Dermacentor variabilis (Ixodida: Ixodidae) in Panama: report associated with tourism

Abstract

Ticks are the principal vectors of several pathogenic agents in animals and can transmit disease agents to humans (Dantas-Torres et al. 2009). The global tourism industry, international pet commerce, and the general expansion of international travel have facilitated the transportation of ticks to new localities outside their natural distributions. For example, 99 species of exotic imported ticks have been reported in the United States (Keirans and Durden 2001), ten species of reptile ticks originating from South America were found in the United Kingdom (Pietzsch et al. 2006), and ten exotic species have been reported in Brazil (Dantas-Torres et al. 2009). Although rare, humans can carry attached ticks to non-endogenous areas through tourism and migration. In this paper, we report the finding of a partially engorged tick female, on a 10-year-old child from Baltimore, MD, U.S.A. who was visiting Panama. The child arrived in Panama on 1 July 2009 and remained in Panama City until 10 July 2009, when he travelled to Carti, Kuna Yala, on the eastern Caribbean coast. The tick was removed on 11 July 2009, when his mother saw it on the child's head during the trip to Carti. The tick was transported to the Medical Entomology Branch in the Gorgas Memorial Institute (ICGES) in Panama City, where it was identified as Dermacentor variabilis according to the key of Yunker et al. (1986) and later confirmed by Lance Durden and Lorenza Beati at Georgia Southern University, Statesboro, GA, U.S.A. The specimen has been deposited in the Zoologic Collection “Dr. Eustorgio Méndez” in ICGES, codified as E-031. While in Panama City, the child participated in various activities, such as swimming and football; nevertheless, during the ten days after the arrival from the U.S.A., the presence of the tick was not evident. It is likely that the tick attached beneath the hair in the United States and remained undetected, or that the tick had infested clothing and attached to the scalp later in Panama. Whatever the origin of the bite, it is important to note the possibility that ticks can travel through human tourism. Only one previous case of a D. variabilis tick transported by a human to a non-native area has been reported. In this similar case, a partially engorged female was removed from a woman who had returned to Canberra, Australia, from New York, U.S.A., two weeks prior (Halliday and Sutherst 1990). According to these authors, D. variabilis could expand its distribution in regions such as Central and South America based on geo-climatic and host aspects. Dermacentor variabilis is endogenous in North America, parasitizing various species of mammals, including humans (Smith et al. 1946, Dantas-Torres 2007). This species is the primary vector of Rickettsia rickettsi, the pathogen that causes Rocky Mountain spotted fever (RMSF) (Dantas-Torres 2007). RMSF is a moderate to severe illness characterized by systemic symptoms, including rash and fever, and can progress to end-stage organ damage and death if left untreated. This disease is endemic to the Americas, with most cases occurring in the U.S. In Latin America, RMSF (often called “spotted fever”) is transmitted by other ticks vectors such as Rhipicephalus sanguineus, Amblyomma cajennense, and A. aureolatum (Labruna 2009). Although R. sanguineus could be infected, it rarely bites humans. Other tick species recorded as feeding on humans in Panama are Amblyomma cajennense, A. naponense, A. oblongoguttatum, A. ovale, A. parvum, A. sabanerae, Dermacentor latus, D. imitans, Ixodes boliviensis, Rhipicephalus sanguineus, and immature unidentified Amblyomma spp. (Fairchild et al. 1966). Additionally, other species present in Panama, such as A. coelebs, A. dissimile, A. longirostre, and R. microplus, were reported biting humans in South America (Guglielmone et al. 2006). Accurate knowledge of native tick species is important in order to recognize and monitor exotic species, especially those that are a risk to human and animal health. The public health significance of the international transport of exotic tick species is unclear. For many ticks collected from animals there is no known association with human disease. However, vectors of known pathogens can pose a threat to human or animal health depending on their ability to survive or become established in a non-indigenous area. This depends on a variety of environmental and ecologic conditions, such as climate and native hosts. Also, the ability of an introduced female tick to undergo parthenogenesis or to lay viable eggs in a foreign location could be important. We thank Lance Durden and Lorenza Beati (Georgia Southern University, U.S.A.), for confirming the identification and for comments and Marcelo Labruna (University of Sao Paulo, Brazil) for manuscript comments.