Nipah virus emergence a case study in strategic research

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					                          Image: pigs at the
                          forefront




        Nipah virus emergence:
       a case study in strategic research
Juliet Pulliam and the Henipavirus Ecology Research Group
        “One World, One Health” Consultation, Winnipeg, March 2009
                                                                                 Background
                            Human Nipah cases in Malaysia, 1997-1999




                                                                                    Pulliam et al. (in revision)




Data from MMWR (CDC) & courtesy of Department of Veterinary Services, Malaysia
                         Background
Species chain for Nipah virus transmission in Malaysia




                       Graphic: flying fox ->
                       pig -> human
                       transmission chain




                   B         P         H
                                           Assessing risk
                               Bat distribution and seroprevalence

                                                                 B       P        H



                                                            •   Surveys suggest
                                                                Nipah virus circulation
                                                                is widespread in flying
                                                                foxes

                                                            •   Subpopulations may
                                                                go for long periods
                                                                without exposure




Pulliam et al. (in revision)
                       Assessing risk
             Transmission from bats to pigs




                                        Figure: flying fox
                                        roosts, pig farm
B      P          H                     locations




    Fruit trees
    Cats/dogs
                     Assessing risk
         Transmission from bats to pigs


                 B        P           H


• Bats, pigs, fruit trees
  – Perak
  – Johor

• Pigs, fruit trees, few or no bats:
  – Melaka
  – Selangor [Sepang, Gombak]
  – Pulau Pinang [Sabang Perai Selantan]
           Assessing risk
Transmission between pig farms




        Figure: pig farm
        locations            B   P   H
                               Assessing risk
                 Transmission between pig farms

                           B         P          H

• Large farms, which may
  permit persistence &
  spread
   – Perak                                          Figure: risk as a
                                                    function of farm size
   – Johor


• Dense pig farming, which
  may allow local spread
   – Pulau Pinang
   – Selangor [Sepang]
   – Melaka [Alor Gajah]
                                Assessing risk
                          Transmission to humans

                                                             <1
                                                             ≥1,<2
                                                             ≥2, <3
      B       P       H                                      ≥3


•   Pulau Pinang, Melaka
    – many farms, few                     Figure: expected
    cases/farm                            number of human
                                          cases given
•   Perak, Selangor –                     exposure
    intermediate number
    of farms, some with >3
    expected cases

•   Johor – few farms, but
    expect multiple cases
    on several
                                   Assessing risk
                                 Conclusions

•   Different areas are at risk for
    different steps in the transmission
    chain
                                                    Image: Nipah virus
•   Perak & Johor are at highest risk               micrograph
    for spillover from flying foxes

•   Perak & Johor also have the
    largest farms, increasing risk of
    persistence and spread from
    these states

•   If allowed to spread from site of
    spillover, Pulau Pinang, Selangor
    expected to have the most
    human cases
                                             A broader perspective
                   Nipah virus… in Malaysia and beyond
                                                                         Host: Pteropus giganteus
                                                                           Recurrent epidemics
 Host: Pteropus giganteus                                                >100 documented human
                                                                                 cases
 66 human cases (9 conf.)
                                                                       Documented human-to-human
Suspected human-to-human
                                                                             transmission
       transmission
                                                                       No intermediate host required
  Respiratory symptoms
                                                                        (indirect transmission from
     common (51%)
                                                                         Pteropus bats to people)
No known intermediate host


                                                                     Hosts: P. vampyrus, P. hypomelanus
                                                                             265 human cases
                       Difference in amount of shedding by      No documented human-to-human transmission
                                 flying fox host?
                                                                Intermediate host (pigs) seems to be required
                            Difference in infectious dose for                  to amplify virus
                                   human infections?
                                                                  Respiratory involvement in human cases
                            Difference in viral genetics and      limited (14% had nonproductive cough)
                                 infection mechanism?
                            Difference in human population
                                 genetics or behavior?
                                      ……………
                                                                                 Hume Field, Craig Smith



                                                                                         Paul Epstein
 Peter Daszak, Jon Epstein, Tom Hughes, Aleksei Chmura
                                                                 Kaw Bing Chua
               Raina Plowright, Janet Foley

                                                       Aziz Jamaluddin, Sohayati Abdul
                                                         Rahman, Johara Mohd Yob           Lim Boo Liat
                                Kevin Olival,
                                Juan Carlos
                                  Morales


Sai Kit Lam

                                                                                  Andrew Cunningham
                            Tom Ksiazek, Steve Luby           Patrick Foley




 Juliet Pulliam, Andy Dobson,
       Jonathan Dushoff                 Alex Hyatt, Kim Halpin, Lin Fa Wang, Greer Mehan, Rhys
                                          Fogarty, Peter Daniels, Bryan Eaton, Debra Middleton
                       Acknowledgements
  Dr. Peter Daszak, Dr. Jon Epstein, Tom Hughes, Aleksei Chmura
              (Consortium for Conservation Medicine)
           Drs. Andy Dobson, Simon Levin (Princeton)
         Drs. Jonathan Dushoff, Lynn Enquist (Princeton)
               Katie Hampson, Dr. Parviez Hosseini,
                    & Princeton Disease Cabal
        Rhys Fogarty, Drs. Alex Hyatt, Kim Halpin (CSIRO)
 Craig Smith, Dr. Hume Field (ARI), Dr. Mike Bunning (CDC/USAF)
       Drs. Sohayati Abdul Rahman, Dr. R. Mahendran (VRI)
Dr. Aziz Jamaluddin, Dr. Lim, Dr. S. P. Loganathan, Dr. Ong Bee Lee,
      Mr. Chang (Department of Veterinary Services, Malaysia)
         Dr. Kaw Bing Chua (Ministry of Health, Malaysia)


                NSF Graduate Research Fellowship
                  NIH/NSF EID Henipavirus Grant