Cattle Farming and Plantation Forest are Associated with Bartonella Occurrence in Wild Rodents

Bartonella spp. are intracellular hemotropic bacteria primarily transmitted by arthropod vectors to various mammalian hosts, including humans. In this study, we conducted a survey on wild populations of sigmodontine rodents, Akodon azarae and Oxymycterus rufus, inhabiting the Paraná River delta region. The study involved eight grids organized in a crossed 2 × 2 design, where four of the grids were exposed to cattle while the other four were not, and four grids were located in implanted forest while the remaining four were in natural grasslands. Our objective was to examine whether the occurrence of Bartonella spp. in rodents was associated with silvopastoral activities (cattle raising associated with timber production) conducted in the region. Additionally, we evaluated the associations between Bartonella infection and other environmental and host factors. We present compelling evidence of a significant positive association between Bartonella prevalence and the presence of implanted forests and cattle. Furthermore, we identified the presence of a Bartonella genotype related to the pathogen Bartonella rochalimaea, infecting both A. azarae and Ox. rufus. These findings suggest that anthropogenic land-use changes, particularly the development of silvopastoral practices in the region, may disrupt the dynamics of Bartonella.

[Autochthonous Rickettsia parkeri rickettsiosis in the Paranaense Forest, Misiones, Argentina]

We report an autochthonous case of Rickettsia parkeri rickettsiosis occurred in June 2018 in a forested area of the Urugua-í Provincial Park, Misiones, Argentina. No previous records of this disease in humans have been previously reported in this region. The epidemiological, ecological, clinical, and laboratory features required for a proper diagnosis and adequate treatment are described here. The fact of considering rickettsiosis as a differential diagnosis in a patient with exanthematic acute febrile syndrome is highlighted, being the epidemiological history of exposure to the vector (ticks of the genus Amblyomma) an essential element.

Detection of Neorickettsia sp. in Oligoryzomys flavescens rodent from a protected urban area in Buenos Aires City (Argentina)

Rodents play an important role in vector-borne pathogens cycle. To detect Anaplasma, Ehrlichia, Neorickettsia, Rickettsia and Borrelia species in rodents from a protected urban area in Buenos Aires City (Argentina) were analyzed 203 organ pools of Mus musculus, Oligoryzomys flavescens, Rattus norvegicus, Deltamys kempi and Scapteromys aquaticus by PCR. Only one O. flavescens (1.2%) was positive by PCR for 16S rRNA fragment for the Anaplasmataceae family and the sequence had 99.7% identity with Neorickettsia risticii. Plus, the sequence obtained for a fragment of the p51 gene for the genus Neorickettsia from positive sample had 95.3-96.1% identity with N. risticii found previously in bats Tadarida brasiliensis from Buenos Aires City. Our study presents the first finding of Neorickettsia in rodents from natural environment, but further studies are necessary about these vector-borne bacteria and the rol of rodents in its epidemiology.

Rickettsia spp., Ehrlichia sp. and Candidatus Midichloria sp. associated to ticks from a protected urban area in Buenos Aires City (Argentina)

The aim of this study was to determine the infection with Rickettsiales in ticks and birds from the main protected urban area of Buenos Aires City (Argentina). One Amblyomma aureolatum (0.2%) and one Ixodes auritulus (0.1%) were positive by PCR targeting Rickettsia 23S-5S rRNA intergenic spacer. Phylogenetic analysis shows to findings in A. aureolatum are closely to Rickettsia bellii and for I. auritulus are related to 'Candidatus Rickettsia mendelii'. One I. auritulus (0.1%) and three A. aureolatum (0.6%) were positive by PCR for a fragment of the 16S rRNA gene of the Anaplasmataceae family. The sequences obtained from A. aureolatum were phylogenetically related to Midichloriaceae endosymbionts. The sequence from I. auritulus s.l. had 100% identity with Ehrlichia sp. Magellanica from Chile and two genotypes of Ehrlichia sp. from Uruguay. The results of our study show that Rickettsia and Ehrlichia are present in ticks in the main protected urban area of Buenos Aires City.

A novel Ehrlichia strain (Rickettsiales: Anaplasmataceae) detected in Amblyomma triste (Acari: Ixodidae), a tick species of public health importance in the Southern Cone of America

The aim of this work was to report the detection of a putative novel Ehrlichia strain associated with the tick Amblyomma triste. Free-living adult ticks determined as A. triste were collected by drag-sampling in Argentina and Uruguay. Molecular detection of Ehrlichia agents was performed targeting three different loci: 16S rRNA gene, dsb gene and a fragment of groESL heat shock operon. In total, 164 adults of A. triste (38 from INTA E.E.A Delta del Paraná in Argentina and 126 from Toledo Chico in Uruguay) were analyzed. One tick (0.6%) collected in INTA E.E.A. Delta del Paraná (Argentina) was positive. The phylogenetic analyses show that the Ehrlichia strain found in this study (named Ehrlichia sp. strain Delta) represents an independent lineage within the genus Ehrlichia, close to E. chaffeensis and E. muris. This is also the first report of an Ehrlichia agent infecting the tick A. triste. The medical and veterinary significance of Ehrlichia sp. strain Delta remains to be demonstrated. However, it is important to mention that adults of A. triste are aggressive to humans and domestic mammals. Therefore, the potential role of A. triste in the transmission of Ehrlichia agents to humans or domestic animals across its distributional range should be highlighted, even more considering that Ehrlichia sp. strain Delta is phylogenetically related to the zoonotic E. chaffeensis, which is recognized as pathogenic to both humans and animals.

Molecular detection and identification of Bartonella in the cat flea Ctenocephalides felis felis collected from companion animals in a border area in northeastern Argentina

Molecular methods were used to detect and identify Bartonella species in the cat fleas Ctenocephalides felis felis from Puerto Iguazú, a border area in northeastern Argentina. The fleas were collected from 12 household animals, 9 dogs (Canis lupus familiaris) and 3 cats (Felis silvestris catus) during July 2016. Out of 15C. f. felis analyzed for PCR, only one flea collected from a cat was positive (6.66%) in screened for Bartonella spp. based on the gltA gene. Bartonella clarridgeiae was identified in the genetic analyses, this specimen clustered monophyletically with others B. clarridgeiae isolated from different geographical origins (1.0 PP), even, all shared the same haplotype. The results obtained provide evidence of the presence of B. clarridgeiae in cat fleas from Argentina suggesting the probable presence of related flea-borne diseases in the region and the role of cat fleas in the transmission of Bartonella among mammals including humans.

Borrelia spp. in ticks and birds from a protected urban area in Buenos Aires city, Argentina

This study was aimed to know epidemiological aspects of Borrelia spp. in a protected urban area of Buenos Aires city, Argentina, where thousands of people visit this area for recreational purposes. Ticks were collected from vegetation, birds and dogs. Three hundred and forty birds belonging to 43 species, 41 genera, 18 families and six orders were captured (90.3% corresponded to the order Passeriformes). One hundred and twenty ticks were collected from 47 birds (13.8%) belonging to 10 species (23.2%), all of them from to the order Passeriformes (Emberizidae, Furnariidae, Parulidae, Thraupidae, Troglodytidae, Turdidae). Ticks were identified as Ixodes auritulus (56 larvae, 44 nymphs and 8 females) and Amblyomma aureolatum (1 larva and 11 nymphs). One thousand and ninety-one ticks collected from vegetation, 100 ticks collected from birds, and 89 ticks from dogs were tested for Borrelia infection by PCR trials targeting the flagellin (fla) and 16S rRNA genes. In addition, 101 blood and 168 tissue samples from birds were analyzed. Nine nymphs of A. aureolatum (2.1%) and four nymphs of I. auritulus (0.7%) collected from vegetation were positive. Five nymphs of A. aureolatum (45.4%), and five pools of larvae (minimum infection rate 13.5%), 18 nymphs (40.9%) and one female (14.3%) of I. auritulus collected on birds were also positive. The remaining samples were negative. The phylogenetic tree generated with fla sequences shows that seven of the eight different haplotypes of Borrelia detected in I. auritulus conform an independent lineage within the Borrelia burgdorferi sensu lato complex together with sequences of Borrelia sp. detected in I. auritulus from Canada and Uruguay. The fla sequences of Borrelia obtained from A. aureolatum and one sequence of a single specimen of I. auritulus conform a phylogenetic group with Borrelia turcica, Borrelia sp. isolated from a tortoise in Zambia, Borrelia spp. detected in Amblyomma maculatum from USA and Amblyomma longirostre from Brazil. The epidemiological risk that implies the infection with Borrelia genospecies associated with I. auritulus seems to be low because this tick is not aggressive to humans, but it helps to maintain borrelial spirochetes in the enzootic transmission cycles. The pathogenicity to humans of the Borrelia found in A. aureolatum is unknown; however, adults of this tick species are known to bite humans. This is the first report of the presence of Borrelia in A. aureolatum. Further investigations are necessary to know the risk of transmission of borreliosis by hard ticks in the study area.

Molecular characterization of Ehrlichia canis infecting dogs, Buenos Aires

Canine monocytic ehrlichiosis (CME) is a worldwide potentially fatal tick-borne rickettsial disease of dogs caused by Ehrlichia canis and transmitted by Rhipicephalus sanguineus sensu lato. CME diagnosis includes indirect (serology) and direct (e.g. blood smears and PCR) methods. PCR is more sensitive and specific than direct microscopic examination and positive PCR results confirm infection, whereas positive serologic test results only confirm exposure. The aim of the present study was to perform a molecular characterization of E. canis from canine samples of the Metropolitan Area of Buenos Aires. We studied 223 blood samples of dogs submitted to our institute for CME diagnoses. The samples were initially screened for Anaplasmataceae family by PCR, resulting in 30 positive dogs (13.4%). Subsequently, positive DNAs were analyzed by nested PCR 16S rRNA specific for E. canis or Anaplasma platys, resulting in 15 (6.7%) and 16 (7.2%) positive dogs, respectively. For molecular characterization, samples positive for E. canis were subjected to amplification of a fragment of the dsb and p28 genes. The nucleotide sequences obtained for the dsb fragment resulted in 100% identity with others E. canis found in dogs from different regions of worldwide. The nucleotide sequences obtained for p28 gene resulted in 100% of identity with each other and closely with E. canis str. Jaboticabal (Brazil). Identity with others sequences of E. canis ranged from 76.9 to 79.7%. The occurrence of canine cases molecularly confirmed in Metropolitan Area of Buenos Aires highlights the need for more studies in order to understand epidemiological factors associated with CME, especially the disease transmission dynamic in South America given the existence of two lineages of R. sanguineus sensu lato with different vectorial capacity for transmission of E. canis.

[Molecular detection of Rickettsia massiliae and Anaplasma platys infecting Rhipicephalus sanguineus ticks and dogs, Bahía Blanca (Argentina)]

BACKGROUND

Rickettsioses, ehrlichioses and anaplasmoses are caused by Gram negative obligate intracellular bacteria and transmitted mainly by arthropods.

AIM

To detect and perform the molecular characterization of these pathogens in ticks and domestic dogs in Bahia Blanca City (Buenos Aires, Argentina).

METHODS

Fifty six blood samples from dogs and 82 ticks (75 Rhipicephalus sanguineus and 7 Amblyomma tigrinum) were studied. The samples were analyzed by PCR for Rickettsia (intergenic space 23S-5S rRNA), Ehrlichia/Anaplasma (16S rRNA), and Anaplasma platys (16S rRNA).

RESULTS

12% of R. sanguineus resulted positive for Rickettsia, identified by sequencing as Rickettsia massiliae; and 37.5% of the canine blood samples analyzed were positive for A. platys. Molecular characterization was also performed by amplification of the fragment of the citrate synthase gene (gltA) (Rickettsia genus) and the groESL gene (A. platys). Phylogenetic trees were constructed using the neighbor-joining method. These trees revealed that sequences obtained are similar to those from other geographical regions.

CONCLUSION

The results indicate the presence of R. massiliae in R. sanguineus ticks for the second time in an urban area of South America and A. platys infection in dogs, being the southernmost region of Argentina where it has been notified.

Molecular characterization of Rickettsia massiliae and Anaplasma platys infecting Rhipicephalus sanguineus ticks and domestic dogs, Buenos Aires (Argentina)

Rickettsioses, ehrlichioses and anaplasmoses are emerging diseases that are mainly transmitted by arthropods and that affect humans and animals. The aim of the present study was to use molecular techniques to detect and characterize those pathogens in dogs and ticks from Buenos Aires city. We studied 207 Rhipicephalus sanguineus ticks and 52 canine blood samples from poor neighborhoods of Buenos Aires city. The samples were molecularly screened for the genera Rickettsia, Ehrlichia, and Anaplasma by PCR and sequencing. DNA of Rickettsia massiliae (3.4%) and Anaplasma platys (13.5%) was detected in ticks and blood samples, respectively. For characterization, the positive samples were subjected to amplification of a fragment of the 190-kDa outer membrane protein gene (spotted fever group rickettsiae) and a fragment of the groESL gene (specific for A. platys). A phylogenetic tree was constructed using the neighbor-joining method, revealing that the sequences were closely related to those of strains from other geographic regions. The results indicate that human and animal pathogens are abundant in dogs and their ticks in Buenos Aires city and portray the potentially high risk of human exposure to infection with these agents, especially in poor neighborhoods, where there is close contact with animals in an environment of poor health conditions.

[Molecular detection of Saint Louis encephalitis virus in mosquitoes in Buenos Aires]

During March 2013 a population of eared doves (Zenaida auriculata) was established in the center of City of Buenos Aires. Considering the role of these birds as host competent for Saint Louis encephalitis virus (SLEV), a CDC light trap was put in place to perform entomologic surveillance. During this month 5 pools of mosquitoes (n = 48) were collected and taxonomically determined. Three of them were classified as Culex pipiens (n = 10) and the other two were Culex spp. (n = 38). In this case, the mosquitoes species could not be determined due to that individuals were damaged. One of the Culex spp. pool was found to be positive for Saint Louis encephalitis virus by molecular techniques. This was then sequenced and classified as genotype III.