Bats: important reservoir hosts of emerging viruses

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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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Pallid Bat(Antrozous pallidus)
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Western Pipistrelle(Pipistrellus hesperus)
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Red Bat(Lasiurus blossevillii)
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Little brown bat(Myotis lucifugus)
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Townsends Big-eared bat (Corynorhinus
townsendii)
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Blyth's (Glossy) Horseshoe Bat (Rhinolophus
lepidus)
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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

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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

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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.

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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

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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)

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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!

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Order Chiroptera, Family Megachiroptera

• Subfamily
• Pteropodidae
• Genera Species
• 42 186

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Large Flying Fox (Pteropus vampyrus)
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Order Chiroptera, Family Microchiroptera

• Subfamily Genera Species
• 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

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Total number of viruses isolated from bats of
various species 77
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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

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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

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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.
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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)

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Nipah virus

• 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!

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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

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Nipah virus isolated from fruit bats
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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). 10214040-14045.

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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

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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

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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

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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

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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

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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

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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

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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

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Virus isolated from a bat

• Family Papillomaviridae
• genus new, unnamed
• isolated from an Egyptian fruit bat

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Viral RNA detected in bats

• Family Filoviridae
• Genus Marburgvirus Number of bat species
• Lake Victoria marburgvirus 3
• Genus Ebolavirus
• Zaire ebolavirus 3

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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

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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.

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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.

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There is more work to be done!
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