Dust-up over dust storm link to ‘Valley Fever’ disease

[GoodTaste]

Dust-up over dust storm link to ‘Valley Fever’ disease
Researchers are divided over whether rising cases of the fungal infection in the United States can be linked to dust storms.

Source: Nature

I don't understand why "link" rather than "links" is used in the headline.
Why?

 

[Skrej]

It's considered as just one connection (link). In the headline, 'link' is used as a noun, not a verb.

For example, one might discuss the link between smoking and cancer. There might actually be several pieces of evidence linking the two, but we refer to the 'link' in general.