Fourteen cases of asthma exacerbation due to HS were identified (Table 2). The mean age was 58.6 years. The male to female ratio was 5:2. Twenty one percent of the patients presented with one or more comorbid conditions including ischemic heart disease, Cushing syndrome, rheumatoid arthritis, among others. All expect one were born in endemic areas for Strongyloides, and one patient was born in a developed country but served as military personnel in a high-risk country for STH. More than half of the cases (57.1%) presented to health care centers in developed countries.
Among clinical manifestations, 64% of the patients presented with respiratory distress and 21% with gastrointestinal (GI) symptoms. Fever was inconsistently reported. Two patients presented hemoptysis. Eosinophilia was reported in 20% of the cases that included this laboratory result (10 reports), while hyper-eosinophilia was seen in 30% of them. BAL and/or sputum were positive in 93% of the patients, and the remaining patient was diagnosed with HS by lung histopathology, which yielded numerous larvae during the autopsy. Stool examination was positive for larvae of Strongyloides in 67% of those patients tested (8 out of 12). Anti-parasitic therapy was administered to 86% of individuals (12 out of 14); being ivermectin the drug of choice in 42% of the cases (5 out of 12). Two of those patients received Ivermectin plus another anti-parasitic drug. Overall, mortality rate was 46% (6 out of 13; 1 outcome is unknown). Patients treated with ivermectin alone or in combination therapy had a survival rate of 100% (5 out of 5), while only 33% of patients (2 out of 6) treated with another anti-parasitic drug survived.
Strongyloidiasis has become an emergent disease in developed countries because of immigration. Ostera et al. detected a prevalence of 4.2% among Latin American immigrants in Washington DC, USA (35). More than half of the cases included in the literature review (Table 2) were reported in developed countries including the USA, England, France, and South Korea (13-18,20,24). However, all the patients were exposed to endemic areas. This is an important finding as the popularization of traveling and globalization could favor the presentation of Strongyloides in otherwise non-endemic areas; a trend noticed over the last twenty years (2,5).
Clinical manifestations of S. stercolaris infection may range from asymptomatic to chronic symptoms, and HS with multiple systems involved (2,4). HS is the result of the high replication and migration of the larvae, typically seen in patients with impaired cell-mediated immunity as in the HTLV-1 co-infection, transplant patients, chronic or high-dose corticosteroids use (2,4,7,8). On the other side, HIV has not been frequently associated to HS (2,3). It usually presents with fever and GI complaints (nausea, vomiting, abdominal pain, diarrhea, bleeding) but extra-intestinal manifestations are also common, including dyspnea, wheezing, pulmonary infiltrates or alveolar hemorrhage (2-4). HS may complicate with shock, disseminated intravascular coagulation and respiratory failure (2,4,7,8). Interestingly, the main presentation of HS noticed in the literature review, as well as in this case was pulmonary involvement (64%), as opposed to the expected GI manifestation caused by a helminth.
Strongyloides infection in healthy individuals characteristically produces marked eosinophilia (2-5). In contrast, patients with HS may present with a higher number of larvae but few eosinophils (2,5,8). Increased eosinophil count was observed in half of cases with available data (5 out 10 patients); and it was present only in one third of patients who died. As stated before, corticosteroid therapy is one of the most frequent risk factors for HS in developed countries and may contribute to an adverse outcome (5). Steroids affect T-helper type-2 (Th2) response and eosinophil migration to the site of infection. Also, there is evidence suggesting that steroids can play a role as molting signals for eggs which enhances parasite production and promotes dissemination (2-5).
Although malnutrition and HTLV-1 infection are strong risk factors for strongyloidiasis in developing countries (2), this information was unavailable during the literature review. Our patient had low albumin levels; probably reflecting his defective nutrition. He also tested negative for HIV and HTLV-1. The latter is especially important in Strongyloides HS, as it may induce a predominant Th1 cell response with high levels of IFN-? and TNF-?. Furthermore, there is a decreased Th2 response that impairs the secretion of IL-4, IL-13, IL-5, and Ig E, which further reduces eosinophil recruitment and blunts the normal inflammatory response against the parasite (3,5). Thus, investigation of HTLV-1 status is mandatory in patients with strongyloidiasis.
Exams revealing larvae in bronchial fluids are an important criterion for confirming HS and dissemination (5). Traditional stool-based techniques have low sensitivity (