Field evaluation of the ICT Malaria Pf/Pv immunochromatographic test for the detection of asymptomatic malaria in a Plasmodium falciparum/vivax endemic area in Thailand.

Abstract

Abstract. Rapid antigen assays provide an effective tool for the detection of malaria in symptomatic patients. However, the efficacy of these devices for detecting asymptomatic malaria, where parasite levels are normally significantly lower than in symptomatic patients, is less well established. We evaluated the efficacy of a new combined Plasmodium falciparum-Plasmodim vivax immunochromatographic test (ICT Malaria Pf/Pv) in a cross-sectional malaria survey of the village of Ban Kong Mong Tha, Kanchanaburi Provice, Thailand, from August to December 2000. A total of 1,976 bleeds were made from 559 individuals over the course of the study. Blinded microscopy of thick and thin blood films was used as the gold standard; all discordant and 10% of concordant results were cross-checked. Of 1,976 ICT Malaria Pf/Pv dipsticks tested, 98.3% (n ‫ס‬ 1,943) performed as expected, as evidenced by the appearance of the control line. The ICT Malaria Pf/Pv test was both sensitive (100.0%) and specific (99.7 %) for the diagnosis of falciparum malaria with parasitemias of Ն 500 trophozoites/L; however, only 15.9% (13/82) of infected individuals had parasitemia rates this high. When P. falciparum parasitemia rates were < 500/L, the sensitivity of the diagnosis was only 23.3%, with a positive predictive value (PPV) and a negative predictive value (NPV) of 76.2 and 97.2%, respectively. The ICT Malaria Pf/Pv test was specific, but not sensitive, for the diagnosis of vivax malaria with parasite rates of Ն 500 trophozoites/l, with sensitivity, specificity, PPV, and NPV of 66.7%, 99.9%, 66.7%, and 99.9%, respectively. At parasite rates of < 500/L, corresponding values were 0.0%, 99.9%, 0%, and 95.1%. Because of the relatively high cost of these assays, low parasite rates found in the majority of asymptomatic individuals, and low sensitivity of this assay with rates of < 500/l, use of this assay as a tool for active case detection is of limited value in western Thailand.

An investigation on the prevalence and efficiency of immunochromatographic testing in suspected malarial patients of Rawalpindi and Islamabad, Pakistan

“…These results are in accordance with the findings of previous researchers (16)(17)(18)(19)(20)(21)(22)(23). The widely reported accuracy of the ICT in diagnosing both P. falciparum and P. vivax, with the added advantage of it being a rapid test, makes the value of the ICT in making on-the-spot diagnoses significant.…”

Comparison of the diagnosis of malaria by microscopy, immunochromatography and PCR in endemic areas of Venezuela

“…The OptiMAL test shows sensitivity similar to those reported for other dipsticks, such as ParaSight and ICT Malaria Pf/Pv, which ranged from 86-100 and 58-96%, respectively (3,20,(28)(29)(30)(31)(32)(33) Coleman et al (35) evaluated the efficacy of the ICT Malaria Pf/Pv in a large study of 559 asymptomatic patients from an endemic area of Thailand using conventional microscopy as the reference method, and found that the sensitivity for P. falciparum dropped from 100 to 23.3% when the parasitemia was below 500 trophozoites/µL. For P. vivax infections, the sensitivity dropped from 66.7% to 0 at parasitemia below 500 trophozoites/µL.…”

Evaluation of Two Nested PCR-Based Diagnostic Assays for Plasmodium Falciparum Infection

“…Nested PCR of protocol A showed that it is useful for detecting asymptomatic infection, which is difficult to detect by microscopy because of low parasitemia [26].…”