Ebola
Massimo Galli
DIBIC L. Sacco
Università di Milano
III Div Mal. Inf, AO Sacco
As of October 23, 2014,
450 healthcare personnel
are known to have
become infected with
Ebola, of whom 244 died
Ebola: aree interessate
da epidemie nell’uomo
• Dal 1976 (prima epidemia a Yambuku, DRC
ex Zaire) al 2007-2008 (epidemia nel Kasai
occidentale, DRC) EBOV causa, secondo i
dati del CDC, 1383 casi di EVD, 1378 dei
quali nel contesto di 11 epidemie, con un
tasso di letalità del 78%
Ebola Virus Disease in the Democratic
Republic of Congo
• The outbreak began in Inkanamongo village in
the vicinity of Boende town in Équateur province
• Genome
revealed
Ebola
virus (EBOV,
and has sequencing
been confined
to that
province.
A total
Zaire
as the
cause or
of confirmed
this outbreak.
of 69 species)
suspected,
probable,
cases
• A
coding-complete
genome
of EBOV 7,
were
reported between
Julysequence
26 and October
that
isolated
this outbreak
showed
2014,was
including
8 during
cases among
health care
99.2%
identity
with
the most
closely
related
workers,
with 49
deaths.
As of
October
7,
variant
from theapproximately
1995 outbreak
Kikwit in the
there havebeen
sixingenerations
DRC
and 96.8%
to outbreak
EBOV variants
of cases
of EVDidentity
since the
began.that
The
are
currently
circulating
in Westpeaked
Africa.
reported
weekly
case incidence
in the
weeks of August 17 and 24 and has since fallen
sharply.
Maganga et al. NEJM 2014; oct 15
Perché così tanti casi di EVD ?
• I paesi colpiti più popolosi di quelli colpiti in passato.
• Il virus ha potuto rapidamente raggiungere le capitali
• Si tratta inoltre di paesi molto poveri, due su tre dei
quali sono reduci da spaventose guerre civili.
• L’area colpita per prima è stata oggetto di intensiva
deforestazione
• Non è stato possibile finora tracciare validamente i
contatti delle persone colpite
• I dati filogenetici fanno risalire (a oggi) l’epidemie in
Sierra Leone e Liberia a contatti interumani, senza
l’interposizione di animali serbatoio o altri animali
infetti
• The estimated basic reproduction numbers (R0) are
1.71 (95% CI, 1.44 to 2.01) for Guinea, 1.83 (1.72 to
1.94) for Liberia, and 2.02 (1.79 to 2.26) for Sierra
• Assuming no change in the control measures
Leone.
this epidemic,
by
November
2,
2014,
the
• for
Al
25/10
riportati
10.144
casi:
effetto
• The
estimated
current reproduction
numbers
(R) aredelle
1.81
cumulative
reported
numbers
of confirmed
and
misure
di prevenzione,
rallentamento
(95%
CI, 1.60
to
2.03) for
Guinea,
1.51
(1.41 to 1.60)
cases
predicted
5740
in
dell’epidemia
o are
sottonotifica??
forprobable
Liberia, and
1.38
(1.27
to 1.51) to
for be
Sierra
Leone;
• The
corresponding
times
are5000
15.7 days
(95% CI,
Guinea,
9890 doubling
in Liberia,
and
in Sierra
12.9
to 20.3)
for Guinea,
23.6 days
(20.2 to 28.2) for
Leone,
exceeding
20,000
in total.
Liberia, and 30.2 days (CI, 23.6 to 42.3) for Sierra
Leone.
Effects of immunising asymptomatic
infections on Liberia outbreak projections
Bellan et al. Lancet 15 Oct 2014; published online
How many asymptomatic
infections?
• Evidence suggests that many EBOV infections
are asymptomatic. Particularly,results from one
post-Ebola outbreak serosurvey in Gabon1
showed that 71% of seropositive individuals did
not have the disease; another study2 reported
that 46% of asymptomatic close contacts of
patients with Ebola were seropositive.
1Heffernan
2
et alJ Infect Dis 2005; 191: 964–68.
Leroy et al.Lancet 2000; 355: 2210–15.
Si possono trovare anticorpi anti Ebola in persone
sane senza precedenti noti di malattia?
 IgG anti EBOV nel 15,3% dei
4.349 abitanti
di 220 villaggi in
 Questi
dati sollevano
Gabon.
importanti
domande riguardo:
 La prevalenza sale nei villaggi più
- la patogenicità
EBOV,
vicini
alla foresta edicon
l’età, ma
- lavaria
possibilità
di infezioni
non
dopo i 20
anni.
lievi
o paucisintomatiche,
 Non
altri
fattori di rischio per
- la possibilità
di di precedente
EBOV,
ne evidenza
immunizzazione e di
malattia.
 I dati
suggeriscono
l’esposizione
protezione
naturale,
a- una
fonte d’infezione
di
l’esistenza
di reazioni
accesso
facile
generalizzato,
crociate
cone altri
filovirus
come
esempio la frutta
nonad
patogeni
contaminata da saliva di
pipistrello.
Becquart et al PLoS One 2010,5: e9126
Transmissione.
1: da serbatoi animali
• Ebola viene introdotto nelle popolazioni umane
mediante contatto diretto con sangue, secrezioni,
fluidi corporei di animali infetti.
• In Africa sono state documentate infezioni dopo
contatto con alcune specie animali, in alcune delle
quali (ad esempio lo scimpanzè, il gorilla e alcune
specie di cefalofi) l’infezione, ha esiti di regola
letali (specie amplificatrici), mentre altre, che
comprendono varie specie di pipistrelli frugivori,
rappresentano il più probabile serbatoio
dell’infezione.
La trasmissione di EBOV dal
serbatoio naturale
Prediction and
prevention of the next
pandemic zoonosis
• La maggior parte delle infezioni
pandemiche, come HIV/AIDS,
SARS, influenza—originano in
animali, sono causate da virus, e
sono portate ad emergere da
fattori ecologici o socioeconomici.
• Nonostante i sostanziali effetti
delle infezioni pandemiche sulla
salute pubblica globale e la
crescente comprensione dei
processi mediante i quali emergono,
nessuna di esse è stata prevista
prima che si manifestasse
Morse SS et al. Lancet.2012; 380: 1956–65
Esempi di RNA virus zoonotici recentemente ‘emersi’
Agente
(famiglia)
Data
isolamento
Animale fonte
(principale)
Via di
trasmissione
Trasmissione
interumana
Marburg
1967
Rousettus
aegyptiacus
C
Pochi cicli
Ebola
1976
Hypsignathus
monstrosus
C
Pochi cicli
HIV-1
1983
Pan troglodites
troglodytes
S/P/V
Si
HIV-2
1986
Cercocebus atys
atys
S/P/V
Si
Sin Nombre
1993
Peromyscus
maniculatus
A/(C)
?
Nipah
1998
Pteropus
hypomelanus
C/(A)
Rara
SARS CoV
2003
Rhinolophus
ferrumequinum
A/C
Si
MERS CoV
2012
Taphozus
perforatus (?)
A/C
Si
(Filoviridae)
(Filoviridae)
(Retroviridae)
(Retroviridae)
(Bunyaviridae)
(Paramixoviridae)
(Coronaviridae)
(Coronaviridae)
(pandemico)
(diff. limitata)
A= aerea; C= contatto; P= parenterale; S= sessuale; V= verticale
Ebolavirus
• Il genere Ebolavirus comprende 5 specie distinte:
-
Ebola* virus (EBOV)
Sudan virus (SUDV)
Reston virus (RESTV)
Taï Forest virus (TAFV)
Bundibugyo virus (BDBV)
• La differenza interspecie varia tra il 37% e il
41% a livello nucleotidico e dal 34% al 43% a
livello aminoacidico
* precedentemente denominato Ebola Zaire
Carrol et al. J. Virol. 2013, 87: 2608-16
Ebola Reston
• Ebola Reston viene
identificato
nel 1989 negli
• Del
tutto inaspettatamente,
in M.fascicularis
a USA
partire
dal 2008, sonoin
cattività
e successivamente
stati
individuati
focolai di
nelle Filippine
in esemplari
infezione
ad elevata
letalità in
in libertà
allevamenti di maiali nelle
Filippine.
• L’infezione ha elevata
ma in
• È letalità
possibilenelle
che scimmie,
il serbatoio
non hasiaavuto
effetti di da
natura
rappresentato
rilievo neiamplexicaudatus
25 casi umani
Rousettus
documentati.
Macaca fascicularis
R.amplexicaudatus
• A novel filovirus, provisionally named Lloviu virus (LLOV),
was detected during the investigation of Miniopterus
schreibersii die-offs in Cueva del Lloviu in Spain.
• LLOV is genetically distinct from other marburgviruses and
Mononegavirales
ebolaviruses and is the first filovirus detected in Europe
Phylogenetic Analysis of the
Ebolavirus Genus, Including the
EBOV Strains from Guinea.
• La posizione più ‘basale’ del clade della Guinea ne
suggerisce la derivazione da un serbatoio locale e
depone contro un’introduzione di un ceppo di EBOV
coinvolto nelle epidemie in Gabon e Congo.
Baize et al. NEJM 2104
Tutte le epidemie da EBOV sono state
causate da ceppi diversi tra loro
• Studi filogenetici su sequenze virali
da carcasse di animali e da persone
infettate dimostrano che i virus
implicati sono diversi tra loro in tempi
e in luoghi diversi, mentre sono molto
simili le sequenze ottenute da uomini
e animali durante la stessa epidemia e
nella stessa area geografica.
• Teoria dello spillover: ogni epidemia è
stata generata dall’emergere ex novo
dal serbatoio animale di un ceppo
diverso dai precedenti.
• Fino ad oggi, prima di quella in corso,
tutte le epidemie si sono esaurite
dopo pochi passaggi interumani.
Ebola e pipistrelli: evidenze e incongruenze
• La prevalenza di anticorpi
• Anticorpi anti EBOV
anti EBOV e il tasso di PCR
sarebbero stati
positive non sono così elevati
evidenziati in
da far pensare a un’infezione R.lescehnaulti in
molto diffusa nelle diverse
Bangladesh (prevalenza
specie trovate positive
3.5%) (Olival et al 2013),
• In molti paesi in cui i
in R. leschenaulti, P.
pipistrelli sono presenti Ebola pipistrellus e Myotis
non si è mai visto.
spp in Cina (Yuan et al.
2012) e in Pongo
• Presenza selettiva del virus
pygmaeus in Kalimantan
nelle diverse colonie e sua
(Nidom et al. 2012)
assenza in alcune aree
Rousettus aegyptiacus
geografiche?
Areale di
distribuzione di
Hypsignathus
monstrosus
Egyptian fruit bat
Rousettus aegyptiacus
Geographic range
L’Ebola è un prezzo inaccettabile
per il bushmeat
Mercato a Brazzaville, Repubblica del Congo
Duikers and Ebola
• Duikers are small to medium-sized
antelopes native to Sub-Saharan
Africa.
• The 22 extant species form the
subfamily Cephalophinae, which
includes 3 genera (Cephalophus,
Philantomba and Sylvicapra).
• Duikers generally live alone or in
pairs (limited interactions).
• Some duikers, despite being
herbivorous, in addition to being
directly infected by the natural
host(s), might also become
infected by licking or eating fresh
carcasses of infected animals
Philantomba monticola
The blue duiker, occasionally found to be
infected by EBOV
Transmission.
2: Trasmissione interumana
• Risulta da contatti diretti di cute o mucose con
sangue, secrezioni, fluidi corporei di persone
infettate e da contatti indiretti con contesti
ambientali contaminati da tali fluidi.
• La trasmissione avviene prevalentemente in contesto
familiare, in occasione di •cerimonie funebri, negli
ospedali
durante
le fasi inizialidadelle
epidemie
e se
• Non
è provata
la trasmissione
soggetti
asintomatici
non vengono tempestivamente e correttamente messe
in atto le misure di contenimento.
• Il rischio di trasmissione è massimo in seguito a
contatto con paziente sintomatico con manifestazioni
emorragiche o con cadaveri di deceduti per EVD
Is sexual transmission possible ?
• Men who have recovered from the
disease can still transmit the virus
through their semen for up to 7 weeks
after recovery from illness.
Assessment of the Risk of Ebola Virus
Transmission from Bodily Fluids and Fomites
• Ebola virus was detected by culture and/or PCR in 16
of 54 clinical specimens (including saliva, stool, semen,
breast milk, tears, nasal blood, and a skin swab) from
26 laboratory-confirmed cases and in 2 of 33
environmental specimens.
• EBOV is shed in a wide variety of bodily fluids during
the acute period of illness but the risk of transmission
from fomites in an isolation ward and from convalescent
patients is low when currently recommended infection
control guidelines for the viral hemorrhagic fevers are
followed.
Bausch et al JID 2007; 196 Suppl 2:S142-7.
The survival of filoviruses in liquids, on
solid substrates and in a dynamic aerosol
• Survival of EBOV and MARV)
in liquid media in tissue
culture media (closed shapes)
and guinea pig sera (open
shapes) over 46 days at 4C
(a) and room temperature (b),
was assessed by the TCID50
microtitre plate assay over
time.
Piercy et al. J Appl Microbiol
2010;109, 1531–1539
Ebola virus RNA copy levels in sera over time
from 45 EVD patients (27 fatal, 18 non-fatal)
Ebola virus RNA levels at the time of fever and symptom onset
are typically low (near the detection threshold limits) and in some
patients may not be reliably detectable during the first 3 days of
Towner et al. J Virol. 2004;78:4330-4341.
illness
Ebola virus detection by RT-PCR in body fluids collected from EVD
patients during an outbreak in Gulu, Uganda and the maximum
described persistence after symptom onset described in the literature
Body Fluid
Acute phase
n detected/n tested
(percent)
Convalescent phase
n detected/n tested
(percent)
Last day detected
after symptom onset
described in the
literature
Skin
1/8 (13%)
0/4 (0%)
6
Saliva
8/12 (67%)
0/4 (0%)
8
Urine
0/7 (0%)
0/4 (0%)
23
Stool / Feces
2/4 (50%)
n/d
29
Breast milk
1/1 (100%)
1/1 (100%)
Comments
Ebola virus antigen
has been detected
in the urine in other
studies20
15
Ebola infects
circulating
macrophages which
are present in
breast milk16
Sexual transmission
of Marburg virus
(but not Ebola virus)
has been described36
Semen
n/d
1/2 (50%)
101
Vaginal fluid
n/d
n/d
33
Case definition recommendations
for Ebola or Marburg Virus
Diseases
As of 09 August 2014
Standard definition for contacts
persons of Ebola or Marburg cases
• Ebola or Marburg case contacts: Any person having
been exposed to a suspect, probable or confirmed case
of Ebola or Marburg in at least one of the following
ways:
- has slept in the same household with a case
- has had direct physical contact with the case (alive or dead) during
the llness
- has had direct physical contact with the (dead) case at the funeral
- has touched his/her blood or body fluids during the illness
- has touched his/her clothes or linens
- has been breastfed by the patient (baby)
• Provided that this exposure has taken place less than
21 days before the identification as a contact by
surveillance teams.
• Re-examining the samples delivered to a
reference center for the diagnosis of Lassa
fever in Sierra Leone (where, as in areas
bordering Guinea and Liberia disease is
hyperendemic) a compatible serology for
acute infection with Ebola virus was found in
8.2% of febrile patients tested negative for
Lassa fever.
EID 2014 Jul;20:1176-82
EVD: clinica
Ebola hemorrhagic fever: pathogenesis
• The final event of serious Ebola infection is a shock resulting from
systemic viral replication, immunosuppression, increased vascular
permeability and coagulopathy.
Human fatal zaire ebola virus infection is
associated with an aberrant innate immunity
and with massive lymphocyte apoptosis
• 42 nonsurvivors vs 14 survivors from the five outbreaks
occurred between 1996 and 2003 in Gabon and Republic of
Congo.
• Fatal outcome was associated with:
-Hypersecretion of proinflammatory cytokines
(IL-1β, IL-1RA, IL-6, IL-8, IL-15 and IL-16),
-Hypersecretion of chemokines and growth factors
(MIP-1α, MIP-1β, MCP-1, M-CSF, MIF, IP-10,
GRO-α and eotaxin).
-No increase of IFNα2 was detected in patients.
low levels of IL-2, IL-3, IL-4, IL-5, IL-9, IL-13
-Significant drop of CD3+CD4+ and CD3+CD8+
-High increase in CD95 expression on T lymphocytes.
Wauquier et al PLoS Negl Trop Dis. 2010, 4(10). pii: e837.
Incubation period
• The incubation period, that is, the time
interval from infection with the virus to
onset of symptoms, is 2 to 21 days
(according to the last data, the mean
incubation period is 11 days)
• Abrupt onset of fever, chills, nonspecific
signs and symptoms.
Clinical Features: stage 1, unspecific
• Extreme asthenia (body weakness)
• Diarrhea, nausea and vomiting,
anorexia abdominal pain
• Headaches
• Arthralgia (neuralgic pain in joints)
• Myalgia (muscular pain or
tenderness), back pain.
• Mucosal redness of the oral cavity,
dysphagia (difficulty in swallowing)
• Conjunctivitis.
• Erythematous maculopapular rash all
over body except in face, most
noticeable in fair-skinned individuals.
Demographic Characteristics in Confirmed and Probable
Ebola Case Patients with aDefinitive Clinical Outcome in
Guinea, Liberia, Nigeria, and Sierra Leone
• Estimated case fatality rate among persons with known clinical
outcome of infection was 70.8% (95% CI, 69 to 73).
WHO Ebola response group. N Engl J Med 2014;371:1481-95
Time from onset of illness to death in 25
fatal cases of Marburg and Ebola HF
• Death occurs mostly during the second week
of illness in patients without a demonstrable
antibody response.
• The main autopsy findings consist of extensive
bleeding,
The medianhepatocellular necrosis, widespread
survival
is 9lymphatic
days.
loss of
tissue
• In survivors convalescence is prolonged, with
persistent fatigue, weight loss,skin
desquamation and loss of hairs.
• The virus can persist for weeks or months in
the anterior chamber of the eye and testes
(sexual transmissionis theoretically possible).
All
Died
Recovered
OR
WHO Ebola response group. N Engl J Med 2014;371:1481-95
Manifestazioni emorragiche
WHO Ebola response group. N Engl J Med 2014;371:1481-95
EVD hemorragic manifestations
Lassa Fever in West Africa: Evidence
for an Expanded Region of Endemicity
• Lassa fever is a public health
problem in Sierra Leone/ Guinea/
Liberia (the Mano River region)
and Nigeria.
• There is evidence for an expanded
endemicity zone in southern Mali,
Burkina Faso,Côte d’Ivoire, Ghana,
which shares a similar ecozone
(Tropical Wooded Savanna).
• The disease is a zoonosis due to a
ss RNA virus of the Arenaviridae,
family and the animal reseivoir is
Mastomys natalensis.
• The incident cases of LHF are 100,000-300,000 each year with
about 5,000 deaths (overall fatality rate ≈ 1%), with a 15%-20%
fatality rate in patients hospitalized.
The clinically approved drugs amiodarone,
dronedarone and verapamil inhibit
filovirus cell entry.
• Amiodarone, a multi-ion channel inhibitor and
adrenoceptor antagonist, is a potent inhibitor of
filovirus cell entry at concentrations that are
routinely reached in human serum during antiarrhythmic therapy.
• A similar effect was observed with the amiodaronerelated agent dronedarone and the L-type calcium
channel blocker verapamil.
Gehring et al. J Antimicrob Chemother 2014
Ebola vaccines
• Two candidate vaccines have clinical-grade vials
available for phase 1 pre-licensure clinical trials.
• cAd3-ZEBOV has been developed by GSK in
collaboration with the US NIAID. It uses a
chimpanzee-derived adenovirus vector with an Ebola
virus gene inserted.
• rVSV-ZEBOV was developed by the Public Health
Agency of Canada in Winnipeg. The license for
commercialization of the Canadian vaccine is held by an
American company, the NewLink Genetics company. The
vaccine uses an attenuated or weakened vesicular
stomatitis virus; one of its genes has been replaced by
an Ebola virus gene
Perché il rischio di Ebola in Italia
è effettivamente basso.
• Non voli diretti dai paesi colpiti
• I cittadini dei paesi colpiti sono probabilmente
meno di 7000 su oltre 3.5 milioni di stranieri
residenti in Italia.
• I provenienti clandestinamente via mare
attraverso il Mediterraneo non costituiscono
pericolo in quanto le nazionalità dei paesi colpiti
sono virtualmente non rappresentate e perché la
lunghezza del precedente viaggio via terra
supererebbe comunque il limite massimo di
incubazione di EVD.
Grazie per l’attenzione