I, too, cannot find any more current information than from the first week of November. Your guess or mine that the outbreaks have slowed or stopped is unfortunately just a guess. I understand that there was a great effort to spray to get rid of the mosquitoes, and perhaps the efforts have worked.
If you haven't gone to the CDC (Centers for Disease Control and Prevention), here's what seems to be the latest on Dengue Fever. It does give some good hints, especially with regard to mosquito repellent. CDC Traveler's Health Advisory, Dengue Fever
Dengue Fever has been called "break-bone fever" because of the severe pain that often accompanies it. Note the CDC cautions about using painkillers. Acetaminophen [or you might know it as Paracetamol], in the US the most recognized brand is Tylenol(tm), is the only one recommended for reducing fever and pain. They counsel to avoid aspirin or other NSAIDs such as naproxyn sodium or ibuprofen due to the risk of causing bleeding.
If it were me, I'd go to the Cape Verdes and meet my son. I'd use a good mosquito repellent (my favorite is "Mosquito Milk" Tropical Version which you most likely will be able to find in the Canaries), and care at dawn and dusk, and read more on the above web site.
Of course you will have to decide for yourself. If you're headed to the Caribbean you'll find it's endemic there, and so you will continue to have to be careful about mosquito bites.
Our global travel has facilitated global outbreaks of diseases, so it's becoming more difficult nowadays for a cruiser to avoid them.
Wishing you health and fair winds,