Bronchial changes in airborne tularemia

Abstract

We describe seven typhoidal tularemia patients without ulcers or lymphadenopathy, who underwent diagnostic bronchoscopy. Four patients had had obvious airborne exposure to F. tularensis during farming activities, and the remaining three had respiratory symptoms also. Bronchoscopical findings were pathological in all cases, varying from local to diffuse haemorrhagic inflammation; in one case a granulomatous tumour was seen. Early histopathological changes in three biopsies consisted of haemorrhagic oedema progressing to a non-specific inflammatory reaction, which could still be found 45 days after the onset of symptoms. Granulomatous inflammation, indistinguishable from tuberculosis or sarcoidosis, was seen in four biopsies from two patients, three to seven months after the onset. Most patients had radiographic hilar enlargement. We conclude that transmission of typhoid tularemia usually occurs through inhalation leading to bronchial changes, which correspond skin ulcerations in ulcero-glandular tularemia, the hilar enlargement corresponding to the lymph node component. We emphasize that usage of the term 'typhoidal' tularemia should be discontinued. Instead, tularemia transmitted through inhalation should be called pulmonary or respiratory.

Tularaemia

“…In a study of seven patients putatively infected by airborne transmission, bronchoscopy disclosed haemorrhagic oedema progressing to mononuclear inflammatory reaction [49]. In most cases, hilar enlargement was disclosed by radiography and the authors suggested the changes to correspond to the primary ulcer and regional lymph node reaction of the ulceroglandular form.…”

“…Instead, tularaemia with no local signs of aquisition were classified as typhoidal or cryptogenic. Strong circumstantial evidence later justified the inclusion of respiratory tularaemia among forms defined according to route of transmission [48,49]. Compared with the ulceroglandular form, outbreaks of respiratory tularaemia occur infrequently but tend to comprise large numbers of cases.…”

“…It is well known from the former Soviet Union but is virtually absent in Western literature. The term typhoidal tularaemia, finally, should be reserved for cases with no indicated route of entrance [48,49].…”

The Infectious Dose ofFrancisella Tularensis(Tularemia)

“…Dermal contact, arthropod bites, and intracutaneous inoculation often produce an ulcerated lesion at the site of contact and/or swelling of the regional lymph nodes, although some individuals exposed through these routes can present with fever and other signs indicative of systemic infection (Dennis et al, 2001;Evans, 1985;Saslaw et al, 1961), including pulmonary involvement (bronchopneumonia and hilar adenopathy) (Miller & Bates, 1969). Inhalation of F. tularensis also produces systemic disease in humans and may produce pneumonia (McCrumb, 1961;Overholt et al, 1961), oval lesions in the lungs (Overholt & Tigertt, 1960), and/or bronchial changes (Syrjala et al, 1986). Although it has been demonstrated experimentally that humans can develop tularemia through inhalation of F. tularensis (McCrumb, 1961;Sawyer et al, 1966), rapid disease onset and delay in examination make it difficult to determine in some cases if pulmonary involvement precedes or follows systemic infection.…”

“…Cough frequently occurs in patients with and without objective pulmonary involvement (Dennis et al, 2001;Saslaw et al, 1961). Although McCrumb (1961) reports that patients exhibited a lack of sputum production and nonproductive cough, case reports indicate that some patients exhibit increased mucous and sputum production, and productive cough (Cluxton, Jr., Cliffton & Worley, 1948;Syrjala et al, 1986).…”