Wildlife trafficking is the world's fourth most lucrative criminal enterprise, generating over $200 billion annually for criminal networks — and a sweeping new study published in the journal Science warns it also poses a serious threat to global public health. Researchers analysed four decades of data covering more than 2,000 traded species and found that over 40% share an infectious agent with humans, compared with just 6% for the same species when not commercially traded. The elevated risk stems from conditions inherent to the trade — capture, storage, transport and sale force stressed animals into close contact with other species, creating ideal conditions for viruses to spread and mutate; one documented example saw U.S. owners of pet prairie dogs contract monkeypox after the animals had been housed alongside Gambian rats imported from Ghana.