‘Dipstick test’ for rapid diagnosis of Plasmodium falciparum is based on:-
**Core Concept**
The dipstick test for Plasmodium falciparum relies on detecting the presence of a specific antigen in the patient's blood, which is indicative of malaria infection. This test is a rapid diagnostic tool used to identify P. falciparum in resource-limited settings.
**Why the Correct Answer is Right**
The correct answer is based on the detection of Histidine-Rich Protein 2 (HRP2), a protein produced by P. falciparum parasites. HRP2 is released into the bloodstream and can be detected using a rapid diagnostic test (RDT). The RDT typically involves a dipstick or cassette format, where a sample of blood is applied to the device, and a colored line appears if HRP2 is present. This test is highly specific for P. falciparum and is widely used in field settings due to its simplicity and rapid results.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because HRP2 is specific to P. falciparum, and other Plasmodium species produce different antigens. While some tests may detect other antigens, HRP2 is the primary target for P. falciparum diagnosis.
**Option B:** This option is incorrect because the rapid diagnostic test for P. falciparum is not based on detecting lactate dehydrogenase (LDH). LDH is an enzyme found in various cells and is not specific to P. falciparum.
**Option C:** This option is incorrect because the rapid diagnostic test for P. falciparum is not based on detecting aldolase. Aldolase is an enzyme involved in glycolysis and is not specific to P. falciparum.
**Option D:** This option is incorrect because the rapid diagnostic test for P. falciparum is not based on detecting antigens from Plasmodium vivax. While P. vivax also produces antigens, the test is designed to detect HRP2 from P. falciparum.
**Clinical Pearl / High-Yield Fact**
It's essential to note that the HRP2-based RDT has some limitations, such as false-positive results due to cross-reactivity with other substances or the presence of HRP2 in the blood after treatment. Therefore, a negative result does not rule out malaria, and a confirmatory test may be necessary.
**Correct Answer: B. HRP2**