Tropical lung

Tropical lung

1. Hystoplasmosis

   • Is a common endemic mycosis that is usually asymptomatic but occasionally results in severe illness
     • Hystoplasmosis ant its causative agent is Histoplasma capsulatum.
       • Are found worldwide but particularly in North and Central America.
         • H. capsulatum proliferates best in soil contaminated with bird or bat droppings, which are believed to alter the soil characteristics and increase the nitrogen content, favoring sporulation of the organism
         • RESERVOIR
           • Sites commonly associated with exposure to H. capsulatum include chicken coops or farm buildings with large accumulations or bird droppings, abandoned buildings, bird roost sites, caves. Activities that have been associated with exposure include: excavation, construction, demolition, remodeling, etc.
   • PATHOGENESIS
     • The lungs provide the portal of entry for H.capsulatum in the vast majority of cases . Patients who inhale a large inoculum can develop severe and potentially fatal acute diffuse pulmonary infection. Infect macrophages serve to disseminate the infection hematogenously during the first two weeks of infection, before specific immunity has developed. Celular immunity to H. capsulatum develops approximately 10 to 14 days after exposure, it is demonstrable first in the lungs and mediastinal lymph nodes and the reticuloendothelial system
     • Senstitized T. lymphocytes activate macrophages to develop fungicidal properties, and the infection is brought under control in immunocompetent hosts. Tumor necrosis factor (TNF) and interferon gamma play critical roles in defense against H.capsulatum
   • CLINICAL MANIFESTATIONS
     • Symptomatic pulmonary histoplasmosis
       • In most patients, the illness presents several weeks following exposure. Symptoms are usually mild, and the events causing the exposure are difficult to identify.
       • Fever, chills, headache, myalgias, anorexia, cough and chest pain generally develop between two and four weeks after exposure but may be seen within one week in more heavily exposed cases. Coryza and sore throat are not typical of histoplasmosis and should suggest alternative diagnoses. Chest pain usually is described as substernal and often is agravated by deep inspiration. Symptoms typically resolve within several weeks, but fatigue and asthenia may persist for months. The pulmonary lesion is characterized by a lobular or acinar bronchopneumonia, initially with neutrophilic infiltration. Chest radiographs usually show enlarged hilar o mediastinall lymph nodes with focal infiltrates