Our data suggest that HHV-8 is acquired primarily through horizontal transmission in childhood from intrafamilial contacts and that transmission continues into adulthood potentially through nonsexual routes.
Recovery from ebolavirus infection in humans is associated with the development of both cell-mediated and humoral immune responses. According to recent studies, individuals that did not survive infection with ebolaviruses appear to have lacked a robust adaptive immune response and the expression of several early innate response markers. However, a comprehensive protective immune profile has yet to be described. Here, we examine cellular memory immune responses among survivors of two separate Ebolavirus outbreaks (EVDs) due to Sudan virus (SUDV) infection in Uganda—Gulu 2000–2001 and Kibaale 2012. Freshly collected blood samples were stimulated with inactivated SUDV, as well as with recombinant SUDV or Ebola virus (EBOV) GP (GP1–649). In addition, ELISA and plaque reduction neutralization assays were performed to determine anti-SUDV IgG titers and neutralization capacity. Cytokine expression was measured in whole blood cultures in response to SUDV and SUDV GP stimulation in both survivor pools, demonstrating recall responses that indicate immune memory. Cytokine responses between groups were similar but had distinct differences. Neutralizing, SUDV-specific IgG activity against irradiated SUDV and SUDV recombinant proteins were detected in both survivor cohorts. Furthermore, humoral and cell-mediated crossreactivity to EBOV and EBOV recombinant GP1–649 was observed in both cohorts. In conclusion, immune responses in both groups of survivors demonstrate persistent recognition of relevant antigens, albeit larger cohorts are required in order to reach greater statistical significance. The differing cytokine responses between Gulu and Kibaale outbreak survivors suggests that each outbreak may not yield identical memory responses and promotes the merits of studying the immune responses among outbreaks of the same virus. Finally, our demonstration of cross-reactive immune recognition suggests that there is potential for developing cross-protective vaccines for ebolaviruses.
Background: Rift Valley Fever (RVF) is a viral hemorrhagic fever that can be fatal to humans and livestock. During June-October 2018, reported RVF cases increased sharply in eight western and central Ugandan districts. We investigated to identify the scope of the outbreak, determine risk factors, and recommend control measures.Methods: We defined a probable case as acute onset of unexplained fever with thrombocytopenia or leukopenia, plus ≥1 of: unexplained bleeding, blurred vision, or unexplained death during June–October 2018 in a resident of the affected districts. A confirmed case was a probable case with a positive PCR test for RVF. We reviewed medical records and actively searched for cases in communities. In a case-control study, we compared exposures of cases and age-, sex-, and neighbourhood-matched controls. We reviewed livestock RVF surveillance data.Results: We identified 19 cases (17 confirmed, 2 probable); 13 (68%) died. The mean age of the case-patients was 36 (range: 27-55) years. The attack rate in men (15/10,000) was 19 times higher than in women (0.78/10,000). Stratified epidemic curves indicated multiple point-source outbreaks, often following skinning/butchering livestock or eating grilled meat from livestock that had been sick or died of unknown causes (‘sick/dead livestock’). All case-patients with data (n=18) ate or butchered meat from sick/dead livestock. Of the 18 case-patients and 90 controls who participated in the case-control study, 10 case-patients (56%) and five controls (5.6%) cut or handled raw meat from sick/dead livestock (ORadj=14, 95%CI=2.8-72). RVF-seropositive livestock were identified from serum samples taken from farms where human cases had occurred.Conclusion. Human RVF outbreaks in Western and Central Uganda in 2018 were caused by contact with raw meat of sick/dead livestock. We recommended wearing protective gear during butchering, and safe handling and disposal of carcasses of sick/dead livestock. RVF surveillance data between human and livestock health sectors should be shared to facilitate early warning and detection for RVF.
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