TABLE 1.
Characteristics associated with 15 false-positive results produced by malaria RDT kits and malaria ELISAs
| No. of RDTs used | Sample no. | Gendera | Age (yr) | IgM RFb (IU/ml) | Test resultsc |
Absorbance value of SD Bioline malaria antigen Pf ELISA for HRP-2 detectiond (cutoff, 0.1575) | Absorbance value of Genedia malaria antigen ELISA for pLDH detectiond (cutoff, 0.12) | ANAe | Diagnosisf | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| BinaxNOW malaria |
OptiMAL-IT |
SD Bioline malaria Ag P.f/Pan rapid test |
Humasis malaria P.f/Pan antigen test |
|||||||||||||
| HRP-2 | Aldolase | PfLDH | pLDH | HRP-2 | LDH | HRP-2 | LDH | |||||||||
| 1 (RF: 348 ± 277.7 IU/ml) | 1 | F | 36 | 113.9 | + (weak) | − | − | − | − | − | − | − | 0.326 | 0.085 | + | Rheumatoid arthritis |
| 2 | F | 73 | 117.4 | − | − | − | − | + (weak) | − | − | − | 0.268 | 0.171 | + | HTN DM | |
| 3 | M | 54 | 156.1 | + (weak) | − | − | − | − | − | − | − | 0.371 | 0.079 | + | Rheumatoid arthritis | |
| 4 | F | 20 | 208.9 | + (weak) | − | − | − | − | − | − | − | 0.134 | 0.069 | − | Arthritis | |
| 5 | M | 56 | 338.8 | + | − | − | − | − | − | − | − | 0.553 | 0.265 | − | Asthma | |
| 6 | M | 44 | 410.1 | + (weak) | − | − | − | − | − | − | − | 0.136 | 0.098 | − | Health check-up | |
| 7 | F | 18 | 500.3 | − | − | + (weak) | + (weak) | − | − | − | − | 0.694 | 0.136 | + | Rheumatoid arthritis | |
| 8 | M | 62 | 938.5 | − | − | − | − | − | − | + (weak) | + (weak) | 0.237 | 0.178 | + | Rheumatoid arthritis | |
| 2 (RF: 713.4 ± 608.8 IU/ml) | 9 | M | 45 | 341.8 | + (weak) | − | − | − | − | − | + (weak) | − | 0.583 | 0.251 | − | Health check-up |
| 10 | F | 71 | 382.5 | + (weak) | − | − | − | − | − | + (weak) | − | 0.34 | 0.059 | − | Bursitis | |
| 11 | F | 43 | 1,416.0 | + (weak) | + (weak) | + (weak) | + (weak) | − | − | − | − | 0.606 | 0.098 | + | HBV | |
| 3 (RF: 1147.5 ± 292.0 IU/ml) | 12 | F | 33 | 817.6 | + (weak) | + | + | + | − | + (weak) | − | − | 0.585 | 0.103 | − | HBV |
| 13 | F | 53 | 995.9 | − | + (weak) | + (weak) | + (weak) | − | − | + (weak) | + (weak) | 0.246 | 0.077 | + | Rheumatoid arthritis | |
| 14 | M | 47 | 1,324.2 | − | + | + (weak) | + (weak) | − | − | + | − | 0.352 | 0.125 | + | Rheumatoid arthritis | |
| 15 | M | 55 | 1,452.1 | − | + | + (weak) | + (weak) | − | − | + | − | 0.169 | 0.126 | + | Arthrosis | |
a
F, female; M, male.
b
RF, rheumatoid factor.
c
HRP-2, histidine-rich protein 2; PfLDH, P. falciparum lactate dehydrogenase; pLDH, pan-Plasmodium lactate dehydrogenase; +, positive; −, negative.
d
Enzyme-linked immunosorbent assay (ELISA)-positive results greater than the cutoff value are noted in bold type.
e
RF levels in the antinuclear antibody (ANA)-positive group were not significantly different from those of the ANA-negative group (Mann-Whitney U test, P = 0.346).
f
HTN, hypertension; DM, diabetes mellitus; HBV, hepatitis B virus infection.