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Serological Evidence of Rickettsia Exposure among Patients with Unknown Fever Origin in Angola, 2016-2017

Publication . Barradas, P.F.; Neto, Z.; Mateus, T.L.; Teodoro, A. C.; Duarte, L.; Gonçalves, H.; Ferreira, P.; Gärtner, F.; Sousa, R.; Amorim, I.

Spotted fever group Rickettsia (SFGR) is one among the aetiologies that cause fever of unknown origin in Angola. Despite their occurrence, there is little information about its magnitude in this country either because it is misdiagnosed or due to the lack of diagnostic resources. For this purpose, eighty-seven selected malaria- and yellow fever-negative serum specimens collected between February 2016 and March 2017 as part of the National Laboratory of Febrile Syndromes, from patients with fever (≥37.5°C) for at least 4 days and of unknown origin, were screened for Rickettsia antibodies through an immunofluorescence assay (IFA). Serological results were interpreted according to the 2017 guidelines for the detection of Rickettsia spp. Three seroreactive patients had detectable IgM antibodies to Rickettsia with an endpoint titre of 32 and IgG antibodies with endpoint titres of 128 and 256. These findings supported a diagnosis of Rickettsia exposure amongst these patients and highlight that rickettsioses may be among the cause of unknown febrile syndromes in Angola. Therefore, physicians must be aware of this reality and must include this vector-borne disease as part of aetiologies that should be considered and systematically tested in order to delineate appropriate strategies of diagnostic and control of Rickettsia in Angola.

2020-08-24Journal article

Open access

Molecular detection of Rickettsia spp. in ticks and feas collected from rescued hedgehogs (Erinaceus europaeus) in Portugal

Publication . Barradas, P. F.; Mesquita, J. R.; Mateus, T. L.; Ferreira, P.; Amorim, I.; Gartner, F.; Sousa, R.

Hedgehogs (e.g., Erinaceus europaeus, E. roumanicus) are wild mammals that frequently are observed near residential areas. The aim of this study was to investigate ticks and feas collected from European hedgehogs in Portugal and to evaluate the prevalence of Rickettsia in those ectoparasites. Ticks and feas were identifed by morphological and molecular methods, and molecular detection by PCR and genotypic characterization of Rickettsia spp. was performed targeting ompB, ompA and gltA gene fragments. In total, 1892 ticks and 213 feas were collected from 33 rescued European hedgehogs captured in seven districts of the north and centre of Portugal. Two tick species were identifed – Rhipicephalus sanguineus accounted for 91% (n=1719) of the total ticks collected and 9% (n=173) were Ixodes hexagonus. All feas were identifed as Archaeopsylla erinacei. Regarding pathogen detection, Rickettsia massiliae DNA was found in 22 of the 212 tested Rh. sanguineus. None of the 48 I. hexagonus tested showed to be positive for rickettsiae. Rickettsia asembonensis DNA was identifed in 55 A. erinacei feas tested (n=117). These results show that European hedgehogs are exposed to R. massiliae transmitted by ticks and to R. asembonensis via feas suggesting that these mammals might be involved in the natural transmission cycle of these Rickettsia species. This study is the frst report of R. asembonensis in feas in Portugal.

2021-03-02Journal article

Restricted access

Pathogenic Rickettsia in ticks of spur-thighed tortoise (Testudo Graeca) sold in a Qatar live animal market

Publication . Barradas, P.F.; Mesquita, J.R.; Lima, C.; Cardoso, L.; Alho, A.M.; Ferreira, P.; Amorim, I.; De Sousa, R.; Gärtner, F.

The dissemination of vector arthropods harbouring zoonotic pathogens through the uncontrolled transboundary trade of exotic and pet animals poses an important threat to Public Health. In the present report, we describe the introduction of pathogenic Rickettsia africae and R. aeschlimanni in ticks removed from imported tortoises in Qatar. A total of 21 ticks were collected from pet spur‐thighed tortoises (Testudo graeca) from Doha, May 2018, and studied for species identification and characterization of Rickettsia spp. Morphological and molecular analysis of ticks allowed their identification as Hyalomma aegyptium. Molecular analysis of partial ompA and gltA genes showed that Rickettsia sequences found on these ticks clustered with sequences classified as R. aeschilimanii and R. africae. Since pre‐adult stages of H. aegyptium also feed on humans, this tick species may play a role in the transmission of R. aeschilimanii and R. africae. We alert for the introduction of non‐native pets as vehicles for tick importation, known vectors for animal and human pathogenic agents. Importation of exotic species into non‐autochthonous countries deserves strict control to enforce robust surveillance and mitigate potential exotic diseases epidemics.

2019-10-01Journal article

Open access

Serological and molecular evidence of Bartonella henselae in cats from Luanda city, Angola

Publication . Barradas, P.F.; De Sousa, R.; Vilhena, H.; Oliveira, A.C.; Luz, M.F.; Granada, S.; Cardoso, L.; Lopes, A.P.; Gonçalves, H.; Mesquita, J.R.; Ferreira, P.; Amorim, I.; Gärtner, F.

A total of 100 domestic cats from Luanda (Angola) were tested for the presence of antibodies against Bartonella henselae and spotted fever group of Rickettsia (SFGR) using indirect immunofluorescence assay (IFA). Molecular screening targeting the riboflavin synthase (ribC) gene for Bartonella and outer membrane protein B (ompB) gene for Rickettsia, using conventional PCR and sequencing was also performed in cat´s blood samples. Sixty-six percent of the cats from Luanda had IgG antibodies against Bartonella species but none of them had antibodies against SFGR. Of the total seroreactive cats for Bartonella henselae, 4.5% had an IgG titre of 64 (cut-off), 60.6% a titre of 128, 28.8% a titre of 256 and 6.1% a titre of 512. A statistically significant association was observed between seropositivity for Bartonella henselae and the lack of access to prophylaxis against ectoparasites (p = 0.018). Molecular detection and further sequence analysis of the positive amplicons allowed identification of Bartonella henselae in a 2-year old male cat. To the best of our knowledge this study confirms for the first time, the presence of Bartonela henselae circulating in domestic cats from Luanda. This fact call the attention for the possible cases of cat-scratch disease in humans.

2019-04-14Journal article

Restricted access