Importing geometry data into MySQL using LOAD DATA LOCAL INFILE - mysql

Question

I am trying to import CSV data into MySQL using the LOAD DATA LOCAL INFILE syntax. This is normally a fairly simple task, but in this case the data includes a geometry field that is tripping me up.
When I try to run the import, I'm getting errors like this:
SQLSTATE[HY000]: General error: 4079 Illegal parameter data type longblob for operation 'st_geometryfromwkb'
The records in my CSV file look like this:
'Somewhere', -0.574823, 51.150771, '0x0101000000000000000000F03F000000000000F0BF'
So I have a location name, lat/long coords and a geometry field in binary WKB format. (the example above is a simple geometry that translates to POINT(1,1); the real data has complex polygons, but the content isn't relevant; the issue is the same with this simple example).
My table looks like this:
CREATE TABLE IF NOT EXISTS `mapping` (
`id` int AUTO_INCREMENT PRIMARY KEY,
`location` varchar(80) DEFAULT NULL,
`longitude` double DEFAULT NULL,
`latitude` double DEFAULT NULL,
`geom` geometry NOT NULL,
INDEX mapping_by_location (location),
SPATIAL KEY `mapping_by_geom` (`geom`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
And my import query looks like this:
LOAD DATA LOCAL INFILE '{$file}'
REPLACE INTO TABLE `mapping`
FIELDS TERMINATED BY ','
OPTIONALLY ENCLOSED BY '\"'
LINES TERMINATED BY '\n'
(#col1, #col2, #col3, #col4)
SET
`location` = #col1,
`latitude` = #col2,
`longitude` = #col3,
`geom` = GeomFromWKB(#col4);
As stated, with this import query, I am getting the Illegal parameter data type error shown at the top of this question.
However, the query works if I replace the final line with a hard-coded geometry string, like this:
`geom` = GeomFromWKB(0x0101000000000000000000F03F000000000000F0BF);
Obviously this isn't any good, as I need the field to load from the CVS not a hard-coded value in the query, but it does work, whereas loading the same value from the CSV in #col4 does not.
I have tried a bunch of variations on this query - with and without the call to GeomFromWKB(), with both X'...' and 0x... notations for the hex value; nothing seems to work.
Can anyone give me some help please?