Doomsday viruses

In September 2007, an epidemic of hemorrhagic fever broke out in Africa. The cause of the epidemic was the Ebola virus, which, in addition to harming humans, killed about a quarter of the gorilla population in the last decade

By: Dror Bar-Nir

In September 2007, an epidemic of hemorrhagic fever broke out again in Africa, in the Democratic Republic of the Congo - an extremely deadly disease without treatment. The cause of the plague was Ebola viruses. Ebola viruses, apart from humans, also affect other primates: monkeys and apes - gorillas and chimpanzees. For the gorillas, the Ebola viruses are a real existential danger - about a quarter of the gorilla population died in the last decade from the virus.

The name Ebola was given to the plague (and the more common virus that causes it) because the first recorded natural plague broke out in the Ebola River region, in northern Congo.

Filoviruses

The filoviruses (Filoviridae; "filo" is "worm" in Latin. The name is given to the viruses because of their shape as seen through an electron microscope) are a group of RNA viruses with a cylindrical box. There are two types in the group: Marburg, which has one variety and is named after the city in Germany where it was first discovered; And Ebola, which has four strains, which are also named after the place where they were first found: Zaire (E. Zaire), Sudan (E. Sudan), Ivory Coast (E. Ivory Coast) and Reston (E. Reston - in Virginia in the United States).

The genome of viruses encodes eight proteins, seven of which are structural (make up the virus box) and the eighth is a water-soluble sugar protein. It is speculated that this protein, produced in the host cell immediately after the virus enters it, is involved in suppressing the immune system, probably by reducing the amount of white blood cells.

flu-like symptoms

The hemorrhagic fever begins, after an incubation period of up to 21 days, with flu-like symptoms. To these are added symptoms that vary from patient to patient: fatigue, fever, headache, throat, muscle and stomach pain, vomiting, diarrhea and rash. Later, internal and external hemorrhages develop and the patient bleeds from all openings of his body and dies within a few days. The virus is secreted in all body fluids and is easily transmitted from person to person. It is not yet clear how the first person contracted the chain - probably due to close contact with an infected animal.

The diagnosis of the disease is carried out in the laboratory, by identifying the components of the virus in the patient's secretions. There is no specific treatment for the disease; It is possible to give the patient only supportive care, and of course, to isolate him from other people. Patients who survived are probably immunized against further infection. Researchers plan to test if the blood serum of recovered patients can be used to treat patients.


Ebola viruses (colored in red) break out of cells in culture (derived from kidney cells of a green gonad) even before the cells themselves are destroyed

Is there evidence of Ebola or Marburg in history?

In the last two years, the Mexican epidemiologist Rodolfo Acuoa-Soto hypothesized that the hemorrhagic fever known as Cocoliztli, which killed millions of Aztecs in Mexico in the 16th century, is similar to Ebola.

Akua-Soto relies on a quote attributed to the physician of Philip II, King of Spain: "Blood flowed from the ears and in other cases even flowed from the mouth." It is possible that with the help of modern research tools (the PCR method) it will be possible to test this hypothesis. This is what happened with regard to the Peloponnesian Wars: genetic analysis of teeth from a mass grave from that period that was excavated in Athens showed that the plague that broke out there in 430 BC was typhoid, and not a typhus as they thought according to the description in the scriptures.

Marburg virus

The first recorded outbreak of the Marburg virus was in 1967, when an epidemic of hemorrhagic fever broke out in research laboratories in Marburg and Frankfurt, Germany, and Belgrade, Serbia (then Yugoslavia). All 31 patients were laboratory workers who came into contact with green goons (Cercopithecus aethiops) imported from Uganda. The monkeys themselves showed no signs of illness.

In 1980 and 1987, two European tourists who contracted the virus fell ill and died in Kenya. Between 1998 and 2000 there was a series of outbreaks in the northeast of the Democratic Republic of the Congo; 154 people got sick, 128 of them died. The last recorded epidemic to date occurred in the Uige province of Angola in 2004. 374 patients were reported, of whom 329 died. This year, in August 2007, several cases of miners' illness were reported from Uganda.
Ebola viruses

The year 1976 is considered the year of the outbreak of Ebola - then there were two outbreaks of two different strains. In the first plague, in the Yambuku area, then in Zaire, near the Ebola River, 318 people fell ill and 280 of them died. That's when the virus called Ebola Zaire was characterized and defined for the first time.
The spread of the disease was exacerbated because the medical teams reused injection needles.

In the second epidemic, in the Nzara region of Sudan, 284 people fell ill and 150 of them died. Many of the medical staff also fell ill and died. Then it was discovered that the Sudanese virus, called E. Sudan, was different from the Zairian strain. In this year, a laboratory worker in England also fell ill, after being stabbed by an infected syringe, who luckily survived. After three years of respite, in 1979, another epidemic broke out, in the same place, and out of the 34 people who got sick, 22 died.

A decade passed, and in 1989 shipments of long-tailed macaque monkeys (Macaca fascicularis) from Mindanao in the Philippines arrived in Reston, Virginia. Some of the monkeys contracted a hemorrhagic fever and died, and the rest were destroyed. Four people were exposed to the new virus, dubbed E. reston, and developed antibodies, but did not get sick. The phenomenon returned in 1990, in Texas and Virginia, and in 1992 also in Siena, Italy. Antibody carriers were also found among farm workers in the Philippines where the monkeys were raised. This virus, unlike the others, also passes without direct contact, through mucus droplets in the air.

After 14 quiet years, the Zaire strain broke out in 1994 in Gabon, in 1995 in Kikwit in Zaire, and in 1996 again in Gabon, in two places, due to eating chimpanzee corpses found in the forest. In 2001, two outbreaks occurred, on both sides of the border between Gabon and Congo, and in 2003 - two outbreaks in Congo.

In 1994, a veterinarian in the Ivory Coast fell ill after dissecting a chimpanzee corpse. She was flown to Switzerland in severe isolation, treated and recovered. The virus was different from the known strains and was defined as the Ivory Coast strain. Meanwhile, no additional cases of infection with this species have been discovered.
In 2001-2000, an epidemic of the Sudanese strain broke out in three areas in Uganda. 425 people got sick and 240 of them died. In 2004 there was another outbreak in South Sudan.

What is the natural source of Ebola viruses?

In 1995-1996, after the epidemic subsided in Kikwit, teams of researchers from the CDC (Center for Control and Prevention of Infectious Diseases in Atlanta, United States) and the NIV (National Institute of Virology of South Africa) searched the area, looking for the virus in the bodies of dozens Animal species - without success.

In an attempt to find out which animals the viruses can breed in, a joint team tried to infect different animals and plants with the Zaire strain. After the infection, they were able to isolate the viruses from only a few species of bats, but it is not clear if these species can indeed be a natural reservoir of viruses.
"burst"

Due to their high lethality, and perhaps due to the gruesome sight of the blood bursting from the body, the filoviruses are terrifying, but also provide artistic inspiration. Richard Preston wrote his book "The Hot Zone" about the events of infection with the Hamburg and Ebola viruses (the book was published in Hebrew by Mater). The movie Crisis in the Hot Zone was made on the basis of the book.

The filo viruses, and in particular Ebola, also inspired the movie "Outbreak" starring Dustin Hoffman and Morgan Freeman. The fictional virus in the film, called "Motaba", is similar in its properties to the Ebola virus, and illustrates the possibility of using it for biological warfare.

Unlike the black pox virus that has been eradicated, and polio, for which efforts are being made to eradicate, the Ebola viruses are not only harbored in humans, but also in other harbors, which are not yet known. Therefore, their extinction is probably not on the agenda, and until a vaccine or an effective treatment is developed, victims of the "doomsday viruses" will continue to fall.

Dr. Dror Bar-Nir teaches microbiology and cell biology at the Open University. The article was published in issue 112 of the Galileo journal.