Three unusual cases of parasites in eye.

A 17-year-old male patient presented with cellulitis and mass in the eye noticed approximately 3 months back. The mass was about 1 cm in size and situated at the limbus. All preoperative routine investigations were normal. Surgical exploration revealed a sub-conjunctival cystic mass near the lateral rectus muscle about 1 cm in diameter; the mass was excised. Gross pathological examination revealed a thin-walled cystic mass. There was a hard nodule in the center. Microscopy revealed a wall of cysticercosis. Scolex was also seen. Surrounding tissue revealed sparse acute and chronic inflammatory cells. The case was confirmed by CDC, Atlanta, and was also included in their departmental presentation as an interesting case. A 60-year-old lady presented with complaints of itching over the forehead and right eye for 5 days. She was prescribed steroid eyedrops and antihistaminics. The itching aggravated with eyedrops along with watering and foreign body sensation. On revisit, the ophthalmologist noticed a worm in the right upper subconjunctival space. The worm was carefully removed in toto and sent to the laboratory for identification. The worm was thin, cylindrical, 8-10 cm long and white in color. After microscopic and gross examination of the worm, it was identified as Dirofilaria spp. CDC (Atlanta) confirmed the diagnosis of Dirofilaria. The patient was treated with antihistaminics and was relieved of symptoms without recurrence. A 45-year-old male patient had a painless mass in the eye for the last 3 months. He had no systemic illness. He gave a history of swimming pool use during that time. The mass was excised and submitted for histopathology. Numerous globular cysts representing thick-walled sporangia containing numerous spores diagnostic of Rhinosporidiosis were seen.

Evaluation of the therapeutic and preventive efficacy of 2.5 % moxidectin / 10 % imidacloprid (Advocate(®), Bayer animal health) in dogs naturally infected or at risk of natural infection by Dirofilaria repens.

The objective of this GCP-compliant clinical field study was to evaluate the efficacy of the combination of moxidectin (minimum dose of 2.5 mg/kg body weight) and imidacloprid (minimum dose of 10.0 mg/kg body weight) spot-on (Advocate(®)) as a preventive and therapeutic treatment of natural infection by Dirofilaria repens in dogs in the Czech Republic.There were two arms of the study, both negatively controlled. 34 animals were randomly allocated to two groups of the treatment arm; 90 negative animals were randomly allocated to the prevention arm groups. All enrolled dogs were observed physically and blood was sampled monthly for Dirofilaria repens microfilaria counts for 18 months by modified Knott test and PCR. 34 dogs were positive for microfilaria and enrolled in the treatment arm of this study (treated: 18, untreated: 16). The reduction of the log-transformed microfilaria counts was significantly higher in the treatment group on day 28 (p = 0.007), 56, 84 and 112 (p < 0.001). All animals treated were negative after a single treatment. In the untreated control group 93.75 % remained positive (p < 0.001). 87 dogs were negative for microfilaria prior to allocation to the "preventive" arm (treated: 49; untreated: 38; 3 excluded). One dog in the untreated control group became positive for Dirofliaria repens microfilaria, while none of the treated dogs became positive. Advocate(®) was effective in the treatment of dogs infected with microfilaria of Dirofilaria repens. Due to the low rate of natural infections the preventive efficacy could not be proven, but no dog treated became positive.

Elimination of Dirofilaria (syn. Nochtiella) repens microfilariae in dogs with monthly treatments of moxidectin 2.5%/imidacloprid 10% (Advocate, Bayer) spot-on.

Elimination of microfilaria in dogs infected with zoonotic Dirofilaria repens would be desirable to reduce further spread. Moxidectin has demonstrated efficacy against microfilariae and safety in dogs infected with Dirofilaria immitis and could be an option for controlling D. repens microfilariae. A field study with 64 dogs previously confirmed positive for D. repens microfilaria was conducted in Hungary, in which a spot-on product (Advocate, Bayer) was tested. Treatments were applied to 44 dogs once a month for 3 months (five dogs) or 6 months (22 dogs), alternatively every 2 weeks for 6 months (17 dogs). Twenty dogs remained untreated. Microfilaria counts were performed once a month and for a further 6 months following the last treatment. Two weeks after the first treatment, 38 of 44 dogs were microfilaria negative. Four weeks after the initial treatment, one dog still showed a low microfilaria count. Following the second treatment, all treated dogs were negative. This status was maintained during the 6-month observation period after the last treatment. These data demonstrate the successful long-lasting elimination of microfilariae. Moreover, it may be supposed that adult D. repens were killed based on the observation that no further microfilariae were seen up to 6 months after the end of the treatment period.

Autochthonous Dirofilaria (Nochtiella) repens infection in dogs in Kuwait.

Human dirofilariasis caused by Dirofilaria repens is a rare but increasingly reported zoonosis in the Middle East. However, eligible animal reservoirs seldom have been investigated in the area until now. Seven (1.8 percent) out of 381 dogs examined in Kuwait carried D. repens microfilariae showing compatible cutaneous clinical signs and positive response to the adulticide and microfilaricide therapies. This study indicates that dogs from Kuwait are natural hosts of D. repens and therefore act as an animal reservoir for the zoonotic condition.

Effects of tetracycline on the filarial worms Brugia pahangi and Dirofilaria immitis and their bacterial endosymbionts Wolbachia.

Wolbachia endosymbiotic bacteria have been shown to be widespread among filarial worms and could thus play some role in the biology of these nematodes. Indeed, tetracycline has been shown to inhibit both the development of adult worms from third-stage larvae and the development of the microfilaraemia in jirds infected with Brugia pahangi. The possibility that these effects are related to the bacteriostatic activity of tetracycline on Wolbachia symbionts should be considered. Here we show that tetracycline treatment is very effective in blocking embryo development in two filarial nematodes, B. pahangi and Dirofilaria immitis. Embryo degeneration was documented by TEM, while the inhibition of the transovarial transmission of Wolbachia was documented by PCR. Phylogenetic analysis on the ssrDNA sequence of the Wolbachia of B. pahangi confirms that the phylogeny of the bacterial endosymbionts is consistent with that of the host worms. The possibility that tetracycline inhibition of embryo development in B. pahangi and D. immitis is determined by cytoplasmic incompatibility is discussed.

[Efficacy of ivermectin in preventing Dirofilaria repens infestation in dogs naturally exposed to contagion]. / Sulla validità dell'ivermectina nella profilassi dell'infestione con Dirofilaria repens in cani naturalmente esposti al contagio.

The ability of ivermectin to control canine dirofilariosis in naturally infected dogs was tested. Two studies were carried out in the coast line of Grosseto district (Italy), where D. repens infection is endemic. A sample of 384 dogs from the area was examined as background controls and we found D. repens in 21.1%, D. immitis in 7.8% and both species in 6.5%. In the first study we used 72 privately-owned dogs, of varying sex, breed and age; all animals were negative to Knott's modified test for microfilariae and to CITE test for the adult antigens. All the dogs were treated monthly per os with tablets of ivermectin (> or = 6 mcg/kg) seven times from May 1991. All dogs were found negative for microfilariae 6-8 months after the last treatment. The second experiment was carried out on 16 Beagles aged 5.5-7 months (8 control dogs and 8 treated dogs). The dogs lived in a semi-open kennel in the selected area. We treated 8 dogs--8 times at monthly intervals, starting in June--with ivermectin tablets per os (> or = 6 mcg/kg). The monthly examination for circulating microfilariae (Knott's modified test) showed D. repens in two control dogs 7 months after the beginning of the experiment, one month later in 6 control and in another control animal also positive for D. immitis between the 10th and 11th month. Treated dogs were always negative. At the necropsy of all the dogs, about 11 months after the beginning of the experiment, we found adults or pre-adults of filariae in all the control dogs. Four animals had a double infection, 3 with D. repens and one with D. immitis. We never found adults or pre-adults of filariae in treated dogs.

Ivermectin against larval stages of Dirofilaria repens in dogs.

The prophylactic efficacy of ivermectin against Dirofilaria repens infections in dogs was investigated. A first trial was carried out on 15 dogs exposed to four inoculations of L3 larvae at 15-day intervals and treated, in groups of five, with 0, 6 or 12 micrograms/kg body weight of ivermectin given per os 30 and 60 days after the first inoculation. Necropsy, performed about 9 months later, revealed that worm burdens were reduced by 86.6 and 92.8% for the 6 and 12 micrograms/kg dose levels, respectively. In a second trial with an otherwise identical protocol, a dose rate of 24 micrograms/kg of ivermectin was tested in 12 dogs. Only one of the six treated dogs was found worm free at necropsy. The worm burden was reduced by 87.9% in treated animals as opposed to controls. A lengthening of the prepatent periods, which might be considered dose related, was apparent in all treated groups. Ivermectin was not completely effective in preventing establishment of experimental infections with D. repens in dogs.

Efficacy of ivermectin against Dirofilaria immitis larvae in dogs 30 and 45 days after induced infection.

Forty-two Beagles, 14 to 15 weeks of age, were injected subcutaneously with 50 infective larvae of Dirofilaria immitis and were allotted by weight, within sex, to 6 treatment groups. Group 1 served as nonmedicated vehicle-treated controls; groups 2 through 5 were given an oral tablet form of ivermectin at dosages of 0.3 micrograms/kg, 1.0 micrograms/kg, 2.0 micrograms/kg, and 3.3 micrograms/kg at 30 days after inoculation; group 6 was given the 2.0 micrograms/kg dosage at 45 days after inoculation. Dogs were euthanatized and necropsied 154 days after treatment (day 139 for dogs in group 6) and examined for heartworms. On the numerical bases of helminths recovered in the groups, the efficacies for preventing heartworm maturation were 0% (group 2), 53.2% (group 3), 97.2% (group 4), 98.1% (group 5), and 63.8% (group 6). Drug-related adverse reactions were not detected.

A simple method for the identification of compounds which inhibit tubulin polymerization in filarial worms.

The incubation in vitro of excised ovaries of Dirofilaria immits in medium containing mebendazole between 10(-5) and 10(-8) M for four or six hours results in the accumulation of up to 20% of oogonial cells in arrested mitotic metaphase. In aceto-orcein-stained squashes of the tissue, cells possess condensed chromosomes but no detectable spindle microtubules. Similar results were obtained with colchicine, but the lowest effective concentration of this drug was 10(-7) M. This procedure affords a simple and rapid method for detecting compounds capable of inhibiting tubulin polymerization in filarial worms.

Oxidative decarboxylation reactions in Dirofilaria immitis glucose metabolism.

1. Malic enzyme (EC 1.1.1.39) activity was demonstrated in the mitochondrial fraction of dog heartworm extracts. 2. Data published earlier together with those presented here confirm the presence of all the enzymes of the pentose shunt. 3. 14C from uniformly labelled glucose was incorporated into the nucleic acids, and methylene blue increased production of xylose-5-phosphate and of 14CO2 from [1-14C]glucose indicating a functioning pathway. 4. The oxidative decarboxylation of malate and of 6-phosphogluconate may account for the observed labelled CO2 formed when labelled glucose is metabolized since a functional tricarboxylic acid cycle is doubtful in this parasitic helminth.