Official reprint from UpToDate®
www.uptodate.com ©2015 UpToDate®

Pulmonary manifestations of ascariasis

Peter F Weller, MD, FACP
Karin Leder, MBBS, FRACP, PhD, MPH, DTMH
Section Editor
Edward T Ryan, MD, DTMH
Deputy Editor
Elinor L Baron, MD, DTMH


Ascaris lumbricoides is an intestinal nematode (roundworm); it is one of the most common helminthic human infections worldwide [1]. Issues related to pulmonary infection are reviewed here. The epidemiology, clinical manifestations, and diagnosis of ascariasis are discussed separately. (See "Ascariasis".)


The life cycle of ascariasis is summarized separately (figure 1). In general, within four days following oral ingestion of eggs, they hatch in the small intestine and release larvae which migrate hematogenously to the lungs. Within the alveoli of the lungs, the larvae mature over a period of approximately 10 days, then ascend the bronchial tree and are swallowed.

Respiratory manifestations occur primarily in the first stage of infection; they rarely complicate the intestinal phase.


The syndrome of eosinophilic pneumonitis among patients originally described by Loeffler was attributed to Ascaris infection retrospectively; ascariasis remains the most common cause of Loeffler's syndrome worldwide [2,3]. Transient respiratory symptoms can occur during migration of Ascaris larvae through the lungs; this occurs one to two weeks following ingestion of eggs. The severity of symptoms correlates to some degree with larval burden, although pulmonary symptoms are less common in regions with continuous transmission of A. lumbricoides [4-8].

Symptoms include dry cough and burning substernal discomfort. Some patients experience dyspnea and blood-tinged sputum. Urticaria occurs in about 15 percent of cases [9]. Fever occurs in many patients though rarely exceeds 38.3ºC (101ºF). Over half of patients have crackles and wheezing, in the absence of consolidation. Hepatomegaly may develop. Lymphadenopathy is generally not observed. Symptoms generally subside within 5 to 10 days. Ascaris pneumonia is self-limited and only very rarely fatal.


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Apr 2015. | This topic last updated: Sep 13, 2013.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2015 UpToDate, Inc.
  1. Khuroo MS. Ascariasis. Gastroenterol Clin North Am 1996; 25:553.
  2. LOFFLER W. Transient lung infiltrations with blood eosinophilia. Int Arch Allergy Appl Immunol 1956; 8:54.
  3. Udwadia FE. Leoffler's syndrome. In: Progress in Respiration Research: Pulmonary Eosinophilia, John Wiley & Sons, New York 1975. p.19.
  4. Koino, S. Experimental infections on human body with ascarides. Jpn Med World 1922; 2:317.
  5. TAKATA I. Experimental infection of man with Ascaris of man and the pig. Kitasato Arch Exp Med 1951; 23:151.
  6. Phills JA, Harrold AJ, Whiteman GV, Perelmutter L. Pulmonary infiltrates, asthma and eosinophilia due to Ascaris suum infestation in man. N Engl J Med 1972; 286:965.
  7. Gelpi AP, Mustafa A. Seasonal pneumonitis with eosinophilia. A study of larval ascariasis in Saudi Arabs. Am J Trop Med Hyg 1967; 16:646.
  8. Gelpi AP, Mustafa A. Ascaris pneumonia. Am J Med 1968; 44:377.
  9. Barrett-Connor E. Human intestinal nematodiasis in the United States. Calif Med 1972; 117:8.
  10. Calvert J, Burney P. Ascaris, atopy, and exercise-induced bronchoconstriction in rural and urban South African children. J Allergy Clin Immunol 2010; 125:100.
  11. Bean, WJ. Recognition of ascariasis by routine chest or abdomen roentgenograms. Am J Roentgenol Rad Ther Nucl Med 1965; 94:379.
  12. Weller PF, Bach DS, Austen KF. Biochemical characterization of human eosinophil Charcot-Leyden crystal protein (lysophospholipase). J Biol Chem 1984; 259:15100.
  13. Piggott J, Hansbarger EA Jr, Neafie RC. Human ascariasis. Am J Clin Pathol 1970; 53:223.
  14. BEAVER PC, DANARAJ TJ. Pulmonary ascariasis resembling eosinophilic lung; autopsy report with description of larvae in the bronchioles. Am J Trop Med Hyg 1958; 7:100.
  15. Booth BH, Patterson R, Talbot CH. Immediate-type hypersensitivity in dogs: cutaneous, anaphylactic, and respiratory responses to ascaris. J Lab Clin Med 1970; 76:181.
  16. Gundel RH, Gerritsen ME, Gleich GJ, Wegner CD. Repeated antigen inhalation results in a prolonged airway eosinophilia and airway hyperresponsiveness in primates. J Appl Physiol (1985) 1990; 68:779.
  17. PROFFITT RD, WALTON BC. Ascaris pneumonia in a two-year-old girl. Diagnosis by gastric aspirate. N Engl J Med 1962; 266:931.
  18. Warren KS, Mahmoud AA. Algorithms in the diagnosis and management of exotic diseases. xxii. ascariasis and toxocariasis. J Infect Dis 1977; 135:868.