Many parasites that occur abroad are not seen, or very rarely, in Canada and several of them are major diseases transmitted by arthropods. Companion animals living in Canada will not have met any of these parasites before travelling abroad and are likely to be susceptible. Veterinarians should consider these important diseases when animals travel to tropical and Mediterranean areas. In addition, and not to be neglected, several of these exotic maladies do not have licensed /veterinary medicines available in Canada, which can lead to long delays before obtaining the correct drug by the veterinarian. It is vital to inform pet owners before and after they have been abroad with their animals, especially when they become ill soon after their return to Canada. Travelling animals should adhere to preventive programs against ticks, sandflies, heartworm and tapeworms. These treatments should be always planned according to current knowledge of pathogens’ prevalence in targeted destinations.
Most frequent diseases include: babesiosis, ehrlichiosis, hepatozoonosis, leishmaniasis, Chagas disease, heartworm and tapeworms. Babesiosis, ehrlichiosis and hepatozoonosis are spread by ticks. Whereas babesiosis and ehrlichiosis are transmitted when the tick feeds, hepatozoonosis occurs when dogs (rarely cats) groom off and swallow infected ticks. Symptoms may include: anemia, fever, weakness and red-to-dark-brown urine in the case of babesiosis and fever, bleeding and depression in the case of ehrlichiosis. Usually, animals infected by hepatozoonosis do not display clinical signs unless they are affected by a concomitant immunosuppressive disease. These three diseases can be easily confirmed by blood sample testing but treatment is difficult and require specific drugs. Tick control plans are necessary to minimize the risk of infection.
Leishmaniasis and Chagas disease are transmitted by sandflies and kissing-bugs, respectively. Canine leishmaniasis mainly occurs through the tropics, being highly prevalent in wooded areas of the Mediterranean basin. Leishmania parasites are transmitted by the vector during its blood feeding. Leishmaniasis is manifested by a broad spectrum of clinical signs and degrees of severity, which can start a few months or several years after the infection. Clinical signs may include cutaneous (different kinds of skin inflammation, dermatitis and onychogryphosis) and general manifestations: generalized lymphadenomegaly, lethargy, mucous membrane pallor, splenomegaly, polyuria/polydipsia and fever. Leishmaniasis can be confirmed by testing blood (e.g. detection of specific serum antibodies by immunofluorescence antibody test) or biopsy samples (PCR and parasite culture from tissues). Current treatments are highly aggressive, long and expensive. Moreover, clinical response to treatment can vary from very poor to good depending on the initial status of the animal.
Chagas disease is considered endemic in most of Mexico’s territories, Central America, and South America. Dogs can become infected by Chagas disease by different routes, however, ingestion of infected kissing-bugs represents the most frequent one. Disease symptoms depend on the progression and duration of the infection. Acute phase is characterized by fever, lethargy, swollen lymph nodes, and an enlarged liver and/or spleen. Chronic infection can lead to dilated cardiomyopathy, a severe heart disease that may result in congestive heart failure. Chagas disease diagnostics is highly complex and includes blood testing, urinalysis, X-rays, electrocardiogram and heart ultrasound. Unfortunately, no drug is able to cure Chagas disease, which means that even early-treated dogs will progress to the chronic form of the disease.
Control for both leishmaniasis and Chagas disease should rely on prevention. Prevention measures include: avoiding ‘high-risk’ areas, keep animals inside at dawn and dusk and house dogs indoors at night to reduce exposure to sandflies and kissing-bugs, use repellents, prevent dogs from eating bugs and/or potentially infected animals (mice, rats, etc.). In addition to exotic protozoan parasites, animals travelling abroad may increase their risk of exposure to heartworm and tapeworm infections.