Do All Roads Lead to Rome? The Potential of Different Approaches to Diagnose Aelurostrongylus abstrusus Infection in Cats

Abstract

An infection with the cat lungworm, Aelurostrongylus abstrusus, can be subclinical, but it can also cause severe respiratory clinical signs. Larvae excretion, antibody levels, clinical assessment findings of the respiratory system and diagnostic imaging findings were recorded and compared for six cats with experimental aelurostrongylosis. In five cats, patency started 33–47 days post infection (pi), but two cats excreted larvae only in long intervals and low numbers. Positive ELISA results were observed in four cats with patent aelurostrongylosis, starting between five days before and 85 days after onset of patency. One seropositive cat remained copromicroscopically negative. Mild respiratory signs were observed in all cats examined. A computed tomographic (CT) examination of the lungs displayed distinct alterations, even in absence of evident clinical signs or when larvae excretion was low or negative. The thoracic radiograph evaluation correlated with the CT results, but CT was more distinctive. After anthelmintic treatment in the 25th week post infection, pulmonary imaging findings improved back to normal within 6–24 weeks. This study shows that a multifaceted approach, including diagnostic imaging, can provide a clearer diagnosis and monitoring of disease progression. Furthermore, a CT examination provides an alternative to post mortem examination and worm counts in anthelmintic efficacy studies.

Aelurostrongylus abstrusus Antibody Seroprevalence Reveals That Cats Are at Risk of Infection throughout Germany

“…Overall, these results are comparable to data from Switzerland, a country bordering the south of Germany: 10.7% of 4067 cats were seropositive for A. abstrusus antibodies [ 18 ], whereas between 0.8% and 2.3% of cats were coproscopically positive, with a higher prevalence in stray cats (6.5%) than owned cats (0.7%) [ 1 , 31 ]. Experimental studies showed that antibodies were detectable already 2–3 weeks before the onset of larval excretion [ 19 ], although isolated individuals may seroconvert later than 10 weeks post-infection [ 32 ]. Antibodies were then shown to persist as long as worms were present, therefore not necessarily correlating with patency [ 19 ].…”

“…Antibodies were then shown to persist as long as worms were present, therefore not necessarily correlating with patency [ 19 ]. Overall, a correlation between optical density (OD) values and the number of L1 per gram of faeces was observed, and it was concluded that low larval excretion may lead to OD values below the test threshold [ 32 ]. Antibodies also persisted for weeks after anthelmintic treatment [ 19 , 32 ].…”

“…Overall, a correlation between optical density (OD) values and the number of L1 per gram of faeces was observed, and it was concluded that low larval excretion may lead to OD values below the test threshold [ 32 ]. Antibodies also persisted for weeks after anthelmintic treatment [ 19 , 32 ]. By contrast, chronically infected cats or cats experiencing repeated infections (conceivable for all cats with unrestricted outdoor access) particularly showed an absence of larval shedding [ 7 , 13 , 33 ], hence precluding diagnosis by the Baermann method; this consequently leads to higher sensitivity and detection rates obtained with serological testing.…”

“…Further diagnostic tools may be used, reviewed in [ 40 , 41 ]. Diagnostic imaging, i.e., radiology and computed tomography, illustrates the onset of such damages despite the absence of clinical signs [ 8 , 32 ]. Infected cats may remain undetected by the animal owner for some time, or the clinical signs may be attributed to another respiratory disease, such as feline asthma, pulmonary oedema, neoplasia, or pneumonia-causing pathogens [ 2 , 42 ].…”

A Molecular Survey on Neglected Gurltia paralysans and Aelurostrongylus abstrusus Infections in Domestic Cats (Felis catus) from Southern Chile

“…However, it allows diagnosis only during the patency period, and the sensitivity is impaired by intermittent and/or low excretion of larvae. Molecular detection by PCR from feces or pharyngeal swabs can be used as alternative diagnostic tools for feline aelurostrongylosis [24][25][26]. An ELISA test for detection of A. abstrusus antibodies in serum has been used to improve the diagnosis of feline aelurostrongylosis [24,27].…”