16 the case of big bad bug

The Case of the Big Bad Bug#16: 

The Case of the Big Bad Bug #16 Jim Pointer, MD Alameda County EMS Medical Director

The Call: 

The Call A south county resident calls 9-1-1 complaining of a 2 day history of fever (103˚), headache, maliaise, nausea, weakness, stiff neck, and a rash.

History: 

History The patient is a 74 year old male with a past history of CABG x 3 and prostate cancer. Current medications include: Nitroglycerine Aspirin Proscar No history of foreign travel

Field Assessment: 

Field Assessment Primary survey: WNL Vital signs: B/P – 152/97, PR – 138, RR – 22 Temp – 102.6 p.o. Secondary survey (pertinent findings) HEENT – dry mucous membranes Lungs – clear Skin – warm/dry; erythematous maculopapular rash on neck & trunk Neuro – confused, GCS: 13 - 14

Treatment: 

Treatment IV – normal saline 500cc’s Glucose check – 102 mg/dl Transport to Culex Memorial Hospital

Hospital Course: 

Hospital Course The patient tells the physician that he saw several dead Stellar’s Jays on his property 5-7 days ago. When he picked them up he received several insect bites

Hospital Exam: 

Hospital Exam Vital signs: B/P – 142/98, PR – 126, RR – 20 Temp - 102.7 p.o. Pulse Ox - 98% RA Additional physical findings Mild nuchal rigidity

Laboratory Findings: 

Laboratory Findings CBC – 11.1 K 86 lymphocytes, 10 PMNs, 2 Basophils, 2 Eosinophils Na+, K+, HCO3, Cl-, BUN, creatinine, glucose – WNL Cerebrospinal fluid: Color – clear, WBC – 120 cells/mm3 Protein – 82 mg/dL (n = 20 – 45) Glucose – 78 mg/dL (n = 50 – 80)

West Nile Virus: 

West Nile Virus Ecology: Enzootic cycle – culcine mosquitoes and birds Corrids (crows, ravens, jays) are particularly susceptible “Bridge vector” mosquitoes in late summer Over 30 mosquito species responsible Mammals (humans, horses, ? deer) “dead-end hosts” Surveillance systems – dead birds, “sentinel chickens”, ill horses

West Nile Virus (cont.): 

West Nile Virus (cont.) First isolated in 1937 First occurred in western hemisphere in New York in 1999 About 400 deaths reported in the US to date – about 9,000 cases reported for 2003 Vaccine available for horses (1/3 of infected horses die)

Transmission Cycle: 

Transmission Cycle

Virology: 

Virology Single stranded RNA virus Family: Flaviviridae Genus: Flavivirus Member of Japanese encephalitis virus serocomplex including: Japanese encephalitis St. Louis encephalitis Murray Valley encephalitis Kunjin viris

Geographic Distribution 2004: 

Geographic Distribution 2004

Geographic Distribution Calif.: 

Geographic Distribution Calif.

Geographic Distribution horses: 

Geographic Distribution horses

Clinical Features: 

Clinical Features Incubation period: 3 – 14 days Probably < 20% of those infected will develop clinical infection Febrille illness of sudden onset malaise, myalgias, anorexia nausea, vomiting Eye pain, headache Rash, lymphadenopathy

Clinical Features (cont.): 

Clinical Features (cont.) 1/150 infections result in meningitis/ encephalitis Encephalitis is more common Advancing age most significant risk factor for neurologic disease Age 50 to 59 - 10x higher Age > 80 - 43x higher Severe weakness in 50% of hospitalized patients in U.S.

Table of Symptoms: 

Table of Symptoms

Outcome: 

Outcome Death rates: 4 – 14 % Much higher in older patients or those with diabetes or immunocompromised Morbidity Fatigue Memory loss Depression Difficulty walking

Treatment: 

Treatment Supportive Ribavirin and interferon effective in vitro No clinical trials

Lab Findings: 

Lab Findings WBC – normal or elevated Occasional anemia Low sodium CSF: WBC - 0 to 1782 cells/mm3 Protein - elevated Glucose - normal

Lab Findings (cont.): 

Lab Findings (cont.) MRI – meningeal or periventricular enhancement IgM – most efficient diagnostic method (serum or CSF) Persistent for > 6 months Present in other Flavivirus infections and in vaccinated persons

Reporting: 

Reporting Reportable disease Serum and CSF specimens must be submitted

Prevention: 

Prevention Reduce # of mosquitoes Eliminate breeding sites Apply larvacides or approved pesticides Prevent mosquito bites Use DEET (not > 50% adults/10% kids) Employ barrier methods

Slide27: 

Pull out Betty…pull out! I think you hit an artery

Reference: 

Reference Petersen LR, Marfin AA: West Nile Virus: A primer for the clinician, American Journal of Internal Medicine. 2002; 137 : E 173 - 179