Aelurostrongylus abstrusus

Aelurostrongylus abstrusus

<p align="CENTER"><span style="font-size: medium;"><i><b>Aelurostrongylus abstrusus</b></i></span><span style="font-size: medium;"><b> (Railliet, 1898) Cameron, 1927</b></span></p> <p align="CENTER"><span style="font-size: medium;"><b>(Figures 4-15 through 4-22)</b></span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>ETYMOLOGY: </b></span><span style="font-size: medium;"><i>Aeluro</i></span><span style="font-size: medium;"> = cat and </span><span style="font-size: medium;"><i>strongylus</i></span><span style="font-size: medium;"> = round, plus </span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;"> = hidden from view</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>SYNONYMS:</b></span><span style="font-size: medium;"><i>Strongylus</i></span><span style="font-size: medium;"><i>pusillus</i></span><span style="font-size: medium;"> Mueller, 1890, </span><span style="font-size: medium;"><i>Strongylus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;"> Railliet, 1898, </span><span style="font-size: medium;"><i>Strongylus</i></span><span style="font-size: medium;"><i>nanus</i></span><span style="font-size: medium;"> Braun &amp; Luehe, 1909, </span><span style="font-size: medium;"><i>Synthetocaulus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;"> Railliet and Henry, 1907</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HISTORY:</b></span><span style="font-size: medium;"> This worm was originally found and described by Mueller (1890c) as </span><span style="font-size: medium;"><i>Strongylus</i></span><span style="font-size: medium;"><i>pusillus</i></span><span style="font-size: medium;">. In 1898, Railliet (1898b) changed the name to </span><span style="font-size: medium;"><i>Strongylus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;">. Braun and Luehe (1909a) described a species from the cat that they named </span><span style="font-size: medium;"><i>Strongylus</i></span><span style="font-size: medium;"><i>nanus</i></span><span style="font-size: medium;">. In 1907, Railliet and Henry (1907a) erected the genus </span><span style="font-size: medium;"><i>Sythetocaulus</i></span><span style="font-size: medium;"> to include this worm. Cameron (1927) erected the genus </span><span style="font-size: medium;"><i>Aelurostrongylus</i></span><span style="font-size: medium;"> and concluded that the larva passed in the feces was capable of infecting mice, this work has never been duplicated.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>GEOGRAPHIC LOCATION</b></span><span style="font-size: medium;">: This is a metastrongyloid nematode parasite of the cat around the world (Ash, Center et al., 1990; Charan et al., 1984; Gathumbi et al., 1991; Martinez et al., 1990; Naylor et al., 1984; Pennisi et al., 1995; Wilson-Hanson and Prescott, 1982).</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LOCATION IN HOST:</b></span><span style="font-size: medium;"> The adults live in the terminal respiratory bronchioles and alveolar ducts.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>PARASITE IDENTIFICATION:</b></span><span style="font-size: medium;"> The adult females are 9 to 10 mm long with a vulval opening which, unlike most nematodes, occurs near the anus. The males are smaller, being 4 to 6 mm long, and have a small bursa and relative short and stout spicules. The worms are less than a millimeter wide and have a dark brown to black appearance when observed in fresh tissue. Due to the small worms being deeply within the terminal respiratory bronchioles and alveolar ducts, it is difficult to remove entire worms by dissection. The females lay eggs that contain a single cell when laid anw which embryonate within the alveolar ducts and the surround alveoli. The larvae hatch from the eggs, are carried up the ciliary escalator, swallowed, and passed in the feces. The larvae of </span><span style="font-size: medium;"><i>Aelurostronbylus abstrusus</i></span><span style="font-size: medium;"> are quite active larvae which are easy to recover in the feces using a Baermann apparatus. The larva is approximately 360-390 um long and has a characteristic dorsal spine on the tail (Figs 4-15 to 4-17).</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LIFE CYCLE:</b></span><span style="font-size: medium;"> The life cycle of </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> has been shown to involve a required snail intermediate host (Hamilton and McCaw, 1967). It has also been shown that mice which ingest the infected snail can serve as a paratenic host (Mackerras, 1957). Hobmaier and Hobmaier (1935) also showed that if the larvae from snails were fed to frogs, toads, snakes, lizards ducklings, chickens, or sparrows that the larvae could later be recovered from their tissues. Thus, it seems highly possible that cats become infected typically by the ingestion of infected mice or birds. Stockdale (1970) found that the females began to lay eggs as early as 25 days postinfection; larvae have been found in the feces after 39 days of being infected with third-stage larvae (Gerichter, 1949).</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>CLINICAL PRESENTATION AND PATHOGENESIS:</b></span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> is known to cause severe pulmonary disease with heavy infections (Stockdale, 1970) (Figs. 4-18 to 4-20). Cats infected with 100 larvae showed early radiographic changes 2 weeks after infection (Mahaffey, 1979). The most severe disease was noted 5 to 15 weeks after infection and presented as alveolar disease. Examination of experimentally infected cats followed for up to a year after infection revealed that there was neither pulmonary hypertension or associated right ventricular disease (Rawlings et al., 1980). Pulmonary arteries in experimentally infected kittens show disruption of the vascular endothelium and proliferation of the endothelial cells, and as early as 10 days after infection, there is disruption of the internal elastic lamina (Figs 4-21 to 4-22). Hypertrophy and hyperplasia of the medial and intimal walls of the pulmonary vessels caused complete occlusion of many of the vessels by 24 weeks after infection (Naylor et al., 1984).</span></p> <p align="JUSTIFY"><span style="font-size: medium;"> Mild infections often present with only minimal signs, however, heavy infections can cause severe bronchopneumonia with cats having rapid, open-mouthed abdominal breathing (Vig and Murray, 1986). A retrospective study of 312 cases of cats with eosinophilia revealed that 2% of the cases were infected with </span><span style="font-size: medium;"><i>Aelurostrongylus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;">, while the majority of cases, 20.5%, had eosinophilia as a result of flea-bite allergy dermatitis (Center et al., 1990). Hamilton (1963) reported on one cat that was presumed to have died as a result of its lungworm infection. The 6-month-old cat developed signs of respiratory disease when three-months0old and the disease persisted. During this three month period, the cat was observed to be coughing and sneezing with a muco-purulent discharge. As the disease progressed, the cat became dyspneic, anorexic, emaciated, and with hydrothorax.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>TREATMENT:</b></span><span style="font-size: medium;"> In cats infected with </span><span style="font-size: medium;"><i>Aelurostrongylus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;">, treatment with fenbendazole (55 mg/kg daily for 21 days (Vig and Murray, 1986) or 20 mg/ kg daily for 5 days followed by a second 5 day treatment after a five day hiatus) has been reported to be successful (Smith, 1980). Treatment of 15 cats experimentally infected with </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> with fenbendazole (50 mg/kg, once daily for three days) stopped the shedding of larvae in the feces by 14 days after treatment, but a few days later, the larvae reappeared in small numbers in the feces of the infected cats (Roberson and Burke, 1980). Published reports on the efficacy of ivermectin has not produced conclusive results (Blagburn et al., 1987). However, there is a report of treatment with ivermectin (200 µg/kg followed by a second treatment with 400 µg/kg) clearing a cat of the </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> infection (Kirkpatrick and Megalla, 1987).</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>EPIZOOTIOLOGY:</b></span><span style="font-size: medium;"> Cats probably most typically become infected by the ingestion of captured prey, e.g., small birds and rodents. Thus, to prevent infection it is probably necessary to restrict the hunting of cats. </span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HAZARDS TO OTHER ANIMALS: </b></span><span style="font-size: medium;"> This parasite seems restricted to cats, and the stage passed in the feces is not infectious to other avian or mammalian hosts until after a period of development in a mullusc. Thus, it is unlikely that this worm would pose a threat to other animals in a clinic.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HAZARD TO HUMANS:</b></span><span style="font-size: medium;"> None.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>CONTROL/PREVENTION:</b></span><span style="font-size: medium;"> Control would be by the prevention of hunting by cats. It is unlikely that the monthly heartworm preventatives approved for cats would have any effects on the development of this parasite in the cat.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>REFERENCES:</b></span></p> <p align="JUSTIFY"><span style="font-size: medium;">Ash LR. 1962. Helminth parasites of dogs and cats in Hawaii. J Parasitol. 48:63-65.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Blagburn BL, Hendrix CM, Lindsay DS, Vaughan JL. 1987. Anthelmintic efficacy of ivermectin in naturally parasitized cats. Am J Vet Res 48:670-672.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Center SA, Randolph JF, Erb HN, Reiter S. 1990. Eosinophilia in the cat: a retrospective study of 312 cases (1975-1986). J Am An Hosp Assoc 26:349-358.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Charan K, Sheik-Dawood MM. 1984. Lungworm infestation in a cat. Ind Vet Med J 8:245-247.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Gathumbi PK, Waruiru RM, Buoro I. 1991. A case of feline </span><span style="font-size: medium;"><i>Aelurostongylus</i></span><span style="font-size: medium;"> infection in Kenya. Bull An Hlth Prod Africa 39:361-363.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Gerichter CB. Studies on the nematodes parasitic in the lungs of Felidae in Palestine. Parasitology 39:251-262. 1949.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Hamilton JM. 1963. </span><span style="font-size: medium;"><i>Aelurostrongylus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;"> infestation of the cat. Vet Res 75:417-422,</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Hamilton JM, McCaw AW. 1967. The role of the mouse in the life cycle of </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. J Helminthol 41:309-312.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Hobmaier M, Hobmaier A. 1935a. Intermediate hosts of </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> of the cat. Proc Soc Exp Biol Med 32:1641-1647.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Hobmaier M, Hobmaier A. 1935b. Mammalian phase of the lungworm </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> in the cat. J Am Vet Med Assoc 87:191-198.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Kirkpatrick CE, Megalla C. 1987. Use of ivermectin in treatment of </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> and </span><span style="font-size: medium;"><i>Toxocara cati</i></span><span style="font-size: medium;"> infection in a cat. J Am Vet Med Assoc 190:1309-1310.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Mackerras MJ. 1957. Observations on the life history of the cat lungworm, </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> (Railliet, 1898) (Nematoda: Metastrongylidae). Austral J Zool 5:188-195.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Mahaffey MB. 1979. Radiographic-pathologic findings in experimental</span><span style="font-size: medium;"><i> Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> infection in cats. J Am Vet Rad Soc 20:81.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Martinez AR, Santa-Cruz AM, Lombardero OJ. 1990. Lesiones histopatologicas en la aelurostongilosis felina. Rev Med Vet (Buenos Aires) 71:260-264.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Naylor JR, Hamilton JM, Weatherley AJ. 1984. Changes in the ultrastucture of feline pulmonary arteries following infection with the lungworm</span><span style="font-size: medium;"><i> Aelurostrongylus abstusus</i></span><span style="font-size: medium;">. Brit Vet J 140:181-190.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Pennisi MG, Niutta PP, Giannetto S. 1995. Longwormziekte bij katten veroozaakt door </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. Tijdsch v Diergeneesk 120:263-266.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Rawlings CA, Losonsky JM, Lewis RE, Hubble JJ, Prestwood AK. 1980. Respnse of the feline heart to </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. J Am An Hosp Assoc 16:573-578.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Roberson EL, Burke TM. 1980. Evaluation of granulated fenbendazole (22.2%) against induced and naturally occurring helminth infections in cats. Am J Vet Res 41:1499-1502.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Smith RE. 1980. Feline lungworm infection. Vet Rec 107:256.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Stockdale PHG. 1970. The pathogenesis of the lesions elicited by </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> during its prepatent period. Patholologia Veterinaria 7:102-115.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Wilson-Hanson SL, Prescott CW. 1982. A survey for parasites in cats. Austral Vet J 59:109.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Vig MM, Murray PA. 1986. Successful tretment of </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;"> with fenbendazole. Comp Cont Educ Pract Vet 8:214-222.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-15. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. First stage larva passed in the feces. The characteristic dorsal spine on the larval tail is not evident in this image.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-16. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. First stage larva passed in the feces showing a higher magnification of the kinked tail with a dorsal spine.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-17. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. First stage larva recovered in a tracheal wash from an infected cat stained with Dif-Quik.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-18. </span><span style="font-size: medium;"><i>Aelurostrongylus</i></span><span style="font-size: medium;"><i>abstrusus</i></span><span style="font-size: medium;">. Lungs of an infected cat showing changes in the serosal surface.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-19. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. Higher view of lungs showing numerous areas of apparent consolidation.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-20. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. Radiograph of lungs of infected cat.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-21. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. Histological section of lung showing sections of adult worm along with eggs within the parenchyma in various sstages of development.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Figure 4-22. </span><span style="font-size: medium;"><i>Aelurostrongylus abstrusus</i></span><span style="font-size: medium;">. Transverse sction through lung parenchyma showing the large number of eggs in the tissues in various stages of development and a few free first-stage larvae.</span></p>