Episode 22 - Unleashed: The Dawn of the Leishmania

Unleashed: The Dawn of the Leishmania

Chapter 1: The Attack of the Sandfly

3.17 Sue introduces the topic of leishmaniasis, and Christian describes leishmaniasis as a multisystemic disease affecting humans and animals, primarily dogs. He notes its prevalence in regions like the Mediterranean and its expansion due to climate change and imported infected dogs.

5.19 Sue questions whether leishmaniasis occurs naturally in the UK or is solely imported. Christian mentions reported cases in the UK, suggesting transmission via infected phlebotomine flies brought back by travelers from endemic regions. The conversation shifts to the sandfly vector responsible for transmitting leishmaniasis. Christian describes the sandfly as small, silent, and potentially painless, emphasizing its absence in the UK but the possibility of migration due to global warming. Christian advises against using repellents on dogs in the UK due to environmental concerns but stresses the importance of monitoring the situation, given he acknowledges the likelihood of sandflies reaching the UK in the future.

7.27 John queries if leishmaniasis can be transmitted by other vectors like fleas. Christian affirms that sandflies are the primary vector for the disease, although other potential vectors are suspected but not proven. John then asks if humans can contract the disease from infected dogs. Christian explains that with the vector absent in the UK, human transmission from dogs is unlikely. However, he emphasizes the importance of isolating positive dogs to prevent transmission through blood transfusion.

Chapter 2: The Haunting Symptoms and Diagnosis

9.11 The conversation then transitions to the clinical signs of leishmaniasis. Christian describes typical systemic symptoms such as anorexia, weight loss, lethargy, and mucous membrane pallor, along with some less common signs like polyuria and polydipsia. Christian also discusses characteristic skin lesions, including non-pruritic exfoliative dermatitis and erosive lesions. Sue adds her observations about the scaly appearance of affected dogs without itchiness, contrasting it with parasitic skin conditions. Christian concludes by stressing the importance of diagnostic assistance in accurately identifying the disease, especially considering its varied clinical presentations.

12.09 Sue brings up how leishmaniasis can affect nails, prompting Christian to elaborate on what clinicians might observe. He describes nails that grow unusually long and fast, resembling talons rather than being deformed. Christian notes that this sign is relatively rare in his experience, with scaly dermatitis or ulcerative dermatitis being more common presentations.

13.11 Sue then queries whether certain clinical presentations carry a better prognosis than others. Christian explains that prognosis depends on the severity of internal organ involvement, particularly kidney disease. The disease originates from the skin but can affect various body parts due to the immune system's reaction.

14.12 John asks how general clinicians diagnose it. Christian outlines that diagnosis relies on compatible clinical signs and specific clinical pathologies, notably anemia and changes in protein levels. While general practitioners can conduct serological tests, more specialized examinations may require referral to a laboratory. Christian emphasizes the importance of considering travel history and ruling out other conditions before treatment initiation.

16.40 Sue raises the issue of screening for leishmaniasis in dogs rescued from abroad, inquiring about the incubation period and when to start screening. Christian explains that the incubation period varies greatly, suggesting performing a quantitative serological test six months after returning from an endemic area. If positive, measures like using repellent and excluding the dog from blood transfusion banks are advised. Sue seeks more detail on the blood tests, and Christian elaborates on measuring the amount of Leishmania-specific antibodies using quantitative serological tests. These tests help detect high antibody levels, indicative of infection.

Chapter 3: Eternal Vigilance Against the Parasite

18.55 John then asks about therapy options for positive cases. Christian emphasizes the goal of controlling clinical signs and pathological abnormalities, as complete parasite elimination is rare. Therapy typically involves a combination of leishmanicidal drugs, which aim to kill the parasite, and leishmaniostatic drugs, which maintain a low parasitic level, together aiming to reduce the parasitic load and prevent relapses. He notes the need for topical treatments alongside systemic therapy to manage symptoms like scaly skin.

22.00 John asks about drug availability and Christian mentions challenges in drug availability and potential side effects, particularly with drugs like allopurinol, which can cause adverse urinary effects. He recommends monitoring for crystal formation in the urine and considering alternative treatments if needed, highlighting emerging immunomodulatory drugs as promising options. However, his leishmanicidal drugs of choice would be allopurinol and meglumine antimonate.

23.55 Sue then asks about the expected response time to treatment and the monitoring process. Christian explains that clinical improvement can be seen in about four weeks with meglumine antimonate and two months with Miltefosine, an oral drug. Monitoring every three to four months is crucial, although antibody titres may take longer to decrease.

24.55 John asks about the lifelong management of the disease. Christian confirms that the drugs can be expensive and may need to be imported, emphasizing the importance of compliance and regular check-ups to improve prognosis.

25.51 Sue concludes by highlighting the role of primary care vets and dermatologists in managing the disease. She also enquires about alternative treatments like turmeric and herbal concoctions. Christian stresses the importance of evidence-based treatments and mentions dietary nucleotides and active hexose correlated compounds as effective alternatives.

27.29 Sue thanks Christian and expresses concern about the potential spread of leishmaniasis in the UK due to warmer summers and increased animal movements across borders.