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Bats: important reservoir hosts of emerging viruses

Bats: important reservoir hosts of emerging viruses. Charles H. Calisher (C.S.U., Ft. Collins), James E. Childs (Yale U., New Haven), Hume E. Field (Department of Primary Industries and Fisheries, Brisbane), Kathryn V. Holmes (U.C.H.S.C., Aurora), Tony Schountz (U.N.C., Greeley).

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Bats: important reservoir hosts of emerging viruses

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  1. Bats: important reservoir hosts of emerging viruses Charles H. Calisher (C.S.U., Ft. Collins), James E. Childs (Yale U., New Haven), Hume E. Field (Department of Primary Industries and Fisheries, Brisbane), Kathryn V. Holmes (U.C.H.S.C., Aurora), Tony Schountz (U.N.C., Greeley)

  2. Pallid Bat(Antrozous pallidus)

  3. Western Pipistrelle(Pipistrellus hesperus)

  4. Red Bat(Lasiurus blossevillii)

  5. Little brown bat(Myotis lucifugus)

  6. Townsend’s Big-eared bat (Corynorhinus townsendii)

  7. Blyth's (Glossy) Horseshoe Bat (Rhinolophus lepidus)

  8. Of the more than 4,600 recognized species of mammals … 1,116 (about 25%) are of bats. Bats are grouped into two suborders, Megachiroptera, containing a single family, and Microchiroptera, containing 17 families

  9. Bats • They are the only flying mammals • They echolocate • Some hibernate or enter torpor • Fruit-eating bats may have a wing span of up to 2 meters • Other bats have wing spans as small as 130 mm • Some have been known to live for 35 years • As many as 300 have been known to roost together per 0.09 meters

  10. The people who discovered Carlsbad Caverns found the cave entrance by following what they thought was a plume of smoke. The smoke was actually a column of Mexican free-tail bats exiting the cave. • Mexican free-tail bats at Carlsbad Caverns – • 8.7 million in 1936; approximately 200,000 by 1973. Similar declines have been noted throughout the southwestern United States and Mexico. “Development”, the pesticide DDT, closing old mines, and other changes (stupidity is not a “change”) are thought to be the primary causes of this decline.

  11. Bats disperse the seeds and pollinate the flowers of many plants. Fruits that depend on bats for pollination or seed dispersal include: bananas, peaches, dates, carob, avocados, jack fruit, plantains, mango, guava, cashews, figs, and many more

  12. Dietary characters • Fruit bats: fruits and flowers • Vampire bats: blood (bats of only one species are obligately hematophagous) • Other bats: insects (moths, ants, termites, wasps, leafhoppers, beetles, crickets, flies, bugs, midges, mosquitoes, and others)

  13. Pest control • One bat may eat ~ 500 mosquitoes/hour • ~ 10 hours/night = 5,000 mosquitoes • ~ 200,000 bats x 5,000 mosquitoes = 1 x 109 = • ~ 1, 000, 000, 000 mosquitoes • Per night!

  14. Order Chiroptera, Family Megachiroptera Subfamily Pteropodidae GeneraSpecies 42 186

  15. Large Flying Fox (Pteropus vampyrus)

  16. Order Chiroptera, Family Microchiroptera Subfamily GeneraSpecies Craseonycteridae 1 1 Emballonuridae 13 51 Furipteridae 2 2 Megadermatidae 4 5 Molossidae 16 100 Mormoopidae 2 10 Mystacinidae 1 2 Myzopodidae 1 1 Natalidae 3 8 Noctilionidae 1 2 Nycteridae 1 16 Phyllostomidae 56 160 Rhinolophidae 1 77 Rhinopomatidae 1 4 Thyropteridae 1 3 Vespertilionidae 47 407 Total 151 849

  17. Total number of viruses isolated from bats of various species =77

  18. Recently emerged bat-borne viruses • Hendra virus: • September 1994 – QLD horse trainer, his stablehand, and most of his horses became ill in Hendra, a suburb of Brisbane. The trainer and 14 horses died. • Samples sent to AAHL, Geelong • New virus isolated; named Hendra virus

  19. Epidemiologic investigations Hendra virus not detected in rodents, cats, dogs, goats, sheep, birds, or other vertebrates, or in mosquitoes Antibody to Hendra virus detected in fruit bats Hendra virus isolated from fruit bats

  20. October 1995 – Farmer from Mackay died of Hendra virus. He had had close contact with two horses in August 1994 during their clinical illnesses and when they were autopsied. Subsequent tests at Geelong on tissue from the dead horses revealed Hendra virus.January 1999 – a horse from a property near Cairns died from Hendra disease.December 2004 – Hendra virus confirmed in a dead horse from the Townsville area.

  21. Menangle and Tioman viruses • Mild illness in people at a piggery in New South Wales • Menangle virus isolated from bats roosting near the piggery • Tioman virus isolated from fruit bats (no disease recognized in humans)

  22. 1999 – Outbreak of encephalitis and respiratory illness in Malaysia Diagnosis: “A particularly virulent form of Japanese encephalitis” (a disease caused by an arbovirus) 40% case-fatality rate Ridiculous diagnosis! Nipah virus

  23. Epidemiology • Patients were all adult, male, Chinese, pig farmers (does that sound to you like a mosquito-borne virus?) • Most people in Malaysia are vaccinated against or infected with Japanese encephalitis virus (JEV) when they are young • Pigs also were dying (JEV is not pathogenic for pigs) • Patients did not have IgM antibody to JEV

  24. Nipah virus isolated from fruit bats

  25. September 2005 • Lau SK, Woo PC, Li KS, Huang Y, Tsoi, HW, Wong BH, Wong SS, Leung SY, Chan KH and Yuen KY (2005) Severe acute respiratory syndrome coronavirus-like virus in Chinese horseshoe bats. Proc. Natl. Acad. Sci. (USA). 102:14040-14045.

  26. Viruses isolated from or viral RNA detected in bats • Family Rhabdoviridae • genus Lyssavirus Number of bat species • Rabies virus numerous, world-wide • Lagos bat virus 3 • Duvenhage virus 3 • Australian bat lyssavirus 3 • European bat lyssavirus 1 2 • European bat lyssavirus 2 6 • Aravan virus 1 • Khujand virus 1 • Irkut virus 1 • West Caucasian bat virus 1

  27. Viruses isolated from or viral RNA detected in bats • Family Rhabdoviridae • genus unassigned Number of bat species • Gossas virus 1 • Kern Canyon virus 1 • Mount Elgon bat virus 1 • Oita 296 virus 1 • Family Orthomyxoviridae, genus Influenzavirus A • Influenza A virus 1 • Family Paramyxoviridae, genus Henipavirus • Hendra virus 4 • Nipah virus 3

  28. Viruses isolated from or viral RNA detected in bats • Family Paramyxoviridae • genus Rubulavirus Number of bat species • Menangle virus 1 • Tioman virus 1 • Mapuera virus 1 • Family Paramyxoviridae, genus undetermined • a parainfluenzavirus 1 • Family Coronaviridae • (Group 1) coronaviruses (= 2) 2 • (Group 2) SARS coronavirus 4 • Family Togaviridae, genus Alphavirus • Chikungunya virus 1 • Sindbis virus 2 • Venezuelan eq. enc. virus 3

  29. Viruses isolated from or viral RNA detected in bats • Family Flaviviridae • genus Flavivirus Number of bat species • Bukalasa bat virus 1 • Carey Island virus 2 • Central European encephalitis virus 1 • Dakar bat virus 3 • Entebbe bat virus 2 • Japanese encephalitis virus 3 • Jugra virus 1 • Kyasanur Forest disease virus 2 • Montana Myotis leucoencephalitis virus 1 • Phnom-Penh bat virus 2 • Rio Bravo virus 2 • St. Louis encephalitis virus 1 • Saboya virus 1 • Sokuluk virus 1 • Tamana bat virus 1 • Uganda S 1 • West Nile virus 1 • Yokose virus 1

  30. Viruses isolated from or viral RNA detected in bats • Family Bunyaviridae • genus Bunyavirus Number of bat species • Catu virus 1 • Guama virus 1 • Nepuyo virus 2 • Family Bunyaviridae • genus Hantavirus • Hantaan virus 2 • Family Bunyaviridae • genus Phlebovirus • Rift Valley fever virus 2 • Toscana virus 1 • Family Bunyaviridae • genus unassigned • Kaeng Khoi virus 1 • Bangui virus 3

  31. Viruses isolated from or viral RNA detected in bats • Family Reoviridae • genus Orbivirus Number of bat species • Ife virus 1 • Japanaut virus 1 • Fomede virus 1 • Family Reoviridae • genus Orthoreovirus • Nelson Bay virus 1 • Pulau virus 1 • Broome virus 1 • Family Arenaviridae • Tacaribe virus 2

  32. Viruses isolated from or viral RNA detected in bats • Family Herpesviridae • genus unassigned Number of bat species • Agua Preta virus 1 • a cytomegalovirus 1 • Parixa virus 1 • subfamily Gammaherpesvirinae • gammaherpesvirus 1 4 • gammaherpesvirus 2 2 • gammaherpesvirus 3 3 • gammaherpesvirus 4 2 • gammaherpesvirus 5 1 • gammaherpesvirus 6 1 • gammaherpesvirus 7 1 • subfamily Betaherpesvirinae • betaherpesvirus 1 2

  33. Viruses isolated from or viral RNA detected in bats • Family Picornaviridae • genus undetermined Number of bat species • Juruaca virus 1 • Unclassified • Issyk-kul = Keterah virus 14 • Mojui dos Campos virus 1 • Yogue virus 1 • Kasokero virus 1

  34. Virus isolated from a bat • Family Papillomaviridae • genus new, unnamed • isolated from an Egyptian fruit bat

  35. Viral RNA detected in bats • Family Filoviridae • Genus Marburgvirus Number of bat species • Lake Victoria marburgvirus 3 • Genus Ebolavirus • Zaire ebolavirus 3

  36. Chiropteran species from which viruses have been isolated or in which viral RNA has been detected • Of 1,116 recognized species of bats – • Viruses have been isolated from bats of 80 • 33 viruses have been isolated from bats of 1 • 12 viruses have been isolated from bats of 2 • 4 viruses have been isolated from bats of 5 • 5 viruses have been isolated from bats of 4 • 3 viruses have been isolated from bats of 5-6 • 1 virus has been isolated from bats of 14 • No viruses have been detected in bats of 1,036 species

  37. Why have there been so few studies of viruses in bats? • Bats of many species are “endangered” or “threatened” (or extinct). • Bats of some species are protected and it is illegal to capture them. • It is difficult to capture bats. • Few investigators who are knowledgeable about bats also are knowledgeable about viruses, and vice versa. • Until recently, bats were not considered when epizoological studies of viruses were planned.

  38. Why are these viruses emerging now? • 1. *** We had not looked. *** • 2. We are impinging on natural areas. • 3. We are monumentally and irreversibly altering formerly natural areas. • 4. We are dependent on oil and other extractive industries (These make a mess). • 5. We need more and more food for more and more people.

  39. There is more work to be done!

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