Pairi Daiza is like most things in life not black or white but a shade of grey. Which shade of Grey depends on the person you ask.
I’ll start of by saying what I think modern zoos should aim and stand for. I think the 3 pillars of a modern zoo should be 1 Animal welfare, 2 Conservation and restoration and 3 Education.
Personally, I’m not a big fan of Pairi Daiza(further referred to as PD). But I’ll start of with the good stuff. If you look at the second pilar conservation and restoration I think you must recognize that the PD foundation does a lot of good work. The work with the Spix macaws is but only one example, another is the work in Tasmania to save the Devils from the tumor biting disease (turned out it wasn’t needed but still). I also think that you must recognize the fact that PD has a really impressive collection of animals and does attempt to breed with them helping breeding programs and EEP’s as well as the fact that they’re not afraid to import animals (can also be a minus sometimes).
Now the issues arise once we look at the first and second pillar. Animal welfare is just not great and horrendous in some cases. The problem is PD designs its park in an outdated sense in the way that the exhibit’s are built for people’s enjoyment rather then for the animal it houses. This can be seen in many ways, most to every exhibit has multiple viewing points. While it’s important that the animals have the option to hide and take a breather if they want. Like the aviaries that have a restaurant inside. Next issue is the fact that the exhibits are overpopulated and don’t have enough separation options. If you look at the number of animals in the brown bear exhibit for example: 10 brown bears and 3 grey wolves. While the exhibit would be great for 2-3 bears and wolves if more climbing options were available and less viewing. Or 5 Siberian tigers in their exhibit, with no separation options apart from their small inside feeding cages. This already led to fights. Next up the size of the exhibits, while some are good others are too small, but this is something that in my opinion every zoo has issues with. Next up refurbishment of exhibits: Multiple exhibits don’t offer the refurbishment the animals need. Most famous is their koala exhibit, it being open to the public lead to the death of over 5 imported koalas. Or their pygmy hippo exhibit very open no vegetation no shade. Same with the clouded leopard enclosure very open, less then when it opened but still barely any climbing options and so on. Next up enrichment: Enrichment in PD is very minimal and while it is improving its still very behind. For example, the Asiatic black bears show way to much stereotypical behavior, and barely have any enrichment. Also, I can personally not think of an example of a permanent addition that can act as enrichment to the animals in an exhibit. For example, puzzle boxes for their great apes or so. Another issue I personally have is the fact that all animals have to know Dutch and French while worked with plus commands are obliged by EAZA to be in English. So, for their walruses for example this means they know English commands, Spanish commands since they came from Valencia, Dutch and French now and German since they send their females to Germany to breed. I personally think that one language is enough for an animal to understand. Next up animal care, PD decides to save money for certain animals and not follow the best practice guidelines for feeding. Their polar bears for example are on a much more vegetable and fruit-based diet then recommended as well as their Red ibises are fed with more chick’s rather than the pellets supplemented with chicks and fish, …. Another issue is the fact they work in full contact with animals it’s not recommended. Their elephants are worked with in full contact even sporadically with the bulls. When looking at animal welfare It frustrates me that they claim they’re the best zoo in Europe.
Last pillar education: The biggest problem I have here is the fact the animals aren’t always signed well. It’s important that an exhibit has a sign with which animals live there. Since you want to educate the public about the animals and ecosystems and issues. Also they don’t have a lot of info panels about issues and so on. If you go to animal talks the talks are decent sometimes, they’re only in French which is sad since education should be for all visitors. So, when it comes to education they also score lower then what I personally would expect of Europe’s Best zoo.
Another thing I find frustrating is the fact that zoos should be a non-profit, while most zoos use the for-profit parts like their hospitality industries to supplement their savings and fund expansions or projects, PD does not do this and runs like a business. I personally found it outrages how much money grabbing happens inside the park.
So, your doubts are completely reasonable. However, I always recommend people to visit PD at least once and form their own opinion. I personally only visited PD twice with my last visit being in December 2021. And I don’t intend to visit again any time soon unless they would fix a lot of the described issues.
I’m sorry for the rant like post, I tried to be short and punctual, since there are a plethora of issues and examples.
PS: I don’t know where you have the info about elephant herpes virus, I know the KMDA(Zoo Antwerp and Planckendael) has a large research program on it.