So the first Ebola patient has been confirmed in the USA at a Dallas area hospital.
Does this news frighten you?
No.
Consider
the following:
Four outbreaks occurred in Gabon during 1994–2002, affecting >20 villages and towns, with 208 cases and 151 deaths (overall case-fatality rate, 72.6%) [9–13]. During 2001–2002, outbreaks consisted of multiple independent introductions of the virus into human populations [14].
......
Recently, with a specific ELISA method, we showed that ZEBOV IgG positivity in rural human populations of Gabon is associated with cellular and humoral immune responses. We suspected that this seropositivity could be attributable to asymptomatic infection, mild disease, or simple exposure to viral particles [29].
From
that study:
It is generally accepted that ZEBOV is associated with a case fatality rate of about 90%, but this may be an overestimate. First, seven cases of asymptomatic infection were identified during the 1996 Booué outbreak in Gabon [26]. Second, some ELISA-based serosurveys [27] have shown high antibody prevalence rates among populations living in areas where no cases of EHF have ever been reported, suggesting that ZEBOV might also be capable of causing mild illness or even asymptomatic infection in humans. The IgG seroprevalence was 9.3% in villages located in the 1995 outbreak area around Kikwit, DRC, where no EHF cases were reported [28]. Likewise, a seroprevalence of 13.2% was found in the Aka Pygmy population of Central African Republic, where no ZEBOV outbreaks have ever been reported [29]. These findings confirmed those of older studies based on less-specific immunofluorescence assays that showed an antibody prevalence of around 10% in several non epidemic parts of Africa [30]–[34]. In contrast, a more recent survey showed a low anti-ZEBOV IgG prevalence (1.4%) among 979 people living in the northern region of Gabon that experienced EHF outbreaks between 1994 and 1997 [35]. The authors deduced that mild or asymptomatic EHF infection was possible but rare.