ISSN Leptospirosis is a zoonotic disease that is caused by species of genus Leptospira Order Spirochaetales, Family Leptospiraceae. This is very important on a global level, due to its widespread distribution and diversity of serogroups and serovars that affect an extensive group of animal species. Canines are one of the most affected species, where this bacterium generates an acute renal or hepatic infection. Chronic kidney disease is a common consequence of the infection and miscarriage can also happen in pregnant females.
|Published (Last):||19 September 2006|
|PDF File Size:||15.46 Mb|
|ePub File Size:||18.3 Mb|
|Price:||Free* [*Free Regsitration Required]|
Leptospirosis in dogs and cats: epidemiology, clinical disease, zoonotic implications and prevention. Leptospirosis is a zoonotic disease of worldwide distribution caused by spirochetes of the genus Leptospira. The genus includes a large number of serovars that may be sheed in the urine of infected animals creating a highly infectious source of transmission.
Numerous species of wild and domestic mammals act as maintenance hosts and form reservoirs of the bacteria, with other species being incidental hosts that may develop the disease. In dogs and cats, the disease is caused by different serovars and while dogs act as maintenance host for some serovars, both species are incidental host for others. Dogs and cats may have frequent contact with wild and domestic farm animals, therefore they are an important link in the transmission route.
Leptospira may survive in the environment which increases the complexity of the epidemiology. The presentation of the disease can be highly variable and, particularly for feline leptospirosis, not well described. Laboratory testing is essential for the diagnosis, however, it is complicated due to the need to discriminate between Leptospira infection in animals with clinical disease from leptospiral specific antibody responses in maintenance hosts, or in animals with subclinical infection.
Infection in pets may have important economic and public health implications and because of the risk of transmission from pets to their owners and to other animals, preventive measures need to be applied and an increased awareness is adviced. Key words: leptospirosis, dogs, cats, prevention.
Zoonoses are infections of high relevance since most of the emerging infectious diseases in humans have a zoonotic origin Paul-Pierre The increase in the presentation of emerging zoonotic diseases is a phenomenon closely linked to ecological, climatic and sociocultural changes that have led animals and humans to share their habitats more frequently Dabanch Among the zoonoses, leptospirosis has been reported as one of the most important conditions with sanitary, economic and social impacts worldwide Parreira et al Leptospirosis is a disease caused by infection with a motile spirochaetal bacterium of the genus Leptospira Goldstein The disease is probably is one of the most widespread zoonosis Zavitsanou and Babatsikou and is also recognised as a global public health problem Vijayachari et al The World Health Organization classifies leptospirosis as a neglected tropical disease of global importance.
Further research is needed to better understand the transmission dynamics and how these are influenced by climatic events, environmental factors, animal reservoirs, demographic, social and human trends Lau et al Comprehensive understanding of its eco-epidemiological characteristics is the essential prerequisite to take effective and acceptable control measures Vijayachari et al The aim of this article is to review the main features of leptospirosis in domestic dogs and cats considering basic characteristics of the bacteria, to describe aspects on epidemiology, clinical signs and diagnosis, to highlight the potential zoonotic implications of the infection from pets to their owners and to revise some topics on prevention.
This genus is composed by a varied group of organisms which can live in diverse environments, habitats and life cycles. Within the genus, highly pathogenic host-specific strains can be found, harmless free-living waterborne strains. The genus is divided in about 20 species based on DNA hybridization studies Barthi et al They can be classified in 3 groups as follows Cerqueira and Picardeau :.
According to the above classification, the pathogenic group includes Leptospira strains isolated from humans or animals. The intermediate species are distinct from pathogens and non-pathogenic strains according to their rRNA 16S sequence, and their virulence has not been demonstrated experimentally. On the other hand, the non-pathogenic or saprophitic species are environmental strains Picardeau The genus Leptospira is serologically classified into serovars and it includes more than two hundred pathogenic serovars, based on the structural heterogeneity of the bacterial lipopolysaccharide Xue et al Serogroups comprise antigenically related serovars.
For pathogenic strains, about 24 serogroups have been described Picardeau Leptospires are highly motile, obligate aerobic bacteria measuring about 0. The cells have pointed ends, either or both of which are usually shaped into a distinctive hook and have a typical double membrane structure in which the cytoplasmic membrane and peptidoglycan cell wall are closely associated by an outer membrane Levett Especially stagnant or slow-moving water provide and excellent habitat for them.
Survival in the environment is inhibited by contamination with sewage, high acidity and high salinity. The optimum pH range for the survival of Leptospira is 6. Pathogenic leptospires do not multiply outside the host, therefore, to produce an outbreak of leptospirosis is necessary the presence of carrier animals and favorable conditions for the survival of the bacteria in the environment Acha and Szyfres Leptospira serovars are maintained in the environment by a wide variety of domestic and wildlife animal species, which acts as reservoirs of the bacterium and are called "primary reservoir hosts" Greene et al Mammals are the only animals capable of transmitting the bacteria, even though they have also been identified in reptiles and birds Guerra In the primary reservoir hosts, kidney colonization occurs because the bacterium persist in the kidney tubular epithelial cells Sessions and Greene a.
This infection is normally characterised by the presence of a low antibody response, mild acute clinical signs of disease and a prolonged kidney carrier state which could be associated with chronic renal disease Bolin These hosts can shed the bacterium in the urine for months intermittently or throughout their life, leading to the direct or indirect infection of other animals or humans Van de Maele et al The most important primary reservoir host are small feral mammals Levett Leptospira serovars demonstrated specific but not exclusive host preferences Ko et al Some animals suffer severe clinical signs of leptospirosis when they are infected with serovars for which they are not adapted and they are called "incidental hosts".
In these species the infection is associated with high antibody titres and a short or negligible renal carrier state Bolin , Guerra The transmission of the infection from an incidental host to another animal of the same species is relatively uncommon Bolin An individual may act as primary reservoir for one serovar but incidental host for others Levett Moreover, in humans the infection is always incidental. Some maintenance or primary reservoirs and incidental hosts of common serovars of Leptospira interrogans that infect dogs, cats and other animals have been mentioned by Greene et al and are summarised in table 1.
Table 1. In: Greene C ed. Enfermedades infecciosas del perro y el gato. Copyright Elsevier. Some serovars have worldwide distribution, while others have a more limited geographical spread Miller et al Leptospirosis is especially prevalent in geographic areas with large annual rainfall and warm climate, however factors such as host exposure and the presence of wild and domestic reservoir also influence the geographical distribution of the bacterium Sykes et al The disease tends to be seasonal in temperate climates and year-round in tropical climates.
Outbreaks often increase after periods of flooding or increased rainfall. In arid areas or during drought conditions, infections in incidental hosts are more common around water sources Langston and Heuter Each geographic area is characterised by the serotypes serogroups, serovars determined by the ecology of the area Acha and Szyfres , and both the prevalence of the disease and distribution of serovars vary between different countries, and even between regions within a country.
In Chile, the infection is widespread among domestic animals, especially in the south of the country, where annually it causes extensive losses, for example in cattle, due to reproductive failures Riedemann and Zamora The transmission of the Leptospira infection occurs by contact of intact mucous membranes or abraded skin with infected urine or urine-contaminated soil, water, food and also after bite-wound inoculation or ingestion of infected tissues Sykes et al Pets may become exposed to leptospires excreted by urine of wild or farm animals through activities such as swimming, drinking or walking through contaminated water, soil and mud Brown and Prescott The degree of transmission of the infection depends on climate, population density and contact rates between incidental and maintenance hosts Levett Historically, leptospirosis was recognised as a disease of dogs before it was know in any other animal species, including humans Faine It was first described in Goldstein In , Klarenbeek and Schuffner isolated leptospires from the urine of a dog affecting with nephritis in The Netherlands.
The leptospiral strain was designed as "Leptospira canicola". This leptospiral serotype was isolated from dogs in the United States in Levett In dogs, about 10 different serovars have been serologically associated with clinical disease Gautam et al b and the most frequently described are Canicola, Icterohaemorragiae, Pomona, Bratislava and Grippotyphosa Sessions and Greene a.
However, recent serological evidence, demonstrated a change in the predominant serovars implicated in canine infections, for example in USA and Canada Goldstein et al This change has been attributed to widespread use of bivalent Leptospira vacines introduced in the s, as well as the increased contact between dogs and wildlife reservoirs in expanding suburban environments Stokes et al Dogs are considered as the primary reservoirs of the Leptospira interrogans serovars Canicola and Bataviae Sessions and Greene a.
Some of the Leptospira serovars found in canines, in cross-sectional surveys carried out in different countries worldwide, are listed in the table 2. Table 2. Prevalence of Leptospira infection and frequently reported serovars in dogs in cross-sectional studies carried out in some countries.
Male dogs are more likely to develop leptospirosis than females, probably due to their natural straying behavior. Herding or hunting dogs are at greater risk of becoming infected than dogs kept only as pets. Furthermore, dogs that are exercised by walking in parks and those who wander in fields for example, hound dogs or with access to water sources where they swim have a higher risk of exposure to the bacteria.
Besides, dogs living in suburban or urban settings may also be at risk because of the presence of wildlife reservoir hosts Gautam et al b. Stray dogs that roam free in cities are especially important in the transmission of infection Batista et al , Sontas et al because of the potential contact with infected canines or rodents.
Rural areas has been demonstrated to pose a higher risk of infection because these environments tend to have larger concentrations of reservoirs such as livestock, rodents and small mammals and the contact with the dogs could make possible the infection Ghneim et al Leptospirosis continues to have a significant presence in canine medicine Ananda et al The disease can be fatal for some dogs, but many cases are thought to be subclinical Iwamoto et al Despite this situation, it is noted that the prevalence may be underestimated with a high rate of misdiagnosis, because the disease is not often included in the differential diagnosis of kidney diseases or because the owners do not seek veterinary assistance McDonough The results of cross-sectional surveys of Leptospira infection in dogs worldwide and in Chile are described in the tables 2 and 3 , respectively.
Table 3. Prevalence of Leptospira infection and frequently reported serovars in dogs in published cross-sectional studies carried out in Chile. Regarding the pathogenesis of the disease in dogs, after a variable incubation period, leptospires circulate in the blood before entering in many organs including the kidney, liver, spleen, reproductive tract, eyes and central nervous system, where they replicate Bolin The incubation period of canine leptospirosis is about 5 to 15 days Van de Maele et al The severity of clinical signs depends on the age and immune-competence of the animal, the serovar involved and the virulence of the bacteria.
The disease can be presented as peracute, acute, subacute or chronic Langton and Heuter However, most of the infections produce no pathognomonic signs Silva and Riedemann In the peracute presentation the leptospiremia leads to a rapid and progressive deterioration of health status. Acute leptospirosis is characterised by fever, vomiting, dehydration, tachypnoea and shock which can occur so quickly that hepatic or renal failure do not have time to develop Van de Maele et al ; this form is known as Stuttgart disease Faine Eventually, chronic haepatitis may develop causing icterus, hepatic encephalopathy and weight loss.
Coughing and dyspnoea may also occur with conjunctivitis, rhinitis and tonsilitis. Dogs with chronic leptospirosis could have chronic hepatitis or hepatic fibrosis and signs include anorexia, weight loss, ascites, hepatic encephalopathy and icterus Andre-Fontaine and Hernandez The findings in complete blood count of infected dogs may include neutrophilia, sometimes with a left shift, lymphopenia and mild to moderate non-regenerative anemia.
Hepatic dysfunction may be manifested by increased activities of the enzymes alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and total bilirubin concentration, almost always associated to azotemia.
Dairy, Veterinary & Animal Research
Leptospirosis in dogs and cats: epidemiology, clinical disease, zoonotic implications and prevention. Leptospirosis is a zoonotic disease of worldwide distribution caused by spirochetes of the genus Leptospira. The genus includes a large number of serovars that may be sheed in the urine of infected animals creating a highly infectious source of transmission. Numerous species of wild and domestic mammals act as maintenance hosts and form reservoirs of the bacteria, with other species being incidental hosts that may develop the disease. In dogs and cats, the disease is caused by different serovars and while dogs act as maintenance host for some serovars, both species are incidental host for others. Dogs and cats may have frequent contact with wild and domestic farm animals, therefore they are an important link in the transmission route. Leptospira may survive in the environment which increases the complexity of the epidemiology.
Regret for the inconvenience: we are taking measures to prevent fraudulent form submissions by extractors and page crawlers. Received: October 13, Published: December 5, J Dairy Vet Anim Res 6 2 : DOI: Download PDF. To determine the seroprevalence and the main risk factors associated with serovars of Leptospira in dogs from Culiacan, Sinaloa, we obtained serum from the blood samples of dogs, related humans seropositive blood donors of public hospitals. An epidemiological survey was conducted in order to identify risk factors.