Pulmonary schistosomiasis

Schistosomiasis is highly prevalent in sub-Saharan Africa and diagnosis is difficult for travel medicine practitioners, because it can affect different organs with atypical manifestations. S. haematobium is mostly associated with urinary involvement and rarely with pulmonary lesions. This review aims to summarise the pulmonary forms associated with schistosomiasis, especially with S. haematobium.

Based on a case report of both pulmonary and urogenital schistosomiasis, we performed a systematic literature review of schistosomiasis occurring in migrants and travellers, with a specific focus on pulmonary schistosomiasis.

Pulmonary schistosomiasis can present two different clinical patterns. On the one hand, there is an acute pattern, which more frequently affects non-immune young travellers within three to eight weeks of their return and, on the other hand, there is a chronic pattern, which has been evolving in recent years and which mostly affects people living in endemic areas or migrating from these countries. Nodular pulmonary lesions are described in both patterns. Genus identification should not focus only on known patterns, and identification of S. haematobium should not be associated exclusively with urinary schistosomiasis.

Pulmonary schistosomiasis, even when resulting from S. haematobium, is a rare but existing infection that appears to be spreading with increasing travel and global migration. Physicians need to be more aware of non-specific symptoms that may reveal an atypical presentation of a tropical disease, in order to avoid the chronic complications which can result from parasitic diseases.

A precise timeframe to differentiate acute schistosomiasis (AS) and chronic schistosomiasis (CS) is not well defined. Based on recent published literature, lung nodular lesions in AS and CS seem to have the same pathophysiology, that is, eggs laid in situ by adult worms, during an ectopic migration. Moreover, the occurrence of lung nodules due to clusters of eggs and the systemic immunoallergic reaction of AS (Katayama syndrome) may be two separate clinical entities, which may overlap during the early phase of infection. Consequently, the classical distinction between AS and CS loses much of its conceptual validity. If adult worms play a more important role in the early phase of the disease the clinical management of AS should probably be revised.

Schistosomiasis is a neglected tropical disease that can cause mainly hepatic and genitourinary damage, depending on the species. Involvement of the lungs has been commonly described in acute infection (Katayama syndrome) and chronic infection (pulmonary hypertension). Although rarely reported in the scientific literature, cases of lung nodules due to chronic schistosome infection are also possible and are probably more frequent than commonly thought. Here we report seven cases of African migrants who were diagnosed with chronic schistosomiasis and pulmonary nodules due to deposition of schistosome eggs, and we compare our findings to the case reports found in the scientific literature. We discuss the management of these patients in a non-endemic setting, beginning with a first fundamental step that is to include parasitic infections, namely schistosomiasis, in the differential diagnosis of pulmonary nodules in African immigrants. All patients responded to antiparasitic treatment with praziquantel after a relatively short time. We therefore conclude that lung biopsies and other invasive procedures (performed in the first cases to rule out other potential causes, such as tuberculosis or malignant nodules) can be avoided or postponed.

Eosinophilic meningitis caused by Angiostrongylus cantonensis is a zoonosis endemic to Southeast Asia and the Pacific islands. It is considered an emerging disease because it has been expanding both geographically and in terms of the range of hosts. In South America, the first cases were reported in Brazil and were attributed to eating infected snails. In this study, 70 adult females of Rattus norvegicus (Wistar) were used to evaluate hematology, blood gases, cardiac markers and lung histopathology changes caused by this parasite. Of them, 60 were individually infected by orogastric gavage with 100 L₃ larvae and 10 uninfected animals formed the control group. The results obtained demonstrate that infection caused by A. cantonensis in R. norvegicus promotes significant hematological changes induced in the vertebrate host, manifested mainly in the form of regenerative anemia, thrombocytopenia and eosinophilia. Additionally, histopathological changes in the lung parenchyma demonstrated in rodents reveal the occurrence of areas of necrosis and extensive fibrosis, being directly related to the development of cellular hypoxia and enzyme cardiac changes. This study can contribute to a better understanding of the relationship between A. cantonensis and R. norvegicus.

Parasitic infestations affect millions of the world's population. Global immigration and climate change have led to changes in the natural distribution of parasitic diseases far removed from endemic areas. A broad spectrum of helminthic and protozoal parasitic diseases frequently affects the respiratory system. The wide varieties of clinical and radiographic presentations of parasitic diseases make the diagnosis of this entity challenging. Pulmonologists need to become familiar with the epidemiology, clinical presentation, pathophysiologic characteristics, and bronchoscopic findings to provide proper management in a timely fashion. This review provides a comprehensive view of both helminthic and protozoal parasitic diseases that affect the respiratory system, especially the airways.