Infectious Diseases in Wild Animals in Utah VI. Experimental Infection of Birds with
            <i>Rickettsia rickettsii</i>

Lundgren, D.L.; Thorpe, Bert D.; Haskell, C.D.

doi:10.1128/jb.91.3.963-966.1966

Cited by 15 publications

(10 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…11 , with bacteremia lasting from 5 to 11 DPI (6 days) in capybaras exposed by intraperitoneal inoculation. In addition, similar extents (8-12 days) were registered in diverse studies with other rodent species in the United States 9,32 . In contrast, this bacteremic period is shorter than the 26 days reported for the opossum Didelphis aurita in Brazil 10 , or the 4 week-period reported for Didelphis virginiana in the United States 33 .…”

Section: Infected Capybarassupporting

confidence: 68%

Clinical and serological evaluation of capybaras (Hydrochoerus hydrochaeris) successively exposed to an Amblyomma sculptum-derived strain of Rickettsia rickettsii

Ramírez-Hernández

Uchoa²,

Serpa

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Brazilian spotted fever (BSf), caused by Rickettsia rickettsii, is the most lethal tick-borne disease in the western hemisphere. in Brazil, Amblyomma sculptum ticks are the main vector. capybaras (Hydrochoerus hydrochaeris), the largest living rodents of the world (adults weighing up to 100 Kg), have been recognized as amplifying hosts of R. rickettsii for A. sculptum in BSf-endemic areas; i.e., once primarily infected, capybaras develop bacteremia for a few days, when feeding ticks acquire rickettsial infection. We conducted experimental infections of five capybaras with an A. sculptum-derived strain of R. rickettsii and performed clinical and bacteremia evaluation during primary and subsequent infections. Bacteremia was detected in all capybaras during primary infection, but not in subsequent infections. All animals seroconverted to R. rickettsii (titres range: 64-32,768), and remained seropositive throughout the study. primary infection resulted in clinical spotted fever illness in four capybaras, of which two had a fatal outcome. Subsequent infections in seropositive capybaras resulted in no clinical signs. capybaras developed a sustained immune response that prevented a second bacteremia. this condition may imply a high reproduction rate of capybaras in BSf-endemic areas, in order to continuously generate capybaras susceptible to bacteremia during primary infection. The bacterium Rickettsia rickettsii is the etiological agent of Rocky Mountain spotted fever, also known in Brazil as Brazilian spotted fever (BSF), a disease that has been registered in different American countries including Canada, United States, Mexico, Costa Rica, Panama, Colombia and Argentina 1,2. This bacterium is transmitted by different tick species throughout Americas [i.e., Dermacentor variabilis, Dermacentor andersoni, Rhipicephalus sanguineus sensu lato (s.l.), Amblyomma cajennense species complex, and Amblyomma aureolatum] 2. In Brazil, in the southeastern region, Amblyomma sculptum (a member of A. cajennense species complex) is the main incriminated vector, for which capybaras (Hydrochoerus hydrochaeris) and horses act as primary hosts for all parasitic stages 3,4. BSF is the most lethal tick-borne disease in Brazil with increasing numbers of cases and deaths. Between 2007 and 2015, 17,117 suspected cases of spotted fever (including other spotted fever group rickettsioses) were reported and 1,245 were confirmed as SFG rickettsioses in 12 Brazilian states from all regions 1. Moreover, case-fatality rates have attained values of 30% or higher, which could be associated with low index of suspicion and misdiagnosis by health-care professionals and exposure to particular eco-epidemiological risk factors 1 .

show abstract

Section: Infected Capybarassupporting

confidence: 68%

Clinical and serological evaluation of capybaras (Hydrochoerus hydrochaeris) successively exposed to an Amblyomma sculptum-derived strain of Rickettsia rickettsii

Ramírez-Hernández

Uchoa²,

Serpa

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…For example, one may (rightly) be forbidden to infect wild animals experimentally. A possible exception would be to add ecoimmunological analysis onto epidemiological susceptibility studies such as those used to assess the potential for wild hosts to sustain transmission of zoonotic infections such as rickettsia, brucellosis, or monkeypox (Lundgren & Thorpe 1966a;Lundgren, Thorpe & Haskell 1966b;Xiao et al 2005;Nol, Olsen & Rhyan 2009).…”

Section: E S I G N S 2 -4 : E X P E R I M E N T S I N W H I C H I Nmentioning

confidence: 99%

Fitness consequences of immune responses: strengthening the empirical framework for ecoimmunology

et al. 2010

View full text Add to dashboard Cite

Summary 1.Ecoimmunologists aim to understand the costs, benefits, and net fitness consequences of different strategies for immune defense. 2. Measuring the fitness consequences of immune responses is difficult, partly because of complex relationships between host fitness and the within-host density of parasites and immunological cells or molecules. In particular, neither the strongest immune responses nor the lowest parasite densities necessarily maximize host fitness. 3. Here, we propose that ecoimmunologists should routinely endeavour to measure three intertwined parameters: host fitness, parasite density, and relevant immune responses. We further propose that analyses of relationships among these traits would benefit from the statistical machinery used for analyses of phenotypic plasticity and ⁄ or methods that are robust to the bi-directional causation inherent in host-parasite relationships. For example, analyses of how host fitness depends upon parasite density, which is an evolutionary ecological definition of tolerance, would benefit from these more robust methods. 4. Together, these steps promote rigorous quantification of the fitness consequences of immune responses. Such quantification is essential if ecoimmunologists are to decipher causes of immune polymorphism in nature and predict trajectories of natural selection on immune defense.

show abstract

“…19 This last requirement is very important if one considers that once living in an endemic area, each individual host will develop only one rickettsemia (lasting for a few days or weeks) during its lifetime, since after the rickettsemia, the animal develops strong immunity against the agent, precluding a second rickettsemia. 20,21 In Brazil, at least two animals are incriminated to act as efficient amplifier hosts for A. cajennense: capybaras and opossums (Didelphis spp.). Capybaras are abundant and act as primary hosts for A. cajennense in all RMSFendemic areas of the state of São Paulo, where A. cajennense is the vector, in contrast to many other non-endemic areas for RMSF with abundant populations of A. cajennense sustained by horses in the absence of capybaras.…”

Section: Introductionmentioning

confidence: 99%

“…29 This has been the longest rickettsemic period ever reported for R. rickettsii infection; other animals develop rickettsemia usually lasting for 1 to 2 weeks. 18,20 Opossums are also prolific, the female births 5 to 9 young between 1 and 3 times per year. Finally, a recent study in our laboratory has shown that R. rickettsii-experimentally-infected opossums (Didelphis aurita) developed rickettsemia lasting for 3 to 4 weeks, when ∼5-20% of the A. cajennnense immature ticks that fed on them became infected by R. rickettsii, as shown by PCR performed on the ticks after molting.…”

Section: Introductionmentioning

confidence: 99%

Ecology of Rickettsia in South America

Labruna

2009

Annals of the New York Academy of Sciences

382

256

View full text Add to dashboard Cite

Until the year 2000, only three Rickettsia species were known in South America: (i) Rickettsia rickettsii, transmitted by the ticks Amblyomma cajennense, and Amblyomma aureolatum, reported in Colombia, Argentina, and Brazil, where it is the etiological agent of Rocky Mountain spotted fever; (ii) Rickettsia prowazekii, transmitted by body lice and causing epidemic typhus in highland areas, mainly in Peru; (iii) Rickettsia typhi, transmitted by fleas and causing endemic typhus in many countries. During this new century, at least seven other rickettsiae were reported in South America: Rickettsia felis infecting fleas and the tick-associated agents Rickettsia parkeri, Rickettsia massiliae, Candidatus"Rickettsia amblyommii,"Rickettsia bellii, Rickettsia rhipicephali, and Candidatus"Rickettsia andeanae." Among these other rickettsiae, only R. felis, R. parkeri, and R. massiliae are currently recognized as human pathogens. R. rickettsii is a rare agent in nature, infecting < or =1% individuals in a few tick populations. Contrastingly, R. parkeri, Candidatus"R. amblyommii," R. rhipicephali, and R. bellii are usually found infecting 10 to 100% individuals in different tick populations. Despite rickettsiae being transmitted transovarially through tick generations, low infection rates for R. rickettsii are possibly related to pathogenic effect of R. rickettsii for ticks, as shown for A. aureolatum under laboratory conditions. This scenario implies that R. rickettsii needs amplifier vertebrate hosts for its perpetuation in nature, in order to create new lines of infected ticks (horizontal transmission). In Brazil, capybaras and opossums are the most probable amplifier hosts for R. rickettsii, among A. cajennense ticks, and small rodents for A. aureolatum.

show abstract

Infectious Diseases in Wild Animals in Utah VI. Experimental Infection of Birds with Rickettsia rickettsii

Cited by 15 publications

References 2 publications

Clinical and serological evaluation of capybaras (Hydrochoerus hydrochaeris) successively exposed to an Amblyomma sculptum-derived strain of Rickettsia rickettsii

Clinical and serological evaluation of capybaras (Hydrochoerus hydrochaeris) successively exposed to an Amblyomma sculptum-derived strain of Rickettsia rickettsii

Fitness consequences of immune responses: strengthening the empirical framework for ecoimmunology

Ecology of Rickettsia in South America

Contact Info

Product

Resources

About