Self-Use of Rapid Tests for Malaria Diagnosis by Tourists Poses Difficulties
Abstract & Commentary
Synopsis: A group of collaborative investigators from Germany and Switzerland conducted a study of rapid dipstick methodology for self-diagnosis of malaria at a resort in Mombassa, Kenya, east Africa.
Source: Jelinek T, et al. Self-use of rapid tests for malaria diagnosis by tourists. Lancet 1999;354:1609.
Patients reporting with fevers were asked to carry out the dipstick test (ICT Malaria Pf, ICT Diagnostics, Sydney, Australia). This test is a simple immunochromatographic test that detects circulating histidine-rich protein 2 of Plasmodium falciparum by use of specific antibodies bound to a membrane. In several European countries, such tests are marketed for self-use by tourists.
Patients were nonimmune with regard to malaria and guests or residents at one of several hotels. While awaiting the results of their thick smears, they were asked to perform the dipstick test without any assistance other than the kit manual provided by the manufacturer. Microscopic evaluation of peripheral blood smears was the standard used for confirmation of a malaria diagnosis.
Of 98 patients with fevers, 52 were male, 46 female, and 11 patients had microscopically confirmed malaria. The dipstick was performed successfully by only 67 of the 98 patients, and 10 of the 11 malaria patients were unable to obtain any results. The Table lists the reasons for test failures among the 31 patients who could not obtain a valid result.
|Table-Reason for Malaria Self-Diagnosis Test Failures Number of Patients*|
|Unable to draw blood (finger prick)?||22 (71%)|
|Unable to place the blood drop appropriately on the test kit||8 (26%)|
|Did not wait for the recommended period (8 min.)||12 (39%)|
|Unable to identify the bands indicating the test result||18 (58%)|
|Unable to interpret the results obtained||27 (87%)|
|*Of a total of 31 patients, some patients had more than one difficulty with the diagnostic test kits.|
Comment by Michele Barry, MD
This is a discouraging report—one that suggests travelers who are untrained in the dipstick technique should not use such malaria self-diagnosis methods. The high failure rate among travelers with falciparum malaria may also indicate that ill patients are those most likely going to experience problems with dexterity or interpretation, which prevent skillful use of a dipstick test.
One potential drawback to this study is that the assessment situation was an artificial one for affected travelers, who may not have performed to their utmost knowing their own malaria smears were being performed simultaneously. At the very least, as dipstick tests for malaria self-diagnosis become increasingly available, travel clinics should consider a mock training session illustrating the correct dipstick performance techniques prior to actual field use. The Table lists some reasons for failure of tourists to obtain valid results with the rapid test for falciparum malaria. Training sessions can be aimed at correcting these issues for travelers planning to use them.
Which of the following attributes of malaria self-diagnosis with currently available dipstick methods is most likely to be correct?
a. The average traveler can be relied upon to follow the kit’s manual and obtain a valid test result.
b. All four species of human malaria can be ruled in or out simultaneously.
c. Febrile episodes occurring in travelers to malaria endemic regions are currently best evaluated with a malaria self-diagnosis kit as the first step.
d. Human error in test performance is currently greater than the technological limits of the test itself.