It just occurred to me that when I wrote that I had read about an African word that may have been the basis for the word Jonkannu, I was thinking of the dance called "Yonvalu".

I can find very little online about Yonvalu. There is apparently a book and video about the dance: http://store.soundstrue.com/vt00764d.html . That book describes Yonvalu as "a voudoun invocation to Damballa, the serpent deity."

See http://en.wikipedia.org/wiki/Haitian_mythology for this description of vodou-

"Vodou (also known as Voodoo) is a religion that first appeared in Haiti. It is a syncretic mixture of Roman Catholic rituals introduced during the French colonial period, and African tribal beliefs, with roots in the Yoruba, Kongo and Dahomey mythology. Another important aspect of the Haitian spiritual life is magic and serpent worship."
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That Wikipidia site also provides a listing of the Haitian pantheon. In that pantheon Damballah is described as the father of the loa [gods] and [of] humankind.

Btw, "Dahomey" is the former name for the West African nation of Benin. Yoruba is the name of a large ethnic group in Nigeria, and the language spoken by that group. The Yoruba religion was extremely influential in the survival to this day of African religions in the Caribbean {including Haiti and Cuba}, South America {including Brazil} and the USA {including New Orleans, Louisiana}. "Nago" is an old referent for Yorubas. Persons interested in African religions in the Caribbean and South America and related topica will be familiar with that term.

Jessie Gaston Mulira's essay "The Case of Vodoo In New Orleans {in "Africanisms In American Culture" Joseph E. Holloway's editor; Indiana University Press, 1990} provides this information about voodoo: "The word voodoo ...is Dahomean in origin and.., means spirit or diety in the Fon language...
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In that essay Mulira writes that "In New Orleans the West African voodoo cults merged into one major cult, Damballah, the snake cult, referred to in New Orleans as the Grand Zombi or Vodou" {p. 40}.
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Lest we forget New Orleans is ground central for the Mardi Gras Indians.