Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Potential exposure to Australian bat lyssavirus, Queensland, 1996-1999.

Potential exposure to Australian bat lyssavirus, Queensland, 1996-1999. Resear Resear Resear Resear Research ch ch ch ch Potential Exposure to Australian Bat Lyssavirus, Queensland,1996–1999 Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# *Brisbane Southside Public Health Unit, Cooper’s Plains, Queensland, Australia; †Queensland Department of Primary Industries, Yerongpillly, Queensland, Australia; ‡The University of Queensland, St. Lucia, Australia; §Queensland Health Scientific Services, Cooper’s Plains, Queensland, Australia; ¶Queensland Health; and #CSIRO Australian Animal Health Laboratory, Geelong, Victoria, Australia Two human deaths caused by Australian bat lyssavirus (ABL) infection have been reported since 1996. Information was obtained from 205 persons (mostly adults from south Brisbane and the South Coast of Queensland), who reported potential ABL exposure to the Brisbane Southside Public Health Unit from November 1,1996, to January 31, 1999. Volunteer animal handlers accounted for 39% of potential exposures, their family members for 12%, professional animal handlers for 14%, community members who intentionally handled bats for 31%, and community members with contacts initiated by bats for 4%. The prevalence of Lyssavirus detected by fluorescent antibody test in 366 sick, injured, or orphaned bats from the area was 6%. Sequelae of exposure, including the requirement for expensive postexposure prophylaxis, may be reduced by educating bat handlers and the public of the risks involved in handling Australian bats. Australian bat lyssavirus (ABL) was first ABL is a member of the family Rhabdoviri- reported in July 1996 in a black flying fox dae. Although ABL possesses marked serotypic, (Pteropus alecto) from Ballina, New South Wales antigenic, and molecular sequence similarities to (1,2). ABL has been confirmed in five species of classic rabies virus, it represents a distinct, new Australian bat: four species of flying fox genotype, genotype 7 of the Lyssavirus genus (5). (suborder Megachiroptera, genus Pteropus) and The clinical signs of ABL infection in the two one species of insectivorous bat (suborder human cases were consistent with those of classic Microchiroptera, Saccolaimus flaviventris). Two rabies infection and included a diffuse, nonsuppu- cases of human ABL infection have been rative encephalitis that led to death (3,4). Bats with reported. The first case occurred in a 39-year-old ABL infection are frequently reported to have female animal handler from Rockhampton, had hind limb paresis. While most infected bats Queensland, in November 1996, within 5 weeks are depressed when found, some exhibit of her being scratched and possibly bitten by a uncharacteristic aggression toward humans or yellow-bellied sheath-tailed bat (S. flaviventris) other bats. Frequently, a nonspecific, nonsuppu- (R. Taylor, pers. comm.). The second case rative meningoencephalitis is seen in brains of occurred in a 27-year-old woman from Mackay, infected animals (6,7). Vaccine protection trials Queensland, in December 1998, >2 years after a in mice conducted at the Centers for Disease bite from a flying fox. Both patients died (3,4). Control and Prevention (CDC), Atlanta, Georgia, supported the decision to use human diploid cell vaccine (HDCV) for human ABL prophylaxis Address for correspondence: Bradley J. McCall, Brisbane (7-9). Historically, Australia has been considered Southside Public Health Unit, P.O. Box 333, 39 Kessels Road, free of rabies and rabieslike viruses. Thus, before Cooper’s Plains, Qld 4108, Australia; fax: 61-7-3000-9130; e- mail: [email protected]. the first human case of ABL infection in 1996, no Vol. 6, No. 3, May–June 2000 259 259 259 259 259 Emerging Infectious Diseases Resear Resear Resear Resear Research ch ch ch ch measures existed to prevent rabies or rabieslike demographic information (including occupation, disease acquired as a result of contact with history of professional or volunteer bat handling, Australian domestic animals or wildlife. Since history of rabies vaccination, potential rabies the first human ABL case, the Queensland exposure [bite, scratch, provoked, unprovoked], Health Department, in accordance with the circumstances that led to the exposure, treat- recommendations of the national Lyssavirus ment received, and any laboratory investigation Expert Group, has provided postexposure of the bat). prophylaxis (PEP) to persons who report A separate questionnaire was completed for potential exposure to ABL through bites, each occasion a person contacted BSPHU to scratches, and permucosal or percutaneous report potential ABL exposure. Potential expo- exposure to bat saliva or neural tissue (9,10). sures were reported retrospectively, and the Preexposure prophylaxis is recommended for dates of notification and potential exposure for persons who report frequent contact with bats. each case were included. All information was Colonies of flying foxes are common in recorded and analyzed by using an Epi-Info 6.04b suburban areas of southeast Queensland. The database (13). Age and gender-specific notifica- black flying fox (Pteropus alecto) and the grey- tion rates were calculated by using estimated headed flying fox (P. poliocephalus) live there resident population data for 1997 (12). throughout the year, and the little red flying fox During the same period, healthy bats, sick (P. scapulatus) occurs seasonally. While the and injured bats, and bats involved in a potential population of flying foxes may be decreasing in human exposure to ABL were tested for infection southeast Queensland, fragmentation of colonies with a fluorescein-labeled antirabies monoclonal has resulted in a wider distribution of smaller globulin (CENTOCOR) in a direct fluorescent colonies (L. Hall, pers. comm.). Direct contact antibody test (DFAT) on fresh brain impression with bats by the general public and animal smears at the Queensland Department of handlers is not uncommon (11). Volunteer animal Primary Industries Animal Research Institute or handlers rehabilitate sick, injured, and orphaned at the CSIRO Australian Animal Health bats and are frequently bitten, scratched, or Laboratories. Material from most bats that exposed to bat saliva. Since November 1996, the tested positive for ABL infection and from bats Brisbane Southside Public Health Unit (BSPHU) associated with a potential human exposure to and other state public health units have been ABL were sent to either the Australian Animal involved in coordinating lyssavirus PEP. This Health Laboratory or Queensland Health article describes the pattern of potential human Scientific Services for confirmation by DFAT, exposure to ABL reported to the Communicable virus isolation, and polymerase chain reaction. Disease Control Section of BSPHU between November 1996 and January 1999 and subse- Results quent PEP. Disease prevalence findings are A total of 205 notifications to BSPHU met the presented for bats surveyed in southeast criteria for potential ABL exposure during the Queensland by the Animal and Plant Health study period, an average annual notification rate Service of the Queensland Department of of 8.1/100,000. Complete information was Primary Industries. obtained from 202 persons. Total notifications included 86 males and 119 females (M:F ratio of The Study 1:1.38). The age- and gender-specific average During the study (November 1, 1996, to annual notification rates are presented in Figure January 31, 1999), the Communicable Disease 1. Most reported potential exposures (116 of 204) Control Section of BSPHU served a population of were among persons 19 to 49 years of age. The approximately 1.1 million persons in several local months of potential ABL exposure and notifica- government areas, south Brisbane (part of the tion are presented in Figure 2. Most notifications Brisbane City Council Area), Logan, Redlands, (131 of 205) were made within 2 months of each of Beaudesert, and Gold Coast (12). All persons who the two fatal human cases. Nine (11%) of 80 reported a potential ABL exposure (bat bite, notifications made in the 2 months following the scratch, percutaneous, or permucosal exposure to first reported case were related to exposures that bat saliva or neural tissue) were asked to occurred >2 months before the first human case complete a standard questionnaire, which sought was publicized. The median interval between 260 260 Emerging Infectious Diseases 260 260 260 Vol. 6, No. 3, May–June 2000 Resear Resear Resear Resear Research ch ch ch ch exposure and notification of these 80 potential exposures was 17 days (0 to 1,080 days). In the 2 months following the second case, 22 (43%) of 51 notifications were related to potential exposures that had occurred before the reporting of the first human case. The median interval between exposure and notification of the 51 potential exposures was 728 days (0 to 2,907 days). A further 14 (27%) of the 51 notifications were related to potential exposures that had occurred since the first human case but had not been reported to BSPHU at the time of exposure. Figure 1. Age and gender-specific average annual notification rates of potential human exposure to Season of Exposures Australian bat lyssavirus (n = 204) south Brisbane Potential exposures to ABL were reported to and South Coast, Queensland, 1996-1999. have occurred from 1991 to 1999, most during spring and summer (September to February) (n = 151, 74%). While the occurrence of the two human ABL cases in spring and summer influenced the reporting of potential exposures at these times, this trend of increased spring-summer potential exposures persisted in the period between the two reported human ABL cases. The highest number of potential exposures (105) was reported in the year of the first human case; 99 occurred in the spring or summer of 1996-97. Groups at Risk Notifications were categorized according to the person’s life-style and occupational potential for exposure to ABL (Table). The group at highest Figure 2. Dates of potential Australian bat lyssavirus exposures and notifications to the Brisbane Southside risk, volunteer bat handlers, reported 79 (39%) Public Health Unit, south Brisbane and South Coast, potential exposures; 8 of these handlers reported Queensland, 1996-1999. a second potential exposure during the study. Table. Groups at risk for exposure to Australian bat lyssavirus Median No. of interval potential Mean age between Bite/nonbite Provoked exposures and age Gender exposure and injury (%) Groups at risk (n=203) range (yrs) (m/f) notification (d) (n=202) (n=202) Volunteer bat handlers 79 40.5 15/64 19 56/23 79/79 (16-83) (0-2,105) (100) Household or family member 24 17.5 12/12 27 18/6 24/24 of volunteer bat handlers ( 5-51) (0-1,809) (100) Professional animal worker 28 34 15/13 4 13/14 27/27 (17-69) (0-1,818) (100) Community-intentional 63 39 40/23 10 41/22 62/63 potential exposure ( 6-85) (0-2,907) ( 98) Community-unintential 9 32 4/5 2 3/6 4/9 exposure (16-49) (0-32) ( 44) Vol. 6, No. 3, May–June 2000 261 261 261 261 261 Emerging Infectious Diseases Resear Resear Resear Resear Research ch ch ch ch Twenty-four (12%) notifications of potential Treatment exposure were among household or family PEP was offered to all persons who reported members of volunteer bat handlers. Professional potential ABL exposures, in accordance with animal handlers (e.g., veterinarians, wildlife international and Australian recommendations biologists, park rangers) reported 28 (14%) (8,14). Standard PEP for unvaccinated persons exposures. Community members who handled consisted of human rabies immune globulin bats (usually in the course of freeing them from a (HRIG, 20 IU/kg) on day 0 and 5 doses of HDCV fence or entanglement) reported 63 (31%) administered on days 0, 3, 7, 14, and 28. PEP for potential exposures. Community members re- immunized persons consisted of 2 booster doses ported 9 unintentional potential exposures in of HDCV administered on days 0 and 3. A which contact was initiated by the bat. national shortage of HRIG required modifica- The pattern of notification varied within tions to the standard PEP regimen. Sixty-two groups at risk during the study. The number of potentially exposed persons received standard potential exposures reported by volunteer and PEP, 100 received 5 doses of HDCV only, 16 professional animal handlers declined. Notifica- vaccinated persons received 2 booster doses of tions by all groups were highest in the months HDCV, and 25 persons did not receive treatment after the reported fatal human cases of ABL when the bat tested negative. Two persons infection. The number of potential exposures refused vaccination because of concerns about reported in the 2 months after the first human potential vaccine side effects. Sixteen persons case (n = 80) was higher than after the second ceased treatment when the bat tested negative. case (n = 51), particularly among volunteer bat The estimated cost of providing PEP during handlers, who reported the highest number of this study was A$137,368, which included potential ABL exposures in the 2 months after A$30,930 for medical services funded through the the first human case (43 [53%] of 80), decreasing Commonwealth Medicare system (calculated on to 12 (24%) of 51 in the 2 months after the second the cost of six visits to a medical practitioner for case. Notifications of potential exposures among each person requiring a 5-dose course of PEP and community members who had intentionally three visits for each person requiring 2 doses of handled bats rose from 11 (14%) of 80 in the 2 PEP); A$8,200 for public health officers who months after the first human ABL case to 23 interviewed potentially exposed persons; (45%) of 51 in the 2 months after the second A$10,600 for laboratory testing of the bats; and human ABL case. A$87,638 for HDCV and HRIG. The cost of all vaccines was met by the Queensland Health Nature of Exposure Department. Potential exposures were classified as bite or nonbite exposures in accordance with interna- ABL Test Results in Bats tional recommendations (14). Most potential All bats retrieved from a human exposure exposures were bites (n = 132, 64%). The ratio of incident underwent postmortem examination bite to nonbite potential exposures within groups and testing for ABL infection. Thirty-six bats at risk was highest among volunteer bat handlers were tested; two were positive on DFAT and (56:23) (Table). Potential exposures associated polymerase chain reaction testing for with unintentional contact with bats by Lyssavirus—a black flying fox and a little red community members were predominantly flying fox. The tested bats included 13 black scratches (3 bite: 6 nonbite), whereas potential flying foxes, 11 grey-headed flying foxes, 5 little exposures from intentional contact with bats by red flying foxes, and 7 insectivorous bats. all other risk groups were predominantly by In a separate investigation, the Queensland bites (128 bites: 65 nonbites). Potential Animal Research Institute tested bats by DFAT exposures were categorized as provoked on brain impression smears for evidence of ABL (arising from intentional contact with a bat) or infection since June 1996. From November 1, unprovoked (a contact initiated by the bat). 1996, to January 31, 1999, some 153 healthy Most potential exposures (97%) were described wild-caught flying foxes; 181 healthy wild-caught as provoked (Table). insectivorous bats; 366 sick, injured, or orphaned 262 262 Emerging Infectious Diseases 262 262 262 Vol. 6, No. 3, May–June 2000 Resear Resear Resear Resear Research ch ch ch ch flying foxes; and 39 sick or injured insectivorous and grey-headed flying foxes in southeastern bats from the area served by BSPHU and greater Queensland (15). During each birthing season in Brisbane were tested. Of these, 21 (6%) of the 366 southeastern Queensland, 100 to 300 neonatal sick, injured, or orphaned flying foxes tested and juvenile black or grey-headed flying foxes are positive for ABL infection, including the 2 reared by volunteer bat handlers (H. Luckhoff, involved in human exposures in the BSPHU area. pers. comm.). These orphans are commonly All other bats tested negative. assumed to have been abandoned or separated from their dams. Frequently, orphans are found Discussion still clinging to the body of their dam. Further This is the first description of PEP provided research is required to identify any association to an Australian community after the recognition between orphaned bats and the ABL status of the of human risk for ABL infection. The first human dam. A case of clinical disease in an in-care case triggered a large national public health juvenile black flying fox and the associated campaign and considerable public awareness exposure of eight humans has been described (6). about the risks from bats, particularly in Most potential exposures (107 [52%] of 205) communities such as south Brisbane and the were reported from groups who handled bats. South Coast of Queensland, where large colonies These groups were the target of initial public of bats live close to human urban populations and health information campaigns to raise awareness bat/human interaction is not uncommon. In- of the risks for ABL infection. PEP was provided creased concern was demonstrated by the large to members of these groups after the first human number of notifications of potential exposure that case, and a recommendation was issued that all followed reports of the two human cases workers in these fields be vaccinated with HDCV (Figure 2). Most potential human exposures and that unvaccinated persons, including family were among adults (ages 25 to 49). The increased members of volunteer bat handlers, not handle proportion of women reflects the high proportion bats. Seventy-two (35%) of 205 potential of female volunteer bat handlers in the study exposures occurred among members of the population. community. Most of these (63 [88%] of 72) had The first 2 months of notifications represents rescued a trapped or fallen bat. The test results a catch-up period in which PEP was provided to from bats indicate that sick, injured, or orphaned persons with exposures dating back several bats have a significantly higher crude prevalence years. Relatively few notifications occurred after of ABL infection (p <0.001) than healthy wild- the first 2 months of the study, and it was only caught or captive bats. Consequently, the risk for after the second human case, which had an ABL exposure among volunteer and professional assumed incubation period of approximately 2 bat handlers and persons who rescue bats may be years, that another cluster of notifications relatively increased because these groups occurred (4). The median interval between primarily handle sick, injured, or orphaned bats. potential exposure and notification increased Reporting of potential exposures among from 17 days for those notified in the 2 months groups at risk changed with time during the after the first human ABL case to 728 days for study. One important factor in the management those notified in the 2 months after the second of PEP was the requirement (introduced in 1997) case. The potential exposures reported in the 2 that all bats involved in a potential human months after the second case included 22 persons exposure be surrendered for postmortem exami- who were potentially exposed before the first case nation and laboratory testing for ABL. Those who and 14 with >1 month between potential care for bats are often reluctant to surrender exposure and notification. The second human them for ABL testing. Notifications from case with its prolonged incubation period volunteer bat handlers declined during the study reinforced the public perception of the severity of period. While this may reflect a decline either in this disease and prompted more notifications. the number of bat handlers or in potential Potential exposures occurred most commonly exposures among volunteer bat handlers, in spring and summer, coinciding with the underreporting may be occurring in this group. birthing season (October to December) of the black Anecdotal evidence suggests that this reduction Vol. 6, No. 3, May–June 2000 263 263 263 263 263 Emerging Infectious Diseases Resear Resear Resear Resear Research ch ch ch ch in notifications may reflect handlers’ concern for References the bats. Such underreporting could be associ- 1. Crerar S, Longbottom H, Rooney J, Thornber P. Human health aspects of a possible lyssavirus in a flying fox. ated with future human cases. Most potential Commun Dis Intell 1996;20:325. exposures resulted from intentional handling of 2. Fraser G, Hooper P, Lunt R, Gould AR, Gleeson LJ, bats. The few potential exposures from unpro- Hyatt AD, et al. Encephalitis caused by a lyssavirus in voked encounters suggest that bats rarely fruit bats in Australia. Emerg Infect Dis 1996;2:327-31. initiate contact with humans. 3. Allworth A, Murray K, Morgan J. A case of encephalitis due to a lyssavirus recently identified in fruit bats. The recognition of ABL infection has resulted Commun Dis Intell 1996;20:504. in a large public health program to provide 4. Mackenzie J. Emerging viral diseases: an Australian education, counseling, and prophylaxis to perspective. Emerg Infect Dis 1999;5:1-8. volunteer and professional bat handlers and 5. Gould A, Hyatt A, Lunt R, Kattenbelt JA, Hengstberger members of the community who may be exposed S. Characterisation of a novel lyssavirus isolated from Pteropid bats in Australia. Virus Res 1998;54:165-87. to ABL. The focus of the program has been to 6. Field H, McCall B, Barrett J. Australian bat lyssavirus encourage preexposure vaccination of bat infection in a captive juvenile black flying fox. Emerg handlers, prevention of potential exposures by Infect Dis 1999;5:438-40.7. avoidance of bat handling by nonvaccinated 7. Hooper P, Lunt R, Gould A, Samaratunga H, Hyatt AD, persons, and prompt medical care when potential Gleeson LF, et al. A new lyssavirus—the first endemic rabies-related virus recognized in Australia. Bulletin exposures occur. The cost of PEP for all those Institut Pasteur 1997;95:209-18. potentially exposed to ABL in south Brisbane and 8. Rabies and bat lyssavirus infection. In: Watson C, the South Coast of Queensland during the study editor. The Australian immunisation handbook. 6th ed. was considerable. Future public health interven- Canberra: Australian Government Publishing Service, tions should continue to emphasize the risks 1997:162-8. 9. Lyssavirus Expert Group. Prevention of human associated with interaction with bats to reduce lyssavirus infection. Commun Dis Intell 1996;20:505-7. the requirement for PEP and the likelihood of 10. Lyssavirus Expert Group. Update on bat Lyssavirus. human cases of ABL infection. Commun Dis Intell 1996;20:535. 11. Birt P, Markus N, Collins L, Hall L. Urban flying foxes. Acknowledgments Nature Australia 1998;Spring:55-9. The authors thank Russell Stafford, Helen Luckhoff, 12. Australian Bureau of Statistics. 1997 estimated Les Hall, Nicki Markus, Bruce Harrower, David Gould, the resident population by statistical local area. Australian Queensland Medical Laboratory, and the medical practitio- Bureau of Statistics catalogue no. 3235.3. Canberra, ners of south Brisbane and South Coast for their assistance Australia: The Organization,1997. in aspects of patient management, laboratory investigation, 13. Dean AG, Dean JA, Coulombier D, Brendel KA, Smith vaccine delivery, and for advice throughout the study. DC, Burton AH, et al. Epi-Info, version 6.04b: a word processing, database, and statistics system for Mr. Epstein’s work was supported by grants from the epidemiology on microcomputers (computer program). National Institutes of Health, the Hickey-Peyton Interna- Atlanta, GA: Centers for Disease Control and tional Travel Fellowship, and the Department of Interna- Prevention, 1997. tional Programs, Tufts University School of Veterinary 14. Centers for Disease Control and Prevention. Rabies Medicine. Prevention—United States, 1991. Recommendations of the Immunization Practices Advisory Committee. Dr. McCall, a public health physician, has led the MMWR Morb Mortal Wkly Rep 1991;40:R3:1-19. Communicable Disease Control team at the Brisbane 15. Hall LS. Black flying fox. In: Strachan R, editor. The Southside Public Health Unit for 5 years. His research mammals of Australia. Chatswood, Australia: Reed interests include meningococcal disease, leptospirosis, Books 1995;432-7. and ABL. 264 264 Emerging Infectious Diseases 264 264 264 Vol. 6, No. 3, May–June 2000 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Emerging Infectious Diseases Pubmed Central

Potential exposure to Australian bat lyssavirus, Queensland, 1996-1999.

McCall, B J; Epstein, J H; Neill, A S; Heel, K; Field, H; Barrett, J; Smith, G A; Selvey, L A; Rodwell, B; Lunt, R
Emerging Infectious Diseases , Volume 6 (3) – Aug 1, 167
Download PDF
6 pages

Loading next page...
 
/lp/pubmed-central/potential-exposure-to-australian-bat-lyssavirus-queensland-1996-1999-avP60Wxybu

References

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
Pubmed Central
ISSN
1080-6040
eISSN
1080-6059
Publisher site
See Article on Publisher Site

Abstract

Resear Resear Resear Resear Research ch ch ch ch Potential Exposure to Australian Bat Lyssavirus, Queensland,1996–1999 Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Bradley J. McCall,* Jonathan H. Epstein,* Annette S. Neill,* Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Karen Heel,* Hume Field,† Janine Barrett,‡ Greg A. Smith,§ Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# Linda A. Selvey,¶ Barry Rodwell,† and Ross Lunt# *Brisbane Southside Public Health Unit, Cooper’s Plains, Queensland, Australia; †Queensland Department of Primary Industries, Yerongpillly, Queensland, Australia; ‡The University of Queensland, St. Lucia, Australia; §Queensland Health Scientific Services, Cooper’s Plains, Queensland, Australia; ¶Queensland Health; and #CSIRO Australian Animal Health Laboratory, Geelong, Victoria, Australia Two human deaths caused by Australian bat lyssavirus (ABL) infection have been reported since 1996. Information was obtained from 205 persons (mostly adults from south Brisbane and the South Coast of Queensland), who reported potential ABL exposure to the Brisbane Southside Public Health Unit from November 1,1996, to January 31, 1999. Volunteer animal handlers accounted for 39% of potential exposures, their family members for 12%, professional animal handlers for 14%, community members who intentionally handled bats for 31%, and community members with contacts initiated by bats for 4%. The prevalence of Lyssavirus detected by fluorescent antibody test in 366 sick, injured, or orphaned bats from the area was 6%. Sequelae of exposure, including the requirement for expensive postexposure prophylaxis, may be reduced by educating bat handlers and the public of the risks involved in handling Australian bats. Australian bat lyssavirus (ABL) was first ABL is a member of the family Rhabdoviri- reported in July 1996 in a black flying fox dae. Although ABL possesses marked serotypic, (Pteropus alecto) from Ballina, New South Wales antigenic, and molecular sequence similarities to (1,2). ABL has been confirmed in five species of classic rabies virus, it represents a distinct, new Australian bat: four species of flying fox genotype, genotype 7 of the Lyssavirus genus (5). (suborder Megachiroptera, genus Pteropus) and The clinical signs of ABL infection in the two one species of insectivorous bat (suborder human cases were consistent with those of classic Microchiroptera, Saccolaimus flaviventris). Two rabies infection and included a diffuse, nonsuppu- cases of human ABL infection have been rative encephalitis that led to death (3,4). Bats with reported. The first case occurred in a 39-year-old ABL infection are frequently reported to have female animal handler from Rockhampton, had hind limb paresis. While most infected bats Queensland, in November 1996, within 5 weeks are depressed when found, some exhibit of her being scratched and possibly bitten by a uncharacteristic aggression toward humans or yellow-bellied sheath-tailed bat (S. flaviventris) other bats. Frequently, a nonspecific, nonsuppu- (R. Taylor, pers. comm.). The second case rative meningoencephalitis is seen in brains of occurred in a 27-year-old woman from Mackay, infected animals (6,7). Vaccine protection trials Queensland, in December 1998, >2 years after a in mice conducted at the Centers for Disease bite from a flying fox. Both patients died (3,4). Control and Prevention (CDC), Atlanta, Georgia, supported the decision to use human diploid cell vaccine (HDCV) for human ABL prophylaxis Address for correspondence: Bradley J. McCall, Brisbane (7-9). Historically, Australia has been considered Southside Public Health Unit, P.O. Box 333, 39 Kessels Road, free of rabies and rabieslike viruses. Thus, before Cooper’s Plains, Qld 4108, Australia; fax: 61-7-3000-9130; e- mail: [email protected]. the first human case of ABL infection in 1996, no Vol. 6, No. 3, May–June 2000 259 259 259 259 259 Emerging Infectious Diseases Resear Resear Resear Resear Research ch ch ch ch measures existed to prevent rabies or rabieslike demographic information (including occupation, disease acquired as a result of contact with history of professional or volunteer bat handling, Australian domestic animals or wildlife. Since history of rabies vaccination, potential rabies the first human ABL case, the Queensland exposure [bite, scratch, provoked, unprovoked], Health Department, in accordance with the circumstances that led to the exposure, treat- recommendations of the national Lyssavirus ment received, and any laboratory investigation Expert Group, has provided postexposure of the bat). prophylaxis (PEP) to persons who report A separate questionnaire was completed for potential exposure to ABL through bites, each occasion a person contacted BSPHU to scratches, and permucosal or percutaneous report potential ABL exposure. Potential expo- exposure to bat saliva or neural tissue (9,10). sures were reported retrospectively, and the Preexposure prophylaxis is recommended for dates of notification and potential exposure for persons who report frequent contact with bats. each case were included. All information was Colonies of flying foxes are common in recorded and analyzed by using an Epi-Info 6.04b suburban areas of southeast Queensland. The database (13). Age and gender-specific notifica- black flying fox (Pteropus alecto) and the grey- tion rates were calculated by using estimated headed flying fox (P. poliocephalus) live there resident population data for 1997 (12). throughout the year, and the little red flying fox During the same period, healthy bats, sick (P. scapulatus) occurs seasonally. While the and injured bats, and bats involved in a potential population of flying foxes may be decreasing in human exposure to ABL were tested for infection southeast Queensland, fragmentation of colonies with a fluorescein-labeled antirabies monoclonal has resulted in a wider distribution of smaller globulin (CENTOCOR) in a direct fluorescent colonies (L. Hall, pers. comm.). Direct contact antibody test (DFAT) on fresh brain impression with bats by the general public and animal smears at the Queensland Department of handlers is not uncommon (11). Volunteer animal Primary Industries Animal Research Institute or handlers rehabilitate sick, injured, and orphaned at the CSIRO Australian Animal Health bats and are frequently bitten, scratched, or Laboratories. Material from most bats that exposed to bat saliva. Since November 1996, the tested positive for ABL infection and from bats Brisbane Southside Public Health Unit (BSPHU) associated with a potential human exposure to and other state public health units have been ABL were sent to either the Australian Animal involved in coordinating lyssavirus PEP. This Health Laboratory or Queensland Health article describes the pattern of potential human Scientific Services for confirmation by DFAT, exposure to ABL reported to the Communicable virus isolation, and polymerase chain reaction. Disease Control Section of BSPHU between November 1996 and January 1999 and subse- Results quent PEP. Disease prevalence findings are A total of 205 notifications to BSPHU met the presented for bats surveyed in southeast criteria for potential ABL exposure during the Queensland by the Animal and Plant Health study period, an average annual notification rate Service of the Queensland Department of of 8.1/100,000. Complete information was Primary Industries. obtained from 202 persons. Total notifications included 86 males and 119 females (M:F ratio of The Study 1:1.38). The age- and gender-specific average During the study (November 1, 1996, to annual notification rates are presented in Figure January 31, 1999), the Communicable Disease 1. Most reported potential exposures (116 of 204) Control Section of BSPHU served a population of were among persons 19 to 49 years of age. The approximately 1.1 million persons in several local months of potential ABL exposure and notifica- government areas, south Brisbane (part of the tion are presented in Figure 2. Most notifications Brisbane City Council Area), Logan, Redlands, (131 of 205) were made within 2 months of each of Beaudesert, and Gold Coast (12). All persons who the two fatal human cases. Nine (11%) of 80 reported a potential ABL exposure (bat bite, notifications made in the 2 months following the scratch, percutaneous, or permucosal exposure to first reported case were related to exposures that bat saliva or neural tissue) were asked to occurred >2 months before the first human case complete a standard questionnaire, which sought was publicized. The median interval between 260 260 Emerging Infectious Diseases 260 260 260 Vol. 6, No. 3, May–June 2000 Resear Resear Resear Resear Research ch ch ch ch exposure and notification of these 80 potential exposures was 17 days (0 to 1,080 days). In the 2 months following the second case, 22 (43%) of 51 notifications were related to potential exposures that had occurred before the reporting of the first human case. The median interval between exposure and notification of the 51 potential exposures was 728 days (0 to 2,907 days). A further 14 (27%) of the 51 notifications were related to potential exposures that had occurred since the first human case but had not been reported to BSPHU at the time of exposure. Figure 1. Age and gender-specific average annual notification rates of potential human exposure to Season of Exposures Australian bat lyssavirus (n = 204) south Brisbane Potential exposures to ABL were reported to and South Coast, Queensland, 1996-1999. have occurred from 1991 to 1999, most during spring and summer (September to February) (n = 151, 74%). While the occurrence of the two human ABL cases in spring and summer influenced the reporting of potential exposures at these times, this trend of increased spring-summer potential exposures persisted in the period between the two reported human ABL cases. The highest number of potential exposures (105) was reported in the year of the first human case; 99 occurred in the spring or summer of 1996-97. Groups at Risk Notifications were categorized according to the person’s life-style and occupational potential for exposure to ABL (Table). The group at highest Figure 2. Dates of potential Australian bat lyssavirus exposures and notifications to the Brisbane Southside risk, volunteer bat handlers, reported 79 (39%) Public Health Unit, south Brisbane and South Coast, potential exposures; 8 of these handlers reported Queensland, 1996-1999. a second potential exposure during the study. Table. Groups at risk for exposure to Australian bat lyssavirus Median No. of interval potential Mean age between Bite/nonbite Provoked exposures and age Gender exposure and injury (%) Groups at risk (n=203) range (yrs) (m/f) notification (d) (n=202) (n=202) Volunteer bat handlers 79 40.5 15/64 19 56/23 79/79 (16-83) (0-2,105) (100) Household or family member 24 17.5 12/12 27 18/6 24/24 of volunteer bat handlers ( 5-51) (0-1,809) (100) Professional animal worker 28 34 15/13 4 13/14 27/27 (17-69) (0-1,818) (100) Community-intentional 63 39 40/23 10 41/22 62/63 potential exposure ( 6-85) (0-2,907) ( 98) Community-unintential 9 32 4/5 2 3/6 4/9 exposure (16-49) (0-32) ( 44) Vol. 6, No. 3, May–June 2000 261 261 261 261 261 Emerging Infectious Diseases Resear Resear Resear Resear Research ch ch ch ch Twenty-four (12%) notifications of potential Treatment exposure were among household or family PEP was offered to all persons who reported members of volunteer bat handlers. Professional potential ABL exposures, in accordance with animal handlers (e.g., veterinarians, wildlife international and Australian recommendations biologists, park rangers) reported 28 (14%) (8,14). Standard PEP for unvaccinated persons exposures. Community members who handled consisted of human rabies immune globulin bats (usually in the course of freeing them from a (HRIG, 20 IU/kg) on day 0 and 5 doses of HDCV fence or entanglement) reported 63 (31%) administered on days 0, 3, 7, 14, and 28. PEP for potential exposures. Community members re- immunized persons consisted of 2 booster doses ported 9 unintentional potential exposures in of HDCV administered on days 0 and 3. A which contact was initiated by the bat. national shortage of HRIG required modifica- The pattern of notification varied within tions to the standard PEP regimen. Sixty-two groups at risk during the study. The number of potentially exposed persons received standard potential exposures reported by volunteer and PEP, 100 received 5 doses of HDCV only, 16 professional animal handlers declined. Notifica- vaccinated persons received 2 booster doses of tions by all groups were highest in the months HDCV, and 25 persons did not receive treatment after the reported fatal human cases of ABL when the bat tested negative. Two persons infection. The number of potential exposures refused vaccination because of concerns about reported in the 2 months after the first human potential vaccine side effects. Sixteen persons case (n = 80) was higher than after the second ceased treatment when the bat tested negative. case (n = 51), particularly among volunteer bat The estimated cost of providing PEP during handlers, who reported the highest number of this study was A$137,368, which included potential ABL exposures in the 2 months after A$30,930 for medical services funded through the the first human case (43 [53%] of 80), decreasing Commonwealth Medicare system (calculated on to 12 (24%) of 51 in the 2 months after the second the cost of six visits to a medical practitioner for case. Notifications of potential exposures among each person requiring a 5-dose course of PEP and community members who had intentionally three visits for each person requiring 2 doses of handled bats rose from 11 (14%) of 80 in the 2 PEP); A$8,200 for public health officers who months after the first human ABL case to 23 interviewed potentially exposed persons; (45%) of 51 in the 2 months after the second A$10,600 for laboratory testing of the bats; and human ABL case. A$87,638 for HDCV and HRIG. The cost of all vaccines was met by the Queensland Health Nature of Exposure Department. Potential exposures were classified as bite or nonbite exposures in accordance with interna- ABL Test Results in Bats tional recommendations (14). Most potential All bats retrieved from a human exposure exposures were bites (n = 132, 64%). The ratio of incident underwent postmortem examination bite to nonbite potential exposures within groups and testing for ABL infection. Thirty-six bats at risk was highest among volunteer bat handlers were tested; two were positive on DFAT and (56:23) (Table). Potential exposures associated polymerase chain reaction testing for with unintentional contact with bats by Lyssavirus—a black flying fox and a little red community members were predominantly flying fox. The tested bats included 13 black scratches (3 bite: 6 nonbite), whereas potential flying foxes, 11 grey-headed flying foxes, 5 little exposures from intentional contact with bats by red flying foxes, and 7 insectivorous bats. all other risk groups were predominantly by In a separate investigation, the Queensland bites (128 bites: 65 nonbites). Potential Animal Research Institute tested bats by DFAT exposures were categorized as provoked on brain impression smears for evidence of ABL (arising from intentional contact with a bat) or infection since June 1996. From November 1, unprovoked (a contact initiated by the bat). 1996, to January 31, 1999, some 153 healthy Most potential exposures (97%) were described wild-caught flying foxes; 181 healthy wild-caught as provoked (Table). insectivorous bats; 366 sick, injured, or orphaned 262 262 Emerging Infectious Diseases 262 262 262 Vol. 6, No. 3, May–June 2000 Resear Resear Resear Resear Research ch ch ch ch flying foxes; and 39 sick or injured insectivorous and grey-headed flying foxes in southeastern bats from the area served by BSPHU and greater Queensland (15). During each birthing season in Brisbane were tested. Of these, 21 (6%) of the 366 southeastern Queensland, 100 to 300 neonatal sick, injured, or orphaned flying foxes tested and juvenile black or grey-headed flying foxes are positive for ABL infection, including the 2 reared by volunteer bat handlers (H. Luckhoff, involved in human exposures in the BSPHU area. pers. comm.). These orphans are commonly All other bats tested negative. assumed to have been abandoned or separated from their dams. Frequently, orphans are found Discussion still clinging to the body of their dam. Further This is the first description of PEP provided research is required to identify any association to an Australian community after the recognition between orphaned bats and the ABL status of the of human risk for ABL infection. The first human dam. A case of clinical disease in an in-care case triggered a large national public health juvenile black flying fox and the associated campaign and considerable public awareness exposure of eight humans has been described (6). about the risks from bats, particularly in Most potential exposures (107 [52%] of 205) communities such as south Brisbane and the were reported from groups who handled bats. South Coast of Queensland, where large colonies These groups were the target of initial public of bats live close to human urban populations and health information campaigns to raise awareness bat/human interaction is not uncommon. In- of the risks for ABL infection. PEP was provided creased concern was demonstrated by the large to members of these groups after the first human number of notifications of potential exposure that case, and a recommendation was issued that all followed reports of the two human cases workers in these fields be vaccinated with HDCV (Figure 2). Most potential human exposures and that unvaccinated persons, including family were among adults (ages 25 to 49). The increased members of volunteer bat handlers, not handle proportion of women reflects the high proportion bats. Seventy-two (35%) of 205 potential of female volunteer bat handlers in the study exposures occurred among members of the population. community. Most of these (63 [88%] of 72) had The first 2 months of notifications represents rescued a trapped or fallen bat. The test results a catch-up period in which PEP was provided to from bats indicate that sick, injured, or orphaned persons with exposures dating back several bats have a significantly higher crude prevalence years. Relatively few notifications occurred after of ABL infection (p <0.001) than healthy wild- the first 2 months of the study, and it was only caught or captive bats. Consequently, the risk for after the second human case, which had an ABL exposure among volunteer and professional assumed incubation period of approximately 2 bat handlers and persons who rescue bats may be years, that another cluster of notifications relatively increased because these groups occurred (4). The median interval between primarily handle sick, injured, or orphaned bats. potential exposure and notification increased Reporting of potential exposures among from 17 days for those notified in the 2 months groups at risk changed with time during the after the first human ABL case to 728 days for study. One important factor in the management those notified in the 2 months after the second of PEP was the requirement (introduced in 1997) case. The potential exposures reported in the 2 that all bats involved in a potential human months after the second case included 22 persons exposure be surrendered for postmortem exami- who were potentially exposed before the first case nation and laboratory testing for ABL. Those who and 14 with >1 month between potential care for bats are often reluctant to surrender exposure and notification. The second human them for ABL testing. Notifications from case with its prolonged incubation period volunteer bat handlers declined during the study reinforced the public perception of the severity of period. While this may reflect a decline either in this disease and prompted more notifications. the number of bat handlers or in potential Potential exposures occurred most commonly exposures among volunteer bat handlers, in spring and summer, coinciding with the underreporting may be occurring in this group. birthing season (October to December) of the black Anecdotal evidence suggests that this reduction Vol. 6, No. 3, May–June 2000 263 263 263 263 263 Emerging Infectious Diseases Resear Resear Resear Resear Research ch ch ch ch in notifications may reflect handlers’ concern for References the bats. Such underreporting could be associ- 1. Crerar S, Longbottom H, Rooney J, Thornber P. Human health aspects of a possible lyssavirus in a flying fox. ated with future human cases. Most potential Commun Dis Intell 1996;20:325. exposures resulted from intentional handling of 2. Fraser G, Hooper P, Lunt R, Gould AR, Gleeson LJ, bats. The few potential exposures from unpro- Hyatt AD, et al. Encephalitis caused by a lyssavirus in voked encounters suggest that bats rarely fruit bats in Australia. Emerg Infect Dis 1996;2:327-31. initiate contact with humans. 3. Allworth A, Murray K, Morgan J. A case of encephalitis due to a lyssavirus recently identified in fruit bats. The recognition of ABL infection has resulted Commun Dis Intell 1996;20:504. in a large public health program to provide 4. Mackenzie J. Emerging viral diseases: an Australian education, counseling, and prophylaxis to perspective. Emerg Infect Dis 1999;5:1-8. volunteer and professional bat handlers and 5. Gould A, Hyatt A, Lunt R, Kattenbelt JA, Hengstberger members of the community who may be exposed S. Characterisation of a novel lyssavirus isolated from Pteropid bats in Australia. Virus Res 1998;54:165-87. to ABL. The focus of the program has been to 6. Field H, McCall B, Barrett J. Australian bat lyssavirus encourage preexposure vaccination of bat infection in a captive juvenile black flying fox. Emerg handlers, prevention of potential exposures by Infect Dis 1999;5:438-40.7. avoidance of bat handling by nonvaccinated 7. Hooper P, Lunt R, Gould A, Samaratunga H, Hyatt AD, persons, and prompt medical care when potential Gleeson LF, et al. A new lyssavirus—the first endemic rabies-related virus recognized in Australia. Bulletin exposures occur. The cost of PEP for all those Institut Pasteur 1997;95:209-18. potentially exposed to ABL in south Brisbane and 8. Rabies and bat lyssavirus infection. In: Watson C, the South Coast of Queensland during the study editor. The Australian immunisation handbook. 6th ed. was considerable. Future public health interven- Canberra: Australian Government Publishing Service, tions should continue to emphasize the risks 1997:162-8. 9. Lyssavirus Expert Group. Prevention of human associated with interaction with bats to reduce lyssavirus infection. Commun Dis Intell 1996;20:505-7. the requirement for PEP and the likelihood of 10. Lyssavirus Expert Group. Update on bat Lyssavirus. human cases of ABL infection. Commun Dis Intell 1996;20:535. 11. Birt P, Markus N, Collins L, Hall L. Urban flying foxes. Acknowledgments Nature Australia 1998;Spring:55-9. The authors thank Russell Stafford, Helen Luckhoff, 12. Australian Bureau of Statistics. 1997 estimated Les Hall, Nicki Markus, Bruce Harrower, David Gould, the resident population by statistical local area. Australian Queensland Medical Laboratory, and the medical practitio- Bureau of Statistics catalogue no. 3235.3. Canberra, ners of south Brisbane and South Coast for their assistance Australia: The Organization,1997. in aspects of patient management, laboratory investigation, 13. Dean AG, Dean JA, Coulombier D, Brendel KA, Smith vaccine delivery, and for advice throughout the study. DC, Burton AH, et al. Epi-Info, version 6.04b: a word processing, database, and statistics system for Mr. Epstein’s work was supported by grants from the epidemiology on microcomputers (computer program). National Institutes of Health, the Hickey-Peyton Interna- Atlanta, GA: Centers for Disease Control and tional Travel Fellowship, and the Department of Interna- Prevention, 1997. tional Programs, Tufts University School of Veterinary 14. Centers for Disease Control and Prevention. Rabies Medicine. Prevention—United States, 1991. Recommendations of the Immunization Practices Advisory Committee. Dr. McCall, a public health physician, has led the MMWR Morb Mortal Wkly Rep 1991;40:R3:1-19. Communicable Disease Control team at the Brisbane 15. Hall LS. Black flying fox. In: Strachan R, editor. The Southside Public Health Unit for 5 years. His research mammals of Australia. Chatswood, Australia: Reed interests include meningococcal disease, leptospirosis, Books 1995;432-7. and ABL. 264 264 Emerging Infectious Diseases 264 264 264 Vol. 6, No. 3, May–June 2000

Journal

Emerging Infectious Diseases – Pubmed Central

Published: Aug 1, 167

There are no references for this article.