Download viral hemorrhagic fever

-By the Name Of ALLAH****** for all those who anticipated this sheet earlier……. Sorry 4 the delay ,however you will notice
that it’s a replicate of the slides with only little extra notes!!!
*** I will be writing the title of the slide for orientation ,writing only the extra info’s related !!!
I suggest you read this sheet along with the slides…you will find the title of each slide.
viral hemorrhagic fever
lecture-3# IN this lecture there are much of geography, veterenal medicine in
addition to real medicine !!
- ARBO AND ROBOVIRUSES:
Those viruses are arthropod-borne or rodent-borne viruses.
Are recovered from different geographical locations.
They are dependent on climatic changes as heavy rain falls, which support the
breeding of their vectors
In human… they are associated with three types of clinical syndrome.
# We will discuss only hemorrhagic fever in this course.
#There are two viruses not associated with hemorrhagic manifestations and
they are : West Nile virus and Sand Fly Fever.
- WEST NILE FEVER:
Caused more than 10,000 of cases with high mortality rate since 1997.
The virus assumes different horizons of infections ,involving CNS in the form
of encephalitis ,rhabdomylsis and even
Congenital malformations were linked to this virus.
One of the most important viral infections that emerged in the last decade,
especially in Europe … transmitted via
Migratory course .
Common in Africa… 70% of the people above 4 years of age have antibodies
to the virus, but yet they didn’t develop
Serious infection meaning that the infection is common and asymptomatic
Introduction of the virus into the western countries was associated with high
number of encephalitis with mortality
Rate of 50-60 %.
- SAND FLY FEVER:
Transmitted by the sand fly ( phlebotomous papatasi) which has very small
size – few mms- .
Also sand fly can transmit leishmania . There are 3 foci for sand fly in Jordan :
mowaqqar , jordan valley and in malqa
In the north of Jordan.
Incubation period : 3-6 days…
Site of bite start with itching, then other manifestation develop, which are
followed by complete recovery.
If infection delayed until adulthood, it’s associated with serious manifestations
and it might be confused with Malaria.
# All viruses cause fever, but here the classification is due to hemorrhagic
manifestation
# Now… we will talk about proper hemorrhagic fevers
Introduction :
Bleeding isn’t the cause of death , death is caused by multi-organ failure.
Some cause mild disease while others cause severe disease … mortality
ranges from less than 1% to 90%.
- Classification:
viruses that cause VHF are members of four distinct families:
Arenavirus, filoviruses ( most lethal ) , bunyaviruses and flaviviruses.
The table shows most important hemorrhagic fevers .. in arenaviruses all
types are in south-america but lassa in Africa.
Flaviviruses .. yellow fever in Africa and south – America , dengue has
more spread distribution.
- Clinical picture o VHF-1-:
usually infection start with non-specific manifestations suggestive for viral
infection as fever , fatigue, …
Then more severe manifestations appear including bleeding disorders.
Usually bleeding is the secondary phase of infection .
- Clinical picture of VHF-2-:
incubation period varies from 2 – 21 days
Hemorrhagic diathesis : bleeding tendency.
Diagnosis is usually difficult due to unfamiliarity with this disease and lack
of available diagnostic tests.
- VHF initial symptoms :
This clinical picture doesn’t indicate HF , it can be seen in influenza,
hepatitis and infectious mononucleosis ..
The prodrome isn’t characteristic for such infection and it’s very difficult to
make a diagnosis during this phase
Diagnosis is made during hemorrhagic phase , where clinical picture aids in
diagnosis.
# NOW WITH VIRUSES CAUSING HF:
- ARENAVIRUSES -1-:
First isolated arenavirus is st.louis encephalitis virus which isn’t a
hemorrhagic fever.
Lassa virus in Nigeria, rarely associated with severe HF , however this
outbreak affects Americans who were Stationed at lassa village
of Nigeria… that’s why Americans developed severe manifestations with a
mortality of 60% or more
There are 5 arenaviruses associated with HF , 4 in south-america and one
in Africa , yet there are hundreds of Arenaviruses that have
been discovered without being associated with pathologic condition.
-ARENAVIRUSES -2,3-:
Human infection follows infection among those rodents ( rats and mice)
Rodents shed the virus into the environment through urine , fecal
droppings and other excreta which contaminate Food and water , so
human can become infected as consequence of contamination of these
substances or direct contact….
Also inhalation , person to person transmission…
- ARENAVIRUSES-4-:
LASSA and MACHUPO can cause nosocomial spread of virus.
-ARENAVIRUSE-5-:
Incubation period for arenaviruses is typically between 10-14 days.
Followed by onset of disease last for 2-4 days , this is the prodromal phase
of illness. Most patients with lassa IN Africa will recover
however foreigners acquiring it will develop severe illness.
- LASSA FEVER:
The clinical signs mentioned in the slide were documented among
Americans who were affected by first outbreak, That lead to virus isolation
in 1969.
- BUNYAVIRUSES:
HANTAVIRUSES are transmitted by rodents, while other bunyaviruses are
transmitted by arthropods. Also there is A mention of the exposure to
infected animal tissue as a common mode of transmission.
Human aren’t infectious.
# among these viruses:
1- RIFT VALLEY-1,2,3-:
RVF virus ,endemic in Africa. Cause epizootics ( epidemic among
animals).
The virus crossed the borders between ASIA and AFRICA via imported
sheeps.
Abortion rates can reach 100% depending on the animal.
Most human infections will occur one to two weeks following the
spread of infection among animal. Thus, this 2 Weeks period is
important for the virus to transmit from animals to human…
#RVF human disease:
incubation period of 2-6 days followed by flu-like signs , recovery within
4-7 days. Case fatality of hemorrhagic fever 50% , however HF is seen in
25% of cases.
Hematemesis : bloody vomitus , melena : bloody stool.
THE TABEL in the slides about different effects of the virus depending on
animals types.
2- HANTAVIRUSES-1,2,3-:
Rodents persistently infected ,but show no clinical signs and that’s why
they are dangerous to human.
# hemorrhagic fever with renal syndrome: mortality rate over 15%
# hantavirus pulmonary system: more fatal , mortality rate over 50%
3- CRIMEAN-CONGO HEMORRHAGIC FEVER VIRUS:
ixodid ticks , transmit many viruses with natural animal reservoir.
- MARBURG AND EBOLA VIRUSES-1,2,3,4,5,6,7- :
filoviruses , most lethal viruses.
Ebola was first reported simultaneously in ZAIRE and SUDAN , when two
distinct subtypes with HF were detected… so we have Ebola subtype Zaire ,
subtype Sudan and subtype Reston and Cote-divoire.( ZAIRE , the highest
fatality rate)
ZAIRE and SUDAN ARE AFRICAN , RESTON IS AN ASIAN HF.
Case fatality rate is less for MARBURG.
Survivors develop permanent sequelae.
Filoviruses cause HF among non-human primates, among monkeys.
- YELLOW FEVER VIRUS-1,2,3,4-:
flavivirus , the first virus proved to be transmitted by arthropod vector.
Sylvatic cycle ( among monkeys ) and urban cycle ( human infected , serve
as reservoir.
Annual incidence is believed to be about 200,000 cases with incubation
period of 3-6 days , so people Going to such endemic areas should receive
the vaccine for such virus.
Pathology involve liver, kidney and blood vessels.
- DENGUE VIRUS – 1,2,3- :
Dengue fever is of a severe pain ,also called break-bone fever.
Cases of DHF result from re-infection with hetrologus 3 … Those individuals
infected with dengue ,may be Re-infected with another strain. Antibodies
partially protect but these antibodies complex with the virus and Deposit in
blood vessels causing hemorrhage so hemorrhage is immune-mediated.
- KYASANUR FOREST HEMORRHAGIC FEVER-1,2-: only the slides!
- OMSK HEMORRHGAIC FEVER-1,2-: limited to areas of sovit-union.
# LABORATORY DIAGNOSIS FOR ALL HF VIRUSES:
Usually require specific equipments, only labs of level D are allowed to
work with these viruses whether serology , PCR ….
(D) is of a maximal biological safety level.
#TREATMENT OF VHF :
There’s no approved FDA anti-viral drug to support treatment.
However RIBAVIRIN is a broad spectrum anti-viral agent against RNA and
DNA viruses, used with limited success .
# PREVENTION: only slides!
# vaccination : only slides!
Ruba al assaf