Recently, a relatively well-to-do friend of mine was traveling from New York to Guatemala with two dogs as she has done many times before in the past. Normally, and perhaps this is just an egotistical point of view, she has operated under the assumption (for good reasons) that the countries south of the border would be willing to take whatever she decided to bring with her.
On this particular trip though, disaster kind of struck and it was only because of her local connections and a very considerate veterinarian that she was allowed into the country at all.

now this is a rather ridiculous situation when you think about the overall sanitary differences between Guatemala and the United States (especially in the posh area she comes from) but these various countries make up their own rules and often it is up to the attitude of the particular official that happens to be on duty that day.
This friend of mine called a local contact who was fluent in Spanish and has some connections and that friend organized a veterinarian to come to the airport through security and verify that the dogs didn't have screwworm.
I suppose this is fair enough until you consider that this woman had a vaccination specifically against screwworm but the issue the customs agent had was that the only had electronic versions of the certifications. he wanted to see the original paper copies. This is pure speculation on my part but I think he wanted to enforce his will on a stranger who happened to be American, and happened to be flying first class.
He had already made up his mind that he was going to kick her back before she even showed any certifications of papers of any sort, digital or not.
However, I think it is important if you are going to travel with a pet to avoid these sorts of situations. If she didn't have local connections like she did there would have been no choice on her part but to buy the ticket and fly back to New York with her dogs, which would have introduced a whole world of other problems as well.
Why are they so afraid of screwworm? Well, I'm not really sure that they are but the policy remains and it isn't just this one country either.
According to a simple websearch on my part, screwworm could possibly threaten food supplied in all countries if it were to spread as it attacks living tissue in all animals including humans. That is a the worst case scenario though.

If you do travel with an animal make sure to get tested for screwworms and keep the original document with you. I don't know if customs of various countries are actually well-versed in reading these forms but they do, as of late, seem to have some sort of insistence on actual paper documents. This could be because it would be rather easy for people to forge digital versions of the documents using AI or something.
The story for my friend has a happy ending but she still has another hurdle to pass in that she will eventually need to fly back to the United States and it remains to be seen if they are going to have a problem with the lack of paper documents as well.
There could end up being a rather tragic part 2 to this story but the lesson right now is to travel with paper versions of your documents because some officials are not very keen on a digital form on your phone - and honestly I can kind of understand why that would be.
I have never heard of screw worm and it does sound kind of nasty. If you travel with animals make sure you check what is required and never presume.
it's probably best to take any of these sorts of diseases very seriously. It would just be nice of airport officials understood what the heck they are actually enforcing.
I'm from the UK and recently travelled to France and neighbouring countries with a friend and her dog. She had to get a health certificate for the dog before we left, and on the way back, we had to visit a vet so the dog could be given a worming tablet. It was all quite expensive, but you do have to make sure everything is in order when travelling with pets.
I think that the responsibility should lie on the person who is carrying the pet. I don't think that fluffy the household miniature poodle is the one that ends up spreading horrible livestock diseases but I suppose they have to cover all of their bases.
I wouldn't trust owners to self regulate.
Trips like this, with animals, always require extra care.
That's a must.
They should pay more but it would be nice if there was some sort of universal code as far as the animals traveling is concerned. There probably was at some point but then everyone started taking the piss with their fake emotional support animals so they could get them on the planes for free.
That's a tricky situation, especially when we consider a "universal code" for it.