Leishmaniasis, what is it?
Leishmaniasis is an infectious disease which is caused by a tiny parasite called ‘leishmania infantum’ and it can infect humans and canines. This parasite is able to live quite some time in the host without causing obvious symptoms. When these finally occur they can manifest in many different ways; from dermatological problems to impairments of inner organs- they could all be derived from an infection with leishmania. Therefore it is important to recognize the illness at an early stage to prevent potentially fatal developments.
How does one get infected with leishmania?
Leishmania are transmitted via the bite of a mosquito from the genus of phlebotomes. This mosquito is quite a bit smaller than the common mosquitos and has a sandy colour. Therefore it is easily overlooked; it also does not emit the high pitched buzzing noise typical of other mosquitoes. Only the females bite as they require a blood feast for the maturation of their eggs. Leishmania will only be transmitted when the mosquito has previously sucked blood from an organism (man or dog) already infected with the parasite. After the leishmania have undergone several developmental stages in the mosquito, which will take several days, they can be transmitted to other people or dogs. The infection via direct contact with a leishmania infected dog or person is not possible.
How can I recognize the illness in the dog?
The Ibizan Greyhound has a natural resistance towards the parasite. In all other dog breeds it depends widely on the state of the body’s immune system whether the infection can take a hold and will also determine the emerging symptoms. Almost every dog develops its own individual symptomology. Therefore a typical, recognizable symptom does not exist.
Which people can be infected with leishmaniasis?
Only humans who suffer from a deficiency of their body’s immune system are at risk. Usually a healthy immune system will prevent the manifestation of the illness. Prophylactic treatment with appropriate insect repellants of all dogs in one’s own environment and/or protective vaccination of these dogs can prevent the formation of a source of infection where the mosquitoes get infested with parasites.
Which symptoms in the dog are most commonly found?
The first symptoms noticed by owners could be weightloss and loss of body condition despite of an unchanged food intake. Also occuring frequently are lameness, nose bleeds, inflammation of the eyes or all sorts of skin and hair changes. Once examined clinically the vet may find fever, swollen lymph nodes and/or enlarged inner organs. Ultimately blood tests can diagnose the illness and evaluate the patient’s condition.
It is important to realize that the incubation period – the time between the actual infection with the parasite and the outbreak of symptoms- could be from 6 months to several years!
Can leishmaniasis be treated?
Nowadays in general leishmaniasis can be treated effectively. The success of treatment is largely dependant on early diagnosis. Irrespective of early initiation of therapy the parasite will never be fully eliminated and the patient will continue to be a host. However, with medication an equilibrium between the parasite and the infected organism can be achieved where the animal can be expected to live symptom free.
To prevent relapses it makes sense for the dog to have regular blood tests to monitor this ‘equilibrium’ and if necessary to adjust the therapy.
Can leishmaniasis be prevented?
Nowadays there are two effective ways to prevent an infection with leishmania, one being the prophylactic use of mosquito repellants, the other is for dogs the vaccination against leishmaniasis.
The small mosquito is not very resistant against wind and cold temperatures. In temperatures under 16 degree celsius and in windy conditions there is little danger. Also during the day and in heights above 3 meters one hardly encounters these phlebotomes. The most dangerous time intervalls are during dawn and dusk in rural and built-up areas.
The resistance of the parasite within the mosquito, however, has increased noticeably in the last few years.
The fore-mentioned repellants – for dogs only – are widely marketed in form of collars and spot-on-preparations.
The vaccine consists of a recombinant protein which activates the body’s immune system against the parasite by producing antibodies, so the body can react faster in the event of a leishmania infection.
It is not possible to provoke the manifestation of leishmaniasis symptoms through this vaccination as the serum does not contain any parasite particles.
All healthy dogs from 6 months of age can be vaccinated as long as they are free from leishmaniasis. Therefore we take a blood sample before the vaccination and check via a quick test whether the dog is really without infection. After a negative result the first injection can be administered immediately.