Birds play a central role in the epidemiology of several flaviviruses of concern for public and veterinary health. Seabirds represent the most abundant and widespread avifauna in the western Indian ...Ocean and may play an important role as host reservoirs and spreaders of arthropod-borne pathogens such as flaviviruses. We report the results of a serological investigation based on blood samples collected from nine seabird species from seven islands in the Indian Ocean. Using a commercial competitive enzyme-linked immunosorbent assay directed against the prototypic West Nile flavivirus, antibodies against flaviviruses were detected in the serum of 47 of the 855 seabirds tested. They were detected in bird samples from three islands and from four bird species. Seroneutralization tests on adults and chicks suggested that great frigatebirds (Fregata minor) from Europa were infected by West Nile virus during their non-breeding period, and that Usutu virus probably circulated within bird colonies on Tromelin and on Juan de Nova. Real-time polymerase chain reactions performed on bird blood samples did not yield positive results precluding the genetic characterization of flavivirus using RNA sequencing. Our findings stress the need to further investigate flavivirus infections in arthropod vectors present in seabird colonies.
We report herein the investigation of a leptospirosis outbreak occurring in triathlon competitors on Réunion Island, Indian Ocean. All participants were contacted by phone or email and answered a ...questionnaire. Detection and molecular characterization of pathogenic Leptospira was conducted in inpatients and in rodents trapped at the vicinity of the event. Of the 160 athletes competing, 101 (63·1%) agreed to participate in the study. Leptospirosis was biologically confirmed for 9/10 suspected cases either by real-time PCR or serological tests (MAT or ELISA). The total attack rate, children's attack rate, swimmers’ attack rate, and the attack rate in adult swimmers were respectively estimated at 8·1% 95% confidence interval (CI) 4·3–14·7, 0%, 12·7% (95% CI 6·8–22·4) and 23·1% (95% CI 12·6–33·8). Leptospirosis cases reported significantly more wounds risk ratio (RR) 4·5, 95% CI 1·6–13, wore complete neoprene suits less often (RR 4·3, 95% CI 1·3–14·5) and were most frequently unlicensed (RR 6·6, 95% CI 2·9–14·8). The epidemiological investigation supported that some measures such as the use of neoprene suits proved efficient in protecting swimmers against infection. PCR detection in rats revealed high Leptospira infection rates. Partial sequencing of the 16S gene and serology on both human and animal samples strongly suggests that rats were the main contaminators and were likely at the origin of the infection in humans.
In Tunisia, rabies continues to be considered as a serious public health concern. Very costly mass vaccination of dogs against rabies and expensive post-exposure prophylaxis are prerequisites to ...maintain a low level of human rabies cases. In Tunisia, the implementation of mass vaccination campaigns at the national level has undoubtedly contributed to the drop of rabies endemicity, but the overall outcome is rather suboptimal. In this investigation, we wanted to estimate the extent of the vaccination coverage in dogs in three Governorates (Manouba, Kassrine and Mednine), by collecting data through questionnaires and interviews relevant to 1470 owned dogs. When the campaign is correctly applied, as in Manouba, almost all the targeted dog population can be reached by parenteral vaccination and an almost elimination of the disease can be evidenced. However, in Kasserine and especially in Medenine, where the vaccination coverage is lower than 31%, a reservoir for the disease can be maintained. To match the official figures of vaccination coverage, we should update the statistics of the size of dog population which seems to be bigger than what is assumed. In addition, we wanted to assess the level of involvement of the local population with the vaccination campaigns by marking vaccinated dogs with necklaces and establishing later on the vaccination coverage accordingly. The highest levels of vaccination coverage can be reached in the rural regions. Therefore, the low vaccination coverage in rural areas, reported at the national level, is more attributable to the lack of human and financial resources to reach remote regions. We think that rabies control programmes in Tunisia can be successful if vaccination coverage can reach 70% in all parts of the country. The achieved vaccination coverage should be estimated after random visits in many parts of the country and by checking valid vaccination certificates.
The nature of early interactions between Leishmania and macrophages which determine the outcome of infection can be related directly to parasite biological properties. Here we compared the capacity ...of L. major (Lm) strains, reported to be high (LmHV) and low virulent and (LmLV) in the mouse model and L. infantum (Li) strains, dermotropic (LiD) and viscerotropic (LiV), to infect and modulate cytokine production in human peripheral blood derived monocytes. Monocytes were infected with metacyclic promastigotes for 24, 48 and 72 h. Parasite burden was significantly higher in Lm- than in Li-infected monocytes. LmHV and LiD induced a significantly higher parasite burden than LmLV and LiV respectively. Cytokine production was evaluated in monocytes infected for 24 h. Contrary to interleukin (IL)-12p70, monocyte chemotactic protein-1 and transforming growth factor-β production was increased significantly in infected monocytes with no differences between strains. Lm isolates induced significantly higher quantities of tumour necrosis factor (TNF)-α than Li isolates. Low levels of IL-10 were induced by all Leishmania strains and, interestingly, co-stimulation with lipopolysaccharide (LPS) was accompanied by a dramatic increase in IL-10 production by infected monocytes. In conclusion, Lm isolates displaying different levels of virulence in mice exhibited significant differences in parasite burden but similar abilities to modulate cytokine production in human monocytes. Li strains showed weaker infectivity and TNF-α inducing-capacity compared with Lm strains. The dramatic increase of IL-10 production in infected monocytes co-stimulated by LPS may play a role in disease progression considering the presence of LPS during bacterial superinfections observed during human leishmaniasis.
NADPH oxidase, a multi-subunit protein consisting of cytosolic components and the membrane-bound heterodimer, plays an instrumental role in host defence mechanisms of phagocytes. Genetic deficiency ...of the enzymatic complex results in an inherited disorder, chronic granulomatous disease (CGD), which is characterized by an impaired phagocyte microbicidal activity. X-Linked (XL) CGD results from a mutation in the CYBB gene encoding the gp91phox subunit, while autosomal recessive (AR) CGD is associated with mutations in one of the NCF1, NCF2 and CYBA genes that encode the p47phox, p67phox and p22phox subunits, respectively. In the study reported here, we investigated genetic defects underlying CGD in 15 Tunisian patients from 14 unrelated families. Haplotype analyses and homozygosity mapping with microsatellite markers around known CGD genes assigned the genetic defect to NCF1 in four patients, to NCF2 in four patients and to CYBA in two patients. However, one family with two CGD patients seemed not to link the genetic defect to any known AR-CGD genes. Mutation screening identified two novel mutations in NCF2 and CYBA in addition to the recurrent mutation, DeltaGT, in NCF1 and a splice site mutation previously reported in a North African patient. Our results revealed the genetic and mutational heterogeneity of the AR recessive form of CGD in Tunisia.
To identify approaches for vaccination against leishmaniasis, we analyzed the protective effect of different constructions using recombinant peptides from the protein
Leishmania (
L.)
major histone ...H2B. H2B sequence displays two distinct regions: an amino-terminal region divergent from mammalian H2B (27% identity) and a carboxy-terminal region highly conserved with mammalian H2B (55% identity). We tested the ability of the entire H2B protein, its divergent or conserved regions to provide protection against virulent
L. major challenge. While the recombinant H2B protein adjuved with CpG induces potent cellular and antibody responses when injected to BALB/c mice, only the divergent amino-terminal region of H2B is able to confer potent protection against a virulent challenge. These findings indicate that different portions of the same parasite protein may express contrasting protective effects likely through the induction of different effector mechanisms. Due to its potent protective properties in the BALB/c mouse model, the amino-terminal region of
Leishmania H2B could constitute a good vaccine candidate.
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