Propagation of the tick Amblyomma variegatum in the Caribbean

Abstract

The tropical bont tick, Amblyomma variegatum, is an African tick species which infests livestock and wildlife. It was probably introduced in the central eastern islands of the Caribbean during the 18th or 19th century, with cattle shipped from Senegal. In Africa and the Caribbean, this tick is a vector of heartwater (a rickettsial disease of ruminants) and is associated with acute dermatophilosis (a bacterial skin disease of animals). Until 1948, only Guadeloupe and the neighbouring islands of Marie Galante and Antigua were infested with this tick species. Following increased agricultural commerce between Guadeloupe and Martinique, the latter became infested in 1948. Between 1967 (when the tick was identified in St Croix) and 1988 (when a male tick was reported in St Vincent), fourteen new islands were reached by this tick. Most of the dissemination of the tick to new islands cannot be explained by legal or illegal movements of livestock. Recently-determined circumstantial evidence strongly links the increase in populations of the cattle egret (Bubulcus ibis), a migrating bird established in the Caribbean circa 7960, with increased colonisation of new islands by A. variegatum. Considering the wide range of areas currently occupied by this bird species in the Greater Antilles and on the American mainland, there is a high probability that the tick will also expand its range and invade new areas. Eradication of A. variegatum from the Caribbean and thus from the western hemisphere, and the strengthening of measures to prevent inter-island movements of livestock, would be the only effective means of preventing this threat.

Heartwater – Ehrlichia ruminantium infection

“…While the disease has only become established on the islands of Guadeloupe, Antigua and Marie-Galante (36,37), the tick vector has spread to 14 islands as a result of inter-island trade in tick-infested livestock and the transport of larvae and nymphs by the African cattle egret (Bubulcus ibis) (38). Cattle egrets migrate as far as the American mainland so both A. variegatum and E. ruminantium could continue to spread.…”

Tick-borne rickettiosis in Guadeloupe, the French West Indies: isolation of Rickettsia africae from Amblyomma variegatum ticks and serosurvey in humans, cattle, and goats.

“…19 Over the past 50 years, it has propagated and invaded more than 15 islands, including Martinique, Dominica, St. Lucia, St. Vincent, Barbados, and Puerto Rico. 19 In the Caribbean, cattle and goats are the main hosts of adults, whereas immature forms may parasitize a large variety of hosts, including birds.…”

“…19 Over the past 50 years, it has propagated and invaded more than 15 islands, including Martinique, Dominica, St. Lucia, St. Vincent, Barbados, and Puerto Rico. 19 In the Caribbean, cattle and goats are the main hosts of adults, whereas immature forms may parasitize a large variety of hosts, including birds. Although livestock movements have been implicated in the explanation of the propagation of the tick in the West Indies, Barré and others have suggested that bird migration may play a role in carrying ticks.…”

“…Although livestock movements have been implicated in the explanation of the propagation of the tick in the West Indies, Barré and others have suggested that bird migration may play a role in carrying ticks. 19 The dispersal of hosts carrying ticks is one factor of dissemination of tick-borne diseases, particularly rickettsioses. 1,20 Amblyomma variegatum is a vector of Cowdria ruminantium, the agent of heartwater, a rickettsial disease that affects ruminants in sub-Sahelian Africa.…”

“…21 In the 1980s, this disease was reported in the West Indies. 19 Rickettsia africae is the recently described agent of African tick-bite fever, a spotted fever rickettsiosis occurring in sub-Sahelian Africa. 6,17 Although this rickettsia was initially isolated from ticks including A. variegatum 22 and A hebraeum, 23 the first human case due to R. africae was reported in 1992.…”