Emerging Infectious Diseases: Ebola

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 Emerging diseases are one of the most significant threats to public health in the modern day. The emergence of these diseases, and resurgence of past ones such as tuberculosis and cholera, reflects various changes in human ecology: rural-to-urban migration resulting in high-density areas, increasing long-distance mobility and trade, the social disruption of war and conflict, changes in personal behavior, and, increasingly, human-induced global changes, including widespread forest clearance and climate change. Medical technology itself also poses risks through its use and misuse, such as drug-resistant microbes and contaminated equipment or biological medicines.

The first cases of Ebola were identified in 1976 in Nzara, Sudan, where 281 patients were infected of which 151 died and Yambuku, Zaire (now the Democratic Republic of Congo) where 280 died out of 318 infected patients. The disease was named after the Ebola River which passes through the village where the first outbreak occurred. The most recent outbreak in West Africa began in Guinea, where it spread across to Liberia, Sierra Leone and Senegal through land travel and Nigeria via air travel (Osungbade, 2014). As of January 17 2016, this Ebolavirus disease (EVD) outbreak had infected 28,638 people across all affected countries, of which 11,316 died (World Health Organization, 2016). This outbreak was far more devastating and rapid in its spread, partially due to the high density population of the affected areas (see Figure 1). [pic 5][pic 6]

 Five Ebola species have been identified: Zaïre ebolavirus (ZEBOV), which was first identified in 1976 and is the most virulent, having caused the 2014 West African outbreak, Sudan ebolavirus (SEBOV), Tai Forest ebolavirus, Ebola-Reston (REBOV), originating from the Philippines, and Bundibugyo ebolavirus (BEBOV), the most recent species discovered in 2008 (Liu, 2016).

The viral fragment, which can alter its shape and size depending on environmental conditions (pleomorphism) can be observed in several distinctive shapes (usually in the shape of a "6", a "U", or a circle), and are contained within a lipid membrane. Each virion (the complete, infective form of a virus outside a host cell) contains a single strand of non-segmented, negative-sense viral genomic RNA that must be transcribed as soon as the virus enters the host in order to carry out viral replication and infect the whole host. Ebola virions enter host cells through endocytosis (the taking in of matter by a living cell by invagination of its membrane to form a vacuole) and replication occurs in the cytoplasm. Upon infection, the virus causes coagulation of the host blood and leads to severe immunosuppression (Lee, 2009). Early signs of infection, can be likened to flu symptoms, and may include fever, asthenia, diarrhea, headache, myalgia, arthralgia, vomiting, and abdominal pains. Haemorrhagic symptoms, as shown in Figure 2, may begin 4-5 days later, including haemorrhagic conjunctivitis, bleeding gums, mouth and lip ulcerations and vaginal bleeding as well as haemorrhaging of other internal organs (Center for Disease Control and Prevention, 2014).[pic 7][pic 8]