Fifth European Dirofilaria and Angiostrongylus Days (FiEDAD) 2016

Peer reviewe

Heat treatment and false-positive heartworm antigen testing in ex vivo parasites and dogs naturally infected by Dirofilaria repens and Angiostrongylus vasorum

Abstract Background Heartworm antigen testing is considered sensitive and specific. Currently available tests are reported as detecting a glycoprotein found predominantly in the reproductive tract of the female worm and can reach specificity close to 100%. Main concerns regard sensitivity in the case of light infections, the presence of immature females or cases of all-male infections. Research and development have been aimed at increasing sensitivity. Recently, heat treatment of serum prior to antigen testing has been shown to result in an increase in positive antigen test results, presumably due to disruption of natural antigen–antibody complexes. Cross-reactions in dogs with both natural and experimental infections with Angiostrongylus vasorum and Spirocerca lupi have been reported, but cross-reactions with other helminths have not been extensively studied. In order to evaluate potential cross-reactivity with other canine and feline parasites, two studies were performed. Study 1: Live adults of Dirofilaria immitis, Dirofilaria repens, Toxocara canis, Toxocara cati, Dipylidium caninum, Taenia taeniaeformis and Mesocestoides spp. larvae were washed and incubated in tubes with saline solution. All worms were alive at the time of removal from the saline. Saline solutions containing excretory/secretory antigens were then tested for heartworm with six different, commercially available antigen tests. All results were evaluated blind by three of the authors. Study 2: Sera from dogs with natural infections by A. vasorum or D. repens, living in areas free of heartworm disease, were tested with the same tests before and after heat treatment (103 °C for 10 min). Results Results suggest that antigens detected by currently available tests are not specific for D. immitis. They may give positive results through detection of different parasites’ antigens that are normally not released into the bloodstream or released in a low amount and/or bound to antibodies. Tests may even detect antigens released by male D. immitis adult worms. D. repens appears to release more detectable antigens than the other worms studied. Conclusions Cross-reaction with A. vasorum and D. repens does occur in the field and could potentially occur with other helminths. Heat treatment decreases specificity by enhancing cross-reactivity

First autochthonous clinical case of Hepatozoon silvestris in a domestic cat in Italy with unusual presentation

Hepatozoon spp. is the causative agent of a vector-borne parasitic disease in many animal species. In felids, Hepatozoon felis, Hepatozoon canis and Hepatozoon silvestris have been molecularly isolated. Hepatozoonosis usually causes asymptomatic infections in domestic cats, but clinical cases have recently been reported in Europe. We describe the first Italian case of hepatozoonosis in a cat with an unusual presentation. An 11-year-old neutered European shorthair cat was urgently hospitalized for intestinal intussusception. Hematology, biochemistry, FIV-FeLV tests, blood smears and molecular investigation targeting the 18S rRNA gene of Hepatozoon spp. were performed on blood samples; in addition, histological and molecular investigations were performed to analyze surgical samples to identify Hepatozoon infection. Hepatozoon gamonts were detected in granulocytes in the blood smear, and Hepatozoon spp. DNA was confirmed by PCR on blood. The intussusception was caused by a sessile endoluminal nodule that was surgically removed. Histologically, many elements referring to parasitic tissue forms were identified in the intestinal cells, and then the specimens were molecularly confirmed to harbor H. silvestris. This is the first description of symptomatic hepatozoonosis in a domestic cat in Italy. Hepatozoon silvestris has been described in wild felids, which are usually resilient to the infection, whereas the domestic cat seems to be more susceptible. Indeed, H. silvestris in cats usually presents tropism for skeletal muscle and myocardium with subsequent clinical manifestations. This is the first description of a domestic cat with H. silvestris localized in the intestinal epithelium and associated with intussusception

Elusive Angiostrongylus vasorum infections

The parasitic nematode Angiostrongylus vasorum causes severe clinical signs in dogs. The disease is often challenging because infected animals are often presented with clinical signs overlapping those of other diseases

Occurrence of Aelurostrongylus abstrusus and Troglostrongylus brevior in cats from Italy.

The cat lungworm Aelurostrongylus abstrusus occurs throughout Europe while Troglostrongylus brevior has been recently recorded in cats from Spain, Italy and Greece. This survey investigated the occurrence of A. abstrusus and T. brevior in 835 cats (i.e. 97, 88, 134, 222, 182 and 112 from sites I-VI) from Northern (sites I and II) and Central (sites III-VI) Italy. Faecal samples were microscopically examined and their positivity was confirmed molecularly. Fifty-two (6.2%) cats were positive for A. abstrusus, 35 (4.2%) for T. brevior, while 15 (1.8%) showed a mixed infection. Aelurostrongylus abstrusus was found in 2 (2.1%), 11 (11.4%), 4 (3%), 7 (3.2%), 19 (10.4%) and 9 (8%) samples in sites I-VI, while T. brevior in 1 (1%), 13 (8.6%), 15 (8.2%), 6 (5.4%) in sites I, IV, V and VI. Mixed infections were recorded in sites IV (2/0.9%), V (11/6%) and VI (2/1.8%). Infected cats were classified based on their age in Groups A (0-6 month-old, 43 cats), B (6-24 month-old, 33 cats), C (older than two years, 26 cats). Cats with aelurostrongylosis, troglostrongylosis and mixed infections, belonged to Groups A (13/25%, 21/60% and 9/60%), B (19/36.5%, 11/31.4% and 3/20%) and C (20/38.5%, 3/8.6% and 3/20%), respectively. These results confirm the presence of A. abstrusus throughout Italy and a spreading of T. brevior in central regions, especially in kittens and young cats. These lungworms should be always considered in the differential diagnosis of cat respiratory diseases. Further studies are required on treatment and control of feline infections caused by lungworms

Occurrence of canine and feline extra-intestinal nematodes in key endemic regions of Italy

Extra-intestinal nematodes of companion animals are of growing concern in veterinary medicine for their pathogenic potential and the current expansion throughout Europe. The present study has evaluated the occurrence of major canine and feline extra-intestinal nematodes in regions of Italy having epidemiological relevance. Associations of various recorded parameters related to the examined animals have been statistically evaluated, along with a comparative analysis with the most recent epidemiological data. Overall, 1055 dogs and 1000 cats were tested. Among extra-intestinal nematodes Angiostrongylus vasorum was the most common in dogs followed by Capillaria aerophila and Dirofilaria spp.; Aelurostrongylus abstrusus was the most recorded parasite in cats, followed by C. aerophila and Troglostrongylus brevior. The statistical analysis revealed that outdoor access is associated with A. vasorum, A. abstrusus and T. brevior infections, that were also more prevalent in animals with cardio-respiratory signs. Moreover, cats aged less than 12 months had more chances to be infected by lungworms. The data herein presented confirm the occurrence and the possible risk of expansion of different extraintestinal parasitoses of dogs and cats in Italy, underlining the importance of a constant epidemiologic vigilance and of appropriate control methods