Abstract
Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are two of the most important viral infections in cats. Both affect the immune system and are significant causes of morbidity and mortality in their host. Both viruses have been reported to be present in many countries worldwide. However, neither FIV nor FeLV has been reported in Turkey to date.
Sera from 103 cats brought to veterinary practices and the practice teaching unit of the Veterinary Faculty of Istanbul were collected and stored at −20°C until analysed. The cats were from two populations, distinguished by their lifestyle. Cats belonging to the first population had been kept solely in the house and had no access to the street. This population was considered as a ‘domestic’ cat group in this study. The second population included cats which either had free access to feral cats in the street or were themselves feral cats living in the street. These were considered as a ‘feral’ cat group. Data about individual cats were obtained from the clients and all cats were examined clinically.
Sera were tested for the presence of antibodies to the FIV p24 core protein and for the presence of FeLV p27 using PetChek kits (IDEXX, Portland, ME, USA) as described by the manufacturer. Statistical analyses were carried out using Epi Info 5 (CDC Atlanta, GA, USA).
The results are shown in Table 1. FIV antibodies were detected in 23 (22.3%) sera and FeLV p27 antigen in six (5.8%) sera. Amongst the FIV-positive cats, 15 were male, 14 were feral and 17 were unhealthy, 10 were non-pedigree and 13 pedigree. Most of the seropositive cats were between the ages of 3 and 7 years. Weight loss, anorexia, conjunctivitis and gingivitis were seen commonly in seropositive cats and these signs were more severe in older cats. Two cats had neurological disorders.
Details of cats in survey
Data are given as n/total (%).
Number of cats positive/number of cats tested (% positive).
The risk of FIV infection was higher in males (P<0.05, risk ratio=2.07, 95% CI=0.96–4.44). There was also an association between the presence of gingivitis and seropositivity (P<0.05, risk ratio=2.32, 95% CI=1.08–4.99). There was no overall association with age, but an association was found between seropositivity and age group 3–7 years when the ages were grouped as ≤2, 3–7 and 8–16 years (P<0.05, risk ratio=3.02, 95% CI=1.45–6.28). No association was found between infection with FIV and infection with FeLV (P>0.05). Amongst the six FeLV-positive cats, four were male, four were ‘feral’ and five were unhealthy (Table 1). Weight loss, anorexia and gingivitis were observed in four positive cats, while skin lesions were present in two and neurological disorders in one.
The prevalence of FIV infection found in this study (22.3%) is similar to those found in Japan, the USA, France and the UK but higher than in the Netherlands, Switzerland, Norway and Germany (Courchamp & Pontier 1994). However, the prevalence of FeLV infection is lower than in the USA and the UK (Hosie et al 1989, O'Connor et al 1991). A possible reason why the proportion of FIV-positive cats is relatively high compared to some studies is that most cats have access to the street in Turkey (the ‘feral’ group in this study) and fewer cats are neutered. However, the cats which were kept indoors entirely (the ‘domestic’ group in this study) had an almost identical prevalence to the feral cats, suggesting that they were infected within the first few weeks of life, before going to their permanent homes. It is known that most vertical transmission of FIV occurs late in utero (Rogers & Hoover 1998), and queens can be infected during mating by both biting and, possibly, sexual transmission (Jordan et al 1995).
Most (65.2%) of the FIV-positive cats in this study were male. Several authors (Gruffydd-Jones et al 1988, O'Connor et al 1991) have reported similar results. The reason why male cats get infected more frequently may be related to differences in behaviour between sexes such as territorial fighting, which would promote transmission by biting. However, neutering appeared to have no influence on FIV prevalence. This may be because neutered cats, although they do not indulge in courtship fighting, retain their territorial aggressiveness. In the present study, no association was found between FIV, FeLV and age although FIV was found in relatively older cats, and no FeLV was found in cats between the ages of 8 and 16 years. A similar age distribution in FIV and FeLV infections has been reported in the UK (Hosie et al 1989), and probably reflects the relatively long subclinical period of FIV infection compared to that for FeLV.
Most studies have indicated that the prevalence of FIV and FeLV in ill cats is higher than in healthy cats. This was also observed in the present study as the positivity in ill cats was 25.7% for FIV and 7.5% for FeLV while 16.2% of healthy cats were FIV-positive and 2.7% were FeLV-positive. In the present study, weight loss, anorexia, conjunctivitis and gingivitis were commonly observed in FIV-positive cats, similar to those seen in FIV infections elsewhere (Gruffydd-Jones et al 1988, Hosie et al 1989). Amongst these signs, a statistically significant association was found between FIV infection and gingivitis. FIV appears to be a significant cause of morbidity in Istanbul cats, but for reasons that are unclear, FeLV is a relatively uncommon infection.
Footnotes
Acknowledgements
The help of Veterinary Surgeons Tarik Mungan, Ilhan Gokgol, Oktay Deprem, Huseyin Gun, Erhan Okyar and Aysun Aktas is gratefully acknowledged.