We propose an analysis of the potential effects of control interventions on the dynamics of an Ebola epidemic.
We provide maximum-likelihood estimates of R 0 for EHF and the portion of each infectious phase represented in this value. We subdivided the infectious phases into three stages to account for transmission in the community, in the hospital (including isolation wards), and after death during traditional burial. Our goal is to better understand and to provide insight into where control interventions should be targeted in the future. Here, we analyse previously published EHF data with a stochastic compartmental model which incorporates explicitly the settings of the transmission in the community, in the hospital and during burial ceremonies. These two works did not study the contribution of the different settings for transmission (in the community, in the hospital, during burial ceremonies) in the estimation of R 0. The second study proposed estimates of R 0 based on the chain binomial model. The first study proposed a compartmental model and fitted it to historical data to estimate the R 0. Two studies have proposed estimates of the average number of secondary infections generated by one primary case of Ebola in an entirely susceptible population this quantity is called the basic reproduction number and is denoted R 0. īold text corresponds to the epidemics analysed in this paper. Although there is evidence of asymptomatic carriers, the very low levels of virus detected in these individuals suggest they do not pose a significant source of transmission. However, for epidemics that occurred after 1990, infection from contaminated syringes or through needle-stick injuries has not been documented. During the 1976 outbreak in Democratic Republic of Congo (DRC, formerly Zaire), 86 (26♷%) of the 318 cases were infected either from a contaminated syringe or through needle-stick injury. Ebola is unlikely be transmitted during the incubation period and transmissibility increases with duration of disease and direct contact with infected individuals during the late stages of illness. There is evidence that individuals (health-care workers, relatives) may become infected following contacts with patients' body fluids or direct contact with patients during a visit at the hospital or participation in traditional burial ceremonies. Most individuals acquire infection after direct contact with blood, bodily secretions and tissues of infected ill or dead humans and non-human primates. Survivors may experience severe asthenia, hearing loss, ocular signs and recovery usually occurs in 2 weeks to 2 months after the onset of symptoms. One week after the onset of symptoms a rash often appears followed by haemorrhagic complications, leading to death after an average of 10 days in 50–90% of infections. Patients present most frequently with fever, asthenia, diarrhoea, abdominal pain, headache, arthralgia, myalgia, sore throat, dysphagia, and conjunctivitis.
The typical natural history of the disease begins with an average incubation period of 1–2 weeks.
Very little is known about the virus: natural reservoirs are poorly identified but may include fruit bats vaccine and therapeutic strategies are under development. Since its discovery in 1976, 14 confirmed outbreaks of Ebola haemorrhagic fever (EHF) have been reported, seven of which have occurred since 2000 (see Table 1).
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