A high gene flow in populations of Amblyomma ovale ticks found in distinct fragments of Brazilian Atlantic rainforest.

The genetic structure of populations of the tick Amblyomma ovale from five distinct areas of the Brazilian Atlantic rainforest was evaluated via DNA sequencing and associated with the presence of domestic dogs acting as hosts at the edge of forest fragments. Ticks were collected from domestic dogs and from the environment between 2015 and 2017. Four collection areas were located in the surroundings and within the Serra do Mar State Park, São Paulo State (23°37'21"S, 45°24'43"W), where dogs were bimonthly monitored along 2 years using camera traps and GSM trackers. To determine the spatial limits of genetic structure, ticks collected upon dogs living near the Serra do Baturié, Ceará State (4°15'40"S, 38°55'54"W) were included as well. A total of 39 haplotypes of 16S rRNA and Cox 1 mitochondrial genes sequences were observed, with 27 of them coming from areas within the Serra do Mar State Park. No haplotype was shared between the Serra do Mar and the Serra do Baturié indicating isolation of tick populations at the scale of 2000 km. Although three different haplotype lineages of A. ovale occurred within the Serra do Mar State Park, no genetic structure was found across the study sites within this park, suggesting high tick gene flow across a range of 45 km. Monitoring data from domestic dogs and wild carnivores showed that these species share the same habitats at the forest edge, with dogs playing a likely limited role in tick dispersal. Our findings have important implications for understanding the genetic structure of wide spread A. ovale along Brazilian rainforest remnants, which can further be associated to tick-borne infectious agents, such as Rickettsia parkeri, and used for predicting future patterns of tick diversity in the Brazilian Atlantic rainforest.

Altitudinal Assessment of Amblyomma aureolatum and Amblyomma ovale (Acari: Ixodidae), Vectors of Spotted Fever Group Rickettsiosis in the State of São Paulo, Brazil.

Amblyomma aureolatum (Pallas) and Amblyomma ovale Koch are common ectoparasites of domestic dogs in São Paulo state, southeastern Brazil, where they are vectors of distinct spotted fever group rickettsioses, one caused by Rickettsia rickettsii (transmitted by A. aureolatum), and the other caused by Rickettsia sp. strain Atlantic rainforest (transmitted by A. ovale). For the present study, we performed an altitudinal assessment of all 1992-2012 records of A. aureolatum and A. ovale retrieved from a tick collection. The municipalities with A. ovale records presented significantly (P < 0.05) lower altitude than the ones with A. aureolatum records; the higher the altitude, the lower the chances for the occurrence of A. ovale and the greater the likelihood for the occurrence of A. aureolatum. Regarding A. aureolatum, the chances of finding it in municipalities between 101 and 700 m are nine times higher than in municipalities at ≤ 100 m, or 31.5 times higher in municipalities above 700 m, when compared with municipalities at ≤ 100 m. The reverse was observed for A. ovale, which had its odds ratio diminishing at higher altitudes. These findings have a major role to public health, as A. aureolatum is associated with the transmission of a highly lethal spotted fever (caused by R. rickettsii), whereas A. ovale is associated with the transmission of a milder spotted fever (caused by Rickettsia sp. strain Atlantic rainforest, a R. parkeri-like agent), both in the state of São Paulo.

Evaluation of completeness and timeliness of data in the National Information System for Notifiable Diseases for spotted fever in the state of São Paulo, Brazil, 2007-2017.

OBJECTIVE: to evaluate the completeness and timeliness of notifications of cases of spotted fever (SF) held on the Notifiable Health Conditions Information System (SINAN) in São Paulo State, Brazil, from 2007 to 2017. METHODS: this was a descriptive and ecological study of confirmed human cases of SF regarding completeness and timeliness of ten fields of the notification form (good if ≥ 90% for most variables); time series analysis was performed using the Prais-Winsten technique. RESULTS: we analyzed 736 records; among essential fields, only "Discharge date" showed poor completeness (68.5%). Timeliness was good for the "Investigation" and "Closure" fields; other time lapses were not adequate. CONCLUSION: in São Paulo state, data completeness was good for most variables, whereas timeliness was not adequate (except for "Closure" and "Investigation"), pointing to the need for health education and communication actions about SF.

Ecological aspects of Pintomyia fischeri and Migonemyia migonei in municipalities with Canine Visceral Leishmaniasis, State of São Paulo, Brazil.

The objective was to study the composition of sand fly species, the seasonal activity of the dominant species and correlation with average rainfall, sex association of the dominant species with domicile habitats and analyze different landscape scenarios for the two study sites in the municipalities of Itapevi and Mogi of the Crosses. Sandflies were captured with CDC(s) traps installed in three households at each study site for a period of 24 hours, biweekly for two years. A total of 2970 specimens were collected. The dominant species were P.fischeri and M.migonei. A statistically significant difference was registered between males and females of the two species in relation to the intra and peridomicile. The seasonal activity of both species showed a weak significant positive correlation with rainfall. The species P.fischeri and M.migonei may be potential vectors of CVL in the studied sites.

New records of Amblyomma ticks parasitizing neotropical primates in Brazil.

Amblyomma is an important tick genus for animal and human health, with some species being the vectors of zoonotic pathogens, such as Rickettsia rickettsii, in the Neotropical region. Knowing their hosts may help to understand the distribution of these agents and decrease the occurrence of clinical cases. Primates are intelligent and adaptable animals that can get close to humans in the search for food. So, they may be an important epidemiological link for the spread of these ticks. Beyond that, primates also suffer from these infections, serving as sentinels for different diseases. Thus, the present study aims to report the parasitism by Amblyomma spp. on six species of Neotropical primates from different locations in Brazil. The 337 collected ticks were morphologically identified using stereomicroscopes and taxonomic keys, and six distinct species of ticks were identified. We report here the first record of nymphs of the tick species Amblyomma cajennense sensu stricto on Alouatta belzebul, a male of Amblyomma fuscum on Alouatta guariba clamitans, nymphs of Amblyomma sculptum on Leontopithecus chrysopygus and Callithrix aurita, as well as nymphs of Amblyomma geayi on Saimiri collinsi. Of the 337 tick specimens collected, 256 (75,96%) were nymphs. The importance of primates in the life cycle of these species remains to be elucidated.

Genomic epidemiology unveils the dynamics and spatial corridor behind the Yellow Fever virus outbreak in Southern Brazil.

Despite the considerable morbidity and mortality of yellow fever virus (YFV) infections in Brazil, our understanding of disease outbreaks is hampered by limited viral genomic data. Here, through a combination of phylogenetic and epidemiological models, we reconstructed the recent transmission history of YFV within different epidemic seasons in Brazil. A suitability index based on the highly domesticated Aedes aegypti was able to capture the seasonality of reported human infections. Spatial modeling revealed spatial hotspots with both past reporting and low vaccination coverage, which coincided with many of the largest urban centers in the Southeast. Phylodynamic analysis unraveled the circulation of three distinct lineages and provided proof of the directionality of a known spatial corridor that connects the endemic North with the extra-Amazonian basin. This study illustrates that genomics linked with eco-epidemiology can provide new insights into the landscape of YFV transmission, augmenting traditional approaches to infectious disease surveillance and control.

Epidemiology of Brazilian spotted fever in the Atlantic Forest, state of São Paulo, Brazil.

The tick-borne bacterium Rickettsia rickettsii is the aetiological agent of Brazilian spotted fever (BSF). The present study evaluated tick infestations on wild and domestic animals, and the rickettsial infection in these animals and their ticks in 7 forest areas adjacent to human communities in the São Paulo Metropolitan Area (SPMA). The results were compared to ecological traits of each sampled area. Two main tick species, Amblyomma aureolatum and Rhipicephalus sanguineus, were collected from dogs. The major ticks found on small mammals and birds were Ixodes loricatus and Amblyomma longirostre, respectively. Both anti-R. rickettsii antibodies and R. rickettsii-infected ticks were detected on dogs from only 2 areas in the southern part of the SPMA, which were considered to be endemic for BSF; the remaining 5 areas were considered to be non-endemic. Ecologically, the BSF-endemic areas clearly differed from the non-endemic areas by the presence of significantly more degraded forest patches in the former. The present results corroborate historical observations that have indicated that all human cases of BSF in the SPMA were contracted in the southern part of this metropolitan area. However, not all forest patches in the southern part of the SPMA were shown to be associated with BSF endemism.

Human parasitism by the exotic tick Dermacentor variabilis (Parasitiformes: Ixodida) in Brazil: report of an imported case.

In June 2012, a tick was found parasitizing a man in the city of São Paulo, who had recently returned from a visit to Pennsylvania, in the northeast of the United States. The tick was removed and sent to the São Paulo State Department of Health, where it was identified as a male of the species Dermacentor variabilis (Say, 1821), according to the literature and taxonomic keys. The tick was subjected to a PCR test to search for rickettsiae, but the result was negative. The fact that a human entered Brazilian territory unaware that he was parasitized by a hard tick not belonging to the national tick fauna is significant because of the possibility that an exotic species could be introduced and take hold in this country. Another major risk to public health is that this arthropod could be infected with the bacterium Rickettsia rickettsii, as this ectoparasite is the main vector of Spotted Fever on the East Coast of North America.

Soft and hard ticks (Parasitiformes: Ixodida) on humans: A review of Brazilian biomes and the impact of environmental change.

Records of accidental parasitism by ticks in humans from Brazil are scarce, with most being reported by researchers who are parasitized during their research and by professionals who work with animals. In order to compile these records, an extensive literature review was carried out. Our revision includes studies published between 1909 and 2022, including nine species of the Argasidae family and 32 species of the Ixodidae family that were reported biting humans in the six biomes of the Brazilian territory. The species with the highest number of records of human parasitism was Amblyomma sculptum, followed by Amblyomma coelebs, Amblyomma cajennense sensu stricto, and Amblyomma brasiliense. The Atlantic Forest was the most frequent biome where human parasitism occurred, probably due to the greater number of inhabitants, universities, and researchers in the region; however, this does not mean that this biome is more conducive to the development of ticks and their parasitism in humans. In addition to Amblyomma ovale, a vector of Rickettsia parkeri in the country, two of the main species that act as vectors of Rickettsia rickettsii, A. sculptum, and Amblyomma aureolatum, have been reported, which is quite worrying considering that the wide distribution of the species and life stages most frequently mentioned in parasitism (i.e., nymphs and adults) are the ones that favour pathogen transmission. This research provides a significant contribution to the knowledge of tick species associated with human parasitism in Brazil; however, due to environmental change potentiated by deforestation and fires, it is expected that there will be a geographic expansion of some tick species and the pathogens that use them as a vector and an increase in human parasitism.

Long-term persistence of anti-Rickettsia rickettsii antibodies in capybaras, with passive transfer to offspring.

The bacterium Rickettsia rickettsii is the etiological agent of Brazilian spotted fever (BSF), and its most important vector to humans in Brazil is the tick Amblyomma sculptum. Capybaras are the main hosts of A. sculptum in many BSF-endemic areas and are considered valuable sentinels for BSF surveillance. This study aimed to assess the persistence of anti-R. rickettsii antibodies for long periods in capybaras and their passive transfer to offspring. For this purpose, three adult capybaras previously exposed to multiple infections with R. rickettsii were followed up until 3.1 years after their last exposure. During the study, one female delivered five cubs, of which three survived. Blood samples were collected monthly from adults and infants, and serum samples were titrated by indirect immunofluorescence assay (IFA) to determine endpoint titers of anti-R. rickettsii antibodies. All three adults remained seroreactive to R. rickettsii with high endpoint titers until the end of the study. All infants were seroreactive to R. rickettsii after birth and remained seroreactive for one to four months. This study showed that exposure of capybaras to R. rickettsii-infected A. sculptum ticks elicits a persistent antibody response. In addition, there was evidence of passive transfer of R. rickettsii-reactive antibodies to offspring.

Experimental infection of Amblyomma aureolatum ticks with Rickettsia rickettsii.

We experimentally infected Amblyomma aureolatum ticks with the bacterium Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever (RMSF). These ticks are a vector for RMSF in Brazil. R. rickettsii was efficiently conserved by both transstadial maintenance and vertical (transovarial) transmission to 100% of the ticks through 4 laboratory generations. However, lower reproductive performance and survival of infected females was attributed to R. rickettsii infection. Therefore, because of the high susceptibility of A. aureolatum ticks to R. rickettsii infection, the deleterious effect that the bacterium causes in these ticks may contribute to the low infection rates (<1%) usually reported among field populations of A. aureolatum ticks in RMSF-endemic areas of Brazil. Because the number of infected ticks would gradually decrease after each generation, it seems unlikely that A. aureolatum ticks could sustain R. rickettsii infection over multiple successive generations solely by vertical transmission.

Diffusion of sylvatic yellow fever in the state of São Paulo, Brazil.

We investigated the sylvatic yellow fever (SYF) diffusion process in São Paulo (SP) between 2016 and 2019. We developed an ecological study of SYF through autochthonous human cases and epizootics of non-human primates (NHPs) that were spatiotemporally evaluated. We used kriging to obtain maps with isochrones representative of the evolution of the outbreak and characterized its diffusion pattern. We confirmed 648 human cases of SYF in SP, with 230 deaths and 843 NHP epizootics. Two outbreak waves were identified: one from West to East (2016 and 2017), and another from the Campinas region to the municipalities bordering Rio de Janeiro, Minas Gerais, and Paraná and those of the SP coast (2017-2019). The SYF outbreak diffusion process was by contagion. The disease did not exhibit jumps between municipalities, indicating that the mosquitoes and NHPs were responsible for transmitting the virus. There were not enough vaccines to meet the population at risk; hence, health authorities used information about the epizootic occurrence in NHPs in forest fragments to identify priority populations for vaccination.

Domestic dogs as amplifying hosts of Rickettsia rickettsii for Amblyomma aureolatum ticks.

Brazilian spotted fever (BSF) is an acute infectious disease caused by the bacterium Rickettsia rickettsii, which is transmitted by different tick species. Due to deleterious effects caused on ticks, the horizontal transmission of R. rickettsii through amplifying hosts is crucial for its maintenance in tick populations among BSF-endemic areas. The tick Amblyomma aureolatum is the main vector of R. rickettsii in the São Paulo metropolitan area; nevertheless, it is not known which vertebrate could act as an amplifying host for this tick species. Herein, we evaluated the potential of domestic dogs - primary hosts for A. aureolatum adults in BSF-endemic areas - to act as amplifying hosts. For this purpose, A. aureolatum non-infected adults were allowed to feed on two groups of dogs: the control group (G1), composed of one dog not exposed to R. rickettsii; and, the infected group (G2), composed of three dogs infected with R. rickettsii via tick parasitism. All G2-dogs became ill, seroconverted to R. rickettsii, and rickettsial DNA was detected in 87% of the engorged females that fed on them. Transovarial transmission rate was estimated to be 25% and infected larvae successfully transmitted R. rickettsii to guinea-pigs, confirming transovarial transmission and vector competence. No rickettsial DNA was detected in individual samples of eggs or larvae, which precluded the estimation of filial infection rate, but implies that it was low. Our results suggest that domestic dogs act as amplifying hosts of R. rickettsii for A. aureolatum ticks in BSF-endemic areas in Brazil.

Assessing Diversity, Plasmodium Infection and Blood Meal Sources in Mosquitoes (Diptera: Culicidae) from a Brazilian Zoological Park with Avian Malaria Transmission.

Avian malaria parasites are widespread parasites transmitted by Culicidae insects belonging to different genera. Even though several studies have been conducted recently, there is still a lack of information about potential vectors of Plasmodium parasites, especially in Neotropical regions. Former studies with free-living and captive animals in São Paulo Zoo showed the presence of several Plasmodium and Haemoproteus species. In 2015, a pilot study was conducted at the zoo to collect mosquitoes in order to find out (i) which species of Culicidae are present in the study area, (ii) what are their blood meal sources, and (iii) to which Plasmodium species might they be potential vectors. Mosquitoes were morphologically and molecularly identified. Blood meal source and haemosporidian DNA were identified using molecular protocols. A total of 25 Culicidae species were identified, and 6 of them were positive for Plasmodium/Haemoproteus DNA. Ten mosquito species had their source of blood meal identified, which were mainly birds, including some species that were positive for haemosporidian parasites in the former study mentioned. This study allowed us to expand the list of potential vectors of avian malaria parasites and to improve our knowledge of the evolutionary and ecological relationships between the highly diverse communities of birds, parasites, and vectors present at São Paulo Zoo.

Amblyomma imitator ticks as vectors of Rickettsia rickettsii, Mexico.

Real-time PCR of Amblyomma imitator tick egg masses obtained in Nuevo Leon State, Mexico, identified a Rickettsia species. Sequence analyses of 17-kD common antigen and outer membrane protein A and B gene fragments showed to it to be R. rickettsii, which suggested a potential new vector for this bacterium.

Survey of ticks (Acari: Ixodidae) and their rickettsia in an Atlantic rain forest reserve in the State of São Paulo, Brazil.

The current study investigated the occurrence of ticks and their rickettsiae in the Serra do Mar State Park, which encompasses one of the largest Atlantic rain forest reserves of Brazil. From July 2008 to June 2009, a total of 2439 ticks (2,196 free living and 243 collected on hosts) was collected, encompassing the following 13 species: Amblyomma aureolatum (Pallas), Amblyomma brasiliense AragAo, Amblyomma dubitatum Neumann, Amblyomma fuscum Neumann, Amblyomma incisum Neumann, Amblyomma longirostre (Koch), Amblyomma naponense (Packard), Amblyomma nodosum Neumann, Amblyomma ovale Koch, Haemaphysalis juxtakochi Cooley, Ixodes aragaoi Fonseca, Ixodes loricatus Neumann, and Rhipicephalus sanguineus (Latreille). Ticks were submitted to polymerase chain reaction assays targeting portions of the rickettsial genes gltA and ompA. Polymerase chain reaction products were DNA sequenced and compared with corresponding sequences available in GenBank. Rickettsia bellii, a rickettsia of unknown pathogenicity, was detected in one A. aureolatum, one A. ovale, and three A. incisum specimens. At least 8.8% (3/34) of the free-living A. ovale ticks, 13.6% (8/59) of the A. ovale ticks collected from dogs, and 1.9% (1/54) of the R. sanguineus (Latreille) ticks were found to be infected by Rickettsia sp strain Atlantic rain forest, a novel strain that has been shown to cause an eschar-associated spotted fever in the state of Sho Paulo. Our results suggest that A. ovale is the vector of Rickettsia sp strain Atlantic rain forest in the state of São Paulo.

Implications of domestic dogs in the epidemiology of Rickettsia parkeri strain Atlantic rainforest and Rangelia vitalii in Southeastern Brazil.

This study aimed to evaluate the occurrence of diseases transmitted by Amblyomma ovale in 61 dogs monitored for three years through collections of ticks and blood, interviews, telemetry and camera traps in three areas of Serra do Mar State Park, Brazil. Blood samples were used to investigate infection by Rangelia vitalii by real-time TaqMan PCR and Rickettsia parkeri by IIFA. The collected ticks were submitted to conventional PCR to investigate the presence of R. parkeri . These data were compared with the monitoring results and interviews with the owners. Dogs considered as companion presented a risk of infection by R. parkeri strain Mata Atlantica 5.4 times higher than those not considered as companion (p = 0.009). Dogs that had at least one A. ovale collected during the campaigns had a 10 times higher risk of infection by R. parkeri strain Mata Atlantica than those who did not (p = 0.009). One dog positive for R. vitalii by real-time TaqMan PCR was parasitized by A. ovale frequently during monitoring. Sequenced ompaA - positive DNA samples had 100% identity of R. parkeri strain Mata Atlantica clone As106. From the findings, it is urgent to control domestic dogs around rainforests to reduce zoonoses transmission.

Life cycle of Ixodes luciae (Acari: Ixodidae) in the laboratory.

The life cycle of Ixodes luciae was evaluated for five consecutive generations in the laboratory. Wild mice Calomys callosus and laboratory rats Rattus norvegicus were used as hosts for larvae and nymphs. For adult ticks, opossums Didelphis aurita were used as hosts. Off-host developmental periods were observed in an incubator at 27 degrees C and 95% RH. The life cycle of I. luciae lasted 95-97 days, excluding prefeeding periods. C. callosus, one of the natural host species for I. luciae immature stages, was shown to be much more suitable than the artificial host R. norvegicus. Significantly (P < 0.05), more larvae and nymphs successfully fed on C. callosus than on R. norvegicus. When tick-naïve C. callosus were exposed to three consecutive larval infestations at 24-day intervals, recovery of engorged larvae were greater in the second and third infestations, indicating that previous infestations did not induce acquired resistance to ticks. Larval feeding period typically varied from 5 to 10 days on R. norvegicus, but was significantly (P < 0.05), longer on C. callosus (range, 7-34 days). The majority (71.7%) of I. luciae adult females successfully fed and oviposited after exposed to D. aurita. Mean engorged weight (581.9 mg; range, 237.1-796.0 mg) of these females were much higher than those previously reported for other New World Ixodes species. Our results are in accordance to the current literature that appoints opossums Didelphidae and small rodents (e.g., C. callosus) natural hosts for I. luciae immature and adult stages, respectively.

A human case of spotted fever caused by Rickettsia parkeri strain Atlantic rainforest and its association to the tick Amblyomma ovale.

BACKGROUND: Rickettsia parkeri strain Atlantic rainforest has emerged in Brazil during the last 10 years, with three laboratory-confirmed human cases. While these cases were epidemiologically associated with the tick Amblyomma ovale, in none of them the tick specimens that bit the patients could be identified. RESULTS: We report a clinical case of spotted fever rickettsiosis that was acquired in an Atlantic forest area in Bahia state, northeast Brazil. The case was determined to be caused by R. parkeri strain Atlantic rainforest, based on molecular analysis of the crust removed from the tick bite site (inoculation eschar) of the patients' skin. DNA extracted from the crust yielded partial sequences of three rickettsial genes (gltA, ompA and ompB), which were 99-100% identical to R. parkeri strain Atlantic rainforest. The tick specimen that was attached to patient skin was identified as a female of A. ovale. CONCLUSIONS: We report the fourth confirmed case of spotted fever rickettsiosis caused by R. parkeri strain Atlantic rainforest, providing to our knowledge for the first time, direct evidence of R. parkeri strain Atlantic rainforest transmission by A. ovale.

Comparative susceptibility of larval stages of Amblyomma aureolatum, Amblyomma cajennense, and Rhipicephalus sanguineus to infection by Rickettsia rickettsii.

The current study compared the susceptibility of larval stages of Amblyomma cajennense (F.), Amblyomma aureolatum (Pallas), and Rhipicephalus sanguineus (Latreille) to infection by a Brazilian strain of Rickettsia rickettsii. Guinea pigs experimentally infected by R. rickettsii were simultaneously infested by larvae of the three tick species. Recovered engorged larvae were allowed to molt to nymphs and held in an incubator at 23 degrees C and 85-90% RH. Subsequent flat nymphs were tested for rickettsial infection by polymerase chain reaction (PCR). Concomitant infestations with sibling ticks on noninfected guinea pigs (control) were done. While 10-60% of the A. cajennense nymphs were shown to be infected by R. rickettsii, both A. aureolatum and R. sanguineus were highly susceptible to R. rickettsii, since 80-100% of their nymphs were shown to be infected in the corresponding trials. Most of the engorged larvae (approximately 70-95%), regardless of being infected or not, successfully molted to nymphs. Mortality rates for engorged larvae tended to be statistically similar (P > 0.05) for ticks recovered from R. rickettsii-infected and noninfected guinea pigs, within each tick species. The only exceptions were the significantly higher mortalities (P < 0.05) for engorged A. cajennense larvae recovered from two infected guinea pigs. Therefore, A. cajennense was less susceptible to R. rickettsii infection than A. aureolatum and R. sanguineus, while feeding on rickettsemic guinea pigs. These two later species were similarly highly susceptible.