Case Management of Suspect Influenza A (H5N1) Infection in Humans

1. Case Management of Suspect Influenza A (H5N1) Infectionin Humans

2. Learning Objectives • Recognize clinical features of H5N1 in humans • Treatment of cases • Public health action

3. Clinical Features

4. General Information

5. Signs and Symptoms

6. Laboratory Findings Commonly associated with avian influenza H5N1: • Drop in white blood cell count (lymphocytes) • Mild to moderate drop in blood platelet count • Increased aminotransferases (liver enzymes)

7. Epidemiological Context

8. Exposure to Avian Influenza • Infected poultry, particularly contact with respiratory secretions • Infected wild or pet birds • Other infected animals (e.g., pigs, cats) • Wild bird feces, poultry manure and litter containing high concentrations of virus • Contaminated surfaces

9. Exposures Continued • Under- or uncooked poultry meat or eggs from infected birds • Contaminated vehicles, equipment, clothing, and footwear at affected sites, such as poultry farms with outbreaks • Contaminated air space (e.g., a barn, hen-house, or the air space proximal to barn exhaust fans) • Bodies of water with infected bird carcasses • Close contact with (within 3 feet of) confirmed cases Cultural context can produce unique exposures

10. Specimen Testing

11. Clinical Specimens for Testing Influenza A (H5N1) • Lower Respiratory Tract* • Broncheoalveolar lavage • Tracheal aspirate • Pleural fluid tap • Sputum • Upper Respiratory Tract • Nasopharyngeal swab/aspirate • Oropharyngeal swabs* • Nasal Swab * Preferred specimens

12. Clinical Specimens for Testing • Serology • Acute and convalescent serum specimens • Acute collected within 1 week of symptom onset • Convalescent collected 2-4 weeks after symptom onset • Other infections or concurrent illness • Specimens should be collected within 3 days of symptom onset • Collect all possible specimens, serial collection

13. Avian Influenza H5N1 Chest X-Ray Chest x-ray of an avian influenza H5N1 patient, shown by day of illness Day 5 Day 7 Day 10 Tran Tinh Hien, Nguyen Thanh Liem, Nguyen Thi Dung, et al. New England Journal of Medicine. 18 March, 2004. vol. 350 no. 12. pp 1179-1188.

14. Treating Suspected Cases

15. Treatment Options • Antivirals • Antibiotics • Supportive care

16. Neuraminidase Inhibitor • Two drugs available • Oseltamivir (Tamiflu®) and Zanamivir (Relenza ®) • Should be given as soon as possible • Effective for treatment and prevention • Used for seasonal and avian influenza

17. Other Treatments? • Amantadine and Rimantadine • H5N1 resistant in some isolates • Not as effective as neuraminidase inhibitors • Corticosteroids • Low dose for sepsis • Unclear if high dose useful • Risk of side effects • Ribavirin • Ineffective against influenza viruses

18. Public Health Action

19. Response Overview • Collect Case Information • Classify case according to case definition for surveillance • Facilitate specimen collection and laboratory testing • Information on avian influenza illness • Infection control measures in the home • Active case follow up • Identify close contacts and recommend chemoprophylaxis

20. Case Definitions • Confirmed • Suspect • Report under investigation • Non-case • Refine for outbreaks

21. Active Follow Up • Reasons for follow up • Specimens for testing • Timely notification of results • Monitor delivery of antiviral therapy • Secure antivirals if shortage • Note unusual clinical presentations or complications • Follow up by telephone • Patient • Healthcare provider (when available) • Surrogate (e.g. spouse)

22. Identifying Close Contacts • List of contacts from patient’s case report form • Close contact = Within 3 feet • Sharing utensils, close conversation, direct contact • Follow Up • Characterize exposure • Identify signs and symptoms • Those with symptoms treated as potential avian influenza case

23. Recommendations to Contacts No symptoms • Receive current influenza vaccine • PEP for close contacts of a confirmed avian influenza H5N1 case • Antiviral (neuraminidase inhibitor) and dosage information in Background section

24. Instruction to Contacts No symptoms (continued) • Self monitor for 10 days after last exposure • Fever, respiratory symptoms, diarrhea, and/or conjunctivitis • Seek medical care if symptoms present • Notify public health authorities • Follow infection control measures in the home

25. Summary • For suspect cases, ask about recent exposure and contact with humans or animals that may have had avian influenza H5N1 infection • Important appropriate clinical specimens need to be collected and tested • Begin treatment with neuraminidase inhibitor immediately! Do not wait! • Case management also means identifying contacts

26. Breakout Groups