By Pluto: A BritsinCrete Forum Member
The purpose of this article is to update extensive coverage concerning canine leishmaniasis in the BritsinCrete Forum. That information is far from being out of date, but became incomplete since more recently a vaccine has become available and introduced to Greece and Cyprus.
If you own a dog, you should be aware that Canine Leishmaniasis is a serious and potentially lethal bacterial disease. The good news is that advances in treatment mean that it can be prevented and treated. This debilitating disease is mainly transmitted by sandflies (vectors), which are common in tropical and subtropical areas and found locally in the Mediterranean region such as in the Greek Islands, mainland Greece and Cyprus. Unfortunately efforts to control leishmaniasis in dogs have been largely unsuccessful, though as more research is being carried out, progress is being and will continue to be made.
Etiology and Epidemiology
Leishmania are protozoa, single-celled bacteria that cause cutaneous, muco-cutaneous and visceral diseases in dogs, human beings and other mammals. Rodents and dogs are primary reservoirs, people and cats are incidental hosts. There are about 35 species of Leishmania; 20 infecting humans and about 10 infecting dogs.
Transmission of the disease is different in the Old and in the New World.
In the Old World dogs act as reservoirs for the bacteria and a sand fly, Phlebotomus, is the vector. Sand flies are infected during feeding on an infected subject. They are endemic around the Mediterranean basin spreading towards more northern European countries.
In the New World the vector is also a sand fly but of a different genus, Lutzomyia. They are present on the eastern coast of the Unites States and Canada, in Central and in South America.
The spread of the disease can occur from dog to dog through transmission by fighting, breeding and congenitally (being present from birth).
Dogs generally develop visceral leishmaniasis. This means that after an incubation period, a sub-clinical phase of infection, the dog has no symptoms and which lasts from 1 month to 7 years. Then, cutaneous lesions appear. These may include all or some hardening and swelling of the epiderm (hyperkeratosis), scaling, thickening, muco-cutaneous ulcers, hair loss particularly around the eyes and intra-dermal nodules on the muzzle, ears, pinnae (outer ear) and foot pads.
Common symptoms of visceral leishmaniasis are: weight loss, increased appetite, polyuria (excessive urine), polydipsia (excessive drinking), muscle wasting, vomiting, diarrhea, cough, sneezing, epistaxis (nose bleeding) and melena (blood in the faeces). Later facial alopecia (hair loss) occurs, fever, rhinitis, dermatitis uveitis (affecting the colour of the eye), conjunctivitis and swollen lymph nodes. Most dogs die of chronic kidney disease.
Diagnosis is based on the history, clinical symptoms and evolution, more objectively on a blood test demonstrating the presence of antibodies against Leishmania.
The main drugs used for therapy of the disease are able to improve clinical signs and/or clinico-pathological abnormalities temporarily or cure dogs clinically, but none of these treatments reliably eliminates the infection. Studies on treatments with these drugs, alone or in combination, have shown that most treated animals cure clinically but remain carriers of the parasite and might relapse back to a clinical disease.
The only drugs licensed currently in Europe specifically against Canine Leishmaniasis are meglumine antimoniate, allopurinol and miltefosine. The combination of meglumine antimoniate (N-methylglucamine antimoniate, 75-100 mg/kg for 4 – 8 weeks, S.C.) with allopurinol (10 mg/kg twice a day for at least 6-12 months P.O.) is considered as the most effective therapy and constitutes the first line protocol against the disease.
Allopurinol alone (10 mg/kg twice a day, for at least 6-12 months P.O. ) is the most widely used second line treatment. Urolithiasis (kidney stones) is the main side effect associated with allopurinol administration both alone or in combination therapy. Miltefosine has been recently suggested for treatment in combination with allopurinol (10 mg/kg twice a day for at least 6-12 months P.O.). The main reported side effects of Miltefosine are vomiting and diarrhea.
Overall, the expected clinical response to treatment of sick dogs can vary from poor to good depending on their initial clinico-pathological status and individual response to therapy. Dogs with renal insufficiency are expected to have a lower recovery rate in comparison to those without kidney compromise. The majority of dogs experience clinical improvement within the first month of therapy, although in others, a longer period of therapy is required before any apparent improvement.
The clinicopathological parameters to be monitored during treatment would depend on the individual abnormalities. However, in general, it is recommended to perform complete blood count, biochemical profile and urinalysis. The frequency of monitoring those parameters would vary in each patient but, in most cases, be monitored more frequently initially, i.e. after the first month of treatment and then every 3-4 months. Later on, if the dog is fully recovered clinically with treatment then a recheck would be recommended every 6 months or once a year.
The primary risk for canine leishmaniasis is from dogs acting as reservoir hosts for the organism. Direct contact with the bacteria in open lesions is unlikely to result in human infection. In our region of Mediterranean Greece and Cyprus avoidance of infected sand flies is one means of prevention by keeping animals inside the house during the night time hours from March till November. Another means is the use of repellents containing Imidacloprid and Permethrin, a Scalibor© collar or Advantix© top-on ampoules, which may lessen transmission (85%) in sand flies in endemic regions.
Read the pharmaceutical leaflets carefully!
Always de-worm the dog at the same time you apply an external parasite repellent!
There is a vaccine available, CaniLeish© (Virbac). The first vaccine is given when the dog is at least 6 months of age, healthy and free of Leishmania infection; a booster is given 3 weeks later and a second booster again 3 weeks later. Vaccination is repeated one year after the last injection and for ongoing protection of the dog, repeated annually.
Since canine Leishmaniasis in Europe is most often due to an infection with Leishmania infantum and since the active substance of the vaccine is Leishmania infantum, this vaccine should be very effective. Remember though that no vaccine is 100% effective! This one should approach the 85-90% based on what we know of the vaccine that already exists in Brazil against Leishmania donovani which scores 86%.
This is good news and many of you will be happy to get rid of that annoying Scalibor collar.
The most common side effects of the vaccine are: moderate and transient local reactions that may occur after injection such as swelling, nodule, pain on palpation or erythema. These reactions resolve spontaneously within 2 to 15 days. Other transient signs commonly seen following vaccination may be observed such as hyperthermia, apathy and digestive disorders lasting 1 to 6 days. Allergic-type reactions are uncommon and appropriate symptomatic treatment should then be administered.
For the Cat Owner
Cats are usually subclinically infected and act as secondary vector hosts. Statistical studies in civilized countries show a prevalence of about 3-6% seropositivity in cats. According to Faculty of Veterinary Medicine of the Aristotle University of Thessaloniki (study of February 2009) there is a very low seroprevalence of Leishmaniasis in cats (3,87% of cats were positive, asymptomatic carriers), which doesn’t exclude some cats to be symptomatic, especially in high risk endemic regions.
At a Pan-Hellenic veterinary conference held in 2009, a Professor Kontos presented a Greek epidemiological study concerning human visceral Leishmaniasis. Until the Eighties, of all the reported cases, in which 50% of children under the age of 5 were affected as were 71% of adolescents aged under 15. In the last ten years, these figures have dropped dramatically: 1.5% and 19% respectively. During the last ten years, 434 cases of human visceral Leishmaniasis were reported. At the same time, only 20 cases of skin Leishmaniasis were reported, which in Greece is NOT due to L. infantum but to Leishmania tropic!
For any further information or if in doubt, feel free to ask, posting your question on the topic in the BritsinCrete Forum.
Brits in Crete wishes to thank forum member, PLUTO of Kissamos Dog Boarding Kennels for his valuable contribution in this article on animal husbandry for concerned pet owners.
The disease Leishmaniasis is also spelled as Leishmaniosis.
Photo Credits : With permission, taken from LeishVet* guidelines for the practical management of canine Leishmaniosis
1. Solano-Gallego et al. Parasites & Vectors 2011 4:86
Caption: Infected dogs - Different patterns of cutaneous lesions in CanL: A) Exfoliative periocular alopecia and blepharitis; B) Ulcerative nasal mucocutaneous lesions; C) Papular dermatitis in the inguinal region; D) Nodular crateriform lesions bordering the muzzle; E) Ulcerative erythematous lesions on the plantar surface of the paw and between pads; F) Onychogryphosis.
2. Solano-Gallego et al. Parasites & Vectors 2011 4:86
Caption: Map - The distribution of canine L. infantum infection in Europe
*LeishVet is part of WorldLeish founded by the worldwide authority, Professor Bourdeau, University of Nantes, France.