Leishmaniasis is a complex parasitic disease transmitted to humans through the bite of infected sandflies. The infection is notable for the wide range of symptoms it can cause, which manifest differently depending on where the parasites settle in the body. The appearance can range from an isolated skin sore to severe internal disease with profound outward signs. These varied presentations are influenced by the specific parasite species and the individual’s immune system response to the infection.
The Appearance of Cutaneous Lesions
The most common form of this parasitic infection primarily affects the skin. It begins as a small, firm, red papule or bump at the sandfly bite site, which is typically painless and can take weeks or months to develop. The papule expands into a larger nodule before the center breaks down to form an open sore.
This fully developed sore often presents with a distinctive “volcano sign.” This sign is characterized by a sunken, ulcerated center surrounded by a raised, firm, and erythematous border. The ulcer may be covered by a dry, dark crust or scab, or it might be a moist lesion exuding a serous fluid. These lesions most frequently appear on exposed areas of the body, such as the face, arms, and legs.
Smaller secondary spots, known as satellite lesions, may form close to the primary ulcer. The infection can also spread along lymphatic pathways, causing a chain of subcutaneous nodules. Sores are classified as either “dry” or “wet” depending on the specific parasite species involved. While usually painless, a secondary bacterial infection can introduce pain and swelling, altering the appearance.
Systemic Signs of Visceral Leishmaniasis
When the parasite moves into the body’s internal organs, the resulting disease is often referred to by its traditional name, Kala-Azar, which means “black sickness.” Though the infection is internal, it produces dramatic and visible systemic changes in the affected individual. One of the most striking physical signs is severe emaciation, or wasting, which is a generalized loss of muscle mass and fat.
Patients often exhibit profound pallor, or unnatural paleness, a direct consequence of anemia caused by the parasite’s effect on the bone marrow. The abdomen typically becomes visibly distended and swollen due to the massive enlargement of the spleen and, to a lesser extent, the liver. This condition, known as hepatosplenomegaly, causes the belly to protrude significantly.
The historic name, Kala-Azar, refers to a darkening or hyperpigmentation of the skin, particularly in certain geographic strains of the infection. This darkening appears as a dusky or grayish tint, most prominent on the face, hands, and abdomen. The combination of severe wasting, abdominal distention, and pallor creates a distinctive outward appearance of severe, prolonged illness.
The Appearance of Mucosal Damage
A more destructive form of the disease develops when the parasites spread to the mucous membranes of the nose, mouth, and throat. This progression causes tissue erosion that leads to significant visible damage and disfigurement of the face. Initial symptoms may be internal, presenting as chronic nasal obstruction, persistent stuffiness, or recurrent nosebleeds.
As the infection advances, it begins to destroy the delicate cartilage and soft tissues. This destruction can lead to the perforation of the nasal septum, the wall that divides the nostrils, creating a hole that is sometimes visible externally. The damage may also erode the palate, the roof of the mouth, or the lips, causing severe cosmetic and functional impairment.
Unlike common skin ulcers, this mucosal damage rarely heals without specific treatment and involves deep tissue destruction. The progressive nature of the lesions can result in the collapse of the nose structure, sometimes called “tapir nose,” or severe erosion of the mouth and throat tissues.
Progression and Varied Clinical Presentation
The specific appearance of the infection is highly dependent on the particular parasite species and the effectiveness of the host’s immune response. The timeline of symptoms also varies considerably between the different forms of the disease. Skin lesions typically appear relatively quickly, within a few weeks to months following the sandfly bite.
In contrast, the visible systemic signs of internal infection often take much longer to manifest, sometimes progressing slowly over many months. The destructive mucosal form may not become apparent until years, or even decades, after the original skin lesion has naturally resolved. This chronological separation highlights the delayed and secondary nature of the mucosal complication.
Post-Kala-Azar Dermal Leishmaniasis
A distinct visible manifestation is a skin condition that can appear months to years after a patient has been successfully treated for the systemic form. This condition, known as Post-Kala-Azar Dermal Leishmaniasis, presents as a scattering of macules, papules, or nodules on the face, trunk, and extremities. These spots are a late-stage skin manifestation indicating the parasite has moved to the skin after the internal infection was cleared.