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Journal: The Journal of Veterinary Medical Science

Manuscript ID: JVMS-08-0061

Manuscript Type: Full Paper

Date Submitted by the Author:

30-Mar-2008

Complete List of Authors: Blanco, Kinndle; Rancho Margot, Rescue Center Prendas, Jorge; Universidad Nacional, School of Veterinary MedicineCortés, Rocío; Universidad Nacional, School of Veterinary Medicine Jiménez, Carlos; Universidad Nacional, School of Veterinary Medicine Dolz, Gaby; Universidad Nacional, School of Veterinary Medicine

Keywords: infectious disease, Virology, domestic animals

Category: Virology

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Virology1

Full paper2

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FELINE VIRUSES IN DOMESTIC CATS IN COSTA RICA4

5

Kinndle BLANCO¹,3, Jorge PRENDAS², Rocío CORTES², Carlos JIMENEZ² and Gaby 6

DOLZ27

8

¹ Rancho Margot Rescue Center, P.O. Box 124-4417, Castillo, Alajuela, Costa Rica9

² School of Veterinary Medicine, Universidad Nacional, P.O. Box 304-3000, Heredia, 10

Costa Rica11

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³Corresponding author:13

P.O.Box: 380-1300 San José, Costa Rica 14

Fax: (506) 2479-725915

E-mail: kblanco@ranchomargot.org16

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ABSTRACT1

A cross sectional survey of a convenience sample of domestic cats of the metropolitan area 2

of Costa Rica was carried out to determine the prevalence of antibodies against feline 3

herpesvirus type 1 (FHV-1), feline calicivirus (FCV), feline parvovirus (FPV), feline 4

immunodeficiency virus (FIV) and antigens of feline leukemia virus (FeLV). Blood 5

samples were collected from at least 96 cats from June 1998 to December 2001, data of 6

individual cats and household variables were obtained by questionnaire. Antibodies against 7

FHV-1 were found in 71.9% of the cats sampled, all seropositive cats had protective 8

antibody titres, but only 25.0% of them had been reported as previously vaccinated. 9

Antibodies against FCV were detected in 30.1% of the cats tested, however 67.7% of these 10

seropositive animals showed low titres (1:2 to 1:8) and only 16.5% were reported as 11

previously vaccinated. The prevalence for FPV determined was 92.8%, all positive cats 12

showed protective antibodies titres, however, only 16.5% of them were vaccinated 13

previously. Antigens of FeLV were detected in 16.7% of the sampled cats, 10 (58.8%) out 14

of 17 positive cats were between one to six years old. No differences were found between 15

the proportion of seropositive males and females. Antibodies against FIV were detected in 16

8.8% of the samples tested, 55.5% of these seropositive cats were 1 to 3 years old, also a 17

greater proportion of seropositive males (66.6%) were determined.18

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Keywords: feline herpesvirus type 1, feline calicivirus, feline parvovirus, feline 22

immunodeficiency virus, feline leukemia virus.23

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INTRODUCTION1

Infections of feline herpesvirus type 1 (FHV-1), feline calicivirus (FCV), feline parvovirus 2

(FPV), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are known 3

to cause clinically important diseases in domestic cats [14]. FHV-1 and FCV are associated 4

with upper respiratory diseases, stomatitis and conjunctivitis [11], whereas FPV is the 5

causative agent of panleukopenia and diarrhea [10]. Finally, FeLV induces anemia and FIV 6

leads to immune suppression, and both are associated with AIDS like-syndromes [15, 21]. 7

Epidemiological surveys have been conducted in advanced countries [1, 2, 7, 9, 12, 17, 19], 8

but there are only few reports of the prevalence of these viruses in tropical countries [18, 9

20, 22], although a worldwide distribution is suspected [14].10

Approximately 25% of the total area of Costa Rica is under protection to preserve 11

biological diversity and six New World felids (Leopardus tigrina, Leopardus wiedii, 12

Leopardus pardalis, Herpailurus yaguaroundi, Panthera onca) are found in these protected 13

zones. However, due to rapid population growth, the habitats of these wild felids are being 14

fragmentated, and an exposure with domestic animals is possible. Studies of viral diseases 15

in domestic cat populations are therefore important, to assess a possible risk for populations 16

of endangered wild felids [5, 13, 20].17

The purpose of the present study was to determine the prevalence of antibodies to FHV-1, 18

FCV, FPV and FIV and antigens to FeLV in domestic cats from the metropolitan area of 19

Costa Rica.20

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MATERIALS AND METHODS1

Serum samples 2

A cross-sectional survey of a convenience sample of domestic cats of the metropolitan area 3

of Costa Rica was carried out to determine the prevalence of antibodies against feline FHV-4

1, FCV, FPV, FIV and antigens of FeLV. Blood samples were collected from domestic cats 5

from June 1998 to December 2001. At least 96 animals were tested, this number was 6

determined with Winepiscope 1.0 (95% confidence, 10% acceptable error), and based on 7

the assumption, that the total number of cats in the metropolitan area of Costa Rica was 8

proportional to 5% of the human population in this area. Selection of the animals for 9

sampling was based on voluntary participation of the owners of the cats in the different 10

veterinary clinics or on home-to-home solicitation. Blood samples were collected from the 11

medial saphenous, jugular or femoral veins. Serum was separated and stored at -20°C until 12

arrival at the Laboratory of Virology, School of Veterinary Medicine, Universidad 13

Nacional. Data of individual cats (age, sex), lifestyle habits (indoor or outdoor cats), 14

household variables (one cat or multiple cat household) and information about previously 15

vaccination with Eclipse (Fort Dodge. USA), only available vaccine in the country at that 16

time, was obtained by questionnaire and analysed descriptively.17

Serological surveys18

Antibodies against FHV-1 and FCV were detected by serum neutralization (SN) assay as 19

described elsewhere [6]. SN tests were performed in a microtitre system (Nunclon®: Brand 20

Products, Denmark) with 100-200 TCID50 of FHV-1-CR1 or FCV-CR1, field strains 21

isolated by Velandos [23]. Serum was examined by serial two-fold dilutions (1:2 to 1:1024) 22

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and in duplicate with Minimal Essential Medium (MEM). Previously, serum was 1

inactivated for 30 minutes at 56ºC. Virus-serum mixtures were incubated at 37ºC, 5% CO22

for 1h before addition of Crandell Feline Kidney (CRFK) cells and incubated 3 days. 3

Antibody titers to FHV-1 and FCV were determined as the last dilution, where 4

citopatogenic effect was not observed. In each plate cell control (CRFK cells and MEM) 5

and virus control (FHV-1-CR1 or FCV-CR1) was included.6

To detect antibodies to FPV a haemagglutination inhibition assay was carried out as 7

described previously [4]. Inactivated serum samples were adsorbed for 8h at 4°C with 0.1M 8

PBS (pH 7.2) containing 1% swine erythrocytes and 10% Foetal Bovine Serum (FBS). 9

Each serum was centrifuged to separate the erythrocytes. Serial two-fold dilutions (1:10 to 10

1:20480) of sera in PBS were added to V-form plates (Sigma®: Thermo Labsystems, USA) 11

and incubated 90 minutes at room temperature with 4-8 haemagglutination units of virus 12

(Eclipse). Finally, 1% swine erythrocytes in PBS, 10% FBS were added to the plates and 13

incubated for 45 min at 4ºC. Antibody titers to FPV were determined as the last dilution 14

haemagglutination inhibition was observed. In each plate an erythrocyte (PBS, 1% 15

erythrocyte) and a virus control (Eclipse) was included. Feline parvovirus from the 16

Eclipse vaccine was used as antigen in this assay after formaline and heat inactivation.17

To detect FeLV antigen and antibodies against FIV a commercial kit (Cite-Combo, 18

IDEXX Co., Portland, Maine, USA) was used, following the manufacturer’s instructions.19

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RESULTS1

Antibodies to FHV-1 were detected in 69 (71.9%) out of 96 cat sera tested (Table 1). The 2

antibodies titres determined were between 1:2 and 1:1024, presenting a bimodal 3

distribution (titre 1:4: 15.9%, titre 1:128: 23.2%, Table 2). All age categories showed 4

similar proportions of seropositives to FHV-1. No differences were observed between the 5

proportion of seropositive males and females and indoor and outdoor cats, however, in the 6

group of one cat households, a lower proportion of seropositive cats was determined (Table 7

1). Of the total of seropositive cats to FHV-1, only 24 (34.8%) had been reported as 8

previously vaccinated, no differences were observed between the proportion of seropositive 9

vaccinated and not vaccinated animals (Table 1).10

Antibodies against FCV were found in 31 (30.1%) out of 103 cat samples tested (Table 1) 11

and the titres determined were between 1:2 and 1:512, however, 67.7% of these animals 12

showed low titres (1:2 to 1:8) (Table 2). With increasing age a higher proportion of 13

seropositive animals to FCV was determined. No differences were found between the 14

proportion of seropositive males and females, however the group of indoor cats and multi 15

cat households showed a higher proportion of seropositive animals. From the total FCV-16

seropositive felines, 17 (53.1%) were reported as previously vaccinated, a greater 17

proportion of seropositive animals was observed in the group of vaccinated animals 18

(53.1%) in contrast to the group of not vaccinated animals (14.0%) (Table 1).19

Antibodies against FPV were detected in a total of 90 (92.8%) out of 97 sera tested (Table 20

1). The distribution of antibodies titres was homogenous in titres 1:160-1:2560 in 72 (80%) 21

of the sera tested (Table 2). All age categories showed similar proportion of seropositives to 22

FPV. No differences were observed between the proportion of seropositive animals within 23

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the variables gender, indoor or outdoor cats and one cat or multi cat household. Only 16 1

(17.8%) of the positive cats to FPV were reported as previously vaccinated, no differences 2

were observed between the proportion of seropositive vaccinated and not vaccinated 3

animals (Table 1).4

Antigens of FeLV were determined in 17 (16.7%) out of 102 serum samples analysed, 5

being 10 cats (58.8%) between one and six years old. No differences were found between 6

the proportion of positive males and females, although 5 of these animals lived in one cat 7

households, they were allowed to go out (Table 1). 8

Antibodies against FIV were found in 9 (8.8%) out of 102 samples tested. A greater 9

proportion of positive animals were found in the following categories: cats 1 to 3 years old10

(55.5%), males (66.6%), outdoor cats (55.5%) and living in multi cat households (66.6%) 11

(Table 1).12

13

DISCUSSION14

The results of the serological surveys carried out in domestic cats from the metropolitan 15

area of Costa Rica determined high prevalences of FHV-1 and FPV, similar to that reported 16

in studies carried out in Mexico and Guatemala, whereas the prevalences determined for 17

FCV, FIV and FeLV were similar to that reported elsewhere [2, 9, 12, 16, 18, 19, 22]. 18

Of interest is the fact, that in most countries FCV is generally reported to be more 19

distributed among domestic cats than FHV-1 [2, 12, 19, 20]. In contrast, the results 20

obtained in the present study, suggest that FHV-1 is widely distributed among the domestic 21

cat population of Costa Rica, what is in accordance with a survey performed in Guatemala 22

[18], and also with studies carried out in Costa Rica by Velandos [23], who examined nasal, 23

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ocular and oral swabs from 24 cats with upper respiratory tract disease and diagnosed 8 1

(33.3%) and 2 (8.3%) cats with FHV-1 and FCV infections, respectively. High prevalences 2

of FHV-1 were determined in all age categories and only the group of animals living in one 3

cat households showed a lower proportion of seropositives, confirming that this virus is 4

possibly transmitted by direct contact between cats in Costa Rica [14], since only 34.8% of 5

the seropositive animals were reported as previously vaccinated and no differences were 6

found between the proportion of seropositive vaccinated and not vaccinated animals. 7

The prevalence determined for FCV in domestic cats from Costa Rica was similar to that 8

reported in Japan [19] and the United Kingdom [2]. The distribution of FCV antibodies 9

determined in the different age categories suggest, that cats got infected with increasing 10

age, eventually due contact with persistently FCV-infected animals, especially in multi cat 11

households, what is reported elsewhere [2]. Although differences were observed in the 12

proportion of seropositives between vaccinated and not vaccinated animals [2], most of the 13

naturally infected or vaccinated cats showed low titres, which are considered as non 14

protective [8], eventually due to the antigen source used in the serological assay [19].15

The prevalence for FPV determined in domestic cats of the metropolitan area of Costa Rica 16

was in accordance with that reported in captive wild felids from Costa Rica [3] and feral 17

cats from Mexico [22]. No differences were found between the proportion of seropositive 18

animals within the different age categories and the variables indoor or outdoor cats, one cat 19

or multi cat household and vaccinated or not vaccinated cats, suggesting a natural exposure 20

of cats to the relatively stable and resistant FPV at early ages in Costa Rica, eventually due 21

to the high presence of the agent in the cat population, specially if taking into account, that 22

only 17.8% of the seropositive cats were reported as previously vaccinated. 23

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The determined prevalences of FeLV and FIV in domestic cats of Costa Rica are similar to 1

that reported in Guatemala, Germany and Czech Republic [9, 16, 18]. FeLV seems to be 2

more prevalent than FIV in domestic cats from Costa Rica, infecting animals of different 3

ages without gender preferences, whereas most positive animals to FIV were determined in 4

the categories of male, cats 1 to 3 years old and outdoor cats, what is in accordance with 5

reports in the literature [7, 16, 17].6

The results presented in this study determined high prevalences of FHV-1 and FPV and the 7

presence of FCV, FIV and FeLV in domestic cats in Costa Rica. A previous study 8

determined also a high prevalence of FPV and the presence of FCV in captive wild felids of 9

Costa Rica [3], confirming a possible risk of populations of endangered wild felids, due to 10

rapid population growth and fragmentation of their habitats, that may lead to an exposure to 11

infected domestic cats, especially taking into account, that most domestic cats of Costa 12

Rica had the habit to go out and are not vaccinated.13

14

ACKNOWLEDGMENTS15

The authors wish to thank Ph.D. Luis Nazario Araya and Ph.D. Marco Vinicio Herrero for 16

their comments. This work was supported partially by the Center of Investigation, Rescue 17

and Rehabilitation of Wild Cats PROFELIS and by VETIM.18

19

REFERENCES20

1. Arjona, A., Escolar, E., Soto, I., Barquero, N., Martin, D. and Gomez-Lucia, E. 2000. 21

Seroepidemiological survey of infection by feline leukemia virus and 22

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immunodeficiency virus in Madrid and correlation with some clinical aspects. Journal 1

of Clinical Microbiology 38: 3448-3449.2

2. Binns, S. H., Dawson, S., Speakman, A. J., Cuevas, L. E., Hart, C. A., Gaskell, C. J., 3

Morgan, K. L. and Gaskell, R. M. 2000. A study of feline upper respiratory tract 4

disease with reference to prevalence and risk factors for infection with feline 5

calicivirus and feline herpesvirus. Journal of Feline Medicine and Surgery 2: 123-133.6

3. Blanco, K., Peña, R., Hernández, C., Dolz, G. and Jiménez, M. Serologic survey of 7

viral agents in captive wildcats of Costa Rica. Journal of Zoo and Wildlife Medicine8

Submitted February 2nd, 2008.9

4. Carmichael, L. E., Joubert, J. C. and Pollock, R. V. H. 1980. Hemagglutination by 10

Canine Parvovirus: Serologic studies and diagnostic applications. American Journal 11

Veterinary Research 41: 784-791.12

5. Dasek, P., Cunningham, A. and Hyatt, A. 2000. Emerging infectious diseases of 13

wildlife - threats to biodiversity and human health. Science 287: 443-449.14

6. Dawson, S., Mcardle, F., Bennett, M., Carter, M., Milton, I. P., Turner, P., Meanger, J. 15

and Gaskell, R. M. 1993. Typing of feline calicivirus isolates from different clinical 16

groups by virus neutralisation tests. Veterinary Record 133: 13-17.17

7. Dorny, P., Speybroeck, N., Verstraete, S., Baeke, M., De Becker, A., Berkvens, D. and 18

Vercruysse, J. 2002. Serological survey of Toxoplasma gondii, feline 19

immunodeficiency virus and feline leukaemia virus in urban stray cats in Belgium. 20

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8. Fenner, F., Gibbs, E., Bachman, P., White, D. and Murphy, F. 1987. Caliciviridae. pp. 22

448-449. In: Veterinary Virology, 2nd ed., Academic Press, United States.23

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9. Fuchs, A., Binzel, L. and Lonsdorfer, M. 1994. Epidemiology of FeLV and FIV 1

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10. Gaskell, R. M. 1994. Feline panleucopenia. pp. 445-452. In: Feline Medicine and 3

Therapeutics, 2nd ed. (Chandler, E. A., Gaskell, C. J. and Gaskell, R. M. eds.), 4

Blackwell Scientific Publications, Oxford.5

11. Gaskell, R. M. and Dawson, S. 1994. Viral induced upper respiratory tract disease. pp. 6

453–472. In: Feline Medicine and Therapuetics, 2nd ed. (Chandler, E. A., Gaskell, C. 7

J. and Gaskell, R. M. eds.), Blackwell Scientific Publications, Oxford. 8

12. Harbour, D., Howard, P. and Gaskell, R. 1991. Isolation of feline calicivirus and feline 9

herpesvirus from domestic cats 1980 to 1989. Veterinary Record 128: 77-80.10

13. Hoffmann-Lehmann, R., Fehr, D., Grob, M., Elgizoli, M., Packer, C., Martenson, J., 11

O´Brien, S. and Lutz, H. 1996. Prevalence of antibodies to feline parvovirus, 12

calicivirus, herpesvirus, coronavirus and immunodeficiency virus and feline leukemia 13

virus antigen and the interrelationship of these viral infections in free-ranging lions in 14

east Africa. Clinical and Diagnostic Laboratory Immunology 3: 554-562.15

14. Horzinek, M. C. 1990. Virusinfektionen bei Katzen, Ferdinand Enke Verlag, Stuttgart, 16

Germany.17

15. Jarrett, W. L., Mackey, L. J., Jarret, O. and Laird, H. M. 1972. Feline Leukaemia 18

Infection: the spectrum of associated disease and its relevance to the pathogenesis and 19

immunology of leukaemia. In: Comparative Leukaemia Reseach: Proceedings of the 20

Vth International Symposium 1971 (Bibliotheca Heamatologica), Karger, Basle and 21

New York.22

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16. Knotek, Z., Hajkova, P., Svoboda, M., Toman, M. and Raska, V. 1999. Epidemiology 1

of feline leukaemia and feline immunodeficiency virus infections in the Czech 2

Republic. Zentralblatt Veterinaermedizin (B) 46: 665-671.3

17. Levy, J. K., Scott, H. M., Lachtara, J. L. and Crawford, P. C. 2006. Seroprevalence of 4

feline leukemia virus and feline immunodeficiency virus infection among cats in North 5

America and risk factors for seropositivity. Journal of American Veterinary Medical 6

Association 228: 371-376.7

18. Lickey, A. L., Kennedy, M., Patton, S. and Ramsay, E. C. 2005. Serologic survey of 8

domestic felids in the Petén region of Guatemala. Journal of Zoo and Wildlife 9

Medicine 36: 121–123.10

19. Mochizuki, M., Kawakami, K., Hashimoto, M. and Ishida, T. 2000. Recent 11

epidemiological status of feline upper respiratory infections in Japan. Journal of 12

Veterinary Medical Science 62: 801-803.13

20. Nakamura, K., Ikeda, Y., Miyazawa, T., Nguyen, N. T., Duong, D. D., Le, K. H., Vo, 14

S. D., Phan, L. V., Mikami, T. and Takahashi, E. 1999. Comparison of prevalence of 15

feline herpesvirus type 1, calicivirus and parvovirus infections in domestic and leopard 16

cats in Vietnam. Journal of Veterinary Medical Science 61: 1313-1315.17

21. Pedersen, N. C., Yamamoto, J. K., Ishida, T. and Hansen, H. 1989. Feline 18

immunodeficiency virus infection. Veterinary Immunology and Immunopathology 21: 19

111-129.20

22. Suzán, G. and Ceballos, G. 2005. The role of feral mammals on wildlife infectious 21

disease prevalence in two nature reserves within Mexico City limits. Journal of Zoo 22

and Wildlife Medicine 36: 479-484.23

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23. Velandos, M. A. 1995. Isolation and characterization of viral agents associated with 1

upper respiratory tract diseases in cats from Costa Rica. Vet. Med. Thesis, Universidad 2

Nacional, Heredia, Costa Rica (in Spanish). 3

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Table 1. Prevalence of antibodies against FHV-1, FCV, FPV and FIV and of antigens of 1

FeLV in domestic cats in the metropolitan area in Costa Rica2

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Variable Categories No. of positive cats / No. of cats tested (positive %)

FHV-1 FCV FPV FeLV FIV

<1 year 26/36 (72.2) 5/30 (16.7) 30/36 (83.3) 0/28 (0.0) 1/28 (3.6)1-3 years 16/25 (64.0) 6/28 (21.4) 27/27 (100.0) 5/28 (17.9) 5/28 (17.9)4-6 years 6/7 (85.7) 3/7 (42.9) 7/8 (87.5) 5/9 (55.6) 0/9 (0)7-9 years 2/2 (100.0) 1/2 (50.0) 2/2 (100.0) 1/2 (50.0) 1/2 (50.0)10-12 years 5/6 (83.3) 5/6 (83.3) 0/0 (0) 0/6 (0) 0/6 (0)>13 years 4/4 (100.0) 3/3 (100.0) 0/0 (0) 0/4 (0) 2/4 (50.0)

Age

NDa) 10/16 (62.5) 8/27 (29.6) 24/24 (100.0) 6/25 (24.0) 0/25 (0)

Female 34/47 (72.3) 14/44 (31.8) 35/40 (87.5) 6/44 (13.6) 3/44 (6.8)Male 26/37 (70.3) 12/43 (27.9) 40/42 (95.2) 6/44 (13.6) 6/44 (13.6)

Sex

ND 9/12 (75.0) 5/16 (31.3) 15/15 (100.0) 5/14 (35.7) 0/14 (0)

Outdoor 24/37 (64.9) 10/39 (25.6) 44/49 (89.8) 6/41 (14.6) 5/41(12.2)Indoor 27/37 (73.0) 13/30 (43.3) 15/16 (93.8) 1/27 (3.7) 2/27 (7.4)

Cat lifestyle

ND 18/22 (81.8) 8/34 (23.5) 31/32 (96.9) 10/34 (29.4) 2/34 (5.9)

Multi cat 47/62 (75.8) 20/62 (32.2) 48/53 (90.6) 2/59 (3.4) 6/59(10.2)One cat 8/17 (47.1) 4/14 (28.6) 15/17 (88.2) 5/16 (31.2) 1/16 (6.2)

Household

ND 14/17 (82.4) 7/27 (25.9) 27/27 (100.0) 10/27 (37.0) 2/27 (7.4)

Vaccines Vaccinated 24/33 (72.7) 17/32 (53.1) 16/18 (88.9) -- --Not vaccinated 32/45 (71.1) 6/43 (14.0) 48/52 (92.3) -- --ND 13/18 (72.2) 8/28 (28.6) 26/27 (96.3) -- --

Total 69/96 (71.9) 31/103 (30.1) 90/97 (92.8) 17/102 (16.7) 9/102 (8.8)a) ND: Not determined4

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Table 2. Titres of antibodies detected to HVF-1, CVF and FPV in domestic cats in the

metropolitan area of Costa Rica

HVF-1 CVF FPV

Titre n % Titre n % Titre n %

1:2 5 7.3 1:2 5 16.1 1:10/1:20 0 0.0

1:4 11 16.0 1:4 9 29.0 1:40 1 1.1

1:8 7 10.1 1:8 7 22.6 1:160 17 18.9

1:16 4 5.8 1:16 3 9.7 1:320 13 14.4

1:32 7 10.1 1:32 2 6.5 1:640 12 13.3

1:64 4 5.8 1:64 3 9.7 1:1280 15 16.7

1:128 16 23.2 1:128 0 0.0 1:2560 15 16.7

1:256 7 10.1 1:256 1 3.2 1:5120 7 7.8

1:512 2 2.9 1:512 1 3.2 1:10240 4 4.4

1:1024 6 8.7 1:1024 0 0.0 1:20480 6 6.7

TOTAL 69 100.0 TOTAL 31 100.0 TOTAL 90 100

n: Number of cats

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