Rabies

1. Rabies Presentation ECN; ADRIKO GOPHIN

2. Introduction • Rabies is a preventable viral disease of mammals, most often transmitted through the bite of a rabid animal • Rabies attacks the central nervous system of its host, causing encephalopathy and ultimately, death • Common animal reservoirs in Africa include the dog, domestic cat, farm animals, especially cattle, jackals, wildcats, and the mongoose • Animal vaccination programs and programs to eliminate stray dogs have been shown to reduce the incidence of human rabies, but the cost of these programs is prohibitive and can be a drain on public health resources even in the most developed countries Center for International Emergency Disaster and Refugee Studies

3. Introduction • Rabies mortality ranks ten in all infectious diseases worldwide • There are still about 50,000 to 60,000 human deaths annually although effective vaccines for post-exposure treatment are available • Most affected are the tropical countries in Africa, Asia, South America, and Oceania Center for International Emergency Disaster and Refugee Studies

4. Introduction • The vast majority (95-98%) of the 60,000 annual human death cases worldwide occur in canine (dog rabies) endemic regions with large stray dog population. Center for International Emergency Disaster and Refugee Studies

5. Introduction • Control of the disease is hampered by cultural, social and economic realities • A variety of different rabies vaccines and other treatments for rabies exist • Their availability varies from country to country Center for International Emergency Disaster and Refugee Studies

6. Introduction • In the rabies infested developing countries modern cell culture vaccines are hardly affordable. Dangerous neural tissue derived vaccines are still used • Three dose-saving treatment schedules have been developed: • The reduced dose intramuscular 2-1-1 regimen • The two-site intradermal • The 8-site intradermal regimen Center for International Emergency Disaster and Refugee Studies

7. Presentation • Human rabies evolves through 5 different clinical phases • an incubatory phase • a prodromal phase • an acute neurologic phase • coma • death Center for International Emergency Disaster and Refugee Studies

8. Presentation • Incubation phase • The host’s immune defenses play an important role in the outcome of infection • Our current therapeutic modalities are targeted at this stage Center for International Emergency Disaster and Refugee Studies

9. Presentation • Incubation phase • Since the patient is entirely asymptomatic during the incubation period, the clinician must rely on history, local epidemiologic data, and rarely, a tissue sample from the offending animal, in making a decision whether or not a patient requires post-exposure prophylaxis • Once rabies infection has progressed beyond the incubation phase, it is universally fatal and the clinician’s role becomes supportive care Center for International Emergency Disaster and Refugee Studies

10. Presentation • Prodromal phase • follows incubation and usually lasts 2 - 10 days • its onset is heralded by the development of a nonspecific, flu-like illness, consisting of • varying degrees of fever > 38.3 C • Headache • Dizziness • Malaise • gastrointestinal upset • URI symptoms • Anorexia • fatigue Center for International Emergency Disaster and Refugee Studies

11. Presentation • Prodromal phase • subtle mental changes may be evident • insomnia, nightmares, and hallucinations may also occur • neuralgia, a burning or tingling sensation at the site of the exposure, is the only specific prodromal finding. Center for International Emergency Disaster and Refugee Studies

12. Presentation • Acute neurologic phase • follows the prodrome and usually last 2- 7 days • neurologic symptoms at this stage specifically suggest rabies • the patient may present • furiously, exhibiting bizarre or aggressive behavior • nervous system hyperactivity • Disorientation • muscle fasciculations at the site of the bite • Hyperventilation • Lacrimation • focal or generalized seizure activity Center for International Emergency Disaster and Refugee Studies

13. Presentation • Acute neurologic phase • in contrast, the patient may have a dumb presentation, consisting of paralysis, cranial neuropathies, and mechanical respiratory insufficiency Center for International Emergency Disaster and Refugee Studies

14. Presentation - Acute neurologic phase Center for International Emergency Disaster and Refugee Studies

15. Presentation • Coma follows the acute neurologic phase of infection and is followed in time by death. The overall symptomatic phase of the illness lasts an average of 18 days. Center for International Emergency Disaster and Refugee Studies

16. Diagnosis • During the incubation period of rabies, no diagnostic test is available that will indicate infection • Several laboratory tests can be used to reject or confirm the clinical diagnosis of rabies in animals and humans once symptoms develop • The standard test for rabies involves direct flourescent antibody staining of rabies antigen • This test may be used on neural tissue of the animal suspected of transmitting rabies or on human tissue Center for International Emergency Disaster and Refugee Studies

17. Treatment • Post-exposure prophylaxis is indicated for patients with a potential exposure to rabies virus • The administration of post-exposure rabies prophylaxis is a medical urgency, not an emergency • Thus, all patients presenting with an animal bite should first be evaluated for life-threatening injuries • They should be administered care appropriate for any animal bite including tetanus prophylaxis, cleansing of the wound with 20% soap and water, and antibiotics if indicated.. Center for International Emergency Disaster and Refugee Studies

18. Treatment • In deciding whether to initiate post-exposure rabies prophylaxis, the following should be considered: • Type of exposure • Type of animal involved • How the exposure occurred • Vaccination status of the animal • Availability of animal for quarantine or post-mortem examination Center for International Emergency Disaster and Refugee Studies

19. Treatment • In developing countries, equine anti-rabies immune globulin (ERIG) is often used in place of HRIG due to issues of cost, high demand, and minimal supply • ERIG has the disadvantage of being foreign, and is associated with higher rates of hypersensitivity reactions. Center for International Emergency Disaster and Refugee Studies

20. Treatment • The rabies vaccine is administered for post-exposure prophylaxis in combination with RIG into the deltoid at a dose of 1ml IM on days 0, 3, 7, 21, and 28. • Injections of vaccine at other IM sites, particularly in the gluteal region, have been associated with vaccine failure and should be avoided • The side effects of these vaccines are usually minimal, consisting of arm swelling and erythema • Occasionally, more severe allergic or anaphylactic reactions may develop. Center for International Emergency Disaster and Refugee Studies

21. Treatment • A variety of other vaccines are produced in developing countries and administration regimens are similar • Cell culture derived vaccines such as PVRV, and PDEV are generally safe, efficacious, and less costly than their American counterparts • A few countries continue to use inactivated viral vaccines derived from the nervous tissue of adult animals or suckling mice • Due to the incidence of neuroparalytic reactions, these vaccines should not be used unless alternative vaccines are unavailable. Center for International Emergency Disaster and Refugee Studies

22. Treatment • Most vaccines and RIG can be administered safely to children • The doses are the same as for adults • Caution should be utilized in administering RIG and rabies vaccines to pregnant women • Immunocompromised patients can be safely immunized with inactivated rabies viral vaccines • They should initially receive the standard rabies treatment regimen • Patients who have received pre-exposure rabies prophylaxis or who have been treated for rabies in the past can receive a simplified rabies post-exposure regimen • They do not require RIG and only two booster vaccinations are required on days 0 and 3 (1ml/ dose IM) Center for International Emergency Disaster and Refugee Studies

23. Treatment Center for International Emergency Disaster and Refugee Studies

24. Treatment Center for International Emergency Disaster and Refugee Studies

25. Treatment • Treatment of the symptomatic patient • Once a patient has developed the symptoms of rabies, care is largely supportive and directed at the clinical complications of the disease • The fatal prognosis of the disease should be discussed with the patient (if lucid) and his or her family Center for International Emergency Disaster and Refugee Studies

26. Disposition • Asymptomatic patients receiving post-exposure prophylaxis should be admitted overnight to the hospital for monitoring following receipt of RIG • They may subsequently be discharged and treated with the remainder of vaccine doses on an outpatient basis • Patients with symptomatic rabies should be admitted for supportive care • Standard precautions should be taken when dealing with these patients • No documented cases of human to human rabies transmission have ever been reported. Center for International Emergency Disaster and Refugee Studies