Viral haemorrhagic fever Flashcards
Name some viral haemorrhagic fevers.
- Chikungunya haemorrhagic fever
- Dengue fever
- Lassa fever
- Ebola virus disease
- Congo/Crimean haemorrhagic fever
- Yellow fever
Other:
- Argentine haemorrhagic fever - Junin
- Bolivian haemorrhagic fever - Machupo
- Korean haemorrhagic fever - haemorrhagic fever with renal syndrome - Hantaan (Hantavirus)
- Kyasanur forest disease
- Marburg disease
- Omsk haemorrhagic fever
- Rift Valley disease
Define viral haemorrhagic fever.
A group of diseases that are caused by several distinct families of viruses. The term refers to a condition that affects many organ systems of the body, damages the overall CVS, and reduces the body’s ability to function on its own.
Symptoms vary but often include bleeding, or hemorrhaging.
Some VHFs cause relatively mild illness, while others can cause severe, life threatening disease.
What do VHFs have in common?
- RNA viruses
- Enveloped in lipoprotein - making them easier to destroy with physical heat and chemicals
- Naturally exist in animals and insects and restricted to where the host species live
- Can spread human-to-human
- Outbreaks hard to predict
What are the challenges associated with VHFs?
- More of the world’s population is at risk now - due to globalisation
- Person to person transmission may occur
- Confirmation of VHFs takes time - laboratories not prepared
- Prevention is difficult - outbreaks are sporadic and difficult
- Availability of vaccines and treatments are limited
What is the usual host of Lassa fever? Where is it endemic?
African rat
Endemic in West Africa e.g. Sierra Leone, Liberia, Guinea, Nigeria (named after town in Nigeria where it first occurred)
What are the clinical features of Lassa fever?
Usually mild: fever, malaise, headache.
20% have severe disease: haemorrhaging from mucous surfaces, ARDS, vomiting, facial swelling shock. Hearing loss, tremors and encephalitis.
Most common complication: Deafness in both mild and severe cases
What is the management of Lassa fever?
Supportive therapy
Ribavirin - most effective in early course of illness
How is Lassa fever diagnosed?
ELISA detecting IgM and IgG and Lassa antigen
What is the usual host of Dengue viruses? Where are they endemic?
Aedes mosquito
Dengue outbreaks are occurring in many countries of the world in the Americas, Africa, the Middle East, Asia, and the Pacific Islands. Has been a worldwide problem since 1960s
What are the clinical features of Dengue?
Ranges from asymptomatic to severe disease (1 in 4 asymptomatic)
Mild: non-specific febrile illness, nausea, vomiting, rash, aches, positive tourniquet test, leukopenia
Warning signs: abdominal pain, persistent vomiting, fluid overload, mucosal bleeding, hepatomegaly.
Severe dengue: severe plasma leakage causing shock or fluid accummulation with ARDS, bleeding, organ failure with ALT/AST >1000 IU/L, confusion, heart failure.
Does infection with dengue protect against future infection?
Yes - but only for that specific strain, not the other three
How do you diagnose Dengue?
Molecular or serology testing - virus RNA testing ursing NAAT or NS1 antigen and IgM testing.
What is the management of Dengue fever?
Supportive treatment +/- monitoring in ICU
No specific treatments are available
Prevention with vaccination - approved for use in children ages 9-16yrs with previous dengue living in an endemic area
What is the host of Yellow Fever? Where is it endemic?
What are the clinical features of Dengue?
Mild: suddent onset, headache, fever, malaise, dizziness, vomiting, Faget’s sign (bradycardia in relation to elevated body temperature)
Severe: epigastric pain, jaundice, renal insufficiency, CVS instability, bleeding diathesis, scleral and dermal icterus.
What are the clinical features of CCHF?
Presents as a sudden-onset, severe illness with initial influenza-like symptoms, red eyes, and petechiae leading to signs of haemorrhage around day 4.
What are the clinical features of Chikungunya?
Chikungunya means ‘that which bends up’ in the Makonde language (spoken in a border area between Mozambique and Tanzania where the first outbreak was described), which refers to the arthritis that the infection can cause.
Fever and joint aches, usually self-limited, but some may have chronic debilitating arthritis.
What are the clinical features of Ebola?
The most common symptoms reported on admission during the 2014 outbreak were:
* fever (76%),
* fatigue (71%),
* anorexia (64%),
* headache (56%),
* diarrhoea (51%),
* vomiting (50%),
* myalgia/arthralgia (48%),
* abdominal pain (40%),
* sore throat (29%),
* conjunctivitis (27%).
Other less common symptoms included difficulty swallowing (22%), difficulty breathing (18%), hiccups (13%), haemorrhagic signs (11%), confusion (9%), and rash (3%)
