Exotic ticks on horses imported from Portugal to Brazil

Carrapatos exóticos em eqüinos importados de Portugal para o Brasil

Horse; tick; Rhipicephalus bursa; Hyalomma marginatum; Brazil; exotic

Eqüino; carrapato; Rhipicephalus bursa; Hyalomma marginatum; Brasil; exótico

COMMUNICATION

[Comunicação]

Exotic ticks on horses imported from Portugal to Brazil

[Carrapatos exóticos em eqüinos importados de Portugal para o Brasil]

M.B. Labruna¹, A. Pinter¹, N.V. Roncati¹, M.C. Pereira², J.L.H. Faccini³

¹ Faculdade de Medicina Veterinária e Zootecnia da USP

Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária

05508-000 - São Paulo, SP

2 Departamento de Parasitologia, ICB - USP

3 Departamento de Parasitologia Animal, IB - UFRRJ

Recebido para publicação, após modificações, em 3 de outubro de 2000

The Brazilian Ixodid fauna is composed of 56 tick species (Aragão & Fonseca, 1961; Barros-Battesti & Knsyak, 1999). The world ixodid fauna is composed of more than 750 species (Oliver, 1989) and the risk of introduction of exotic tick species (and consequently exotic tick borne diseases) in new areas through the international trade of domestic and wild animals is a reality. Fortunately, most of the Ixodids are extremely adapted to particular environmental conditions such as climate and vegetation (Klompen et al., 1996) that limit the risks of introduction into new areas.

In April 1999, five specimens of ticks were collected from two horses in a professional horse farm in the State of São Paulo, Brazil, and were brought alive, inside tied plastic vials to the laboratory for identification. As these horses had come from Portugal one day before, the veterinarian was concerned that the ticks could be exotic to Brazil. From one of the horses, a single adult male was collected and was identified as Hyalomma marginatum, according to the taxonomic keys and description by Hoogstraal (1956) and Tendeiro (1962). Four ticks were collected from the second horse, being three males and one engorged female, which were identified as Rhipicephalus sp. Males of this genus have more distinct morphological features and is the sex of choice for taxonomic identification. As these three males were dead and dehydrated in the laboratory, several deformities were present in their cuticles and it was difficult to identify them at the species level. On the other hand, the engorged female was still alive and it was kept in an incubator at 27^oC and relative humidity higher than 85%, for oviposition. The larval progeny of this female was reared in laboratory with the purpose of obtaining new adults for further identification. Larvae of approximately 30-day-old were allowed to feed on a naive White New Zeland rabbit, under controlled conditions according to the methodology described by Rechav et al. (1997). Briefly, an area of dorsum of the rabbit was shaved and a cotton bag (20 x 20 cm) was glued (Kamar heat detector adhesive (Kamar, Steamboat Springs, CO, USA)) to the rabbit. Approximately 800 larvae were released into the bag that was opened daily for observation of natural detachment. Detached engorged ticks were counted and immediately taken into the incubator at 27^oC and relative humidity higher than 85%, where they were observed daily.

The Rhipicephalus species showed a two-host life cycle pattern since all the approximately 400 larvae (50%) that had engorged on the rabbit molted to nymphs while attached on the host. Emerged nymphs attached to the rabbit skin right after ecdysis, a behavior characteristic of two-host ticks (Balashov, 1972). Engorged larvae molted to nymphs from the 9^th to the 14^th day after infestation. Detachment of engorged nymphs began 19 days after larval infestation and continued for six days, showing a mean feeding period of 21.7 days. A total of 278 engorged nymphs were recovered and 65 (23.4%) molted to adults. Thirty-nine nymphs molted to adult males, the premolt period averaging 36.9 ± 1.92 days (range: 33-40). The premolt period of 26 female nymphs averaged 38.5 ± 1.24 days (range: 36-40). The sex ratio was 1.5:1 (male:female). All F₁ adult ticks were killed in alcohol 70% and identified as Rhipicephalus bursa, according to Tendeiro (1962). Besides the two-host life cycle pattern showed by the ticks, the duration of the feeding and premolt periods of larvae and nymphs were similar to those reported for R. bursa by Nuttall (1915) and Yeruham et al. (1995). According to Tendeiro (1962), adult males of R. bursa can be distinguished from other Rhipicephalus species from Portugal through its particular adanal shield shape (Fig. 1a) and the presence of a ventral retrograde spur on palpal article 1. Rhipicephalus evertsi is another important two-host tick infesting livestock in the Old World but it can be distinguished from R. bursa through the orbited eyes in the former species but not orbited in the later species (Fig. 1b). R. bursa females can be differentiated from other Portuguese Rhipicephalus species by the ventral retrograde spur on papal article 1 (Fig. 1c) and the scutum punctation pattern (Tendeiro, 1962).

Except for the dog tick, Rhipicephalus sanguineus, all remaining 15 species from the Portuguese tick fauna are exotic to the New World (Caeiro & Simões, 1989). R. bursa and H. marginatum are among the most common tick species of livestock in the Mediterranean area. H. marginatum is distributed from India to Portugal, extending northward to the Soviet Union and southward to northern Africa, Kenya and Sudan (Tendeiro, 1962). Adults are commonly found on large domestic animals such horses and cattle while immature ticks are more common on small mammals and birds (Strickland et al., 1976). R. bursa is a two-host tick endemic to the Old World, restricted to the northern hemisphere (Tendeiro, 1962; Yeruham et al., 1995). Population of this tick are distributed in the Mediterranean basin, the Balkans, southern former Soviet Union, Iraq and Iran (Yeruham et al., 1985). Wild Perissodactyla are the natural hosts for all stages of R. bursa in the Old World (Hoogstraal & Valdez, 1980). Goats, sheep, horses and cattle are usual hosts for this tick in areas where they coexist (Tendeiro, 1962; Yeruhan et al., 1985).

The major significance of R. bursa lies in its ability to transmit Babesia ovis, Theileria ovis, Anaplasma ovis, which affect sheep and goats, and of Babesia equi to equines. H. marginatum is a vector of Babesia caballi and several viruses (Papadopoulos et al., 1996). Except for B. equi and B. caballi, all above tick-borne pathogens are not established in Brazil. Due to the noteworthy significance of R. bursa and H. marginatum in the areas of their natural distribution it is relevant to report the presence of these ticks in a farm of Southern Brazil. Procedures to prevent the establishment of these ticks in the farm were performed. The two horses were kept for three consecutive weeks in closed individual stalls from the day they arrived in the farm. During this period, they were dipped with a pirethroid acaricide (Deltametrin,Butox®, Hoechst Roussel) on the 1^st, 7^th and 14^th days and were orally treated with moxidectin (Equest®, FortDodge) on the 1^st and 14^th days. Careful examinations for the presence of ticks were performed daily over the body of the horses but no tick specimens were found during this period. All the wood shavings used in the stalls and the horse wastes were incinerated. Right after the stall evacuation on the 14^th day the stall walls, floor, roof and edges were treated by a fire jet machine.

Decades ago Aragão (1936) reported the presence of R. evertsi and Hyalomma egyptium on imported goats in Rio de Janeiro, Brazil. According to the author, appropriate procedures at that time prevented the establishment of these exotic species in Brazil. Although R. bursa and H. marginatum are exotic ticks that could threaten livestock activities in the New World, there is no information concerning the possibilities of establishment of these ticks in Southern Brazil. Abundance of suitable hosts is a favorable situation but abiotic factors like climatic and vegetation might be barriers for colonization of both species.

Keywords: Horse, tick, Rhipicephalus bursa, Hyalomma marginatum, Brazil, exotic

RESUMO

Em abril de 1999, cinco espécimens de carrapatos foram colhidos de dois eqüinos que haviam chegado há um dia de Portugal em uma propriedade rural no interior do Estado de São Paulo. Os carrapatos foram enviados vivos ao laboratório e foram identificados como Hyalomma marginatum e Rhipicephalus bursa. Esta última espécie foi criada em laboratório para obtenção de novos adultos para confirmação da identificação. Tanto H. marginatum como R. bursa são espécies consideradas restritas ao Velho Mundo, onde atuam como vetores de vários patógenos para os animais domésticos. Os procedimentos técnicos realizadas com o objetivo de prevenir um possível estabelecimento desses carrapatos na propriedade rural são descritos.

Palavras-Chave: Eqüino, carrapato, Rhipicephalus bursa, Hyalomma marginatum, Brasil, exótico

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Publication Dates

• Publication in this collection
  05 June 2002
• Date of issue
  Apr 2001

History

• Received
  03 Oct 2000