Lassa fever is a viral hemorrhagic fever caused by the Lassa virus and transmitted by rodents. It is endemic in West Africa, with an estimated 100,000-300,000 cases and 5,000 deaths annually. There is currently an outbreak in Nigeria affecting 12 states and 397 cases, resulting in 40 deaths so far. Clinical signs include gradual fever, headache, bleeding, and neck swelling. Diagnosis involves ELISA and PCR tests, and treatment is supportive care and the antiviral drug ribavirin. Preventing transmission involves avoiding contact with infected rodents and person-to-person spread through medical settings.

1. A N A D A P T A T I O N F R O M C D C P R E S E N T A T I O N , W H O
F A C T S H E E T S A N D N E M A E P I D E M I C S U P D A T E .
A N U G O M A . E M E K A
Lassa Fever Presentation.

2. Welcome & Introductions
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 Logistics
 Emergency exits
 Restrooms

3. Agenda
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 Lassa fever Disease
 Importance of Topic.
 Clinical Signs and Symptoms.
 Diagnosis and Treatment
 Preventing Lassa fever

4. What is Lassa Fever?
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 A viral haemorrhagic fever caused by
the Arenavirus Lassa. A single
stranded RNA virus that is animal-
borne. This was discovered following
the death of two Nurses in Nigeria in
1969 and named after the town in
Borno state, Nigeria, where it was
first discovered.
 Transmitted from rodents to humans.
The species of rats transmitting this
disease is prevalent in West Africa.
(‘The multimammate rat’, mastomys
species-complex), and is spread via
their urine and droppings.

5. What is Lassa Fever?
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 There is secondary human to human
transmission, via body fluids exchange or
in hospitals, via reused needles or
contaminated medical equipment
 The virus can be transmitted through
direct contact with these materials or via
cuts and sores or via poorly stored food
(as Mastomys rodents are home
scavengers)
 It can also be airborne via inhalation of
tiny particles in air contaminated with
rodents excreta.
 Also since mastomys are consumed as
food source, it may also occur via direct
contact when they’re caught and
prepared for food.

6. What is Lassa Fever?
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 It’s seasonal, with clusters in late
rainy and early dry season,
affecting all age groups and both
sexes.
 Its is endemic in areas of West
Africa including Nigeria, Liberia,
Sierra Leone and Guinea.
 Annual incidence of 100,000 to
300,000 with approximately
5,000 deaths in West Africa.
 Incubation period is 5-21 days

7. Importance of Topic.
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 There is a recent outbreak in
Nigeria over the past 7weeks,
which has claimed 40 lives, with
Edo state accounting for 22 of
this.
 11 of the 36 states in Nigeria
have been affected by this and a
total of 397 cases have been
reported, out of which 87 have
been confirmed.
397 cases
40 deaths
12 States

8. Map of States With Lassa fever Cases in Nigeria
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9. Graphical Display of Prevalence in Nigeria
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1
15
326
1
1
5
6
5
4
29
4
Prevalence of lassa Fever in
Nigeria as at 12th Feb 2012
Anambra
Ebonyi
Edo
Gombe
Lagos
Nasarawa
Ondo
Plateau
Rivers
Taraba
Yobe
Anambra 1
Ebonyi 15
Edo 326
Gombe 1
Lagos 1
Nasarawa 5
Ondo 6
Plateau 5
Rivers 4
Taraba 29
Yobe 4

10. Clinical Signs and Symptoms
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 Gradual fever onset
 Headache
 Malaise
 Other Non-specific symptoms
 Pharyngitis
 Myalgia, retro-sternal pain
 Cough
 Gastrointestinal symptoms
 Few have the Classic symptoms of :
- Bleeding
- Neck/facial swelling
- Shock

11. Clinical Signs and Symptoms
0 10 20 30 40 50 60 70 80 90 100
Swollen Neck or Face
Bleeding
Deafness
Conjunctivitis/Subconjunctival
Hemorrhage
Abdominal Pain/Tenderness
Cough
Dizziness
Retro-sternal Pain
Headache
Fever
Arthralgias/Myalgias
Sore throat/Pharyngitis
Weakness
Vomiting
Diarrhea
Chills
Lymphadenopgathy
Confusion
Percent

12. Clinical Signs and Symptoms
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 Case fatality of Hospitalized cases:15-
20%
 Its severe in pregnant women and their
offspring.
-Increase 3rd Trimester mortality (>30%)
-Increased fetal/neonatal mortality (>85%)
 Deafness is a common sequela, not
related to severity of acute illness, maybe
bilateral/unilateral and may persist for
life in one-third of those affected.

13. Diagnosis and Treatment
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 Clinical diagnosis is often difficult
 ELISA (Enzyme-linked immunosorbent
assays) for antigen, IgM, and IgG
 Postmortem tissue
Immunohistochemistry
 Reverse trancription-PCR for reasearch.
 Supportive Measures
 Drug of Choice is: Ribavirin
-Most effective when started within first
6days of illness.
-It is presently contraindicated in
pregnancy but maybe warranted if
mother is at risk)
-Doesn’t reduce incidence of severity of
deafness.
-Side effects are: reversible mild hemolysis
and suppression of erythropioesis

14. Preventing Lassa Fever
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 Avoid contact with Mastomy rodents
and bush burning
 Store food properly in rodent-proof
containers
 Keep homes clean and discourage
rodent entry.
 Using rodent as food source is
discouraged.
 Clean traps and dispose carcass neatly.
 Prevent person-person transmission
via use of PPEs (Masks,Gloves,Gowns
and Goggles) especially for health
workers
 Sterilize equipment after use
 Isolate infected patients from contacts.

15. Questions
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