Ebola

Ebola virus disease (EVD), also known as Ebola hemorrhagic fever, is a serious illness.

It is caused by specific viruses in the genus Ebolavirus. This disease affects humans and several types of primates. It is considered a zoonotic disease. This means it can spread from animals to humans. The virus is highly dangerous and can cause large outbreaks. Understanding how it moves and works is vital for medical science.

The virus works through a complex life cycle inside a host's cells.

First, a virus particle, or virion, attaches to specific receptors on a cell surface. These receptors include C-type lectins, DC-SIGN, or integrins. Next, the viral envelope fuses with the cell's membrane. The virus enters the cell and travels to acidic compartments called endosomes and lysosomes. There, a protein called glycoprotein (GP) is cleaved to allow the virus to release its genetic material.

This material is a single-stranded RNA genome. The virus then uses the cell's machinery to create new proteins and replicate its genome. Finally, new virions bud off from the cell membrane to infect other cells.

There are six known ebolaviruses, but only four cause disease in humans.

These four species are the Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV), and the Ebola virus (EBOV). The EBOV, or Zaire ebolavirus, is the most dangerous species. It is responsible for the highest number of outbreaks. The other two viruses, Reston virus (RESTV) and Bombali virus (BOMV), do not cause disease in humans. However, they have been known to infect other primates.

Scientists believe fruit bats are the natural reservoir for these viruses.

A reservoir is a host that carries the virus without getting sick. Three types of fruit bats may carry the virus naturally. These include Hypsignathus monstrosus, Epomops franqueti, and Myonycteris torquata. Other animals like monkeys, chimpanzees, gorillas, and even pigs can be infected. Humans often contract the virus through direct contact with infected animals or their body fluids. This frequently happens when handling bushmeat, which is meat from wild animals. Deforestation can also increase contact between humans and wildlife.

Symptoms of EVD usually begin after an incubation period of two to 21 days.

Most people show symptoms within four to 10 days. The first stage often feels like the flu, with fever, fatigue, and muscle pain. As the disease progresses, patients may experience vomiting, diarrhea, and abdominal pain. This can lead to severe dehydration. About half of the cases involve a maculopapular rash, which is a red area with small bumps. Some patients also experience bleeding from mucous membranes or needle puncture sites. Death often occurs between six and 16 days after symptoms start due to shock from fluid loss.

Ebola is a significant global health challenge with high mortality rates.

The average mortality rate is approximately 50%, though it can range from 25% to 90%. The largest recorded outbreak was the 2014 Western African epidemic. Outbreaks have occurred intermittently in Sub-Saharan Africa since the disease was first reported in 1976. Managing these outbreaks requires rapid detection and contact tracing. It also requires the proper disposal of the dead through methods like cremation or burial.

Modern medicine has provided new ways to fight the virus.

In December 2019, the US FDA approved an Ebola vaccine. In October 2020, the treatment Inmazeb was approved for Zaire ebolavirus. This treatment uses monoclonal antibodies to help patients. Other treatments like ansuvimab also show improved outcomes. Early supportive care, such as intravenous fluids, can also increase survival rates. These medical advances are essential for controlling the spread of the disease in communities.