Epidemiological, Clinical and Entomological Characteristics of Yellow Fever Outbreak in Darfur 2012

Abstract

The study aims at analyzing the epidemiological, clinical and entomological characteristics of Darfur yellow fever epidemic. It is a descriptive, cross-sectional study. According to operational case definition, suspected yellow fever cases are included in case spread sheet with variables like age, sex, locality, occupation, status of vaccination, onset of symptoms, presenting symptoms, date of blood sampling and confirmation of diagnosis either by laboratory results or epidemiological link. Data about important entomological indices were collected by surveys conducted in 17 localities of 3 Darfur states (Central, West and south Darfur). All Darfur states (especially Central Darfur) have been affected by Yellow Fever outbreak. There is a need to review the non-specific case definition of Yellow Fever which seems to overwhelm the system during outbreaks with cases of other endemic diseases. The significant risk factors of this outbreak included male sex, adult age, outdoor occupation and traditional mining. The fatality rate was significantly associated with vaccination status. The highest fatality rate was recorded by children less than 2 years old (42.9%). Generally, increase in certain entomological indices was followed by increase in number of reported cases 7 days later. Central Darfur state was significantly higher in most studied entomological indices.

A community-level investigation following a yellow fever virus outbreak in South Omo Zone, South-West Ethiopia

“…The majority of cases were seen in 15–44 year-old individuals (75.8% of cases) who may have been infected while working outdoors during the day and dusk, the peak mosquito biting times; a risk factor also described in Kenya (1992–1993) where 81% of cases were <40 years old (Reiter et al, 1998). The overall CFR in SOZ was 37.6%, which is higher than in the Darfur epidemic of 2012 (20.3%) and in Uganda in 2011 (24.9%) (Alhakimi et al, 2015). Only four cases were reported from outside of SOZ (Gamo Gofa, Konso, and Mirab Abaya), which may be from individuals visiting the region, for example, becoming infected at the weekly Saturday market in Jinka Town; rather than autochthonous YFV transmission.…”

A community-level investigation of the yellow fever virus outbreak in South Omo Zone, South-West Ethiopia, 2012–2014

“…The majority of cases were seen in 15-44 year olds (75.8%) who may have been infected while working outdoors during the day and dusk, the peak mosquito biting times; a risk factor also described in Kenya (1992-1993) where 81% of cases were <40 years old (34). The overall CFR in SOZ was 37.6%, which is higher than in the Darfur epidemic of 2012 (20.3%) and in Uganda in 2011 (24.9%) (33). Only 4 cases were reported from outside of SOZ, which may be from individuals visiting the region, e.g.…”

“…In SOZ, the CFR in males (48.5%) was almost double compared to females (22.1%), which was consistent with the YF outbreak in Uganda (29.6% in males compared to 17.8% in females) and may be explained by males often reporting later (and sicker) to health facilities, due to underestimating the severity of the disease at symptom onset. By contrast, during outbreaks in The Gambia (1978-1979) and Ghana (1969-1970), children <15 years of age were the most affected, due to the stopping of routine mass YF vaccination campaigns in the early 1960s (33).…”

Wild-Type Yellow Fever Virus RNA in Cerebrospinal Fluid of Child

“…Children < 15 years of age accounted for 21.4% of these case-patients, and 15.6% of them had seizures. In the same study, ≈8% of case-patients were reported to have been vaccinated, suggesting that the immunity caused by the vaccine might be affected by other factors that influence the effectiveness and duration of the vaccine ( 8 ).…”

“…In a study in Darfur, Sudan, during a 2012 yellow fever epidemic, 844 cases of suspected yellow fever were reported ( 8 ). Children < 15 years of age accounted for 21.4% of these case-patients, and 15.6% of them had seizures.…”