Transcript Case Study MICR 454L Emerging and Re

Case # 64
Lucia Rosas, Sandra Isnasious, Bita Bahrami
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30-year-old woman
Symptoms: fever, back aches and headache for 2
days, pain on moving her eyes, myalgias in the upper
arms.
Exposure: Recent trip to El Salvador with high
mosquito exposure
Physical exam:
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Erythematous rash on face, arms, trunks and thighs (Fig. 1).
There was no enanthem, murmur, or splenomegaly.
White blood cell count was l,600/ml (normal 4,500-10,000/ml)
Platelet count was l40,000/ml (normal 150,000/ml-400,000/ml
Hemoglobin was 17.5 g/dl (normal 12-15.2g/dl)
Convalescent-phase antibodies to
a mosquito-borne viral disease
were diagnostic.
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Symptoms:
– Fever, Back ache and Headache
– Myalgias in the upper arms: muscle and joint pain
– Pain with the movement of the eyes
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Recent Trip to El Salvador: tropical environment
with Dengue endemic.
Exposure to Mosquitoes: female Aedes aegypti
Erythematous rash (petechiae).
Positive for mosquito viral borne antibodies.
Classic Dengue fever
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Family Falviviridae
Enveloped, single-stranded (+) RNA genome
The four distinct serotypes are DEN-1, DEN-2,
DEN-3, and DEN-4.
The female Aedes mosquito is this virus’ biological
vector
microbiologybytes.com
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Classic dengue primarily occurs in non-indigenous adults
individuals
Symptoms begin after a 5 to 10 day incubation period and
last 3 to 10 days.
Transmitted to humans via the bite of a mosquito. Not
transmitted from human to human.
Majority of infected individuals are asymptomatic.
Individuals who do present with symptoms present: Fever,
headache, muscle and joint pain, retro orbital pain, rash
A small percent of individuals can develop Dengue
Hemorrhagic fever and can potentially develop Dengue Shock
Syndrome. Both of these can lead to death.
•Necessary
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Criteria for DHF:
Fever or recent fever
Hemorrhagic manifestations
Low Platelet Count (100,000/ml)
Evidence of leaky capillaries
•Symptoms:
Gingival, nasal,
gastro intestinal bleeding, hematuria,
skin hemorrhages
•Necessary Criteria for DSS:
– 4 criteria for DHF
– Evidence of circulatory failure
•Both
DHF and DSS lead to death.
niaid.nih.gov
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Balsitis, Scott, et al. 2010, Lethal Antibody
Enhancement of Dengue Mice is Prevented by Fc
Modification, PLoS Pathogens 6: 1-13.
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Experimental set up: Mice models with 4 groups.
◦ Uninfected, infected with DENV-2 normal levels, infected
with DENV-2 high levels, DENV-1 antibodies with DENV2 infection.
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What they found:
◦ Secondary DENV infection results in enhanced infection
or may offer some protection in vivo.
◦ Can prevent enhanced infection by modifying Fc region of
DENV antibody to prevent binding to
Fc receptor.
aalaslearninglibrary.org
Primary Research Article
Contributing to the Understanding of
this Disease
Main Figure:
Negative
Control
DENV-1
antibodies
+DENV-2
infection
DENV-2
infection
Positive
Control
This article helps us understand how our patient is at risk for DHF and DSS upon
secondary infection.
It also shows that partial short-term cross-reactive protection can occur.
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ELISA
Virus Isolation
◦ Cell culture,
◦ Mosquito inoculation
◦ Fluorescent antibody test
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st.mahidol.ac.th
RT-PCR
Tourniquet Test
omegahealthcare.co.uk
thaitravelclinic.com
Positive Tourniquet
Test
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No specific drugs to treat the virus.
Patient recommendations:
– Get plenty of rest and stay hydrated.
– You can take medication to reduce your fever but
make sure to avoid NSAIDs.
– Take precautions against mosquitos as you may be still
infectious.
– If you feel worse and develop vomiting and abdominal
pain seek emergency medical treatment.
– This is not the time to get any invasive procedures.
– This should resolve itself within 2 weeks, you will
be fine.
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There is currently no vaccine available.
Targeting the mosquito vector can prevent infection.
– Insecticides
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When infected, early recognition and prompt supportive
treatment can substantially lower the risk of developing
severe disease leading to death.
Traveling recommendations:
– Items that collect rainwater or to store should be covered or
properly discarded.
– Staying in screened or air-conditioned rooms
– Spraying rooms with aerosol bomb insecticides to kill adult
mosquitoes indoors using a repellent, DEET, on exposed skin.
– Wearing protective clothing treated with repellant.
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Infection with one serotype does not protect against the
others, and sequential infections put people at greater risk
for dengue hemorraghic fever (DHF) and dengue shock
syndrome (DSS).
With more than one-third of the world’s population living in
endemic areas in Central America
Dengue infection is a leading cause of illness and death in
the tropics and subtropics. As many as 100 million people
are infected yearly.
These mosquito vectors are found here in the U.S. and
there have been reported cases of dengue infections in
Texas, Arizona, Hawaii.
Vectors can become resistant to insecticides.
•Dengue
virus can manifest itself as: Classic Dengue Fever, DHF,
DSS.
•Classic Dengue fever symptoms include fever, rash, headache,
muscle and joint pain.
•Pathogen is an enveloped, (+) ssRNA virus known as the flavivirus.
•Diagnostics include ELISA, RT-PCR and Tourniquet tests.
•Therapy includes fluids, rest, and fever reducers.
•Prognosis is good, most people recover completely within two
weeks. Only 1% develop DHF or DSS which could lead to death.
•Preventative measures: window screens, insect repellent and
insecticides. No vaccine or drug is available.
•Transmission is via the female Aedes aegypti mosquito.
•Threats include 2.5% mortality, reports of infections in the U.S. and
vector resistance.
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Argüello A.F., Luxemburger C, Quiñones L, Muñoz J. L., Beatty M, Lang J.,
Tomashek K. M., 2008. Epidemiological and Clinical Observations on Patients with
Dengue in Puerto Rico. Am. J. Trop. Med. Hyg., (79)123-127
BalsitiS.J., Williams K.L., Lachica R., Flores D., Kyle J.L., Mehlhop E., Johnson S.,
Diamond M.S., Beatty P. R., and Harris E., 2010. Lethal Antibody Enhancement of
Dengue Disease in Mice Is Prevented by Fc Modification, Plos pathogens, (6) issue
2.
Gubler D. J., 1998. Dengue and Dengue Hemorrhagic Fever
Clin Microbiol Rev. (11) 480–496.
Johansson M.A., Dominici F., Glass G.E., 2009. Local and Global Effects of Climate
on Dengue Transmission in Puerto Rico. Plos. (3) 382.
Muñoz-Jordán J., L.,Collins C.S., Vergne E., Gilberto A. Santiago, L Petersen L., Sun
W., and Linnen J. M.,2009. Highly Sensitive Detection of Dengue Virus Nucleic Acid
in Samples from Clinically Ill Patients Journal of Clinical Microbiology, (47) 27-931
Wahala M.P.B., Donaldson E.F., Alwis R., Accavitti-Loper M.A., 2010. Natural Strain
Variation and Antibody Neutralization of Dengue Serotype 3 Viruses. Plos Pathogens,
(6) issue 3.
CDC (center for disease Control and Prevention)
Lecture