Viral Zoonotic Encephalitis: Australian Bat Lyssavirus and Hendra

Viral zoonotic encephalitis: Australian Bat

Lyssavirus and Hendra

Bev Paterson Hunter© by Medicalauthor Research Institute University of Newcastle Australia ESCMID OnlineEmail: [email protected] Library Encephalitis in Australia

 Causes substantial morbidity and mortality  Herpes simplex virus is the most commonly identified causative pathogen  70% of adult encephalitis hospitalisations no pathogen identified  57% of deaths no pathogen identified  (Reference: Huppatz et al. CDI,© 2009; by Huppatzauthor et al. EID, 2009)

ESCMID Online Lecture Library Viral zoonotic encphalitis

 Several recently emerged or resurging pathogens are known to cause an encephalitis syndrome

 Vectorborne and transmitted flaviviruses – MVEV, WNEV-KUN and JEV © by author  Bat-borne viruses – Australian Bat Lyssavirus (ABLV) and Hendra virus ESCMID Online Lecture Library Impact of climatic conditions

ESCMID Online Lecture Library Australian Bat Lyssavirus

 Australia has no endemic rabies  ABLV is a member of the family Rhabdoviridae, genus Lyssavirus  ABLV is very closely related to rabies (genotype 7 of the Lyssavirus genus)  Reservoir is bats © by author  Two deaths from ABLV

ESCMID Online Lecture Library Human exposure

ESCMID Online Lecture Library Epidemiology of human disease

 Two fatal human cases – coastal Qld – encephalitis indistinguishable from classic rabies  1996 – 39yr female, a few weeks after scratches from bat  1998 – 37yr female, 27 months after bite from bat © by author  References (Samaratunga et al 1998, Hanna et al 2000).

ESCMID Online Lecture Library Australian Public Health responses

 All bat exposures managed similarly (flying foxes or microbats)  Importance of immediate rigorous wound cleaning – reduce mortality by 50%  Immunoglobulin (HRIG) 20 IU/kg – max. into wound; multiple wounds dilute with normal saline  Rabies human diploid cell vaccine (HDCV) – 2.5 IU/IM dose – Essen© schedule by author – 0,3,7,14,28  Omit HRIG where > 7 days has elapsed since the first vaccine dose ESCMID Online Lecture Library Hendra (Family Paramyxoviridae)

 Related but not identical to Nipah virus

Newcastle disease © by author

ESCMID Online Lecture Library Hendra (HeV)

 Reservoir in fruit bats, Pteropus  First isolated in 1994  One of the world’s rarest diseases  Fatality rate of close to 60%  Seven confirmed human HeV infections  Four deaths  All human infections epidemiologically linked to horses © by author

ESCMID Online Lecture Library Transmission

 Not very contagious, luckily  Bat to horse

 Bat to person  Horse to horse  Horse to person  Person to person © by author

ESCMID Online Lecture Library Infections in humans – 7 cases

 Self limiting ILI (2 cases)  IlI complicated by severe pneumonic illness contributing to death (1 case)  Aseptic meningitis with apparent recovery then death from encephalitis 13 months later (1 case)  Acute ILI followed© byby encephalitisauthor at seroconversion, followed by recovery (1 case) and death (2 cases) ESCMID Online Lecture Library Treatment

 No known specific treatment for Hendra  Antivirals haven’t been found to be effective  Three people have recovered with general medical support  Research into the use of monoclonal antibodies © by author

ESCMID Online Lecture Library Vaccine

 Vaccine still in the clinical trial stage  Preliminary work on cats and ferrets looks promising

ESCMID Online Lecture Library What are we missing?

 What does cause viral encephalitis in Australia?

 Are we missing cases of ABLV or Hendra (or did we miss them in the past)?  Are there other highly pathogenic viruses out there, that we just don’t know about yet? © by author

ESCMID Online Lecture Library Acknowledgements

 David Durrheim  Nigel Perkins

 Ben Ewald

ESCMID Online Lecture Library Questions?

ESCMID Online Lecture Library