tests used in diagnosis are Antigen Detecting Rapid Diagnostic Tests and blood smear examination, and, therefore, there would not be any problems faced for malaria diagnosis by banning the Antibody Detecting Rapid Diagnostic Test.
About Malaria Rapid Diagnostic Tests
According to the World Health Organization (WHO), Malaria rapid diagnostic tests (RDTs) assist in the diagnosis of malaria by providing evidence of the presence of malaria parasites in human blood. RDTs are an alternative to make diagnosis based on clinical grounds or microscopy, particularly where good quality microscopy services cannot be readily provided. Variations occur between products such as targets and formats, though the principles of the tests are similar. Malaria RDTs detect specific antigens (proteins) produced by malaria parasites in the blood of infected individuals. Some RDTs can detect only one species (Plasmodium falciparum) while others detect multiple species (P. vivax, P. malariae and P. ovale). Blood for the test is commonly obtained from a finger-prick.
RDTs are lateral flow immuno-chromatographic antigen-detection tests, which rely on the capture of dye-labeled antibodies to produce a visible band on a strip of nitro-cellulose, often encased in plastic housing, referred to as cassettes. With malaria RDTs, the dye-labeled antibody first binds to a parasite antigen, and the resultant complex is captured on the strip by a band of bound antibody, forming a visible line (T - test line) in the results window. A control line (C- control line) gives information on the integrity of the antibody-dye conjugate but does not confirm the ability to detect parasite antigen9.
Typical Rapid Diagnostic Tests Cassette
Inside the cassette is a strip made of filter paper and nitrocellulose. Typically, a drop of blood is added to the RDT through one hole (A; sample well), and then a number of drops of buffer usually through another hole (B; buffer well). Buffer carries the blood along the length of the RDT.
Conclusion:
The government's decision to prohibit the use of Antibody Detecting Rapid Diagnostic Tests for routine diagnosis of malaria is in wider public interest owing to various reasons like rampant usage of these kits due to factors like their low cost and easy availability leading to a lot of false positive results for many patients.
Footnotes
8. http://www.cdsco.nic.in/writereaddata/S_O_1352(E)%20dated%2023_03_2018.pdf
9. http://www.who.int/malaria/areas/diagnosis/rapid-diagnostic-tests/about-rdt/en/
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