**6. Soft ticks in the Brazilian Amazon**

*R. amblyommatis* were detected in this species in the Amazon in the municipalities of Governador Jorge Teixeira and Pimenta Bueno, in the state of Rondônia [53, 105]. Adults of the tick *A. ovale* have been reported to parasitize humans in several areas of the state of Rondônia [38]. As previously reported in this chapter, adults of *A. ovale* parasitize mainly domestic and wild carnivores, while immature (larva and nymph) parasitize rodents of the families Cricetidae and Echimyidae, with sporadic reports on wild birds [17, 75, 83]. This preference for such host groups was observed in the laboratory [111]. This tick is a vector of the protozoan *Hepatozoon canis* and the bacterium *R. parkeri*, agents of importance in veterinary and human medicine, respectively [83]. In the Amazon region, the bacterium *R. bellii* was identified in this species in the municipalities of Governador Jorge Teixeira and Monte Negro, in

the state of Rondônia; and in the municipality of Cururupu, in the state of

found parasitizing humans in the north of the state of Pará (municipality not reported) [108]. In this same state, the larval and adult stages of this tick were found on humans in the municipality of Rurópolis [96, 112]. The life cycle of this

tick was studied under laboratory conditions [113].

Mato Grosso, respectively [53, 88].

Tocantins [118].

**52**

Zoobotanical Park of the Museu Paraense Emílio Goeldi [114].

The adult stage of the species *A. romitii* (published as *Amblyomma tasquei*) was

Parasitism by adults of *A. rotundatum* was recorded in the municipality of Belém in the state of Pará on a human who worked in frequent contact with reptiles in the

Adults of the *A. scalpturatum* have been reported to parasitize humans in the state of Pará (municipality not reported) [108], and in the Maicurú River located in this state [93, 106]. Human parasitism by the nymphal and adult stages of this species has been reported in the states of Mato Grosso (municipality of Jauru) and Rondônia (municipality not precisely indicated), however in this latter state it was not specified whether these adult ticks were fixed or walking on humans [38, 93]. The nymphal stage was also collected from a human who was probably infested with this tick in the municipality of Porto Velho in the state of Rondônia [115]. The nymph and adult stages of this species were also found parasitizing humans in the state of Amazonas, in the municipalities of Coari, Fonte Boa, Jutaí, Presidente Figueiredo and Santa Isabel Rio Negro [31, 107]. In the Amazon biome, two species of rickettsiae (*R. bellii* and *R. amblyommatis*) were detected in *A. scalpturatum,* in the municipalities of Governador Jorge Teixeira and Sinop, states of Rondônia and

Human parasitism by adults of *A. sculptum* was recorded in the municipality of Jauru in the state of Mato Grosso [90]. The Jauru territory comprises 90% of the Amazon biome and 10% of the Cerrado biome, so this human record in this region is in accordance with the transition area of the occurrence of this species in sympatry with *A. cajennense* s. s. [90]. The bioecology of this native tick has been extensively studied due to its aggressive parasitism towards domestic animals and humans in the Brazilian territory. In the geographical area in which this species occurs, it completes an annual generation, with larvae occurring mostly during autumn, nymphs during winter, and adults during spring and summer, with larval behavioral diapause being the main regulating factor of its life cycle [116, 117]. Besides being considered a pest for domestic animals (dogs, cattle and horses), the species can transmit to humans the Brazilian Spotted Fever caused by the bacterium *R. rickettsii*, being this the most important zoonotic disease transmitted by ticks within the limits of the National territory. Additionally, *A. sculptum* has also been identified with the bacterium *R. amblyommatis* in the municipality of Pium, state of

There is a trend of seasonal behavior for some species of *Amblyomma* in the Amazon biome, with immatures predominating in the dry period (June to October),

Maranhão [53, 91].

*Ecosystem and Biodiversity of Amazonia*

Taxonomy of Argasidae is currently questionable and relies on five schemes that divide the family in up to ten genera [120]. Achieving a consensus between soft tick taxonomists depends now chiefly on the molecular characterization of early collected type specimens for some genera. For instance, elucidating the status of pivotal taxa such as *Alectorobius* is mandatory if we are to understand the systematics of the Argasidae, particularly in the American Continent. Considering a practical approach, in this chapter we adopt but not necessarily endorse the classification of soft ticks into five genera, namely: *Antricola, Argas, Nothoaspis, Ornithodoros*, and *Otobius* [121].

The fauna of argasid ticks in Brazil is currently composed by 24 species [15]. Ticks of this family parasitize terrestrial vertebrates including amphibians in this country [25, 26]. With the exception of larvae from an undetermined *Ornithodoros* sp. collected on *Potus flavus* (Procionidae) [84], reports of soft ticks parasitizing mammals in the Brazilian Amazon are few and almost restricted to larvae collected on bats. Adults and nymphs have been collected either inside bat-inhabited caves or over massive rock formations where bats shelter (**Table 4**).

The first record of a soft tick in the Brazilian Amazon was published by North American entomologists Robert A. Cooley and Glen M. Kohls back in 1941. They received a tick collected inside a bat-inhabited three hole at Marajó Island (Pará state) and identified it as female of *Ornithodoros hasei* (mentioned as *Ornithodoros dunni*) [126]. Nowadays, we know that *O. hasei* is a wide spread species in Brazil and that three-roosting bats *Artibeus planirostris* and *Noctilio* spp*.* could act as main hosts [87, 130–132]. With the exception of recent collection of larvae on *A. planirostris* [87], knowledge on the distribution of *O. hasei* along the Brazilian Amazon is still poorly vague.

*Tadarida laticaudata* were the first bats reported to be parasitized by soft ticks in the Brazilian Amazon [133]. This report referred to *Ornithodoros setosus,* which was recently reclassified as *Nothoaspis setosus* [124]. In 1972, the bats *Noctilio labialis* and *T. laticaudata* were reported to be parasitized by *Ornithodoros stageri* in the Brazilian Amazon [129], which was recently confirmed [11]. A report in the Brazilian Amazon is a remarkable fact for *O. stageri*, since it also has distribution in Southern United States and Mexico [126, 134].

Bat inhabited caves constitute excellent niches to find argasid ticks. In particular, special, large colonies of insectivorous bats dwelling inside small chambers create high temperature conditions (28-40°C) where hundreds of *Antricola*, *Nothoaspis* and *Ornithodoros* ticks might occur [135]. Between 2004 to 2010 collections of ticks performed in hot caves from Porto Velho (Rondônia) fostered the description of two novel species (e.g., *Nothoaspis amazoniensis* and *Ornithodoros rondoniensis*) [122, 123]; the redescription of larvae and description of postlarval stages of *Ornithodoros marinkellei* [127], and the expansion of geographical distribution of *Antricola delacruzi* and *Antricola guglielmonei* into Brazilian Amazon [122]. At least for two species, *O. marinkellei* and *O. rondoniensis*, further collections performed in caves from Pará state underpined a larger distribution along the Amazon ecosystems [128].

Most amazing feature of soft ticks inhabiting hot caves, is that adaptation to this particular milieu seems to have modified their morphology and biology drastically. For instance, evidence showing that adults of *Antricola* ticks lack the capacity to


**7. Conclusion**

humans.

**55**

**Conflict of interest**

No conflict of interest declared.

Ticks parasitize a wide variety of vertebrates around the world such as amphibians, reptiles, mammals and birds, including humans. Although there are a variety of studies of parasitism by ticks on animals and humans in the different ecoregions of Brazil, in the Amazon biome they are scarce and fragmented. Because of this, it is

underestimated. In the Amazon, amphibians and reptiles were important hosts for *A. rotundatum*, *A. dissimile* and *A. humerale*, hard ticks common in these hosts in other regions of the country. Birds and mammals, on the other hand, proved important for the maintenance and dispersion of over 30 species of hard ticks in the Amazon, but there are still many gaps between hosts and their ticks in this region. Interestingly, immature *A. humerale* appears to be frequent on wild birds in this biome. No soft ticks have been reported parasitizing amphibians, reptiles, birds and/or non-flying mammals (except for a single record of *Ornithodoros* sp. on *P. flavus*), possibly due to scarcity of more studies in this biome. Some studies show that bats seem to have an important role spreading soft tick populations along Amazonian caves and that the diversity described for this group is still very poor. Two vector species of spotted fevers were found in the Amazon biomes parasitizing humans (*A. sculptum* and *A. ovale*). However, to date, there are no reports of BSF in humans in the region. Finally, it is of paramount importance that researchers (acarologists and epidemiologists) direct their attention to the Amazon biome, in order to fill the numerous existing gaps in the diversity of ticks in Brazil and prevent possible outbreaks of diseases transmitted by these ectoparasites to animals and

possible to infer that the diversity of ticks in the Brazilian Amazon is

*Ticks from the Brazilian Amazon: Species, Distribution and Host-Relations*

*DOI: http://dx.doi.org/10.5772/intechopen.94862*

#### **Table 4.**

*Soft ticks and their respective hosts occurring in the Brazilian Amazon.*

digest blood has been gained after transcriptomic analyses of their saliva [136]. In fact, scoop-like short mouth parts suggest that adults of *Antricola* do not suck blood [137]. Moreover, adults of *Antricola*, *O. marinkellei* and *O. rondoniensis* possess huge spiracular plates [122, 127, 137], perhaps necessary to thrive in such hot and extremely humid environments.

Except for larvae of *Ornithodoros kohlsi* collected on the bat *Molossops mattogrossensis* [30], prospections performed by our group between 2016 and 2019 focused mainly in the search for soft ticks inside natural cavities over massive rock formations. During these expeditions, *Ornithodoros cavernicolous* and *Ornithodoros peropteryx* were collected for the first time in caves from Monte Negro (Rondônia), extending their distribution of both species to the Brazilian Amazon [125]. Furthermore, analyses performed on large larvae isolated from *Molossus molossus* bats clarified that *O. setosus* was incorrectly classified in its original description. Indeed, *O. setosus* matches morphologically and molecularly within the genus *Nothoaspis* therefore the statement of *N. setosus* n. comb. was proposed [124]. It is important to note that our last collections performed at Monte Negro included several morphotypes of *Ornithodoros* pending formal description. Consequently, the fauna of soft ticks occurring in the Brazilian Amazon is likely to increase soon.

*Ticks from the Brazilian Amazon: Species, Distribution and Host-Relations DOI: http://dx.doi.org/10.5772/intechopen.94862*
