Origin, etiology, transmission, clinical signs, diagnosis, prevention and control

1. Viral Diseases
Faculty of Veterinary Medicine & Animal
Husbandry
Somali National University
Mogadishu, Gaheyr Campus
Nov. 03. 2021
EBOLA HEMORRHAGIC FEVER

3. Ebola hemorrhagic fever (Ebola HF) is a
severe, often-fatal disease in humans and
nonhuman primates (monkeys, gorillas, and
chimpanzees) that has appeared
sporadically since its initial recognition in
1976.

4. The disease is caused by infection with Ebola
virus, named after a river in the Democratic
Republic of the Congo (formerly Zaire) in
Africa, where it was first recognized.
Confirmed cases of Ebola HF have been
reported in the Democratic Republic of the
Congo, Gabon, Sudan, the Ivory Coast (Côte
d’Ivoire) ,Uganda, and the Republic of the
Congo

5. Summary of known human Ebola cases
1972 1 non-fatal case (retrospective
diagnosis)
Tandala, Congo (not confirmed)
1976 318 cases, 280 deaths Yambuku, Congo (discovery of the virus)
1976 284 cases, 151 deaths Nzara, Maridi, Tembura and Juba, Sudan
1977 1 fatal case Tandala, Congo
1979 34 cases with 22 deaths Nzara and Yambio, Sudan
1980 1 suspected case Kenya (not confirmed)
1994 44 cases, 28 deaths Minkouka, Gabon
1994 1 non-fatal case Tai Park, Côte d'Ivoire
1995 315 cases, 255 deaths Kikwit, Congo
1996 1 non-fatal case Plibo, Liberia (not confirmed)
1996 37 cases with 21 deaths Mayibout and Makokou, Gabon
1996 60 cases with 45 deaths Booué, Gabon.
One exported case in South Africa with one
fatal secondary case.
2000 425 cases with 224 deaths Gulu, Masindi, Mbarara (Uganda)
2002 43 deaths in Congo, 53 deaths
in Gabon
Gabon - Congo
2002 No reliable numbers available Mbomo, Congo

6. 2003 About 140 cases with about
120 deaths (February-March).
Flare-up in November-
December, with 35 cases (29
deaths).
Mbomo, Congo
2004 25 cases with 6 deaths Mbomo and Mbandza, Congo Brazzaville
2005 About 10 cases Etoumbi, Congo
2007
2008
2008-
9
2009
2011
2012
About 187 cases
About > 90 cases
New epidemic in Congo,
lasting till early 2009.
Number of cases unclear
In March 2009, accidental
needle stick injury in
Hamburg (virologist)
Isolated case (May 2011) in
Uganda
Number of cases unclear
Kampungu, Mweka, Luebo, Congo (Western
Kasai)
Western Uganda
Mweka, Congo
Germany, the first time that vesicular stomatitis
virus-based vaccine is used in a human (post-
exposure)
November 2009, new outbreak in Mweka,
Congo.
July 2012, outbreak in Kibaale, Uganda and
quasi simultaneous in August 2012 outbreak is
Isiro and Viadana, HAut-Uele, Congo

7. In 15 November 2012 and early 2019, a
fresh outbreak of the deadly Ebola virus
was reported in Uganda that has killed at
least two people, and a third person was
also suspected to have died in that area of
the Haemorrhagic fever.

8. Etiology:
 Ebola virus is one of two members of the
Filoviridae family.
 Filoviridae, is a family of single-stranded
non segmented RNA viruses, comprises
two genera, Marburg virus (MARV), and
Ebola virus (EBOV),

9.  Several Ebola subtypes are known to
date:
 Ebola Zaire, (ZEBOV)
 Ebola Sudan, (SEBOV)
 Ebola Ivory Coast , Cote d'Ivoire
ebolavirus, (CIEBOV)
 Ebola Reston.
 Bundibungyo ebolavirus (BEBOV) .

10.  Zaire, Sudan and Bundibungyo species
have been associated with large Ebola
hemorrhagic fever (EHF) outbreaks in
Africa with high case fatality ratio (25–
90%) while Côte d’Ivoire and Reston
have not.
 Reston species can infect humans but no
serious illness or death in humans have
been reported to date.

11.  Infections with these Ebola viruses are
rare, but they occupy a special place on
account of their virulence and the media
attention they receive.

12.  The natural reservoir of this virus is unknown.
Monkeys can be infected but, because they
become sick, are unlikely to be the reservoir.
 Certain fructivorous and insectivorous bats can be
experimentally infected and certain species are
seropositive in nature.
 These animals develop an asymptomatic
infection.
 It becomes more and more likely that those large
bats play a role in Ebola epidemiology.

13.  on the basis of available evidence and the
nature of similar viruses, researchers
believe that the virus is zoonotic and is
normally maintained in an animal host that
is native to the African continent.

14. Transmission:
 Infections with Ebola virus are acute. There is
no carrier state.
 Because the natural reservoir of the virus is
unknown, the manner in which the virus first
appears in a human at the start of an outbreak
has not been determined.
 However, researchers have hypothesized that
the first patient becomes infected through
contact with an infected animal.

15. After the first case-patient in an outbreak
setting is infected, the virus can be transmitted
in several ways;
People can be exposed to Ebola virus from
direct contact with contaminated blood,
organs, semen or other bodily secretions.
Thus, the virus is often spread through
families and friends because they come in
close contact with such secretions when
caring for infected persons.

16.  People can also be exposed to Ebola
virus through contact with objects, such
as needles, that have been contaminated
with infected secretions.
 Nosocomial transmission occurs
frequently during Ebola HF outbreaks.

17. Symptoms:
The incubation period for Ebola HF ranges
from 2 to 21 days. The onset of illness is
abrupt and is characterized by fever,
headache, joint and muscle aches, sore throat,
and weakness, followed by diarrhea,
vomiting, and stomach pain. A rash, red eyes,
hiccups and internal and external bleeding
may be seen in some patients.

18. Diagnosis:
Tests include antigen-capture ELISA, IgM-
capture ELISA, polymerase chain reaction,
and virus isolation.

19. Differential Diagnosis:
In early stages, Ebola or Marburg HFs may
resemble influenza, malaria, typhoid fever;
arboviral fevers (various forms of
encephalitis, dengue fever, and other viral
hemorrhagic fevers.

20. Treatment:
There is no specific treatment for Ebola or
Marburg HF. Supportive care includes
maintaining fluid and electrolyte balance,
oxygenation, blood pressure stabilization, blood
and clotting factor replacement.

21. Prevention:
 The prevention of Ebola HF in Africa
presents many challenges. Because the
identity and location of the natural
reservoir of Ebola virus are unknown,
there are few established primary
prevention measures.

22.  If cases of the disease do appear, current
social and economic conditions often favor
the spread of an epidemic within health-
care facilities.
 Therefore, health-care providers must be
able to recognize a case of Ebola HF
should one appear.

23. They must also have the capability to
perform diagnostic tests and be ready to
employ practical viral hemorrhagic fever
isolation precautions, or barrier nursing
techniques.

24. These techniques include the wearing of
protective clothing, such as masks, gloves,
and gowns,; the use of infection-control
measures, including complete equipment
sterilization; and the isolation of Ebola HF
patients from contact with unprotected
persons.

25. The aim of all of these techniques is to avoid
any person’s contact with the blood or
secretions of any patient. If a patient with
Ebola HF dies, it is equally important that
direct contact with the body of the deceased
patient be prevented.

26. Marburg Hemorrhagic Fever

27.  Marburg Hemorrhagic Fever is a rare,
acute, infectious, hemorrhagic viral fever
which affects both human and nonhuman
primates (monkeys, gorillas, and
chimpanzees).
 The causative agent is the Marburg virus,
a member of the family, Filoviridae (or
"thread" viruses), which also includes the
Ebola virus.

28.  The virus was first documented in 1967,
when some people became ill in the
German town of Marburg, after which it
is named, as well as in Yugoslavia.
 The outbreak was traced to infected
African monkeys taken from Uganda and
used in developing polio vaccines.

29.  Marburg virus is indigenous to Africa.
While the geographic area to which it is
native is unknown, this area appears to
include at least parts of Uganda and
Western Kenya, and perhaps
Zimbabwe.

30. As with Ebola virus, the actual animal host
for Marburg virus is not definitely identified,
but recently (2009) , bats of multiple species
have been identified as possible natural hosts
of Zaire ebolavirus (ZEBOV) in Gabon and
Republic of Congo, and also of Marburg
virus (MARV) in Gabon and Democratic
Republic of Congo.

31. However, as with Ebola, humans who become ill
with Marburg hemorrhagic fever may spread the
virus to other people. This may happen in several
ways.
 Persons, who have handled infected monkeys
and have come in direct contact with their fluids
or cell cultures, have become infected.
 Spread of the virus between humans has
occurred in a setting of close contact, often in a
hospital.

32.  Droplets of body fluids, or direct contact
with persons, equipment, or other objects
contaminated with infectious blood or
tissues are all highly suspect as sources of
disease.

33. Signs and Symptoms:
 After an incubation period of 5-10 days,
the onset of the disease is sudden and is
marked by fever, chills, headache, and
myalgia.
 Around the fifth day after the onset of
symptoms, a maculopapular rash, most
prominent on the trunk (chest, back,
stomach), may occur.

34.  Nausea, vomiting, chest pain, a sore throat,
abdominal pain, and diarrhea then may
appear.
 Symptoms become increasingly severe and
may include jaundice, inflammation of the
pancreas, severe weight loss, delirium,
shock, liver failure, massive
hemorrhaging, and multi-organ
dysfunction.

35.  Because many of the signs and
symptoms of Marburg hemorrhagic
fever are similar to those of other
infectious diseases, such as malaria or
typhoid fever, diagnosis of the disease
can be difficult, especially if only a
single case is involved.

36.  Patients who are at greatest risk of dying
experience diffuse or extensive
hemorrhage into the skin, mucous
membranes, internal organs, stomach, and
intestines.

37.  Swelling of the spleen, lymph nodes,
kidneys, sometimes pancreas, and
especially brain occurs. Patients finally
experience coma and convulsions,
followed by death. Death from shock
usually occurs 6-9 days after clinical
onset of symptoms.

38. Diagnosis:
For patients presenting with Marburg
symptoms, initial possible diagnoses can
include malaria and typhoid fever. As with
Ebola, diagnosis of Marburg virus is
confirmed by IgG ELISA, although IgM
ELISA can be used to distinguish acute
infections from old infections.

39. IFA results can be misleading. Electron
microscopy is useful in diagnosing
Filoviruses infection, but does not help
distinguish Marburg from Ebola.

40. Marburg virus can be clearly diagnosed from
specimens of deceased patients via
immunohistochemistry, virus isolation, or
PCR (polymerase chain reaction) of blood or
tissue specimens.

41. Treatment:
Supportive therapy (there is no specific
treatment for Marburg hemorrhagic
fever. However, the virus itself is sensitive
to lipid solvents, detergents, commercial
hypochlorite disinfectants, and phenolic
disinfectants. The virus can also be
destroyed by ultraviolet and gamma
radiation.