Paracoccidioidomycosis (PCM), also known as South American blastomycosis, is a fungal infection that can occur as a mouth and skin type, lymphangitic type, multi-organ involvement type (particularly lungs), or mixed type. If there are mouth ulcers or skin lesions, the disease is likely to be widespread. There may be no symptoms, or it may present with fever, sepsis, weight loss, large glands, or a large liver and spleen. The cause is fungi in the genus Paracoccidioides, including Paracoccidioides brasiliensis and Paracoccidioides lutzii, acquired by breathing in fungal spores. Diagnosis is by sampling of blood, sputum, or skin. The disease can appear similar to tuberculosis, leukaemia, and lymphoma. Treatment is with antifungals, such as itraconazole. For severe disease, treatment is with amphotericin B followed by itraconazole, or trimethoprim/sulfamethoxazole as an alternative. It is endemic to Central and South America, and is considered a type of neglected tropical disease. In Brazil, the disease causes around 200 deaths per year.
Signs and symptoms
Asymptomatic lung infection is common, with fewer than 5% of infected individuals developing clinical disease. It can occur as a mouth and skin type, lymphangitic type, multi-organ involvement type (particularly lungs), or mixed type. If there are mouth ulcers or skin lesions, the disease is likely to be widespread. There may be no symptoms, or it may present with fever, sepsis, weight loss, large glands, or a large liver and spleen. Two presentations are known, firstly the acute or subacute form, which predominantly affects children and young adults, and the chronic form, predominantly affecting adult men. Most cases are infected before age 20, although symptoms may present many years later.
Juvenile (acute/subacute) form The juvenile, acute form is characterised by symptoms, such as fever, weight loss, and feeling unwell together with enlarged lymph nodes and enlargement of the liver and spleen. This form is most often disseminated, with symptoms manifesting depending on the organs involved. Skin and mucous membrane lesions are often present, and bone involvement may occur in severe cases. This acute, severe presentation may mimic tuberculosis, lymphoma or leukaemia.
Adult (chronic) form The chronic form presents months to years after the initial infection occurs and most frequently presents with a dry cough and shortness of breath. Other symptoms include excess salivation, difficulty swallowing, and difficulties with voice control. Upper respiratory tract mucosal lesions may be present, as well as increased mucus production and coughing up blood. Both pulmonary and extrapulmonary involvement is common. Up to 70% of cases have mucosal involvement, with lesions often found in the mouth, oropharynx, larynx, and palate. Classic lesions are superficial, painful granular ulcers, with small spots of bleeding.
Cause Paracoccidioidomycosis is caused by two species of fungi that can exist as a mold or yeast depending on temperature, Paracoccidioides brasiliensis and P. lutzii. In protected soil environments, near water sources, that are disturbed either naturally or by human activity, P. brasiliensis has been epidemiologically observed (although not isolated). A known animal carrier is the armadillo. In the natural environment, the fungi are found as filamentous structures, and they develop infectious spores known as conidia. Human-to-human transmission has never been proven.
Mechanism Primary infection, although poorly understood due to lack of data, is thought to occur through inhalation of the conidia through the respiratory tract, after inhaling fungal conidia produced by the mycelial form of P. brasiliensis. This occurs predominantly in childhood and young adulthood, after exposure to agricultural activity. Infection may occur through direct skin inoculation, although this is rare. After inhalation into the alveoli, there is rapid multiplication of the organism in the lung tissue, sometimes spreading via the venous and lymphatic systems. Approximately 2% of people develop clinical features after the initial asymptomatic infection. The type of immune response determines the clinical manifestation of the infection, with children and HIV co-infected individuals most commonly developing the acute/subacute disseminated disease. Most of those infected develop a Type 1 T-cell (Th1) mediated immune response, resulting in fibrosing alveolitis and compact granuloma formation that control fungal replication, and latent or asymptomatic infection. It then is thought to remain dormant in residual lung lesions and mediastinal lymph nodes. A deficient Th1 cell response results in the severe forms of the disease. In these individuals, granulomas do not form, and the affected person develops Th2 and Th9 responses, resulting in activation of B lymphocytes, high levels of circulating antibodies, eosinophilia, and hypergammaglobulinemia. Lung involvement subsequently occurs after a dormant phase, manifesting in upper respiratory tract symptoms and lung infiltrates on imaging. The commonest, chronic form is almost certainly a reactivation of the disease, and may develop into progressive scarring of the lungs (pulmonary fibrosis). It can cause disease in those with normal immune function, although immunosuppression increases the aggressiveness of the fungus. It rarely causes disease in fertile-age women, probably due to a protective effect of estradiol.
… excerpt ends here. Continue reading the full article.
