RABIES IN A CAPTIVE BAT COLONY: A CASE STUDY

Vincent C. Gresham, DVM, MS, DACVPM, DACLAM Elizabeth J. Browder, DVM, MS

Comparative Medicine Program, Texas A&M University, College Station, Texas

Pallid Bat

Antrozous pallidus

Description

• Medium sized bat (12-17g)

• Broad wings, large ears• Females larger than

males• Pelage is light cream

below, washed brown or grey on top

• Not easily confused with other species

Distribution

• Little is known about migratory habits

• Thought to hibernate throughout summer range

Life History

• Inhabit rocky outcrops• Roost in caves, mines,

rock slabs and buildings

• Colonies contain 12-100 bats

• Unusual foraging strategy – terrestrial

• Mating occurs in October, parturition early May – June

• Twins are usual

Quarantine housing

Bats are utilized for a non-invasive protocol observing the dynamics of blood flow within the wing membrane

Rabies

• A single stranded RNA virus• Was first of seven lyssavirus genotypes to be

identified• All cause fatal encephalitis in people except Lagos

bat virus• In the Americas, all rabies are genotype 1• 1958-2000, 35 cases of indigenous human rabies, 32

related to insectivorous –bat strains of rabies virus• Recent death in 2006, of a Texas teenager bitten by a

bat

Rabies

• Rabies antibody has been detected in apparently healthy vector species (including insectivorous bats)

• Seropositive bats can survive for at least 3 years• The original colony, consolidation of colonies started

in August 2003 (1-14) and August 2004 (15-31), #15,17,20, 28 and 29 had serologic titers and were not vaccinated.

• Bat 15 died – rabies negative• Bat 17 died (10/05/06) – rabies negative• Bat 20 died (7/02/06) – rabies negative• Bat 28 retired to bat rehabilitation

Postexposure Prophylaxis for Non-immunized Individuals

TreatmentRegimen• Wound cleansing All postexposure prophylaxis should begin with

immediate thorough cleansing of all wounds with soap and water. If available, a virucidal agent such as povidine-iodine solution should be used to irrigate the wounds.

• RIG If possible, the full dose should be infiltrated around any wound(s) and any remaining volume should be administered IM at an anatomical site distant from vaccine administration. Also, RIG should not be administered in the same syringe as vaccine. Because RIG might partially suppress active production of antibody, no more than the recommended dose should be given.

• Vaccine HDCV or PCECV 1.0 mL, IM (deltoid area), one each on days 0, 3, 7, 14, and 28.

Postexposure Prophylaxis for Previously Immunized

Individuals

TreatmentRegimen• Wound cleansing. All postexposure prophylaxis should begin with

immediate thorough cleansing of all wounds with soap and water. If available, a virucidal agent such as povidine-iodine solution should be used to irrigate the wounds.

• RIG RIG should not be administered.• VaccineHDCV or PCECV 1.0 mL, IM (deltoid area), one each on

days 0 and 3.• If exposed to rabies, previously vaccinated persons should receive two IM doses (1.0 mL

each) of vaccine, one immediately and one three days later. Previously vaccinated persons are those who have received one of the recommended preexposure or postexposure regimens of HDCV, RVA, or PCECV, or those who received another vaccine and had a documented rabies antibody titer. RIG is unnecessary and should not be administered to these persons because an anamnestic response will follow the administration of a booster regardless of the pre-booster antibody titer.

24 Pallid bats (Antrozous pallidus) were captured from a school in Valentine Texas in September 2006.

The bats were treated for ectoparasites prior to arrival on the Texas A&M campus

Bats were placed in quaratine for 6 months (CDC recommends 1 month quarantine)

Bats were bled for serologic evaluation of rabies titer utilizing the rapid florescent focus inhibition test (RFFIT).

Rabies antibody titers were performed using the RFFIT by Kansas State University College of Veterinary Medicine Rabies Laboratory (KSUCVM).

Bats were scheduled for Rabies vaccination after release from quarantine (0.1 ml) Rabvac 3 ®.

History

• January 1, 2007: Bat (B36) was found on the bottom of the cage…Treated for dehydration 1.5 ml LRS SQ.

• The technician was bitten during treatment and started on post exposure prophylaxis

• January 2, 2007: Bat (B36) was found dead and body submitted of rabies examination…Positive

History

• January 18, 2007: Bat (B51) was found convulsing and was euthanized

• Body was submitted for rabies examination…Positive

• A caretaker received a scratch on the hand while moving the cage to cage wash…deemed as an exposure by OccHealth and started on post exposure prophylaxis

CMP Decision

• Lengthy discussions with CDC, TX Zoonosis Control Veterinarian, Department of State Health Services Region 7 and Veterinarians within CMP

• Bat colony was euthanized

• All bats were tested for rabies, all negative

• Tissues harvested for further testing or tissue share program

CMP Decision

• In retrospect, treat all bats as if they are rabies positive

• Vaccinate earlier in the quarantine period (may cause disease to develop if animal is incubating)

• PR nightmare

References

Warrell MJ, and Warrell DA.H Rabies and other Lyssavirus diseases, Lancet 2004; 363: 959-69.

Badrane H, Bahoul C, Perrin P, Tordo N. Evidence of two Lysssavirus phylogroups with distinct pathogenicity and immunogenicity. J Virol 2001; 75: 3268-76.

Familusi JB, Moore DL. Isolation of a rabies related virus from the CSF of a child with “aseptic meningitis”. Afr J Med Sci 1972; 3: 93-96.

Familusi JB, Osunkoya BO, Moore DL, KempGe, Fabiyi A. A fatal human infection with Mokola virus. Am J Trop Med Hyg 1972; 21: 959-63.

Crick J. Rabies. In Gibbs EPJ, ed. Virus diseases of food animals. London: Academic Press, 1981: 469-516.

Arguin PM, Murray-Lillibridge K, Miranda ME, Smith JS, Calaor AB, Rupprecht CE. Serologic evidence of Lyssavirus infections among bats, the Philllipines. Emerg Infect Dis 2002; 78: 258-62.

Amengual B, Whitby JE, King A, Cobo JS, Bourhy H. Evolution of European bat lyssavirus. J Gen Virol 1997; 78: 2319-28.

Serra-Cobo J, Amengual B, Abellan C, Bourhy H. European bat lyssavirus infection in Spanish bat populations. Emerg Infect Dis 2002; 8: 413-20.

Sikes RK. Pathogenesis of rabies in wildlife: 1, comparative effect of varying doses of rabies virus inoculated into foxes and skunks. AM J Vet Res 1962; 23: 1041-47.

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