Biology Reference
In-Depth Information
20.1
Introduction
Chronic interstitial pneumonitis has been described in both human and canine
leishmaniasis (CanL) in the absence of specific respiratory symptoms. In dogs,
diffuse interstitial pneumonitis is also associated with arterial obstruction and has
been reported in experimental (Keenan et al. 1984 ) and natural Leishmania
infantum infections (Duarte et al. 1986 ; Tafuri et al. 2001 ). Histopathological
findings of chronic and diffuse pneumonitis associated with fibrosis have been
observed in dogs naturally infected with Leishmania chagasi ( sin. L. infantum )
and were included in a study conducted in Brazil. In this study, the presence of
pulmonary lesions was correlated with the disease independent of the presence and
severity of clinical signs (Goncalves et al. 2003 ). In addition, specific respiratory
symptoms have not been reported in CanL, and there are no references about the
correlation between interstitial pneumonitis and clinical status (Goncalves et al.
2003 ). Recently, cardiac and pulmonary alterations in dogs naturally infected with
L. chagasi have been investigated by means of histopathological, cytological, and
immunohistochemical analyses (Alves et al. 2010 ). Inflammatory lesions in pulmo-
nary tissues were mostly focal and not diffuse as previously reported, and, upon
cytological examination, the presence of amastigotes in lung imprints was revealed
in only 2 of 22 examined dogs (Alves et al. 2010 ).
Chronic pulmonary diseases may lead to pulmonary arterial hypertension
(PAH), a serious progressive pathological condition that affects the subject's
quality of life and exercise capacity, which has a poor prognosis if not identified
and treated early. PAH clinical signs are vague and aspecific and usually correlate
to the primary causative disease. Pulmonary vasoconstriction in response to alveo-
lar hypoxia and tissue acidosis is the most important mechanism of PAH secondary
to chronic pneumonitis; the exiting muscular hypertrophy and intimal fibrosis of
pulmonary arteries further complicate the hypertensive status (Johnson et al. 1999 ;
Glaus et al. 2003 ).
The gold standard method for diagnosing PAH is cardiac catheterization. Nev-
ertheless, Doppler echocardiography can be used for noninvasive predictions of
systolic and/or diastolic pulmonary artery pressure starting by the measurements of
maximal velocity of regurgitant flow across the tricuspid or pulmonic valve,
respectively (Johnson et al. 1999 ). Other Doppler-derived PAH markers have
been proposed, including the right ventricular acceleration time (AT), the accelera-
tion time index that is the AT/right ventricular ejection time ratio (AT/ET) (Shober
and Baade 2006 ), the right ventricular Tei index that is an index of myocardial
performance (Teshima et al. 2006 ; Vonk et al. 2007 ), the pulmonary velocity profile
examination (Johnson et al. 1999 ; McQuillan et al. 2001 ), and recently tissue
Doppler imaging, an ultrasound technique that allows quantitative assessment of
segmental myocardial motion (Serres et al. 2007 ).
The pulmonary lesions observed in human and canine leishmaniasis may result
in PAH development, but until now no data was available to support the presence of
PAH in L. infantum -infected dogs or the correlation between the histopathological
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