West Nile and Zika Virus Flashcards
West Nile Virus
Causes sporadic infections and outbreaks which may be associated with severe neurological disease
Found in the continental US Puerto Rico
Birds serve as an amplifying host and disease is spread through mosquitos
Can be transmitted through blood transfusion and organ transplantation
Generally, an underreported disease as most patients are asymptomatic or do not seek care for mild symptoms
West Nile Virus Symptoms
Acute symptoms usually last 3-10 days, sometimes prolonged recovery. Abrupt onset of fever, headache, malaise, back pain, myalgia, anorexia, eye pain, hyaryngitis, GI symptoms, and pain. May not have fever, or may be low grade.
20-40% of infected patients
Incubation period usually 2-14 days, but can be longer
After acute infections patients may have persistent symptoms- fatigue, memory impairment, weakness, headache, balance problems
Once revovered- lifelong immunity
Approximately 25% develop West Nile fever and 1 in 15-250 develop neuroinvasive disease
West Nile Virus Risk Factors
Fever- increased viral load, females
Neuroinvasive disease- diabetes, htn, alcohol abuse, renal disease, male gender, advanced age, malignancy, organ transplantation, genetic factors
West Nile Rash
Appears in 25-50% of patients with West Nile Fever.
Usually on chest, back and arms.
Morbilliform or maculopapular..
Sometimes with dysethesia and pruritus.
Usually lasts <1 week an occurs when fever resolves.
Decreased risk of neuroinvasive disease and death.
West Nile Virus Neuroinvasive Disease
Presents with fever, meningitis, encephalitis, flaccid paralysis or a mixed pattern of disease.
Encephalitis more common in elderly.
Mortality is approximately 10%.
Can cause acute flaccid paralysis syndrome with asymmetric weakness of limbs within 48 hours of symptom onset.
May also have chorioretinitis, retinal hemorrhage, vitreitis, rhabdomyolysis, hepatitis, pancreatitis, myocarditis, myositis, hemorrhagic fever.
West Nile Virus Lab Testing
Peripheral blood samples do not distinguish WNV from other viral infections.
CSF may show elevated protein and moderate increased cell count with a predominance of lymphocytes, may also be predominance of neutrophils.
Serologic testing for IGM antibody using ELISA should be performed.
-Testing should also be performed on CSF.
-May repeat testing 10 days after symptoms onset if initially negative.
West Nile Virus Treatment
Usually seen in late summer/early fall.
Treatment is usually supportive in nature.
Severe neurological disease- alfa interferon may be helpful.
Zika Virus
Spread by bite of an infected Aedes species mosquito
No vaccine or preventative medication
Can be transmitted sexually, through blood transfusion and through placenta.
Increased Guillain-barre in Zika infected areas.
Zika Virus Symptoms
Mild to no symptoms
Fever, rash, headache, joint pain, red eyes, myalgia
Usually last several days to a week
Most people do not get sick enough to seek care
Once infected likely protected from future infections
Zika Virus and Pregnancy
Can lead to microcephaly and brain defects
Linked to miscarriage, stillbirth and other birth defects
Zika Virus Prevention and Treatment
Avoid mosquito bites, use condoms to prevent transmission. Males transmit for 3 months, females for 2.
Treatment- symptomatic in nature, no ASA or NSAIDS
Zika Virus Testing
Go through health department
Specimens obtained from serus, csf, semen, urine, & amniotic fluid.
