Seroprevalence of feline leukemia virus, feline immunodeficiency virus and heartworm infection among owned cats in tropical Mexico

Study of feline immunodeficiency virus prevalence and expert opinions on standards of care

OBJECTIVE

The purpose of this study was to identify knowledge gaps in the global prevalence of feline immunodeficiency virus (FIV) and to obtain professional opinions and experiences regarding FIV in selected countries. We conducted a literature review of abstracts that reported the prevalence of FIV and interviewed experts in feline medicine and retroviruses from different countries to determine regional perspectives.

METHODS

A total of 90 articles reporting FIV prevalence as a primary unbiased population-level analysis between 1980 and 2017 were indexed. FIV prevalence, demographics, year and location were analyzed. Statistics were evaluated and compared. In total, 10 experts were interviewed. Results were analyzed for congruence with the findings of the literature review.

RESULTS

FIV prevalence was typically in the range of 5-8%, with a global prevalence of 4.7%, and remained largely constant over the reporting period (1980-2017). Over 90% of articles reported greater prevalence in older male cats. More studies were conducted in North America and Europe and reported the lowest prevalence. Expert-estimated prevalence approximated literature review prevalence. Attitudes and recommendations for management were consistent among experts. The limitations of the present review include varying inclusion criteria of cats tested in different studies, variation in testing modalities and the inability to conduct summary statistics across dissimilar cohorts.

CONCLUSIONS AND RELEVANCE

The global prevalence of FIV has not changed since its discovery 40 years ago. Prevalence is higher in older male cats and is lower in North America and Europe than other continents. Experts agree that FIV is not typically a disease of high concern and is often associated with infections of the oral cavity. Vaccination is not typically recommended and has been discontinued in North America. The evaluation of risk factors for FIV progression is useful in managing infections. Recommendations for future research include analyses to determine copathogen and environmental factors that impact progression, assessment of life span impacts and investigations of treatment efficacy and side effects.

Occurrence and risk factors of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) in cats of Lebanon

A cross-sectional study was carried out between April 2020 and August 2021. Blood samples were collected from 260 household cats recruited in different clinics in North and Mount Lebanon, with the aim of determining the seroprevalence of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV). The seroprevalence reported reached 18.84% (95% CI 0.14-0.24) and 13.84% (95% CI 0.09-0.18) for FIV and FeLV, respectively. FIV seropositivity was associated with a younger age, health and neuter status, lymphoma, lethargy, and vomiting. Furthermore, male sex, neuter status, lymphoma, anaemia, lethargy, and vomiting were significantly associated with FeLV seropositivity. This first data from Lebanon emphasizes the need for implementing preventive programmes to cope with FIV- and FeLV-associated morbidity and mortality among cats.

Detection and genetic characterization of feline retroviruses in domestic cats with different clinical signs and hematological alterations

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are globally distributed retroviruses that infect domestic cats and cause various syndromes that can lead to death. The aim of this study was to detect and genotype feline retroviruses in Mexican domestic cats. We used PCR assays to identify proviral DNA and viral RNA in 50 domestic cats with different clinical signs and hematological alterations. Endogenous FeLV (enFeLV) was identified in the genomic DNA of all cats in the study, and we detected transcripts of the LTR region of enFeLV in 48 individuals. Exogenous FeLV (exFeLV) was found in 13 cats. Furthermore, we detected FIV proviral DNA in 10 cats. The enFeLV sequences were shown to be the most variable, while the exFeLV sequences were highly conserved and related to previously reported subgroup A sequences. Sequencing of the FIV gag gene revealed the presence of subtype B in the infected cats.

Undetectable proviral DNA and viral RNA levels after raltegravir administration in two cats with natural feline leukemia virus infection

Feline leukemia virus (FeLV) infection was discovered over 50 years ago; however, the serious clinical changes associated with FeLV infection still have great importance in the diagnosis, prevention, and clinical management of symptomatic patients. Progressive infection with FeLV leads to a reduction in the patient's life expectancy and quality of life. This report describes the use of an antiretroviral integrase inhibitor, raltegravir, in two cats with natural FeLV infection. Raltegravir was administered orally at a dose of 40 mg/cat every 12 h in both cases. In case one, 13 weeks after starting raltegravir, RNA loads were undetectable, while proviral DNA loads were still detectable. In case two, proviral DNA loads were undetectable after 32 weeks of medication, while RNA loads were undetectable throughout the treatment. No adverse effects or laboratory test abnormalities were detected with the use of raltegravir in either patient. The patients are currently clinically healthy, still receiving the drug, and are under close observation. To our knowledge, this is the first report describing the use of raltegravir in naturally infected FeLV-positive cats and its effects on circulating viral load. Moreover, the patients described here were followed-up for a longer period than those in previously reported cases.

Feline immunodeficiency virus (FIV) infection in domestic pet cats in Australia and New Zealand: Guidelines for diagnosis, prevention and management

Despite the passage of over 30 years since its discovery, the importance of feline immunodeficiency virus (FIV) on the health and longevity of infected domestic cats is hotly debated amongst feline experts. Notwithstanding the absence of good quality information, Australian and New Zealand (NZ) veterinarians should aim to minimise the exposure of cats to FIV. The most reliable way to achieve this goal is to recommend that all pet cats are kept exclusively indoors, or with secure outdoor access (e.g., cat enclosures, secure gardens), with FIV testing of any in‐contact cats. All animal holding facilities should aim to individually house adult cats to limit the spread of FIV infection in groups of animals that are stressed and do not have established social hierarchies. Point‐of‐care (PoC) FIV antibody tests are available in Australia and NZ that can distinguish FIV‐infected and uninfected FIV‐vaccinated cats (Witness™ and Anigen Rapid™). Although testing of whole blood, serum or plasma remains the gold standard for FIV diagnosis, PoC testing using saliva may offer a welfare‐friendly alternative in the future. PCR testing to detect FIV infection is not recommended as a screening procedure since a negative PCR result does not rule out FIV infection and is only recommended in specific scenarios. Australia and NZ are two of three countries where a dual subtype FIV vaccine (Fel‐O‐Vax® FIV) is available and offers a further avenue for disease prevention. Since FIV vaccination only has a reported field effectiveness of 56% in Australia, and possibly lower in NZ, FIV‐vaccinated cats should undergo annual FIV testing prior to annual FIV re‐vaccination using a suitable PoC kit to check infection has not occurred in the preceding year. With FIV‐infected cats, clinicians should strive to be even more thorough than usual at detecting early signs of disease. The most effective way to enhance the quality of life and life expectancy of FIV‐infected cats is to optimise basic husbandry and to treat any concurrent conditions early in the disease course. Currently, no available drugs are registered for the treatment of FIV infection. Critically, the euthanasia of healthy FIV‐infected cats, and sick FIV‐infected cats without appropriate clinical investigations, should not occur.

A prospective epidemiological, clinical, and clinicopathologic study of feline leukemia virus and feline immunodeficiency virus infection in 435 cats from Greece

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses causing significant morbidity and mortality in cats. The aim of this study was to describe the epidemiological, clinical and clinicopathologic aspects of FeLV and FIV infections in different populations of cats in Greece, including client-owned cats, stray cats and cats who live in catteries. A total of 435 cats were prospectively enrolled. Serological detection of FeLV antigen and FIV antibody was performed using a commercial in-house ELISA test kit. The results showed that 17 (3.9 %) and 40 (9.2 %) of the 435 cats were positive for FeLV antigen and FIV antibody, respectively, whereas 5 (1.1 %) had concurrent infection with FeLV and FIV. Factors that were associated with FeLV antigenemia, based on multivariate analysis, included vomiting, rhinitis, infection with FIV, neutropenia, decreased blood urea nitrogen and increased serum cholesterol and triglyceride concentrations. Factors associated with FIV seropositivity included male gender, older age, outdoor access, weight loss, fever, gingivostomatitis, skin lesions and/or pruritus and hyperglobulinemia. Various clinical signs and laboratory abnormalities were found to be significantly associated with retroviral infections, suggesting that current guidelines to test all sick cats should be followed, taking into particular consideration the high-risk groups of cats found in this study.

Prevalence of Feline Immunodeficiency Virus and Toxoplasma gondii in Feral Cats on St. Kitts, West Indies

Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite that infects all warm-blooded species including humans. The definitive hosts of T. gondii are felid vertebrates including the domestic cat. Domestic cats shed oocysts for approximately two weeks in their feces after the primary infection. It has been shown that feline immunodeficiency virus (FIV) positive cats have a higher prevalence of and a higher titer of antibodies to T. gondii than those of FIV-negative cats. The main purposes of this study were to determine FIV prevalence and to investigate the oocysts shedding in FIV-positive and FIV-negative feral cats on St. Kitts. Fecal samples were collected from feral cats while their FIV statues were determined using a commercial SNAP kit. Total fecal DNA of each cat was tested for the presence of T. gondii DNA using a polymerase chain reaction (PCR) consistently detecting one genome equivalent. A FIV-positive status was detected in 18 of 105 (17.1%, 95% confidence interval (CI): 9.9%−24.3%) feral cats sampled. Furthermore, males were three times more likely to be FIV positive than females (p = 0.017) with an odds ratio of 3.93 (95% CI: 1.20–12.89). Adults were found to have at least twice the prevalence of FIV compared to cats younger than one year of age (p = 0.056) with an odds ratio of 3.07 (95% CI: 0.94–10.00). Toxoplasma gondii DNA was not detected in the feces of any of the 18 FIV-positive (95% CI: 0%−0.18%) and 87 FIV-negative cats (95% CI: 0%−0.04%). A follow-up study with a much bigger sample size is needed to prove or disprove the hypothesis that FIV-positive cats have a higher prevalence of shedding T. gondii oocysts than FIV-negative cats.

Recommendations on vaccination for Latin American small animal practitioners: a report of the WSAVA Vaccination Guidelines Group

The World Small Animal Veterinary Association Vaccination Guidelines Group has produced global guidelines for small companion animal practitioners on best practice in canine and feline vaccination. Recognising that there are unique aspects of veterinary practice in certain geographical regions of the world, the Vaccination Guidelines Group undertook a regional project in Latin America between 2016 and 2019, culminating in the present document. The Vaccination Guidelines Group gathered scientific and demographic data during visits to Argentina, Brazil and Mexico, by discussion with national key opinion leaders, visiting veterinary practices and review of the scientific literature. A questionnaire survey was completed by 1390 veterinarians in five Latin American countries and the Vaccination Guidelines Group delivered continuing education at seven events attended by over 3500 veterinarians.

The Vaccination Guidelines Group recognised numerous challenges in Latin America, for example: (1) lack of national oversight of the veterinary profession, (2) extraordinary growth in private veterinary schools of undetermined quality, (3) socioeconomic constraints on client engagement with preventive health care, (4) high regional prevalence of some key infectious diseases (e.g. feline leukaemia virus infection, canine visceral leishmaniosis), (5) almost complete lack of minimal antigen vaccine products as available in other markets, (6) relative lack of vaccine products with extended duration of immunity as available in other markets, (7) availability of vaccine products withdrawn from other markets (e.g. Giardia vaccine) or unique to Latin America (e.g. some Leishmania vaccines), (8) accessibility of vaccines directly by pet owners or breeders such that vaccination is not delivered under veterinary supervision, (9) limited availability of continuing education in veterinary vaccinology and lack of compulsion for continuing professional development and (10) limited peer‐reviewed published scientific data on small companion animal infectious diseases (with the exception of leishmaniosis) and lack of support for such academic research.

In this document, the Vaccination Guidelines Group summarises the findings of this project and assesses in evidence‐based fashion the scientific literature pertaining to companion animal vaccine‐preventable diseases in Latin America. The Vaccination Guidelines Group makes some recommendations on undergraduate and postgraduate education and academic research. Recognising that current product availability in Latin America does not permit veterinarians in these countries to vaccinate according to the global World Small Animal Veterinary Association guidelines, the Vaccination Guidelines Group makes a series of “pragmatic” recommendations as to what might be currently achievable, and a series of “aspirational” recommendations as to what might be desirable for the future. The concept of “vaccine husbandry” is addressed via some simple guidelines for the management of vaccine products in the practice. Finally, the Vaccination Guidelines Group emphasises the global trend towards delivery of vaccination as one part of an “annual health check” or “health care plan” that reviews holistically the preventive health care needs of the individual pet animal. Latin American practitioners should transition towards these important new practices that are now well embedded in more developed veterinary markets.

The document also includes 70 frequently asked questions and their answers; these were posed to the Vaccination Guidelines Group during our continuing education events and small group discussions and should address many of the issues surrounding delivery of vaccination in the Latin American countries. Spanish and Portuguese translations of this document will be made freely available from the on‐line resource pages of the Vaccination Guidelines Group.

Prevalence of feline immunodeficiency virus and feline leukaemia virus in domestic cats in Hungary

OBJECTIVES

Feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) are retroviruses affecting cats worldwide. The objectives of the study were to estimate the prevalence of these retroviruses in domestic cats in Hungary and to characterise the phylogenetic relationships of FIV strains.

METHODS

A total of 335 anticoagulated whole-blood samples obtained from both a healthy and ill cat population were examined for the presence of FIV and FeLV with two methods: ELISA and PCR. Statistical analysis was carried out to analyse the data obtained. Sequencing and phylogenetic analysis of partial polymerase (pol) gene sequences was performed to describe circulating FIV subtypes.

RESULTS

Statistical analysis showed 11.8% and 9.9% true prevalence of FeLV and FIV, respectively, with ELISA. The apparent prevalence calculated from the PCR results were 17.3% for FeLV and 13.1% for FIV. Phylogenetic analysis of partial pol gene sequences obtained from 22 FIV strains showed that all observed Hungarian strains belonged to FIV subtype B. The strains were grouped into several monophyletic subgroups reflecting the geographic locations of the origin of the samples. The overall mean genetic similarity between the analysed strains was 98.2%.

CONCLUSIONS AND RELEVANCE

We report the first thorough overview of the prevalence of FeLV and FIV in Hungary, which is relatively high, and give insight into the genetic diversity of Hungarian strains of FIV.

Comparative meta-analysis of feline leukemia virus and feline immunodeficiency virus seroprevalence correlated with GDP per capita around the globe

Feline Leukemia Virus (FeLV) and Feline Immunodeficiency Virus (FIV) are two prevalent transmittable diseases for domestic cats. This paper reports the frequency of these two diseases compared globally across Gross Domestic Product (GDP) at purchasing power parity per capita (PPP). Information around FeLV and FIV rates of infection in specific locations around the world was analyzed from 47 published articles. Results show that based on the data available, the statistical model indicates that the highest percentage of FeLV or FIV infected cats live in areas of lower PPP (p ≤.001) with a decreasing rate of infection of FeLV and FIV with increasing income. Two theories for this could be that the lower PPP locations in this study were also in areas of greater feral cat and cat colony populations, as well as were areas with less emphasis on animal welfare and animal control programs. Additional research should be conducted to strengthen the study size in South America and Africa before further conclusions can be drawn.

Toxoplasma gondii in Captive Wild Felids of Mexico: Its Frequency and Capability to Eliminate Oocysts

There is little information about Toxoplasma gondii in wild felids, even when these species have been associated with cases of toxoplasmosis in humans. In this study, samples of serum and whole blood were collected from 42 felids from 10 different species, in 4 Mexican zoos. Stool samples from 36 animals were also collected, corresponding to 82% of the felids included in the study. Stool samples were used for the search of oocysts by light field microscopy and PCR. Serum samples were analyzed by indirect immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) and indirect fluorescent antibody test (IFAT). DNA samples were purified from whole blood and stool for the amplification of a fragment of the SAG1 gene of T. gondii by a nested PCR (nPCR). The seroprevalence of IgG anti-T. gondii-specific antibodies by means of the ELISA was 100% (42/42) and 52.4% (22/42) by IFAT. The titers obtained varied from 1:80 to 1:2560. DNA of T. gondii was detected in 9.5% (4/42) of the blood samples by using nPCR. No oocysts were observed in the stool samples analyzed by light field microscopy. However, the DNA of the parasite was identified in 14.3% (5/35) of the stool samples evaluated. These results indicate a high prevalence of T. gondii in the studied populations of wild felids in captivity, with evidence of parasitemia and elimination of few oocysts even in adult hosts.

Prevalence of and factors associated with feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) in cats of the state of Santa Catarina, Brazil

A cross-sectional study was conducted in 274 cats for determination of FeLV antigenemia and FIV seropositivity and factors associated with those infections in cats presented at the Veterinary Hospital of the Santa Catarina State University - UDESC (Brazil). Apparent prevalence for sick cats at the hospital population was 28.41% (95%CI 21.88-34.94%) for FeLV, 7.65% (95%CI 3.71-11.50%) for FIV and 2.18% (95%CI 0.56-5.47%) for both viruses. For healthy cats, the apparent prevalence was 9.89% (95%CI 3.75-16.02%) for FeLV, 2.20% (95%CI 0.34-7.75%) for FIV by immunoassay (ELISA). Average age for FeLV- and FIV-positive individuals was 38.32 and 64.25 months, respectively. Behavior such as aggressiveness and sex (male) were both associated with increased odds of result positivity test for FeLV and FIV; older animals were also associated with FIV test results. A very small proportion of the animals were vaccinated against FeLV and none against FIV. Most of the animals were adopted from shelters or rescued from streets, living with multiple cats that had access to outdoors. The high prevalence of FeLV suggests a need for better control strategies against this disease.

Efficacy of a nonadjuvanted recombinant FeLV vaccine and two inactivated FeLV vaccines when subject to consistent virulent FeLV challenge conditions

The purpose of this study was to compare the efficacy of three FeLV vaccines, under identical conditions in a laboratory challenge model that closely mimics natural infection. Four groups of cats (n = 20 per group) were administered two doses of vaccine, 21 days apart, starting at 9-10 weeks of age (Purevax^® FeLV, Versifel^® FeLV, Nobivac^® feline 2-FeLV, and a placebo). Cats were challenged 3 weeks later with a virulent, heterologous FeLV isolate. FeLV antigenemia was determined at weekly intervals from 3 to 15 weeks postchallenge. Circulating proviral DNA was determined on terminal PBMC samples. Following challenge, persistent antigenemia developed in 15 (75%) placebo-vaccinated cats, 3 (15%) cats in the Versifel FeLV vaccinated group, and 1 cat (5%) each in the Purevax FeLV and the Nobivac FeLV vaccinated groups. The prevented fractions for three vaccine groups were 93%, 93%, and 80% respectively. The adjusted p-values for all vaccine group comparisons fail to approach statistical significance. There was excellent agreement between proviral FeLV DNA in circulating PBMCs and persistent antigenemia. It is shown that when cats are managed under the same conditions during a virulent challenge, via the normal route of infection, the tested vaccines all show a comparable degree of protection.

Feline immunodeficiency virus (FIV), feline leukaemia virus (FeLV) and Leishmania sp. in domestic cats in the Midwest of Brazil

ABSTRACT: This search aimed to investigate FIV and FeLV infections in domestic cats, analysing the epidemiological profile of the disease as well as additional infection with Leishmania sp. We evaluated 88 domestic cats for the presence of FIV, FeLV and Leishmania sp. infection. Eleven (12.5%) cats were positive for FIV infection, four (4.5%) were positive for FeLV, and two were co-infected. However, none was infected with Leishmania sp. The prevalence for FIV infection was higher than FeLV, and those observed in other regions, but no factor was associated with the infection by FIV and FeLV in this study.