Wow. After a substantial amount of research, I’m pretty sure this may be almost impossible to find an exact figure for.

There’s several reasons for that. First of all, even today, soldiers in the field don’t report “minor” injuries—essentially, anything you could patch up with a first aid kit. This would be almost everything related to the plants in the region—like poison ivy or nettles—and most snake bites. Keep in mind that only about 20% of snake species in Vietnam are venomous. If a snake isn’t venomous, its bite is a simple puncture wound which can be dressed with antibiotics and a bandage. Essentially, most wildlife can’t do serious damage to humans—especially not well-armed ones, like soldiers.

The only time injuries would be reported is if they became major, needed special treatment, or were life-threatening. This might include venomous snake bites, tiger attacks (rare, but they happened), and crocodile attacks.

Overall, these sorts of injuries were pretty rare, and would hardly ever get reported if they weren’t really serious. What’s more, the Defense Casualty Analysis System does not come anywhere close to the level of specificity you’re hoping for—they only separate hostile and nonhostile injuries, the latter of which would include accidents, friendly fire, illness, disease, and the wildlife you’re talking about.