Background
Rickettsia
bacteria are responsible for diseases in humans and animals around the world, however few details are available regarding its ecology and circulation among wild animals and human populations at high transmission risk in Brazil. The aim of this study was to investigate the occurrence of ticks and
Rickettsia
spp. in wild boars, corresponding hunting dogs and hunters.
Methods
Serum samples and ticks were collected from 80 free-range wild boars, 170 hunting dogs and 34 hunters from southern and central-western Brazil, from the Atlantic Forest and Cerrado biomes, respectively, between 2016 and 2018. Serum samples were tested by indirect immunofluorescent-antibody assay (IFA) to detect IgG antibodies against
Rickettsia rickettsii
,
Rickettsia parkeri
,
Rickettsia bellii
,
Rickettsia rhipicephali
and
Rickettsia amblyommatis
. Tick species were identified by morphological taxonomic keys, as previously described. A total of 164 ticks including
A
.
sculptum
,
A
.
brasiliense
and
A
.
aureolatum
were tested in PCR assays for Spotted Fever Group (SFG)
Rickettsia
spp.
Results
A total of 58/80 (72.5%) wild boars, 24/170 (14.1%) hunting dogs and 5/34 (14.7%) hunters were positive (titers ≥ 64) to at least one
Rickettsia
species. A total of 669/1,584 (42.2%) ticks from wild boars were identified as
Amblyomma sculptum
, 910/1,584 (57.4%) as
Amblyomma brasiliense
, 4/1,584(0.24%) larvae of
Amblyomma
spp. and 1/1,584 (0.06%) nymph as
Amblyolmma dubitatum
. All 9 ticks found on hunting dogs were identified as
Amblyomma aureolatum
and all 22 ticks on hunters as
A
.
sculptum
. No tested tick was positive by standard PCR to SFG
Rickettsia
spp.
Conclusions
The present study was the concomitant report of wild boar, hunting dog and hunter exposure to SFG rickettsiae agents, performed in two different Brazilian biomes. Wild boar hunting may increase the risk of human exposure and consequently tick-borne disease Wild boars may be carrying and spreading capybara ticks from their original habitats to other ecosystems. Further studies can be required to explore the ability of wild boars to infecting ticks and be part of transmission cycle of
Rickettsia
spp.