That’s because whoever wrote this has little clue what they are talking about.

What they are calling “long fatigue” is medically known as “post-acute infection syndrome” and contains hundreds of symptoms which don’t necessarily include fatigue.

It can be caused by both viral and bacterial infections, Lyme being one of the bacterial ones.

It is, but the article seems to conflate post-viral fatigue with long-term fatigue in the grouping:

Post-viral fatigue has long been poorly understood, and for many years was often dismissed as psychological. But this long-term fatigue with varying degrees of severity has been linked to infections ranging from Sars to Ebola, Epstein-Barr virus and influenza, as well as infections with tick-borne pathogens such as the bacteria Borrelia burgdorferi, which causes Lyme disease.