I am not a climate change denier, but the headline is sensationalist and even debunked in its own story, albeit 18 paragraphs down:

“Some combination of these factors (or something else as yet unidentified) may be causing this yellow fever outbreak to be worse than the one that typically hits Brazil in cycles of six or seven years”

In other words, they don’t freakin’ know.  The article is also pretty clear in stating that vaccination rates  are spotty.

Yellow fever killed a lot of people when the climate was more stable, and was a scourge  until a vaccine was developed in the 30s.  If people in affected areas aren’t diligent in getting shots and boosters, outbreaks will happen.  They may or may not be exacerbated by climate change, but given the lack of proof that it is a causal factor, it is irresponsible to say so in a headline.