Sir, ascariasis is an important tropical round worm infestation. This parasitic infestation is still prevalent in many countries. Extraintestinal manifestation of ascariasis is not common and can be misdiagnosed. An important extranintestinal manifestation is pulmonary ascariasis. The disorder namely “Loeffler’s syndrome”, which manifests as eosinophils accumulation in the lung as a response to a parasitic infection, is an important concern in tropical medicine (1). This syndrome can be a response to several parasitic infestations. Ascariasis is a common etiology of this syndrome. Acar et al. suggested that “Loeffler’s syndrome must be considered early in the differential diagnosis for community acquired pneumonia when peripheric eosinophilia is seen in patients if they live in an endemic area for parasitic disease (2).” Here, the authors review previous publications on this syndrome in Thailand, a tropical country with high prevalence of ascariasis. From standard database search, Pubmed, Scopus, ISI and ThaiIndexMedicus (from 1,918 till present), there are only 2 previous reported cases on Loeffler’s syndrome due to ascariasis in Thailand (3). The two reported cases are children with confirmed parasitosis from stool examination, one with overt pulmonary symptoms and the other without (with incidental finding, migratory pulmonary infiltrates, from chest X-ray) (3). Eosinophilia could be detected by complete blood count and increase serum IgE could be seen (3). Of interest, there are extremely few reports on Loeffler’s syndrome in Thailand and this is an interesting issue for further discussion. The question is why there are very few reports despite the fact that ascariasis is common in Thailand. The first possibility is that this syndrome is extremely rare in Thailand. Indeed, Loeffler’s syndrome is a rare disease. However, in many settings with lower prevalence of parasitosis, there are many case reports on Loeffler’s syndrome. Second, whether the syndrome is under-investigated and under-reported is a query. One might urge that the present sanitation in Thailand is much improved and the incidence of parasitosis decreases. However, there is a recent report of Loeffler’s syndrome (with approval by antiparasitic trial treatment) in the returning traveler from Thailand (4) indicating that the syndrome should not be extremely rare in Thailand. Indeed, the local pulmonarologist might overlook this syndrome or there might be some unknown immunotolerance mechanism that suppresses the clinical presentation among the patients due to the high parasitosis in Thailand.

Disclosure: The authors declare no conflict of interest.