When the ticks bite, they inject a small amount of blood from their previous host. If the host was a non-ape mammal, then that blood will also contain a sugar, alpha-galactose, that humans lack. Sometimes the immune system misidentifies this sugar as a foreign body and develops antibodies. Now when the bitten person eats red meat their immune system ramps up to attack the alpha-galactose, resulting in a delayed onset allergic reaction.
Having read the article, the appearance of the rash in Vietnam followed by the onset of symptoms suggests something similar make be the cause in the author's case. Her body may have developed antibodies to something food in common foods. This might explain the headaches she experienced when she ate.
http://www.abc.net.au/science/articles/2014/02/25/3951271.ht...
When the ticks bite, they inject a small amount of blood from their previous host. If the host was a non-ape mammal, then that blood will also contain a sugar, alpha-galactose, that humans lack. Sometimes the immune system misidentifies this sugar as a foreign body and develops antibodies. Now when the bitten person eats red meat their immune system ramps up to attack the alpha-galactose, resulting in a delayed onset allergic reaction.
Having read the article, the appearance of the rash in Vietnam followed by the onset of symptoms suggests something similar make be the cause in the author's case. Her body may have developed antibodies to something food in common foods. This might explain the headaches she experienced when she ate.