Thirteen cases of pulmonary dirofilariasis in a single institution in Okinawa Island.

Pulmonary dirofilariasis is an infection caused by Dirofilaria immitis, which is an endemic parasite in Japan. We experienced 13 surgical cases of pulmonary dirofilariasis in our hospital. Of the 13 patients, 61.5% were men. The responsible lesions were located in the right lung in all cases, and 76.9% of them were in the lower lobe. Histologically, 12 cases showed necrotic nodules with peripheral granuloma with worms inside the pulmonary artery. One case did not show a necrotic nodule but showed only thickening and hyalinization of the pulmonary artery wall with a degenerated worm inside. Eosinophils were found histologically in all cases. Thirteen cases of dirofilariasis in one institution seem to be the largest number in Japan, based on previous reports. One reason for this increased prevalence may be the hot and humid climate of our prefecture considering the ecology of the mosquito as a vector. Elastic staining and eosinophils in peripheral granulomatous areas can contribute to the diagnosis when the worms are degenerated.

Entomological and sociobehavioral components of heartworm (Dirofilaria immitis) infection in two Florida communities with a high or low prevalence of dogs with heartworm infection.

OBJECTIVE To assess knowledge, attitudes, and practices regarding heartworms (Dirofilaria immitis) and mosquito vectors among residents (dog owners and non-dog owners) in 2 neighborhoods in Florida and to perform entomological surveys of mosquito species in these neighborhoods and identify mosquito species infected with heartworm. DESIGN Cross-sectional study. SAMPLE 2,572 mosquitoes and 96 residents of 2 northern Florida communities. PROCEDURES A 32-item questionnaire was orally administered to a convenience sample of community residents to collect information on their knowledge, attitudes, and practices regarding heartworms. Afterward, mosquito larvae were collected from the respondents' properties and adult mosquitoes were collected in both communities from surrounding wooded areas and residences of respondents. Mosquito species distribution and D immitis infection rates were determined. RESULTS Many residents (59% [57/96]) were unaware that mosquitoes transmit heartworms. Compared with non-dog owners, dog owners were significantly more likely to know about mosquito transmission, be concerned about heartworms, accurately estimate cost of treatment, and demonstrate willingness to pay for treatment. Most owners (71% [47/66]) administered heartworm preventives; those who did not cited lack of risk awareness, and cost was the least common reason. Of 28 mosquito species collected, Anopheles quadrimaculatus, Culex erraticus, Culex nigripalpus, Coquillettidia perturbans, Culiseta inornata, Aedes albopictus, and Aedes aegypti were positive for D immitis infection. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that improved veterinary and public health messaging regarding the role of mosquitoes as vectors, higher cost of heartworm treatment versus prevention, and mosquito reduction and avoidance methods is needed.

Seroprevalence of heartworm infection, risk factors for seropositivity, and frequency of prescribing heartworm preventives for cats in the United States and Canada.

OBJECTIVE To determine the seroprevalence of heartworm infection, risk factors for seropositivity, and frequency of prescribing heartworm preventives for cats. DESIGN Prospective cross-sectional study. ANIMALS 34,975 cats from 1,353 veterinary clinics (n = 26,707) and 125 animal shelters (8,268) in the United States and Canada. PROCEDURES Blood samples were collected from all cats and tested with a point-of-care ELISA for Dirofilaria immitis antigen, FeLV antigen, and FIV antibody. Results were compared among geographic regions and various cat groupings. RESULTS Seropositivity for heartworm antigen in cats was identified in 35 states but not in Canada; overall seroprevalence in the United States was 0.4%. Seroprevalence of heartworm infection was highest in the southern United States. A 3-fold increase in the proportion of seropositive cats was identified for those with (vs without) outdoor access, and a 2.5-fold increase was identified for cats that were unhealthy (vs healthy) when tested. Seroprevalence was 0.3% in healthy cats, 0.7% in cats with oral disease, 0.9% in cats with abscesses or bite wounds, and 1.0% in cats with respiratory disease. Coinfection with a retrovirus increased the risk of heartworm infection. Heartworm preventives were prescribed for only 12.6% of cats at testing, and prescribing was more common in regions with a higher seroprevalence. CONCLUSIONS AND CLINICAL RELEVANCE At an estimated prevalence of 0.4%, hundreds of thousands of cats in the United States are likely infected with heartworms. Given the difficulty in diagnosing infection at all clinically relevant parasite stages and lack of curative treatment options, efforts should be increased to ensure all cats receive heartworm preventives.

Increasing risks of human dirofilariasis in travelers.

BACKGROUND: Dirofilariasis is a zoonotic nematode infection of domestic and wild carnivores that can be transmitted to man by infected mosquitoes. METHODS: Internet search engines were queried with the key words to examine case reports, series, and descriptive analyses of animal and human dirofilariasis to meet the objectives of this review to describe the increasing prevalence of animal and human dirofilariasis worldwide; to resolve misconceptions regarding the pathophysiology and outcomes of animal versus human dirofilariasis; and to recommend new strategies for the diagnosis, management, and prevention of human dirofilariasis in travelers. RESULTS: Descriptive epidemiological studies in the United States and Europe have now established dirofilariasis as an emergent parasitic disease of dogs and man. Global warming has extended the mosquito-vector-borne transmission cycles, enzootic distributions, and canine microfilarial prevalences of the disease to non-endemic regions. CONCLUSIONS: Travel medicine clinicians must remain vigilant regarding the possibilities of human pulmonary dirofilariasis when solitary "coin lesions" appear on screening chest X-rays or abdominal neuroimaging studies in asymptomatic patients without peripheral hypereosinophilia. The least invasive diagnostic methods are recommended. Future investigations should focus on conducting active epidemiological surveillance for dirofilariasis in humans and animals; on improving canine dirofilarial chemoprophylaxis; and on developing new, rapid molecular methods for diagnosing and differentiating human dirofilarial infections.

Attraction of mosquitoes to domestic cats in a heartworm enzootic region.

Heartworm disease is caused by a mosquito-borne parasite that can affect many different mammalian species and has worldwide distribution. The agent, Dirofilaria immitis (Leidy 1856), infect mainly dogs but feline infection have been frequently reported in the last decade. Feline heartworm infection is difficult to detect, therefore, low reported prevalence could reflect true low prevalence or poor diagnostic efficiency. As mosquitoes are known to be attracted differently by different mammalian species, mosquitoes were collected from both a cattery and a contiguous home located in a canine heartworm enzootic area in Niterói, state of Rio de Janeiro, Brazil. For 14 months, mosquitoes were collected weekly for genus identification, speciation when possible, and for individual blood meal identification. Culex species mosquitoes were the most captured and those most frequently found with feline blood meal, followed by Aedes species that, although captured in lower numbers, also fed on feline blood. While Culex species mosquitoes have been reported as potential secondary heartworm vectors for dogs and primary vectors for cats, the present results suggest that Aedes species mosquitoes may also be involved in feline heartworm transmission in a larger proportion than previously thought.

Survey of 11 western states for heartworm (Dirofilaria immitis) infection, heartworm diagnostic and prevention protocols, and fecal examination protocols for gastrointestinal parasites.

Heartworm infection in dogs and cats in the western United States is a fairly new phenomenon, and for this reason it is often considered to be of minimal significance. The purpose of this survey was to collect data from 11 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming) in an effort to assess awareness of heartworm disease and identify areas in which improvement in understanding is needed. To accomplish this goal, veterinary clinics and hospitals in these states were sent a one-page survey in early 2006. The results of the survey demonstrate that cases of heartworm disease have been reported in all 11 states, illustrating the importance of annual testing and the routine use of preventives.

Human pulmonary dirofilariasis in a patient whose clinical condition altered during follow-up.

Pulmonary dirofilariasis is a rare disease. We have experienced a case which developed pleural effusion while being followed, rendering it difficult to establish the diagnosis. The patient, a 53-year-old woman, had previously undergone two operations; one for uterine cancer and another for breast cancer. She developed a cough in February 2002, and chest computed tomography (CT) scans disclosed a nodular mass in the right lung. A biopsy revealed a fibrous nodule with macrophage aggregation. Pleural effusion was demonstrated on chest CT scans performed in May. As the possibility of malignant tumor could not be ruled out, an operation was undertaken. The nodular lesion showed marked coagulation necrosis, and dead parasites were noted in the vascular lumen. The parasites had the characteristic morphological features of Dirofilaria immitis. Immunological studies produced a positive test result for the anti-dirofilaria immitis antibody; hence a diagnosis of pulmonary dirofilariasis was made.

[Research on Culicidae attracted to dog bait in Piedmont]. / Indagine sui Culicidi attratti da esca canina in Piemonte.

Dog attracted mosquitoes were collected in Piedmont (NW Italy) in 1992 and 1993. Sampling sites where chosen on ecological and epidemiological basis, according to the results of a previous study on the distribution and prevalence of canine filariosis in this region. Dog baited traps were operated monthly (two nights/site from June to September) in six plain sites differing in the prevalence of heartworm infected dogs (including two sites where no positivity was recorded). A single capture was carried out in July-August in three more plain and four hill localities, as well as in a prealpine and a suburban zone inside the heartworm endemic area. The following species were collected (number of specimens in brackets): Aedes caspius (2255), Ae, cantans (1), Ae. cinereus (1), Ae, geniculatus (7), Ae. vexans (58), Aedes spp. (221), Anopheles claviger (1), An. maculipennis s.l. (405), Coquillettidia richiardii (16), Culex modestus (6361), Cx. pipiens (2032), Cx. territans (2), Culex spp. (94), Culiseta annulata (1). Cx. pipiens was captured in 15 sites, Cx. modestus and Ae. caspius in 13, and 12, respectively, An. maculipennis s.l. in 7, Ae. vexans in 6, Cq. richiardii in 4, Ae. geniculatus in 3, Cx. territans in 2, Ae. cantans, Ae. cinereus, An. claviger and Cs. annulata in one. Species abundance and relative composition differed between habitats and between similar habitats with a different prevalence of microfillaraemic dogs. Regression analysis of heartworm prevalence vs. mosquitoes abundance demonstrated a positive linear relationship. Data suggest that four species (Ae. caspius, An. maculipennis s.l., Cx. modestus and Cx. pipiens) are playing a major role in the transmission of canine filariosis in Piedmont.

Ophthalmic dirofilariasis.

PURPOSE: To report a rare case of ophthalmic dirofilariasis in a 68-year-old man with sudden, intense pain and itching in the left eye. The nematode was located in the eye and recognized as Dirofilaria repens. METHODS: Slit-lamp examination disclosed a moving nematelminth under the bulbar conjunctiva of the left eye. The nematode was surgically removed. RESULTS: The nematelminth surgically removed from the subconjunctival space was identified as D repens on the basis of transverse sections and its macroscopic characteristics. CONCLUSION: It is important to identify the nematode as D repens, based on both its microscopic and macroscopic characteristics, to avoid treatment with anthelminthic agents. The surgical removal of the worm is the sole recommended treatment.

[Dirofilariasis in France: a case in Languedoc in an HIV-seropositive patient]. / La dirofilariose en France: un cas languedocien chez un sujet sérologiquement positif pour le VIH.

Dirofilaria repens is an endemic canine parasite in the Mediterranean area. Human infestation is rare. We observed a case in an HIV-positive patient who presented an ocular filaria which was successfully removed under local anesthesia. In man, filariae may be expulsed without a parasite cycle or complete a growth cycle, depending on the individual's immunological status. The disease has been known in southern France for several centuries, mainly in lagoons near the Mediterranean seaside. A review of the literature however shows that observation of clinical cases is rare, only 46 cases having been reported to date. Outcome is favorable.

Effect of heartworm infection on fade of norepinephrine-induced constriction in canine pulmonary vein.

OBJECTIVE: To test the possible role of endothelial cells in mediating fade of norepinephrine-induced constriction and the effect of heartworm infection on these responses. DESIGN: Rings of pulmonary vein from control and heartworm-infected dogs were constricted with norepinephrine (10(-5.5)M) and followed over 65 minutes. Time profiles were established by measuring active tension every 2 minutes for the first 10 minutes, then every 5 minutes for 15 minutes, then every 10 minutes for 40 minutes. Time profiles were done in pulmonary vein rings with and without endothelial cells, and in the presence and absence of N-nitro-L-arginine methyl ester (L-NAME; nitric oxide synthase inhibitor), mefenamic acid (cyclooxygenase inhibitor), or methylene blue (guanylate cyclase inhibitor). ANIMALS: 12 noninfected control and 11 heartworm-infected dogs. RESULTS: Pulmonary vein constricted with norepinephrine spontaneously loses tension (fades) over time. Fade was not different between control and heartworm-infected dogs. In pulmonary vein from control dogs, methylene blue decreased fade while L-NAME and mefenamic acid did not. In pulmonary vein from heartworm-infected dogs, L-NAME and methylene blue significantly decreased fade, but mefenamic acid did not. CONCLUSION: Nitric oxide, but not cyclooxygenase products, mediates fade of norepinephrine-induced constriction in pulmonary vein from heartworm-infected dogs. In control dogs, neither nitric oxide nor cyclooxygenase products appear to be involved in fade. We conclude that in canine pulmonary vein, fade of norepinephrine-induced constriction is mediated, in part, by endothelial cells. CLINICAL RELEVANCE: Altered production of endothelium-derived relaxing factors may be important in the pathogenesis of heartworm disease.

Dirofilaria immitis: heartworm products contract rat trachea in vitro.

Subtle decreases in racing performance have been noted in asymptomatic greyhounds with heartworm burdens insufficient to obstruct pulmonary outflow, suggesting that alternative mechanisms may be involved in the pathogenesis of canine heartworm disease. Endothelium-dependent relaxation is depressed in the in vivo femoral artery of heartworm-infected dogs, in the in vitro pulmonary artery from heartworm-infected dogs, and in the in vitro rat aorta exposed to heartworms, heartworm-conditioned medium, and serum from heartworm-infected dogs. These findings suggest that circulating filarial factors may play a role in the pathogenesis of heartworm infection. We examined the effect of Dirofilaria immitis, the canine heartworm, on acetylcholine-induced contraction of rat tracheal rings. In epithelium-intact rings, both heartworms and heartworm-conditioned medium increased acetylcholine-induced contraction. Pretreatment of the parasites with aspirin prevented the filarial-induced increase in acetylcholine-induced contraction, suggesting that parasite cyclooxygenase products are responsible for the effect. In addition, heartworms caused contraction in both epithelium-intact and denuded rings and this effect was markedly decreased by pretreatment of the worms with aspirin. Filarial cyclooxygenase metabolites may cause airway hyperreactivity and parasite-derived factors could play a role in the subtle changes in exercise performance seen in asymptomatic greyhounds with low worm burdens. Comparable mechanisms may be operating in other filarial diseases, including those that affect humans in tropical countries.

Dirofilariose pulmonar: relato de um caso / Pulmonary dirofilariasis: a case report

Os autores apresentam o caso de um paciente de 60 anos, sexo masculino, que após ter apresentado um episódio de dor torácica desenvolveu quadro de tosse e expectoraçäo. A radiografia simples de tórax mostrou um nódulo solitário em projeçäo do lobo superior direito, sem calcificaçäo, que persistiu inalterado após dez dias do desaparecimento dos sitnomas. Outros exames como tomografía computadorizada, teste de Mantoux, pesquisa de BAAR no escarro e broncoscopia näo acrescentaram nenhuma informaçäo, permenecendo o diagnótico anterior de foco pneumônico. A punçäo transparietal näo permitiu obter-se o diagnóstico definitivo. Foi, entäo, realizada toracotomia e o exame histopatológico do nódulo retirado revelou granuloma com necrose e larvas de Dirofilaria immitis. Os autores discutem os aspectos etiopatogênicos diagnósticos e terapêuticos desta rara afecçäo pulmonar

Human subcutaneous dirofilariasis caused by Dirofilaria repens. Report of a case in Norway and review of recent literature.

A case of dirofilariasis in a Norwegian man is reported. The causal agent was identified as Dirofilaria repens Railliet et Henry, 1911. To the best of our knowledge, this is the first report from a Scandinavian country on dirofilariasis caused by Dirofilaria repens. The infection was probably acquired in Majorca four years before it was diagnosed in Molde, Norway.

Dirofilariasis humana pulmonar: reportaje del primer caso nacional / Human pulmonar dirofilariasis: nacional first case report

La dirofilariasis pulmonar humana es una zoonosis transmitida por un mosquito del perro al hombre, que se presenta a nivel mundial. El presente artículo es el reporte del primer caso nacional de dirofilariasis pulmonar humana que se tenga conocimiento, donde se analiza el cuadro clínico, los exámenes auxiliares y el estudio anatomopatológico realizados y se revisa la literatura actual correspondiente. En nuestro medio es preciso considerarla en el diagnóstico diferencial de otras patologías pulmonares como cáncer, tuberculosis y quiste hidatídico complicado.

Human subcutaneous dirofilariasis. 1. Two new cases in Venice. Identification of the causal agent as Dirofilaria repens Raillet and Henry, 1911.

Two human cases of subcutaneous dirofilariasis are described in a 41 year-old woman and in a 14 year-old boy living in Venice Lido. In the first case, the development of a nodule at the left forearm had been preceded by generalized symptoms such as pruriginous urticarioid patches in various regions of the body, transitory swellings and 8% eosinophilia. From the nodule, an adult female of Dirofilaria repens was recovered with embryos visible in the uterus. In the second case, the parasite was localized in the scrotum, where it had caused an extensive oedema with the formation of a nodule having the size of a nut. An immature female specimen of D. repens was found. In both cases, the serological tests (Indirect Haemoagglutination and Bentonite Flocculation) gave significant titres specific for filariasis (1:256 and 1:20 in the first case, 1:128 and 1:5 in the second, respectively). A parasitological survey of blood samples from 145 stray dogs captured in the territory of the Venice municipality revealed the presence of D. repens in 8.3% of cases, D. immitis in 4.8% and Dipetalonema reconditum in 0.7%. This is the first time that the aetiological agent of human subcutaneous dirofilariasis was identified as D. repens in Italy.