Dirofilaria Species Research Articles

Zoonotic Dirofilaria sp. “hongkongensis” in subcutaneous nodules from dogs and cats, Hong Kong SAR

BackgroundDirofilaria sp. “hongkongensis” is a putative Dirofilaria species, initially identified in subcutaneous nodules in humans in Hong Kong and in other South and Southeast Asian regions. While it differs genetically from the better-known zoonotic species, Dirofilaria repens and Dirofilaria immitis, information on the lesions caused by Dirofilaria sp. “hongkongensis” in the hosts as well as on its biology is scarce. This study documents for the first time the presence of this filarioid nematode in subcutaneous nodules in dogs and cats in Hong Kong, where it was originally described in human patients, therefore providing evidence for the zoonotic nature of this parasite.MethodsRecords of Veterinary Diagnostic Laboratory of City University of Hong Kong were searched between 2019 and 2024 for histological reports of possible filarioid-associated lesions. Tissue samples were collected by excisional surgical biopsy and processed with routine paraffin techniques. Selected slides were stained using various staining techniques [i.e., hematoxylin and eosin, periodic acid–Schiff (PAS), Grocott methenamine silver (GMS) or Ziehl–Neelsen (ZN) and Gram stain]. DNA from formalin-fixed paraffin-embedded tissue were extracted, submitted to conventional polymerase chain reaction (cPCR) and sequencing (i.e., cox1 and 12S rRNA genes) and phylogenetic analyzed.ResultsA total of five subcutaneous nodules from four cats and one from a dog with histopathology suggestive of filariosis were selected. The presence of Dirofilaria sp. “hongkongensis” was morphologically and molecularly confirmed in one dog and one cat. Both histopathological presentation and phylogenetic analysis enabled classification of this species close to D. repens and within the subgenus Nochtiella. In the remaining three cases, one showed histological evidence of aberrant nematode migration, while non-parasitic causes were identified in the other two.ConclusionsThis study provides the first evidence of Dirofilaria sp. “hongkongensis” in subcutaneous nodules in cats and dogs. The histology of clinical lesions of this filarioid species herein described is closely related to those caused by D. repens. Overall, this species should be considered in differential diagnoses of subcutaneous lesions in both animals and humans in the region.Graphical

Peculiar Presentation: Dirofilariasis Unveiled in the Temporalis Muscle of a Teenager.

Dirofilariasis, a parasitic infection typically affecting animals, occasionally presents in humans, transmitted through mosquito bites. This article explores an unusual case of dirofilariasis affecting the temporalis muscle, a rare occurrence. With 40 identified Dirofilaria species, human infections are primarily attributed to Dirofilaria repens and Dirofilaria immitis, causing pulmonary and subcutaneous lesions. While deep tissue infections are exceptionally rare, we present a unique case in a 15-year-old girl. The patient exhibited a 3-month history of a slowly growing swelling in the left temporal region, accompanied by intermittent pain and limited jaw movement. Initial differential diagnoses included benign tumors, cysts, or abscesses. Ultrasound revealed a hypoechoic mass, leading to surgical excisional biopsy. Histopathological examination confirmed Dirofilaria, prompting a combination of antiparasitic medication and surgical intervention. Dirofilariasis in deep tissues, especially muscles, is uncommon. Diagnosis challenges arise due to its rarity and similarity to other conditions. Imaging may not be specific, necessitating histopathological examination. Treatment involves antiparasitic medications like ivermectin, supplemented with surgery in specific cases. Our patient's favorable outcome underscores the importance of early recognition and a multidisciplinary approach for effective management.

Dirofilaria immitis and Dirofilaria striata (Spirurida: Onchocercidae) detected in wild carnivores from Texas, United States

Dirofilaria immitis and Dirofilaria striata (Spirurida: Onchocercidae) are epidemiologically important filarial nematodes detected in wild carnivores sympatric to domestic animals and humans. In this study we surveyed for Dirofilaria species among previous studies archived blood samples (n = 202) of wild carnivores sourced across Texas between the years of 2014–2016 and 2020 to 2023. In total, 117 coyotes (Canis latrans), 67 raccoons (Procyon lotor), 12 gray foxes (Urocyon cinereoargenteus), five bobcats (Lynx rufus), and one striped skunk (Mephitis mephitis) were tested through the amplification of the partial cytochrome oxidase c subunit 1 (COI) gene followed by sequencing. Dirofilaria immitis was detected in 11.39% (95% CI = 7.71–16.51) of the samples (21 coyotes and two raccoons), while D. striata was detected in a single bobcat. Dirofilaria immitis sequences had 99.85%–100% (99.92% ± 0.08) similarity with other D. immitis sequences in GenBank. The sequence of D. striata from the bobcat was 100% similar to the single COI sequence available in GenBank. Data from this study reinforce the role of coyotes as a wild reservoir for D. immitis and suggest that raccoons may also play a role in the epidemiology of this parasite. This study additionally provides molecular data on D. striata, an understudied filarioid of felids.

Dirofilaria immitis and Onchocercidae spp. in wild felids from Brazil.

Among the species described within the Onchocercidae family, Dirofilaria immitis is regarded as the most common worldwide, causing severe and often fatal conditions in dogs, cats, and occasionally humans. Dirofilaria spp. are vectored by mosquitoes, simulids, and culicoids, with their epidemiology dependent on the geographical distribution of competent vectors. Eight species of Dirofilaria have been reported so far in Brazil, of which six parasitize non-human primates, deer, procyonids, and marsupials. Here, we investigated the occurrence of Onchocercidae in wild felids (i.e., Panthera onca, Puma concolor, Herpailurus yagouaroundi, Leopardus geoffroyi, Leopardus guttulus, Leopardus pardalis, Leopardus wiedii, Leopardus munoai) from different locations in Brazil. Overall, 82 samples (n = 63 blood; n = 19 tissues) were molecularly screened for cytochrome c oxidase subunit-1 (cox1) gene. Four (i.e., 4.8%) wild felid samples were positive, and at BLAST analysis, the obtained sequences showed varying percentage of nucleotide identity with the genera Brugia (i.e., 87-88%), Setaria (i.e., 89%), and D. immitis (i.e., 94.4%). Phylogenetic analyses clustered sequences obtained into three distinct clades, one with D. immitis and the remaining two with other Onchocercidae spp. Data herein obtained highlight the need for a more comprehensive understanding of the diversity and biology of Onchocercidae in South America in order to assess the potential impact that these species may have for domestic and wild animals, as well as humans.

The Brief Case: Dirofilaria species causing a subcutaneous nodule after a visit to the beach in Florida.

The Brief Case: Dirofilaria species causing a subcutaneous nodule after a visit to the beach in Florida.

Dirofilaria immitis conquering the regions in Slovakia previously endemic for D. repens

The present study was focused on the current state of Dirofilaria species distribution in the territory of the Slovak Danubian Lowland, a region previously identified endemic for Dirofilaria repens. For the research, blood samples of 330 dogs tested positive for dirofilariosis using concentration tests or “rapid heartworm tests” were sent by private veterinary practitioners for further DNA analyses and species determination. The results revealed an unquestionable change in the pattern of Dirofilaria species distribution with Dirofilaria immitis, diagnosed as the agent of mono- and co-infections with D. repens, responsible for 60.00% of all cases. The results showed that in the course of the last 5 years, D. immitis has spread significantly in Slovakia and has become the dominant causal agent of dirofilariosis in the former endemic areas of D. repens distribution, which increases infection risk for both dogs and humans.

Parasitism of Dirofilaria incrassata Molin, 1858 in coatis (Nasua nasua).

Populations of the coati, Nasua nasua, like the populations of other wild animals, are regulated by several biotic or abiotic factors. For example, parasites act as a biotic factor affecting the dynamics and density of coati populations. The parasitic nematodes of coatis include Dirofilaria species, such as Dirofilaria immitis, Dirofilaria repens, and Dirofilaria incrassata. Considering that there are few records on parasitism by D. incrassata, including information on the life cycle or location in the host body, this study aimed to investigate the infection of N. nasua by D. incrassata in midwestern Brazil. Thus, two coatis (males and adults) from the Cerrado of Goiás, which died (cause unknown) at the Wild Animal Screening Center/IBAMA in the municipality of Goiânia, Goiás, Midwestern of Brazil, were dissected and all helminths found were collected, identified following specific keys and quantified. A total of 85 specimens of D. incrassata were collected, with a mean parasitic intensity of 42.5 and a parasitic amplitude ranging from 40 to 45, measuring 41-93mm in length and 0.23-0.45mm in width. All helminths were adults and were distributed in the superficial and deep fascia (at different levels) from the neck to the hind limb. Most helminths were tangled, with some encased in a connective tissue film. Most reported human heartworm cases refer to subcutaneous or ocular heartworm infection, mainly caused by D. repens, although other species of heartworm may be associated. D. incrassata was not reported as zoonotic agent, diferently of other Dirofilaria species associated with wild animals and with zoonotic potential in the Americas. This study reiterates N. nasua as the definitive host for D. incrassata and the subcutaneous tissue as the site of choice for this helminth in the adult form. In addition, it reports new body regions where the parasite occurs. This study is the first to document the occurrence of D. incrassata infestation in the State of Goiás, Brazil.

Body Imaging of Bacterial and Parasitic Zoonoses: Keys to Diagnosis.

Zoonotic infections, which are transmitted from animals to humans, have been a substantial source of human disease since antiquity. As the human population continues to grow and human influence on the planet expands, humans frequently encounter both domestic and wild animals. This has only increased as deforestation, urbanization, agriculture, habitat fragmentation, outdoor recreation, and international travel evolve in modern society, all of which have resulted in the emergence and reemergence of zoonotic infections. Zoonotic infections pose a diagnostic challenge because of their nonspecific clinical manifestations and the need for specialized testing procedures to confirm these diagnoses. Affected patients often undergo imaging during their evaluation, and a radiologist familiar with the specific and often subtle imaging patterns of these infections can add important clinical value. The authors review the multimodality thoracic, abdominal, and musculoskeletal imaging findings of zoonotic bacterial (eg, Bartonella henselae, Pasteurella multocida, Francisella tularensis, Coxiella burnetii, and Brucella species), spirochetal (eg, Leptospira species), and parasitic (eg, Echinococcus, Paragonimus, Toxocara, and Dirofilaria species) infections that are among the more commonly encountered zoonoses in the United States. Relevant clinical, epidemiologic, and pathophysiologic clues such as exposure history, occupational risk factors, and organism life cycles are also reviewed. Although many of the imaging findings of zoonotic infections overlap with those of nonzoonotic infections, granulomatous diseases, and malignancies, radiologists' familiarity with the imaging patterns can aid in the differential diagnosis in a patient with a suspected or unsuspected zoonotic infection. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

A New Tunisian Case of Subcutaneous Dirofilariasis

Dirofilariasisis an emerging helminthic zoonosis seldom reported. Human involvement is a clinical entity caused by infection with nematode species of the genus Dirofilaria. This cosmopolitan zoonos is usually affecting dogs and cats. Humans are accidental hosts and rarely affected. We reported a new Tunisian case of dirofilariasis presenting as a subcutaneous periorbital and frontal nodule.

Human dirofilariosis (D.repens) in the subcutaneous tissues of the head: Clinical case in the department of neurosurgery of the Interregional Clinical and Diagnostic Center of Kazan

Human Dirofilariasis is a zoonosis caused by thin nematodes of Dirofilaria species (D. repens, D. immitis, D. tenuis и D. Ursi) that belong to the Onchocercidae family. Larval stages of Dirofilaria are usually occur in their primary hosts like cats and dogs and rarely invade incidental hosts - human.
 In the article described a clinical case of a patient with skull base meningioma who was admitted to the neurosurgical department for elective surgical treatment. The dense nodule was palpated in the subcutaneous tissue of the frontal area of the head. While removing the subcutaneous node a thin white alive worm was evacuated during the surgery. The microscopical examination verified D. repens.
 Human Dirofilariasis is a rare disease in the Republic of Tatarstan, Russia. However, there is observed a growth of the number of dirofilariasis cases in the recent years. Nine patients with dirofilariasis were diagnosed in the Republic of Tatarstan within 2019-2022.

Serodiagnostic difficulties and possibilities of heartworm disease in regions where both Dirofilaria immitis and Dirofilaria repens infections occur.

This retrospective study was performed on 71 dogs which had been admitted for heartworm screening or with clinical suspicion of heartworm disease. The examination methods included polymerase chain reaction (PCR) to identify Dirofilaria immitis and/or Dirofilaria repens infections and a heartworm antigen (Ag) test (VetScan). By using PCR, 26 dogs were found positive only for Dirofilaria immitis (Group 1), while 21 dogs for both D. immitis and D. repens (Group 2). Group 3 included 24 dogs with D. repens infection only according to the PCR results. The sensitivity of the VetScan Ag test for the Group 1 and 2 animals proved to be 97.7% (95% Blaker confidence interval; CI 89.0%-99.9%). The specificity of the VetScan Ag test, calculated from the results of Group 3, was found to be 66.7% (95% CI 45.6%-83.1%), which was lower than that reported from the USA, where D. repens does not occur. In cases when PCR results were positive for D. repens but negative for D. immitis, the occult dirofilariosis was the likely explanation for the positive D. immitis Ag tests. These observations highlight the importance of performing more Ag tests simultaneously in those areas where both Dirofilaria species are present.

A new Tunisian case of subcutaneous dirofilariasis

Dirofilariasis is a cosmopolitan zoonosis of dogs and cats, accidentally affecting humans. Human dirofilariosis is a clinical entity caused by infection with nematode species of the genus Dirofilaria D. Repens is the most implicated species. It is responsible for benign skin manifestations but often poses problems of differential diagnosis. Although Dirofilaria infections are rare, we should be aware of their possibility. We reported a new Tunisian case of dirofilariasis presenting as a subcutaneous periorbital and frontal nodule caused by D repens in an old Tunisian man.

Human Dirofilariasis Caused by Dirofilaria repens in Sri Lanka from 1962 to 2020.

Sri Lanka has reported the highest prevalence of human dirofilariasis cases in Asia. Thus far, Dirofilaria repens is the only reported Dirofilaria species that affect humans, dogs, and cats in Sri Lanka. Therefore, this systematic review was carried out to analyse the studies performed on dirofilariasis in Sri Lanka. Peer-reviewed articles were searched on dirofilariasis published on Google Scholar, PubMed, Cochrane, and ResearchGate from January to March 2021. Articles were selected using inclusion and exclusion criteria. Three reviewers assessed the studies and extracted data independently to minimize the risk of bias. Extracted data were compiled, and then the results were compared and discussed in this systematic review. Twenty-five studies performed in Sri Lanka were analysed, and high prevalence areas, frequent clinical presentations, diagnostic methods, reservoir hosts, and treatment were identified. More than 173 cases of human dirofilariasis caused by D. repens were reported from 1962 to 2020 in 20 districts among 25 investigated. The highest number of cases (n = 80) was recorded during 2010-2012 period. Canine and feline dirofilariasis are reported countrywide, and a large number of potential mosquito breeding sites could be seen in Sri Lanka. The number of reported cases of human dirofilariasis has been varied from 1962 to 2020. The highest number of cases has reported in 2010-2012, and then the number of cases has dropped. This may be due to underreporting. Thus, awareness of Dirofilaria repens infection in humans, control measures in endemic areas and further research on dirofilariasis in other districts of Sri Lanka are crucial.

Nematodes of the genus Dirofilaria Railliet et Henry, 1911, parasites of carnivorous mammals in Uzbekistan: spread and ecology

The purpose of the research is study of some issues of fauna, spread and ecology of nematodes of the genus Dirofilaria in biogeocenoses of Uzbekistan.Materials and methods. Nematodes of the genus Dirofilaria (D. immitis and D. repens) were collected from domestic and wild carnivorous mammals within Uzbekistan. The studies were carried out during 2015–2021. 559 individuals of carnivorous mammals were studied by the method of complete helminthological dissection. The found parasites were collected and fixed according to generally accepted methods. The helminths and ectoparasites were identified and their morphology was studied by temporary and permanent specimens using modern microscopes. The parasite species was identified in accordance with the keys and descriptions given in the papers by domestic and foreign researchers. To identify intermediate hosts of Dirofilaria (D. immitis), mosquitoes (Culicidae) were caught and examined on and around dogs. A total of 4064 specimens of mosquitoes were studies in spring, summer and autumn using the generally accepted method. We determined the prevalence and intensity of helminth infection in carnivorous. To study the nucleotide sequences in Dirofilaria, we used mature nematodes D. immitis and D. repens collected from dissected animals. Live nematodes were washed in saline (0.9% NaCl) and fixed in 70% ethanol. We conducted the isolation of genomic DNA, PCR amplification, electrophoresis and sample analysis.Results and discussion. In total, two species of Dirofilaria were found in representatives of carnivores in Uzbekistan, namely, D. immitis (Leidy, 1856) and D. repens Railliet et Henry, 1911. Original data on the spread of Dirofilaria in domestic and wild carnivores, as well as some materials on D. immitis intermediate hosts recorded from mosquitoes Aedes caspius and Culex pipiens were presented. The mtDNA-COI nucleotide sequences were determined to identify species of mature nematodes D. immitis (MN 650648.1), and D. repens (MZ 081850.1) was deposited by GenBank.

Global Climate Change and Human Dirofilariasis in Russia.

Human dirofilariasis is a vector-borne helminth disease caused by two species of Dirofilaria: D. repens and D. immitis. The vectors of the helminth are mosquitoes in the family Culicidae. The definitive hosts of Dirofilaria are dogs and, to a lesser extent, cats. Humans are accidental hosts. Dirofilariasis has been reported in the territory of Russia since 1915. Sporadic cases of the disease have been reported occasionally, but the number of cases showed a distinct increasing trend in the late 1980s–early 1990s, when the number of cases reached several hundred in the southern territories of Russia, with geographic coordinates of 43° N–45° N. A comparison of the timing of the global trend of climate warming during the 1990s with the temporal pattern of the incidence of dirofilariasis in the territory of Russia indicated a close association between the two phenomena. At present, the northern range of Dirofilaria includes latitudes higher than 58° in both the European and Asian parts of the country. The phenomenon of climate warming in the territory of Russia has shaped the contemporary epidemiology of the disease. The emerging public health problem of dirofilariasis in Russia warrants the establishment of a comprehensive epidemiological monitoring system.

Review of Dirofilaria spp. infection in humans and animals in Iran

Dirofilariasis is a metazoonoses transmitted by certain mosquito genera (Culicidae: Diptera). Chiefly canids are the reservoirs of Dirofilaria spp. This article analyzed all published records and researches relevant to Dirofilaria in Iran, to provide a basis for future studies in Iran and around the world. All of the important data from human and animal cases that included the pathogen and its reservoir, dispersion, and retrospective studies were investigated and analyzed. Furthermore, the natural history of parasites, pathogenicity, diagnosis, treatment, control, and the final status of the disease in the world was briefly mentioned. Two species of the genus Dirofilaria, Dirofilaria immitis (canine heartworm) and Dirofilaria repens, are detected in Iran. Till now, 13 human cases have been formally reported including seven subcutaneous and three ocular cases of D. repens, a four cases of D. immitis, including a rare case in testicular hydrocele, one ocular and one pre-ocular, a subconjunctival and two pulmonary cases suspected to be D. immitis. Animal and human infections have been recorded in 11 provinces of Iran. Different investigators have reported D. immitis in dogs (with the frequency of 0.95–62.8%), jackals (2.5 57.4%), foxes (5.7–50%), wolves (20–50%), and cats (0.8%) and D. repens in dogs (1.4–60.8%) and jackals (10%) in different areas of the country. The reports on Dirofilaria in Iran are to some extent scattered as regarded to distribution and other features of the disease. More studies should be taken in dirofilariasis in Iran, specifically in regions from where there are no reports.

Dirofilariasis in humans presenting as a subcutaneous nodule

Human dirofilariasis is an uncommon zoonotic roundworm infection caused by worms belonging to dirofilaria species transmitted by zoo -anthropophilic blood sucking insects which is known to manifest as ocular infection or as a subcutaneous nodule usually in the upper part of the body. We present a case report of subcutaneous dirofilariasis in the left temporal region besides the eye brow in a 65yr old female, clinically diagnosed as epidermal cyst. Gross and histopathological evaluation revealed the presence of an adult worm with granulomatous inflammatory reaction.

Dirofilaria immitis and Dirofilaria repens in mosquitoes from Corsica Island, France

BackgroundDirofilaria immitis and Dirofilaria repens are the main causative agents of heartworm disease and subcutaneous dirofilariasis in domestic and wild canids, respectively. Both pathogens have zoonotic potential and are transmitted by mosquitoes. The present study aimed to determine the transmission period, prevalence and diversity of Dirofilaria spp. vectors from endemic areas of Corsica (France).MethodsA monthly point data model based on average temperature recorded by four meteorological stations during 2017 was used to calculate the Dirofilaria transmission period. From June to September 2017, female mosquitoes (n = 1802) were captured using Biogents® Sentinel 2 traps lured with carbon dioxide and BG-Lure™ or octanol. Mosquitoes were identified to species level, pooled accordingly, and screened using multiplex real-time qPCR to detect D. immitis and D. repens.ResultsThe monthly point data model showed the possible transmission of Dirofilaria spp. from the third week in May to the last week in October in the studied area. Mosquitoes were identified as Ochlerotatus caspius (n = 1432), Aedes albopictus (n = 199), Culex pipiens sensu lato (n = 165) and Aedes vexans (n = 6) and were grouped into 109 pools (from 1 to 27 specimens, mean 11.4 ± 0.7), of which 16 scored positive for Dirofilaria spp. (i.e., n = 13; estimated infection rate [EIR] = 1.1% for D. immitis and n = 3; EIR = 0.2% for D. repens). Specifically, 6 (i.e., EIR = 3.8%) of 15 pools of Ae. albopictus were positive for D. immitis, 2 of 14 of Cx. pipiens s.l. were positive for D. immitis and D. repens, respectively, and 8 of 77 pools of Oc. caspius were positive for D. immitis (i.e., n = 6; EIR = 0.4%) and D. repens (i.e., 2; EIR = 0.1%). The highest mosquito infection rate was recorded in July (EIR = 2.5%), then in June (EIR = 1.3%) and September (EIR = 0.6%).ConclusionsThe data suggest that both Dirofilaria species are endemic and occur possibly in sympatry in the studied area in Corsica, highlighting the need to implement preventive chemoprophylaxis and vector control strategies to reduce the risk of these filarioids in dog and human populations.Graphical

Human dirofilariosis in the 21st century: A scoping review of clinical cases reported in the literature.

Human dirofilariosis is a clinical entity caused by infection with nematode species of the genus Dirofilaria. The traditional picture depicts the disease as a sporadic event associated with the presence of a single immature worm causing a nodular lesion. With the aim to reassess this paradigm, establishing a more accurate picture of the disease and homogenize criteria, a scoping review was conducted by searching, screening and analysing published clinical cases of human dirofilariosis worldwide during the 21st century. After extracting data from 305 publications containing 576 case reports, results showed that human dirofilariosis is currently caused by five Dirofilaria species (mainly D. repens). Maturation was not uncommon, since 42.95% of the parasites recovered were described as mature worms, most of them females, 26.42% of which contained micofilariae in the uterus. Moreover, six microfilaremic cases have been described. The predominant clinical manifestation was the presence of a worm encapsulated within a nodule, but there is a considerable variety of accompanying symptoms depending on anatomical location and type of dirofilariosis. Parasites/nodules were found in 71 different anatomical locations, being the traditional nomenclature of human dirofilariosis unable to properly cover this complex situation. Delay in seeking medical assistance (patient perception) and the frequency of wrong clinical suspicions (doctor knowledge), strongly influenced clinical management. The initial suspicion in cases of subcutaneous and pulmonary dirofilariosis is predominantly a tumour, while in the ocular dirofilariosis a parasite (but not directly Dirofilaria) is mostly suspected. Surgery is usually applied, regardless of the use of non-invasive techniques during preoperative management and although its use is still limited, molecular approach is the most accurate technique to establish a species-level diagnosis. Accurate epidemiological, parasitological and clinical information while handling and reporting human clinical cases is a need for physicians and researchers to improve and standardize the clinical management of human dirofilariosis.

Human dirofilariosis in Austria: the past, the present, the future

BackgroundDirofilariosis is a vector-borne parasitosis caused by filarial nematodes of the genus Dirofilaria. In humans, who represent accidental hosts, dirofilariosis is mostly caused by Dirofilaria repens and Dirofilaria immitis. In Austria, the first reported case occurred in 1978. Since then, several (case) reports have been published.MethodsA systematic and retrospective review of collected published cases and new, unpublished confirmed cases of human dirofilariosis occurring in Austria was performed. A nematode was extracted from the eyelid of a previously unreported case and subsequently characterized histologically and using molecular biology techniques.ResultsData on a total of 39 cases of human dirofilariosis in Austria occurring between 1978 and 2020 are summarized. Over the past four decades the incidence has markedly increased, in particular after 1998. Of the 39 patients, men and women were equally affected, and the mean age was 47.1 years. The area most frequently affected was the head (38.5% of cases). Confined ocular involvement was observed in 23.1% of cases, and nematodes were isolated from the neck/trunk, extremities and the genito-inguinal area in 25.6, 15.4 and 15.4% of patients, respectively. Microfilariae were detected in two cases. Of the 39 patients, only 73.9% tested positive for anti-filarial antibodies and 56.3% for eosinophilia, despite successful isolation of a nematode; consequently, these measures did not represent reliable markers for dirofilariosis. Most patients had a travel history to countries endemic for Dirofilaria species. One patient who had not traveled abroad represented the only autochthonous case recorded to date. Dirofilaria repens was the predominant species, identified in 89.7% of cases. In the newly reported case of subcutaneous dirofilariosis, a live non-gravid Dirofilaria repens adult female of 12 cm length was isolated from the eyelid of the patient, and a video of the extraction is provided.ConclusionsThe incidence of human dirofilariosis cases has increased strikingly over the last four decades in Austria. More cases can be expected in the foreseeable future due to changes in human behavior and (travel) activities as well as climate changes and the associated alterations in the availability of the natural reservoir, the vectors and the intrinsic characteristics of the parasite.Graphical