An outbreak of acute pulmonary histoplasmosis after exposure to guano in a hollow tree in Ecuador

Background: Outside of classic endemic areas, histoplasmosis has gained attention due to an increased incidence in immunocompetent travellers, attributable to changes in behaviours during travel. Methods: A cluster of five patients who presented with acute pulmonary histoplasmosis after travelling to the Ecuadorian Amazon Region is described in this article. Results: Five patients (four females and one male), all in their 20s, presented with acute pulmonary histoplasmosis between sixteen and twenty-three days after the potential airborne exposure after travelling to the Ecuadorian Amazon Region. The initial common exposure is presumed to have occurred during activities inside a hollow tree trunk with guano exposure. Initial symptoms included fever and arthro-myalgias in three cases, and gastrointestinal symptoms with asthenia and lymphadenopathy in the other two cases. Symptoms progressed variably within one week to include chest pain, dyspnoea, and night sweats. Serology was negative in 2 patients during the acute phase but subsequently turned positive in all five cases. Chest CT scans performed within one week from symptom onset in all cases revealed multiple bilateral nodules. In three cases, follow-up chest CT scans performed four-six weeks after symptom onset showed the evolution of nodules into cavitations despite treatment with itraconazole. Conclusions: This cluster of histoplasmosis cases highlights the clinical variability associated with this fungal infection. The development of pulmonary cavitation during the acute phase of the disease is an infrequent finding that poses additional clinical challenges and suggests the requirement of rigorous follow-up in individuals with acute histoplasmosis returning from the Amazon region.