LATEST
ILL THREATS
Ebola
virus disease
An
outbreak of Ebola virus disease (EVD) has been ongoing in West Africa
since December 2013, affecting Guinea, Liberia, Sierra Leone and
Nigeria. The overall situation of the Ebola outbreak in the affected
countries remains critical. As of 6 September 2014, 4 291 cases
including 2 296 deaths have been reported from the affected
countries. To date, no cases have been found to be positive outside
Guinea, Liberia, Nigeria or Sierra Leone with the exception of one
case in Senegal in a Guinean national.
Key
facts
Ebola
virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a
severe, often fatal illness in humans.
The
virus is transmitted to people from wild animals and spreads in the
human population through human-to-human transmission.
The
average EVD case fatality rate is around 50%. Case fatality rates
have varied from 25% to 90% in past outbreaks.
The
first EVD outbreaks occurred in remote villages in Central Africa,
near tropical rainforests, but the most recent outbreak in west
Africa has involved major urban as well as rural areas.
Community
engagement is key to successfully controlling outbreaks. Good
outbreak control relies on applying a package of interventions,
namely case management, surveillance and contact tracing, a good
laboratory service, safe burials and social mobilisation.
Early
supportive care with rehydration, symptomatic treatment improves
survival. There is as yet no licensed treatment proven to neutralise
the virus but a range of blood, immunological and drug therapies are
under development.
There
are currently no licensed Ebola vaccines but 2 potential candidates
are undergoing evaluation.
Background
The
Ebola virus causes an acute, serious illness which is often fatal if
untreated. Ebola virus disease (EVD) first appeared in 1976 in 2
simultaneous outbreaks, one in Nzara, Sudan, and the other in
Yambuku, Democratic Republic of Congo. The latter occurred in a
village near the Ebola River, from which the disease takes its name.
The
current outbreak in west Africa, (first cases notified in March
2014), is the largest and most complex Ebola outbreak since the Ebola
virus was first discovered in 1976. There have been more cases and
deaths in this outbreak than all others combined. It has also spread
between countries starting in Guinea then spreading across land
borders to Sierra Leone and Liberia, by air (1 traveller only) to
Nigeria, and by land (1 traveller) to Senegal.
The
most severely affected countries, Guinea, Sierra Leone and Liberia
have very weak health systems, lacking human and infrastructural
resources, having only recently emerged from long periods of conflict
and instability. On August 8, the WHO Director-General declared this
outbreak a Public Health Emergency of International Concern.
A
separate, unrelated Ebola outbreak began in Boende, Equateur, an
isolated part of the Democratic Republic of Congo.
The
virus family Filoviridae includes 3 genera: Cuevavirus, Marburgvirus,
and Ebolavirus. There are 5 species that have been identified: Zaire,
Bundibugyo, Sudan, Reston and Taï Forest. The first 3, Bundibugyo
ebolavirus, Zaire ebolavirus, and Sudan ebolavirus have been
associated with large outbreaks in Africa. The virus causing the 2014
west African outbreak belongs to the Zaire species.
Transmission
It
is thought that fruit bats of the Pteropodidae family are natural
Ebola virus hosts. Ebola is introduced into the human population
through close contact with the blood, secretions, organs or other
bodily fluids of infected animals such as chimpanzees, gorillas,
fruit bats, monkeys, forest antelope and porcupines found ill or dead
or in the rainforest.
Ebola
then spreads through human-to-human transmission via direct contact
(through broken skin or mucous membranes) with the blood, secretions,
organs or other bodily fluids of infected people, and with surfaces
and materials (e.g. bedding, clothing) contaminated with these
fluids.
Health-care
workers have frequently been infected while treating patients with
suspected or confirmed EVD. This has occurred through close contact
with patients when infection control precautions are not strictly
practiced.
Burial
ceremonies in which mourners have direct contact with the body of the
deceased person can also play a role in the transmission of Ebola.
People
remain infectious as long as their blood and body fluids, including
semen and breast milk, contain the virus. Men who have recovered from
the disease can still transmit the virus through their semen for up
to 7 weeks after recovery from illness.
Symptoms
of Ebola virus disease
The
incubation period, that is, the time interval from infection with the
virus to onset of symptoms is 2 to 21 days. Humans are not infectious
until they develop symptoms. First symptoms are the sudden onset of
fever fatigue, muscle pain, headache and sore throat. This is
followed by vomiting, diarrhoea, rash, symptoms of impaired kidney
and liver function, and in some cases, both internal and external
bleeding (e.g. oozing from the gums, blood in the stools). Laboratory
findings include low white blood cell and platelet counts and
elevated liver enzymes.
Diagnosis
It
can be difficult to distinguish EVD from other infectious diseases
such as malaria, typhoid fever and meningitis. Confirmation that
symptoms are caused by Ebola virus infection are made using the
following investigations:
antibody-capture
enzyme-linked immunosorbent assay (ELISA)
antigen-capture
detection tests
serum
neutralization test
reverse
transcriptase polymerase chain reaction (RT-PCR) assay
electron
microscopy
virus
isolation by cell culture.
Samples
from patients are an extreme biohazard risk; laboratory testing on
non-inactivated samples should be conducted under maximum biological
containment conditions.
Treatment
and vaccines
Supportive
care-rehydration with oral or intravenous fluids- and treatment of
specific symptoms, improves survival. There is as yet no proven
treatment available for EVD. However, a range of potential treatments
including blood products, immune therapies and drug therapies are
currently being evaluated. No licensed vaccines are available yet,
but 2 potential vaccines are undergoing human safety testing.
Prevention
and control
Good
outbreak control relies on applying a package of interventions,
namely case management, surveillance and contact tracing, a good
laboratory service, safe burials and social mobilisation. Community
engagement is key to successfully controlling outbreaks. Raising
awareness of risk factors for Ebola infection and protective measures
that individuals can take is an effective way to reduce human
transmission. Risk reduction messaging should focus on several
factors:
Reducing
the risk of wildlife-to-human transmission from contact with infected
fruit bats or monkeys/apes and the consumption of their raw meat.
Animals should be handled with gloves and other appropriate
protective clothing. Animal products (blood and meat) should be
thoroughly cooked before consumption.
Reducing
the risk of human-to-human transmission from direct or close contact
with people with Ebola symptoms, particularly with their bodily
fluids. Gloves and appropriate personal protective equipment should
be worn when taking care of ill patients at home. Regular hand
washing is required after visiting patients in hospital, as well as
after taking care of patients at home.
Outbreak
containment measures including prompt and safe burial of the dead,
identifying people who may have been in contact with someone infected
with Ebola, monitoring the health of contacts for 21 days, the
importance of separating the healthy from the sick to prevent further
spread, the importance of good hygiene and maintaining a clean
environment.
Controlling
infection in health-care settings:
Health-care
workers should always take standard precautions when caring for
patients, regardless of their presumed diagnosis. These include basic
hand hygiene, respiratory hygiene, use of personal protective
equipment (to block splashes or other contact with infected
materials), safe injection practices and safe burial practices.
Health-care
workers caring for patients with suspected or confirmed Ebola virus
should apply extra infection control measures to prevent contact with
the patient’s blood and body fluids and contaminated surfaces or
materials such as clothing and bedding. When in close contact (within
1 metre) of patients with EBV, health-care workers should wear face
protection (a face shield or a medical mask and goggles), a clean,
non-sterile long-sleeved gown, and gloves (sterile gloves for some
procedures).
Laboratory
workers are also at risk. Samples taken from humans and animals for
investigation of Ebola infection should be handled by trained staff
and processed in suitably equipped laboratories.
WHO
response
WHO
aims to prevent Ebola outbreaks by maintaining surveillance for Ebola
virus disease and supporting at-risk countries to developed
preparedness plans. The document provides overall guidance for
control of Ebola and Marburg virus outbreaks:
Ebola
and Marburg virus disease epidemics: preparedness, alert, control,
and evaluation
When
an outbreak is detected WHO responds by supporting surveillance,
community engagement, case management, laboratory services, contact
tracing, infection control, logistical support and training and
assistance with safe burial practices.
WHO
has developed detailed advice on Ebola infection prevention and
control:
Infection
prevention and control guidance for care of patients with suspected
or confirmed Filovirus haemorrhagic fever in health-care settings,
with focus on Ebola.
What
is ALS?
A
drug used in the treatment of heart failure may be able to treat
amyotrophic lateral sclerosis, according to a recent study.
Researchers
at the Washington University School of Medicine in St. Louis found
that Digoxin may be adaptable for the treatment of amyotrophic
lateral sclerosis (ALS), a progressive, paralyzing disease.
ALS,
also known as Lou Gehrig's disease, destroys the nerve cells that
control muscles. This leads to loss of mobility, difficulty breathing
and swallowing and eventually death. Riluzole, the sole medication
approved to treat the disease, has only marginal benefits in
patients.
The
research team found that when they reduced the activity of an enzyme
or limited cells' ability to make copies of the enzyme, the disease's
destruction of nerve cells stopped. The enzyme maintains the proper
balance of sodium and potassium in cells.
Amyotrophic
lateral sclerosis (ALS), often referred to as "Lou Gehrig's
Disease," is a progressive neurodegenerative disease that
affects nerve cells in the brain and the spinal cord. Motor neurons
reach from the brain to the spinal cord and from the spinal cord to
the muscles throughout the body. The progressive degeneration of the
motor neurons in ALS eventually leads to their death. When the motor
neurons die, the ability of the brain to initiate and control muscle
movement is lost. With voluntary muscle action progressively
affected, patients in the later stages of the disease may become
totally paralyzed.
A-myo-trophic
comes from the Greek language. "A" means no or negative.
"Myo" refers to muscle, and "Trophic" means
nourishment–"No muscle nourishment." When a muscle has no
nourishment, it "atrophies" or wastes away. "Lateral"
identifies the areas in a person's spinal cord where portions of the
nerve cells that signal and control the muscles are located. As this
area degenerates it leads to scarring or hardening ("sclerosis")
in the region.
As
motor neurons degenerate, they can no longer send impulses to the
muscle fibers that normally result in muscle movement. Early symptoms
of ALS often include increasing muscle weakness, especially involving
the arms and legs, speech, swallowing or breathing. When muscles no
longer receive the messages from the motor neurons that they require
to function, the muscles begin to atrophy (become smaller). Limbs
begin to look "thinner" as muscle tissue atrophies.
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