Evaluation by polymerase chain reaction assay of persistent shedding of pathogenic leptospires in the urine of dogs with leptospirosis

Updated ACVIM consensus statement on leptospirosis in dogs

Since publication of the last consensus statement on leptospirosis in dogs, there has been revision of leptospiral taxonomy and advancements in typing methods, widespread use of new diagnostic tests and vaccines, and improved understanding of the epidemiology and pathophysiology of the disease. Leptospirosis continues to be prevalent in dogs, including in small breed dogs from urban areas, puppies as young as 11 weeks of age, geriatric dogs, dogs in rural areas, and dogs that have been inadequately vaccinated for leptospirosis (including dogs vaccinated with 2-serovar Leptospira vaccines in some regions). In 2021, the American College of Veterinary Internal Medicine (ACVIM) Board of Regents voted to approve the topic for a revised Consensus Statement. After identification of core panelists, a multidisciplinary group of 6 experts from the fields of veterinary medicine, human medicine, and public health was assembled to vote on the recommendations using the Delphi method. A draft was presented at the 2023 ACVIM Forum, and a written draft posted on the ACVIM website for comment by the membership before submission to the editors of the Journal of Veterinary Internal Medicine. This revised document provides guidance for veterinary practitioners on disease in dogs as well as cats. The level of agreement among the 12 voting members (including core panelists) is provided in association with each recommendation. A denominator lower than 12 reflects abstention of ≥1 panelists either because they considered the recommendation to be outside their scope of expertise or because there was a perceived conflict of interest.

Comparison of Two Leptospira Type Strains of Serovar Grippotyphosa in Microscopic Agglutination Test (MAT) Diagnostics for the Detection of Infections with Leptospires in Horses, Dogs and Pigs

Simple Summary

Leptospires are bacteria of major health concern as they can cause severe systemic diseases in humans and animals alike. In routine diagnostics, the detection of a leptospirosis heavily relies on the analysis of specific antibodies that were generated by the immune system of an infected species. The most widely used test for the detection of such antibodies is the microscopic agglutination test which itself depends on defined types of laboratory grown Leptospires, so-called serovars. A good judgment of the behaviour of these serovars is vital for interpreting test results and clearly defining what type of Leptospires the patient is infected with as this may have implications for therapy and prognosis. In the following, a study on the reaction pattern of a certain type of serovars named ‘Grippotyphosa’ that itself can be divided into two differently reacting subtypes was conducted. It turned out that, depending on the animal species sampled, a differing reaction patterns to the two Grippotyphosa subtypes in the diagnostic test reflected different distribution of these subtypes in the respective populations. In the future, these insights will further improve test performance and assessment or results.

Abstract

The MAT test is of great importance in the diagnosis of leptospiral infections. Based on various differences, the serovar Grippotyphosa has been divided into two types, Moskva V and Duyster. Differences or similarities of the two type strains in the context of leptospiral diagnostics have not yet been elucidated in more detail; therefore both strains were analysed in MAT diagnostics for the detection of leptospiral infections in pigs, dogs and horses. Serum samples from 2996 pigs, 55 dogs and 35 horses, as well as vitreous and/or aqueous fluid samples from these and 13 additional horses were analysed by MAT; available supplementary samples were tested for leptospires by PCR. In pigs, 92.6% of the samples with both strains received an identical titre result in the MAT test, whereas in dogs and horses only 53.0% and 43.6% had concordant results. Since infections with the serovar Grippotyphosa occur more frequently in dogs and horses overall, more differences were observed here. In the case of discrepant serological results, supplementary samples and PCR examinations were not able to add information on the true status. Further analyses of follow-up studies or at least serum pairs from dogs and horses infected with the serovar Grippotyphosa are necessary.

Isolation of Leptospira interrogans Serovar Canicola in a Vaccinated Dog without Clinical Symptoms

More than one million cases of leptospirosis occur across the globe annually, resulting in about 59,000 deaths. Dogs are one of the most important reservoirs of Leptospira species and play an important role in transmitting the pathogen to humans. Many of these infections are controlled by routine vaccination that has reduced the possible reintroduction of leptospiral serovars into the human population. However, it is still not clear how a vaccinated dog can become infected with one or more Leptospira serovars contained in the vaccine formulation and thus against which it should be immunized. Here, we present the case of an asymptomatic dog who developed leptospiral infection despite being vaccinated. This unusual case emphasizes the substantial impact of immunization on mitigating the acute signs of the disease, even while providing limited protection against infection. Further studies will be required to better understand the role of dogs in the environmental circulation of leptospiral serovars in Sardinia. Asymptomatic leptospiral infection in vaccinated dogs should be considered to allow for better diagnosis and management of the infection. This will be essential for preventing Leptospira outbreaks in the future.

Are Small Animal Practitioners Occupationally Exposed to Leptospirosis? Results of a Serological Survey

Leptospirosis is a worldwide zoonosis frequently responsible for clinical disease in dogs and rarely reported in human people. The risk of human exposure to Leptospira has been investigated in a sample population working in the northeast of Italy, a geographical area with high endemicity of canine leptospirosis. Two-hundred twenty-one human serum samples were analyzed for Leptospira microagglutination test (MAT): 112 clinical freelance small animal practitioners (exposed subjects) and 109 people not occupationally exposed to Leptospira-infected animals (unexposed subjects) were voluntarily enrolled. Despite the previously reported serological detection of antibodies vs. Leptospira in people in different Italian regions, this study did not detect any reactivity in the investigated population. This study shows that veterinarians do not appear to be at a greater risk of leptospirosis than the reference population. This may be due to both veterinarian awareness of the Leptospira zoonotic risk and the efficiency of the preventive measures and management of patients. Moreover, it could be the result of the relatively low excretion of Leptospira in symptomatic dogs, which can be considered as an environmental sentinel for Leptospira presence rather than a vehicle of transmission.