Aelurostrongylus abstrusus larvae in the colon of two cats

Hemorrhagic Meningoencephalomyelitis Due to Ectopic Localization of Aelurostrongylus abstrusus in a Cat: First Case Report

Simple Summary

Aelurostrongylus abstrusus is the most important parasitic nematode affecting cat airways worldwide. The adult nematodes live in the lungs and cause pneumonia with typical respiratory clinical signs such as cough, nasal and ocular discharge, and difficulties in breathing. The localization of adult A. abstrusus in other organs than lungs is not common. This report describes, for the first time, an unusual and fatal localization of A. abstrusus within the central nervous system of a kitten displaying neurological signs.

Abstract

The lungworm Aelurostrongylus abstrusus is one of the main causes of respiratory diseases in cats worldwide. This report describes the unusual case of a kitten infected with A. abstrusus and presented to a veterinary clinic in Brazil with lethargy, dysphagia, non-ambulatory tetraplegia, and pelvic limbs bilateral myoclonus. The clinical picture of the kitten worsened with generalized flaccid tetraplegia and death a few days after hospitalization. At necropsy, hemorrhagic necrosis and subarachnoid hemorrhages were detected in several areas of the central nervous system. Nematode stages were found at post-mortem histological examinations in lungs, cerebellum, subarachnoid space of the brain and spinal cord. Microscopic and molecular (PCRs-coupled-sequencing protocols) examination showed the presence of A. abstrusus in histological samples. This study describes the first neurological aelurostrongylosis due to ectopic localization of adult worms in the central nervous system of a cat, causing acute hemorrhagic multifocal meningoencephalomyelitis. Further studies are necessary to elucidate whether unusual localizations and the migration of A. abstrusus are more frequent than expected.

Cat Respiratory Nematodes: Current Knowledge, Novel Data and Warranted Studies on Clinical Features, Treatment and Control

The nematodes Aelurostrongylus abstrusus, Troglostrongylus brevior and Capillaria aerophila are the most important parasites inhabiting the airways of cats. They are receiving growing attention from academia, pharmaceutical companies and veterinarians, and are now considered a primary cause of respiratory diseases in feline clinical practice and parasitology. In the past few years, several studies have been conducted in both natural and experimental settings to increase knowledge, provide new insights and fill gaps on respiratory parasitoses of cats. Awareness and knowledge of clinical scenarios towards appropriate and timely diagnosis and prompt and efficacious treatment options have become a priority to investigate. At the same time, chemopreventative approaches have been evaluated to assess the geographical spreading of these parasites and the rise in the number of clinical cases in cat populations of different countries. Given the intense accumulation of novel data, this review presents and discusses the state of the art and the latest updates on the clinical features, treatment, and control of major respiratory parasitoses of cats. Moreover, food for thought is also provided with the aim of spurring on new studies in the near future.

Case report: Severe and progressive bronchopneumonia by Aelurostrongylus abstrusus in an adopted stray cat from Portugal

The cat lungworm Aelurostrongylus abstrusus is the most common respiratory parasite of cats. This nematode has a worldwide distribution and is considered an emerging pathogen. Respiratory signs overlap with those of other pathologies, and some agents which co-exist in the same animal may concur in the clinical scenario. Nonetheless, feline verminous bronchopneumonia is underestimated by practitioners and is not commonly included in differential diagnosis in routine practice. The present report describes the clinical presentation of a 6-month old stray cat from central Portugal, which developed respiratory distress. A clinical improvement of lower respiratory signs was achieved after a course of doxycycline and prednisolone course. However, a relapse with a progressive decline in the respiratory functions occurred two weeks later. A further investigation led to the identification of an A. abstrusus infection that was treated with fenbendazole. Ten days after the treatment the cat became negative for A. abstrusus and further analyses performed in the followings 2 months showed improvement of the animal's pulmonary condition and negative results at the faecal examinations. These findings indicate that veterinarians should include aelurostrongylosis in the differential diagnosis of feline respiratory distress even in non-endemic regions and should perform appropriate diagnostics procedures in the presence of compatible signs.

Detection of specific antibodies in cats infected with the lung nematode Aelurostrongylus abstrusus

Feline aelurostrongylosis, caused by the metastrongylid nematode Aelurostrongylus abstrusus, is an underestimated respiratory parasitosis. Its diagnosis currently mainly relies on the isolation of first stage larvae from fresh faecal samples. The aim of our study was to develop a serological test for the detection of specific antibodies against A. abstrusus by ELISA. We used recombinant major sperm protein (MSP) of the bovine lungworm Dictyocaulus viviparus as detection antigen and evaluated two different ELISA plates (Maxisorp and Immobilizer™ Amino-plate, Nunc Roskilde, Denmark) with two different enzyme systems [alkaline phosphatase (AP) and horseradish peroxidase (HRP)]. Sera from cats experimentally (n=54) and naturally (n=17) infected with A. abstrusus and from randomly selected cats with different medical issues (n=160) were used to determine sensitivity and specificity. Furthermore, cross-reactions were evaluated using sera from cats naturally (n=71) and experimentally (n=8) infected with different nematodes. A sensitivity of 100% was obtained with sera from experimentally infected cats at 10 weeks post infection using MSP on the Immobilizer™ Amino-plate with HRP, while it ranged between 90.5 and 95.2% in the other ELISA set-ups. Using sera from naturally infected cats, a sensitivity of 88.2% (95% confidence interval: 63.6-98.5%) was achieved in all four set-ups. The specificity was 85.2-94.4% in sera from uninfected cats prior to experimental infection and 68.1-90% in randomly selected cats depending on the plate and enzyme system. The number of seropositive cats increased over time post infection. Serological follow-up showed a decrease of antibody levels within 30days after anthelmintic treatment. Seropositive reactions were observed with sera from stray cats naturally infected with Toxocara cati, Capillaria sp., hookworms and Taeniidae; however, coproscopic false negative A. abstrusus findings cannot be excluded. The serological detection of specific antibodies against A. abstrusus using ELISA requires a single serum sample and therefore represents a valid alternative for reliable individual diagnosis of A. abstrusus in cats and facilitates mass screening, overcoming the usually difficult collection of cat faeces.

Multiparasitism in a wild cat (Leopardus colocolo) (Carnivora: Felidae) in southern Brazil

Abstract Parasitic diseases reflect the health and balance of ecosystems, affecting not only individuals but also entire populations or communities. The aim of this study was to report on the diversity of parasitic helminths detected in the feces of a wild feline in southern Brazil. Parasites were obtained from fecal samples, and four techniques were used for parasitological examination: direct examination, centrifugal flotation with zinc sulfate (Faust technique), simple sedimentation (Hoffman technique) and Baermann-Moraes. The parasites were identified through micrometry and morphology, as follows: Ancylostoma sp., Toxocara sp., Trichuridae, Aelurostrongylus abstrusus, Alaria sp., and Spirometra sp. We recorded the genus Ancylostoma parasitizing L. colocolo for the first time.

Diagnosis and management of lungworm infections in cats: Cornerstones, dilemmas and new avenues

PRACTICAL RELEVANCE

Respiratory parasites infecting domestic cats are attracting increased attention in feline clinical practice. In addition to the most commonly recognised 'cat lungworm' Aelurostrongylus abstrusus, Troglostrongylus brevior and Capillaria aerophila are now considered important pathogens of the respiratory tract of cats.

GLOBAL IMPORTANCE

These parasites are being increasingly diagnosed in several regions of the world and a continuous update on epidemiological changes and advances in diagnosis and control is of practical importance.

AIMS

This article reviews current knowledge of lungworms affecting cats, with a special focus on recent insights into diagnosis and management of the diseases they cause. The article also explores some potential new avenues for control of feline parasitic respiratory diseases, and highlights some key areas requiring further research.

Updates on feline aelurostrongylosis and research priorities for the next decade

Feline aelurostrongylosis, caused by the metastrongyloid nematode Aelurostrongylus abstrusus, is an important gastropod-borne parasitic lung disease in cats. Infection with A. abstrusus is widespread globally, but the increasing awareness of this parasite and the advent of more sensitive diagnostics have contributed to the apparent increase in its prevalence and geographic expansion. Clinical features may range in severity from subclinical to life-threatening respiratory disease. Parasitological standard techniques, such as visualization of the nematode first larval stage in faecal and respiratory (bronchial mucus or pleural fluid) samples, remain the mainstays of diagnosis. However, diagnosis is evolving with recent advances in serological and molecular testing, which can improve the time to initiation of effective anthelmintic therapy. Despite numerous anthelmintics that are now available as treatment options, the role of host immunity and lifestyle factors in selecting cats that may benefit from more targeted anthelmintic prophylaxis or treatment practice remains unclear and is likely to guide therapeutic choices as newer data become available. This review summarizes the biology, epidemiology, pathophysiology, diagnosis and treatment options currently available for feline aelurostrongylosis.

Felid Lungworms and Heartworms in Italy: More Questions than Answers?

Nematodes infecting the cardiorespiratory system of cats have recently stimulated high scientific interest. Over the past few years, different aspects of these parasites have been clarified and various issues elucidated. This increased knowledge has improved awareness on this topic but, at the same time, some dilemmas have not been solved and new questions have been raised. In this review, we underline and discuss current knowledge of, and new doubts relating to, feline lungworms and heartworms, with the aim of stimulating new studies to fill gaps of basic (i.e., epidemiology and biology) and applied (i.e., clinical aspects) knowledge of the old and new parasites affecting the cardiorespiratory system of cats.

Verminous pneumonia and enteritis due to hyperinfection with Aelurostrongylus abstrusus in a kitten

Severe infestation with Aelurostrongylus abstrusus was identified in the lungs and small intestine of a 2-month-old kitten that died due to verminous pneumonia and enteritis. On clinical examination, the kitten had dyspnoea, pneumonia, pleural effusion, ascites and diarrhoea. An interstitial pattern was evident radiographically in the lungs. The kitten died before treatment could be instituted. On gross and histopathological examination, there was severe interstitial pneumonia and large numbers of A. abstrusus eggs and larvae were present in alveoli, together with fewer adult nematodes in small bronchioles. The mucosa of the small intestine was invaded by large numbers of A. abstrusus larvae. The findings were consistent with a hyperinfection syndrome due to A. abstrusus.

Clinical, laboratory and pathological findings in cats experimentally infected with Aelurostrongylus abstrusus

Aelurostrongylus abstrusus parasitizes the respiratory tract and can heavily affect the breathing and general condition of cats. Experimental infections of six cats were initiated by intragastric administration with 100 or 800 third-stage larvae (L3) obtained from the terrestrial snail Helix aspersa. First-stage larvae were isolated from faecal samples after 35-41 days post infection (dpi) in five animals and until end of study (84 dpi) in two cats. Cough and respiratory sounds were observed starting from 28 to 41 dpi and dyspnoea and panting starting from 52 dpi. All cats had enlarged lymph nodes and, starting from 56 dpi, reduced body weight, and four cats showed intermittent reduced general condition with apathia and anorexia. Eosinophilia and leucocytosis partially with massive lymphocytosis, and occasional basophilia and monocytosis were observed. Mild anaemia was present in five cats, while alterations in coagulation parameters suggested stimulation of the coagulation cascade with increased consumption of coagulation factors (delayed PT, hypofibrinogenemia). Adult A. abstrusus specimens were isolated from the five patent cats at necropsy and all six cats showed pathological changes in the lungs, including disseminated inflammatory cell infiltrates, often associated with incorporated larvae and eggs. There was some degree of overlap between the severity and the inoculation doses. Infections starting from 100 L3 of A. abstrusus had an impact on the lung tissues and on the health of the cats, despite the presence of only mild haematological abnormalities. Due to the worldwide occurrence of feline lung worms, parasitic infections should be considered in the differential diagnosis of lung diseases regardless of the presence of clinical signs and larval excretion.

Feline lungworms: what a dilemma

Aelurostrongylus abstrusus is regarded as the major lungworm infecting Felis catus, although other, albeit poorly studied, nematodes have been described from the respiratory system of domestic cats. Recent records of these neglected parasites have renewed the attention of the scientific community, but their actual role in respiratory disease in cats is blurred. The epidemiology, pathogenic role, and diagnosis of Troglostrongylus spp., Oslerus rostratus, and Capillaria aerophila in domestic cats are far from being clarified. Indeed, recent studies have provided novel information but have also given rise to relevant doubts. We discuss here the state of current knowledge regarding felid lungworms together with the dilemmas recently roused in the scientific literature.