Читать книгу Parasitology - Alan Gunn - Страница 109

Cutaneous leishmaniasis manifests itself in a variety of different forms depending upon the species of Leishmania. Clinically, cutaneous leishmaniasis divides into three basic types depending upon how the disease presents. Localized Cutaneous Leishmaniasis (LCL) generally takes the form of a dry ulcer. It develops at the bite site of the sandfly vector and usually heals by itself although this may take some time and leave permanent scarring. This form of disease is common in India, Central Asia, the Middle East, and parts of southern Europe; L. major and L. tropica are responsible for most infections in these regions. LCL is also common in South America where species such as L. venezuelensis and L. mexicana are responsible. Diffuse (disseminated) cutaneous Leishmaniasis (DCL) is a rarer and much more serious condition than LCL. It manifests as numerous raised (but not ulcerating) papules and nodules that spread to cover large areas of the body. The condition is often associated with immune suppression, and there are several reports of HIV co‐infection (e.g., Corrêa Soares et al. 2020). Unlike LCL, patients with DCL seldom recover without treatment. In the ‘Old World’, Leishmania aethiopica is the most common cause of DCL whilst in South America L. mexicana and L. amazonensis are implicated. As mentioned earlier, any one species of Leishmania may cause different types of leishmaniasis.

Mucocutaneous leishmaniasis (MCL) arises from the formation of an ulcerative lesion that afflicts the mouth, palate, and nose. As a rule, MCL develops and spreads slowly over a period of years and eventually destroys the affected region. It is most common in South America, particularly Brazil and the Amazon regions of Peru, Ecuador, Colombia, and Argentina where the condition is known as ‘espundia’. The discovery of pre‐Inca pottery illustrating disfigured faces suggests that the disease pre‐dates the European invasion of South America. However, some workers claim that the conquistadors and early Spanish settlers introduced MCL into South America. Espundia has a low mortality (~5%) provided the patient receives medical care. However, in the absence of treatment, mortality but would be undoubtedly higher. Death from MCL commonly results from complications such as aspiration pneumonia although some sufferers suffocate owing to laryngeal closure. Leishmania braziliensis is responsible for most cases of MCL although L. guyensis is also important. Leishmania major and some other species of Leishmania can also cause MCL, but these cases are rare. Leishmania guyanensis and L. braziliensis are naturally infected with Leishmania RNA virus 1 (Cantanhêde et al. (2018), and this results in the development of a particularly rapid and aggressive form of MCL (Olivier and Zamboni 2020).