Lassa fever A neglected disease in Africa Who are the ... · WHO Case definition for Lassa fever A...
Transcript of Lassa fever A neglected disease in Africa Who are the ... · WHO Case definition for Lassa fever A...
Lassa fever
A neglected disease in Africa
Who are the patients and what are their outcomes ?
A Dahmane, R Zachariah, R Van den Bergh, T Reid, Y Nzomukunda, M Allaouna ,P Alders ,M Van Herp ,R Souya, Dr
Grant, S Hinderaker, AD Harries
Medecins Sans Frontières Brussels – Luxembourg, Sierra Leone International Union against Tuberculosis and Lung disease, Paris, France
University of Bergen (Norway) ,London School of Hygiene and Tropical Medicine London, UK.
LASSA FEVER
• An acute and severe viral haemorrhagic illness
• Caused by the “Lassa virus”
• Infections /year - 300-500,000
• Deaths - 5000
• Seen in the Lassa fever belt (West Africa)
Côte d’Ivoire
Mali Guinea Bissau
Senegal
Guinea
Reservoir & Transmission (Mastomys Natalensis - Zoonotic disease)
Man to Man - Any body fluid (stool, urine, vomit, saliva,
sweat, mothers milk, blood, aerosol transmission)
Rat to Man - exposure to rat excreta, urine
or blood
Mother to child transmission
SIERRA LEONE
Gondama Referal Center
• 220 bed MSF referral hospital
• Pediatrics and emergency obstetric care
• 2011 : Increased number of Lassa cases in GRC
Operational challenges
Early diagnosis is difficult – Mimics malaria, and
other severe diseases
(No rapid diagnostic test for lassa)
High case fatality – 50%
Nosocomial transmission within MSF health
staff 2 nurses died, ( 2011)
Blood transfusions – perhaps a source of
transmission
MANAGEMENT OF SUSPECTED LASSA FEVER
PATIENTS
• GRC :Identification
and isolation of
suspected cases
• Kenema
hospital:Laboratory
testing and treatment
Lassa Fever - a neglected disease !!
• No preventive vaccine (unlike yellow fever)
• No accessible diagnostics
• Expensive life saving treatment: Ribavirin treatment (5400 Euros/ 1patient!!)
• Limited research – Class A select agent bioterrorism – American military
STUDY OBJECTIVES
In the MSF hospital in Bo Sierra-leone
• To describe the characteristics,
management & outcomes of children
and women with suspected or
confirmed Lassa fever
METHODS 1
Study Design: Retrospective audit of patients files
Period: August - December 2011
Site: Gondama referral hospital (GRC)
Study Population: Confirmed & suspected Lassa fever
Ethics MSF & Union
METHODS 2
WHO Case definition for Lassa fever
A patient with fever > 38 degrees Celsius
• Unresponsive to anti-malarial and broad spectrum antibiotics within 72 hours
• And at least two major or one major and two minor criteria
METHODS 3
MAJOR CRITERIA
• Abnormal bleeding
• Swollen neck or face
• Conjunctivitis or sub-conjunctival haemorrhage
• Spontaneous abortion
• Unexplained tinnitus or altered hearing during a febrile illness
• Persistent low systolic blood pressure
• Known exposure to a confirmed Lassa patient or readmitted within three weeks of inpatient care for illness with fever
• Markedly elevated SGOT/AST
MINOR CRITERIA
• Headache
• Sore throat
• Persistent vomiting
• Diffuse abdominal pain/tenderness
• Retro-sternal pain
• Diarrhoea
• Generalized myalgia and arthralgia
• Profuse weakness
• Proteinuria
• WBC count < 4000 L
Lassa fever “suspect” : Patient fits the case definition but laboratory
negative
Lassa fever confirmed: Patient with Lassa fever laboratory test positive
DELAY FOR RIBAVIRIN TREATMENT
( Ideal delay < 6 days )
Referred patients to GRC
Start anti-malarial and /or AB
Wait for 72 Hrs
Suspicion of Lassa Fever
Test in Kenema hospital
Results in 1-5 days
Start Ribavirin
Time in days
Health centers
RESULTS 1 Characteristics of the study population
Lassa confirmed
N= 36 (43%)
Lassa suspect
N= 48 (57%)
Total cases
N=84
MALE 19 (53%) 27 (56%) 46 (55%)
FEMALE 17 (47%) 21(44%) 38 (45%)
AGE
≤ 2 yrs 21 (58%) 29 (62%) 50 (60%)
> 2 – ≤ 5 yrs 4 (11%) 10 (21%) 14 (17%)
> 5 – ≤ 15 yrs 4 ( 11%) 4 (9%) 8 (10%)
> 15 yrs 7 (19%) 4 (9%) 11 (13%)
RESULTS 2
Case Fatality Rate
Lassa
Confirmed
N=36
Lassa
Suspect
N=48
Total
N = 84
Deaths
22 (61%)
21 (44%)
43 (51%)
RESULTS 4 MAJOR CRITERIA
MAJOR CRITERIA
0
10
20
30
40
50
60
blee
ding
swollen face
conjou
nctiv
itis
Spo
ntan
eous
abo
rtion
tinnitus
low B
P
expo
sure
to LF
read
mission
with
in 3 w
ks
SGOT/
ASAT high
coag
ulation test +
%
lassa lab + (n=36)
lassa suspect (n=48)
Stage 3
RESULTS 5
PRESENTATION - MINOR CRITERIA
MINOR CRITERIA
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
head
ache
sore th
roat
persistent vom
iting
abdo
minal pain
retro
-stern
al pain
diar
rohe
a
mya
lgia/ a
rthralgia
profus
e wea
knes
s
proteinu
ria
WBC <
400
0
%
lassa lab + (n=36)
lassa suspect (n=48)
RESULTS 6 WHO CASE DEFINITION – HOW USEFUL?
DID NOT MEET
WHO CASE DEFINITION
N=84
Lassa Confirmed
17/ 36 (47%)
Lassa Suspect
31/ 48 (65%)
RESULTS 7 TIME DELAY
Admission to Lassa Testing From admission to Testing
0
1
2
3
4
5
6
7
8
9
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Days
nu
mb
er
of
pati
en
ts
Lassa confirmed
lassa suspect
Data available for 81 cases
Desired time to testing ?
RESULTS 8
TIME DELAY
ADMISSION TO RIBAVIRIN
Ribavirin treatment Admission
Deaths Alive
Mean (Days)
14
6
STUDY LIMITATIONS
• Preliminary data analysis
• Missing data in patient files
• No written reports from patients referred to Kenema referral hospital
CONCLUSIONS
• Very high case fatality rate
• Only 50 % of patients fit in the WHO case definition late diagnosis
• Urgent need for improving Lassa diagnostic strategy
• A neglected disease that should benefit from MSF advocacy