Collection & Identification of Ixodid Ticks Infesting Cerdocyon thous in

Mato Grosso do Sul, Brazil

Dr. Fernando Paiva (UFMS), Fernanda Rabelo (UFMS), Lacey Brown (SUNY)

Conclusion References Acknowledgments

Introduction

Theory and Methods

Objective

Results

Cerdocyon thous (family Canidae; common name crab-eating fox) is a species that commonly acts as a host to a variety of ectoparasites, including ticks of the family Ixodidae. From this family, ticks of the genus Amblyomma are known vectors to many diseases affecting members of Canidae in MS, Brazil. Amblyomma ticks have a long life cycle, necessitating 3 unique hosts to progress between larval, nymph, and adult stages. Upon feeding from an infected host, ticks at any stage may become infectious and transmit this pathogen to their next host through their saliva. It is possible that ticks are a primary vector for transmitting diseases between C. thous and domestic dogs.

To identify each species of adult tick collected from C.thous and examine blood, lymph, and fecal samples to screen for responses to vector-borne diseases known to be commonly transmitted by these particular species of tick. It will then be determined if C. thous is susceptible to the same diseases contracted by domestic dogs of this region, and the possibility of inter-species transmission can be explored. Each may act as a reservoir, perpetuating the endemic cycle of pathogenic microorganisms. Samples will be collected over 4 campaigns in the years 2012-2013.

Figure 3. Labeled; a.) A.ovale (dorsal), b.) A.ovale (ventral), c.) A.tigrinum (dorsal), d.) A.tigrinum (ventral). Note: all male.

At the location of Reserva Particular do Patrimônio Natural Engenheiro Eliezer Batista in the Pantanal region of MS, Brazil 15 tomahawk traps were distributed along forest trails during the month of July, 2012. Traps were baited and covered with palm fronds to provide shade and camouflage. Traps were opened each night for 10 days, checked every morning and closed during daylight hours. When an animal was captured, it was sedated with VIRBAC Zoleitil 50 (tiletamina/zolazepam, dosage: 0.2 mL/kg). The animal was weighed and the sex determined. Blood, lymph, and fecal samples were collected. Ticks were removed from the body and preserved in 70% ethanol. Animals were fitted with a microchip in order to identify animals that were previously captured; repeat captures were released without further collection. The animal was replaced at the site of capture, monitored, and released. Ticks were separated into larval, nymphal, and adult stages and adult ticks were categorized by species using a taxonomic key. Adults were separated by sex; females feature an oval shaped genital aperture, a partial conscutum, and two small porous areas on the capitulum. The distance between these areas can aid in identification. Males lack any porous areas, have a flattened genital aperture and possess a full conscutum. We examined the conscutum; any 'ornamentation' present (or absent) is useful for identification, as is the appearance of marginal festoons. In some males, these may or may not extend beyond the edge of the body. A groove on the margins of the scutum was either absent, fully present, or incomplete. We also examined the mouthpieces, comparing the proportions of length and width of each article of the palpus and noting the arrangement of dentition on the hypostome; teeth may be arranged in a 3/3, 4/4, or 5/5 fashion. The number, size, and distribution of spines on each coxa and trochanter of each leg pair were often used in finalizing identification.

Figure 4. An image of the total material collected from each animal.

Figure 5. Right: Labeled diagram of the general mouthpieces of ticks within the family Ixodidae (photo; A.ovale).

a.) Basis capitulib.) Palpus; article Ic.) Palpus; article IId.) Palpus; article IIIe.) Hypostomef.) Dentition (3/3)g.) Cheliceraeh.) Capitulum

At the time of this study, only the process of tick identification in the first campaign (in the month of July) is complete. A total of 264 ticks were collected from 6 animals. Of these, 160 were at the larval stage; having only 3 pairs of legs and no distinguishable sex. Similarly, 95 of the ticks collected were of the nymphal stage; an intermediate stage, with 4 pairs of legs but no discernible sex. Both stages had a prevalence of 100%. Of the 9 adult ticks collected, 5 were identified as A. parvum, 3 as A. ovale, and 1 as A. tigrinum. Adult forms had a prevalence of only 50%. The predominance of larval and nymphal forms can be attributed to the seasonality of the Amblyomma tick life cycle in MS, Brazil. The highest number of ticks found on any individual animal during the time of collection was 78 (CT-05).

Amblyomma ticks are a known vector of Canine Rocky Mountain Spotted Fever, and, of particular interest, A.ovale is a primary vector of Canine Hepatozoonosis. Canine Rocky Mountain Fever is caused by Rickettsia rickettsii. Many symptoms are present and it is often fatal. Canine Hepatozoonosis is also potentially lethal. It is caused by a protozoa Hepatozoon canis and leads to muscle inflammation and debilitation. To explore inter-species transmission, it will become important to determine if the primary mode of infection is via tick saliva or ingestion of mature ticks containing oocysts. Both occur frequently.

D. Barros-Battesti, M. Aruza, G. Bechara (2006). Carrapatos de Importância Médico-Veterinária da Região Neotropical um guia ilustrado para identificação de espécies.

F. Dantas-Torres (2008). Canine vector-borne diseases in Brazil. Biomed central, 10.1186/1756-3305-1-25.

M. Labruna, et. al (2005). Ticks (Acari: Ixodida) on wild carnivores in Brazil. Experimental and applied

acarology, 10.1007/s10493-005-2563-1.

Table 1. Defining characteristics of each species identified.

Figure 1. An image of the outer ear of specimen CT-01 heavily infested with tick.

Species: A. ovale A. parvum A. tigrinum

Defining Characteristics:

On coxa 1, 2 long spines of approximately equal length, 1 short spine on coxa 4. 3/3 dentition, very ornate.

1 spine on coxa 4, 2 on coxa 1 (external larger)

& spurs on 1st trochanter. 3/3

dentition, inornate. Retrograde spine on article 1 of palpus.

Singular spine on coxae 1 & 4,

particularly large on coxa 4. Robust 4th leg

pair, 3/3 dentition, ornate. Spores on

tarsus 2-4.

Stage of Life Cycle:

Prevalence: [# infected hosts/

total # hosts sampled]

Mean Intensity: [# parasites/ # infected hosts]

Mean Abundance: [# parasites/ total #

hosts sampled]

Adult* 50 % 3.00 1.50

Nymphal 100 % 15.8 15.8

Larval 100 % 26.7 26.7

Table 2. Prevalence, mean intensity, and mean abundance according to life stage. * Adult forms include A. ovale, A. parvum, and A. tigrinum.

Figure 2. CT-01 at release.

a.)

b.)

c.)

d.)

e.)

f.)

a.)

h.)

Eye

DorsalGroove

TrochanterCoxa I

DorsalShield orConscutum

Festoons

Spiracular Plate

GenitalAperture

AnusAnalGroove

a.) b.) c.) d.)