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1. EBOLA VIRAL DISEASE (EVD)

ESSENTIALS OF DIAGNOSIS

  • Early stage EVD: a nonspecific febrile illness.

  • Later stage EVD: severe gastrointestinal symptoms, then neurologic symptoms and hypovolemic shock.

  • Hemorrhagic manifestations are late-stage manifestations.

  • Uveitis is prominent.

  • Travel and contact history from an Ebola-affected country raise suspicion.

  • Virus is detected with a RT-PCR.

General Considerations

Genus Ebolavirus is a single-stranded RNA virus in the Filoviridae family. Four different species of Ebolavirus have been identified to cause human disease. Fruit bats are possible reservoir for Ebolavirus. Zoonotic transmission to humans occurs via contact with the reservoir or an infected primate. Ebolavirus can continue to be transmitted among humans who have direct contact with infected body fluids. To acquire EVD, the virus must enter the body via mucous membranes, nonintact skin, sexual intercourse, breastfeeding, or needlesticks. Traditional burial practices in Africa (which entail considerable contact with the corpse) and unprotected direct care of persons with EVD are associated with highest transmission risk. Ebolavirus has been detected in semen up to 9 months after recovery from infection.

EVD has a 2–21-day incubation period. Prior to manifestation of symptoms, Ebolavirus is not transmissible. Even at symptom onset, the risk of transmission is low but increases over time.

The first Ebola outbreak occurred in 1976 as a simultaneous epidemic in the Democratic Republic of Congo and South Sudan. Subsequent outbreaks were confined to the Democratic Republic of Congo, Uganda, and Sudan until March 2014 when the first Ebola case in West Africa was identified in Guinea. Zaire ebolavirus was the associated species. This Ebola outbreak grew to be larger than all prior Ebola outbreaks combined. The number of EVD cases spread rapidly; there were at least 10 affected countries, especially Guinea, Liberia, and Sierra Leone. Many cases and deaths in these countries occurred among healthcare workers. In the United States, 11 persons were treated for Ebola. Most were healthcare workers who were evacuated to the United States and 4 patients were diagnosed in the United States. In total, 35 outbreaks of Ebola have occurred in Africa since 1976.

Sierra Leone contained its last EVD outbreak as of March 2016. Guinea was declared free of EVD transmission in June 2016. Liberia declared the end of its last outbreak in June 2016. The WHO reports that the West African Ebola outbreak was associated with 28,616 cases and 11,310 deaths during the approximately 2-year interval of the outbreak between March 2014 and March 2016.

Two outbreaks were reported in May and August of 2018, both in the Democratic Republic of Congo (where outbreaks also were reported in 2014 and 2017), and while the isolates from the two outbreaks were both the same species, complete genetic homogeneity between the isolates was not present. As of March 9, 2020, 3444 cases (3310 confirmed and 134 probable) and 2264 deaths were reported from 29 health ...

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