Human Dirofilaria repens infection in Serbia.

Human infection by Dirofilaria repens in Serbia has been increasing steadily. The first case was reported in 1971, presented in the form of a single subcutaneous nodule on the back of a young boy. As established by a literature search, eight additional cases were reported until mid-2001. The most frequent site of infection was subcutaneous tissue, with the exception of two cases, in which parasites were found in subconjunctiva and epididymis. Our study, conducted from 2001 to 2008, encompasses 19 new cases. Most of them (63.1%) presented as ocular or periocular infections, in which the parasite was typically found under the conjunctiva. In other cases a parasitic nodule was localized in the temporal region of the head, epididymis, testicle, abdomen, breast or arm. The diagnosis was made by morphological and histological analysis of the extracted intact worms and parasite sections from the tissue. Morphology of the filarial worms was well preserved in more than half of the cases (12/19) and there was never more than one parasite found inside the lesions. Adult worms and immature nematodes were observed in nine and seven cases, respectively. Furthermore, in two cases microfilariae were discovered inside the pseudocoelom, sections of the female reproductive tubes filled with clearly visible larval stages. Dirofilaria repens infection was diagnosed by its morphological features (17/19) or by performing polymerase chain reactions (PCR) using paraffin-embedded tissues (2/19) in the cases where the morphology was insufficient for identification and the parasites had been determined initially as Dirofilaria spp. The amplified 246 bp PCR product showed that the worms were D. repens.

[Human dirofilariasis: diagnosis and the pattern of pathogen-host relations].

Until recently, there has been no consensus of opinion as to that D.repens females can develop in the accidental host (man). The role of man is regarded as a biological dead end for Dirofilaria that are unable to develop the adult stage; human Dirofilaria migration is considered to be larval by the type of larva migrans. Studying these matters on a specific material of 140 cases of invasion by Dirofilaria that had been eliminated in patients in different seasons and the length of their bodies measured showed that the maximum number (51.4%) was mature females, 120 to 190 mm in size; 35.7 and 12.85% had a length of 70-115 and 40-65 mm, respectively, which corresponds to immature young and juvenile specimens. This suggests that Dirofilaria normally develop and achieve the adult stage in the accidental host. A correlation was found in the sizes of the body and the time of D. repens development. Thus, the human organism is not a biological dead end for Dirofllaria. The migration of adult Dirofilaria should be appraised as the imago-migrans phenomenon: As the particular diagnostic sign, it will aid a physician to establish a correct parasitiological diagnosis at the early stages of the disease. In recent years, there has been new evidence in the diagnosis of dirofilariasis that microfilaria have been detected in the skin tumor puncture specimen and blood of the patients. In this connection, it is conceivable that man may be an actual source of mosquito infection even in the presence and paucity of mature males and females.

[The first autochthonous case of subcutaneous dirofilariosis in Austria]. / Der erste autochthone Fall einer subkutanen Dirofilariose in Osterreich.

Dirofilaria repens, a common parasite of carnivore mammals, is transmitted by mosquitos and may also infect humans accidentally causing a subcutaneous dirofilariosis. Autochthonous infections of dogs, foxes or cats with D. repens has not been found in Austria so far; however, 12 cases of imported subcutaneous dirofilariosis in man were noticed between 1981 and 2005. The recent case report deals with the 13(th) human case, which has to be considered as the first autochthonously acquired in Austria.

[Human dirofilariasis: 3 cases in the south of France]. / Dirofilariose humaine: 3 cas autochtones dans le sud de la France.

INTRODUCTION: Dirofilariasis is a zoonosis usually found in dogs and cats. It is rare in humans, who are dead-end hosts for the parasite. CASES: We report 3 cases of subcutaneous dirofilariasis due to Dirofilaria repens, contracted in the south of France (Alpes-Maritimes and Corsica). In the first two cases, the dirofilariasis manifested as lymph node enlargement; in the third case, lung disease suggested a systemic diffusion of microfilariae. DISCUSSION: Dirofilaria repens dirofilariasis is due to the transmission of microfilariae by some mosquito bites (Aedes, Culex, Anopheles, Mansonia, Psorophora and Taeniorhynchus). Usually only one larva develops, producing an immature adult worm inside a node. Ultrasound examination may suggest the parasitic origin of the lesion. It is treated surgically, by excision, without chemotherapy. Very rarely, an adult worm may mature and produce systemic diffusion of microfilariae. The nodule in the third case contained a gravid adult female worm but we found no microfilariae. Dirofilariosis can present problems in diagnosis and treatment. It must be considered in patients with an isolated nodule.

Dirofilaria repens infection in northern Israel.

The fourth case of zoonotic Dirofilaria repens infection in Israel is reported, and the diagnostic morphologic characteristics of this filariid are reviewed. The importance of the exact anatomic diagnosis of this filaria is stressed in view of the fact that Israel has pockets of settlers from East Africa, a region endemic for lymphatic filariasis (Wuchereria bancrofti). Since the possibility of introduction of such an infection into the country exists, differentiating this zoonotic Dirofilaria from other filarial worms is essential. The clinicopathological features of a Dirofilaria repens infection are distinct. The patient initially has a painful subcutaneous or conjunctival swelling; the excisional biopsy shows the presence of a dead or alive, usually female worm that measures 220-660 microns across; the central intestine and the genital organs (two uteri) are located in the pseudocoelom; the thick, multilayered cuticle is provided with 95-105 sharp, longitudinal ridges, the latter being separated from each other by a distance of 12 microns; the circumferential muscle cell layer, covering the inner side of the cuticle, is bilaterally interrupted by the large chord cells, two to five nuclei of which are discernible in each cross section.

Diagnostic features of zoonotic filariae in tissue sections.

The diagnostic features in tissue sections from patients with zoonotic filarial infections are reviewed. In general, two types of infections are recognized: 1) those presenting radiologically in healthy patients as coin lesions, which are usually removed because a clinical diagnosis of carcinoma of the lung is made and infarcts containing Dirofilaria immitis parasites in pulmonary arteries are found; and 2) those presenting as subcutaneous nodules, in which D. tenuis, a parasite from raccoons, D. repens, from dogs and cats, D. ursi , from bears, and Onchocerca spp, from horses or cattle, require delineation. Moreover, nodules that on microscopic examination are seen to be lymph nodes may harbor Brugia spp. The geographic distribution of these infections, with emphasis on the United States, is discussed.

Subcutaneous dirofilariasis in Okinawa, Japan.

A nematode within a subcutaneous nodule excised from an elderly Okinawan man has been tentatively identified in sections as an immature Dirofilaria repens--the first to be reported from Japan.

Dirofilaria striata infection in a North Carolina child.

A living, adult female Dirofilaria striata was removed from the orbit of a 6-year-old boy living in Buncombe County, NC. The specific identification of the filaria was based on its size and the morphological features of the cuticle including the weak, irregular, longitudinal ridges and small but conspicuous lateral alae.

Human subcutaneous dirofilariasis caused by Dirofilaria repens in Ibiza, Spain.

A case of human subcutaneous dirofilariasis contracted in Ibiza, Spain is reported. An incomplete nematode extracted from the eyelid of a woman patient was identified on the basis of its anatomic and histologic characteristics as a nongravid adult female of the species Dirofilaria repens. The subcutaneous location of the worm, together with the epidemiologic data, support this finding.

Pulmonary dirofilariasis: restudy of worms reported gravid.

A worm in the lung of a man in Colombia, whose death was caused by lymphoid leukemia, originally reported as Wuchereria bancrofti with embryos in the uterus, was re-examined and identified as a Dirofilaria sp. and its gravid condition confirmed. A Dirofilaria sp. in the lung of a man in Japan, reported as gravid, was found to be nongravid with sloughed fragments of lining of the uterus mistaken for microfilariae. Noteworthy in the Colombia case is the association of lymphoid leukemia in the host and the gravid condition of the worm.

Dirofilaria repens from the eyelid of a woman in Thailand.

An immature male Dirofilaria repens was removed from a cystic mass in the eyelid of a 51-year-old woman employee of a rubber plantation in Phangnga Province, southern Thailand.

Pitfalls and difficulties in histological diagnosis of human dirofilariasis due to Dirofilaria (Nochtiella) repens.

The authors have conducted a histologic study of over 90 cases of Dirofilaria infection in man due to Dirofilaria repens, the most extensive study of its kind in the world. On the basis of their findings, they illustrate the diagnostic difficulties that may arise when regressive phenomena render the parasite's morphologic characteristics largely or completely unrecognizable. These phenomena are due to the death of the filaria inside the inflammatory nodule weeks or months prior to surgical removal, and to the consequent invasion of inflammatory cells. They start at the nematode's natural orifices (mouth, vulva, anus, cloaca) and gradually spread throughout its body. In cases of difficult diagnosis, therefore, it is recommended that the nodule be sectioned at different points comprising caudal, cephalic and middle body aspects, so as to reveal the few morphologic features that are still recognizable and which may afford a correct diagnosis. The authors present examples of histologic sections in color plates in which the nematode was in an excellent state of preservation and others illustrating the full range of regressive phenomena, from slight to total disintegration of the bodily structure.

New human Dirofilarioses in Hungary.

About ten cases of filariosis have recently been recorded in the Hungarian medical literature, six of them caused by Dirofilaria repens. Dirofilaria repensis a mosquito-transmitted filaroid worm in the subcutaneous tissue of dogs and cats in the temperate areas of the Old World. It accidentally infects man, too, and can remain unidentified due to physicians, poor knowledge of the parasite. In the last two years six new Dirofilaria repensinfections have been found in various parts of the country: five localised dermally and one in the deep tissues. Two of the cases might have been acquired in Italy during summer travels. Four patients, however, have never been abroad, these cases must be considered autochtonous infections. The thickness of the multilayered cuticle of the worm, diameter of the body and the size, form and number of the longitudinal ridges on its surface are used in the histological diagnosis of the the parasite.

Subcutaneous dirofilariasis in Nebraska.

Dirofilaria immitis infection in dogs is an increasing problem throughout much of the United States and is no longer limited to the South. Vector mosquitos are present and transmission may occur during the summer months throughout the southern, eastern, and midwestern states. In addition to pulmonary nodules, D immitis and related species cause symptomatic subcutaneous nodules. Physicians should be alert to this differential diagnostic possibility.

Dirofilaria cancrivori sp. n. (Nematoda: Filarioidea from the crabdog, Procyon cancrivorus, in Guyana.

Dirofilaria cancrivori sp. n. is described from subcutaneous tissues of the crabdog, Procyon cancrivorus, in Guyana, South America. The filarid is morphologically distinct from Dirofilaria tenuis, parasite of a related host, the raccoon, in the southern United States, and all other species of Dirofilaria. The parasite can be distinguished from other dirofilarias based on a combination of morphological features including its size, number, and arrangement of caudal papillae on the male tail, size and shape of the spicules, the presence of longitudinal ridges and transverse striations on the cuticle, and the microfilaria.

Dirofilaria macrodemos and D. panamensis spp. n. (Nematoda: Filarioidea) from Central and South Americal sloths.

Two new species of Diorfilaria, Dirofilaria macrodemos and Dirofilaria panamensis, are described from the subserosa of Central and South American sloths. Dirofilaria macrodemos, described from the three-toed sloth, Bradypus tridactylus, in Guyana, is characterized and differentiated from other dirofilarias by its length (female 214mm, male 64mm), relatively long tail (female 140 micron, male 110 micron), and the number and distribution of the caudal papillae (7 pairs) in the male. Dirofilaria panamensis, parasite of the two-toed sloth, Cholopeus hoffmanni, in Panama, was previously described as Dirofilaria incrassata by Caballero (1947), but can be distinguished from both D. macrodemos and D. incrassata on the basis of body size (female 66 mm long by 360 micron wide, male 34 mm long by 250 micron wide), tail length (female 80 micron, male 80 micron), and number (6 pairs) of caudal papillae in the male.

The species of the genus Dirofilaria, Railliet & Henry, 1911.

Some authors divide the genus Dirofilaria into two subgenera. The subgenus Dirofilaria consists of 5 apparently valid species (D. ailure, D. freitasi, D. immitis, D. lutrae, D. spectans) and 7 species of questionable validity (D. fausti, D. indica, D. louisianensis, D. magalhaesi, D. nasuae, D. pongoi, D. spirocauda). The subgenus Nochtiella consists of 22 apparently valid species (D. acutiuscula, D. bonnei, D. cancrivori, D. corynodes, D. genettae, D. granulosa, D. incrassata, D. linstowi, D. macacae, D. macrodemos, D. magnilarvatum, D. minor, D. pagumae, D. panamensis, D. repens, D. sachsi, D. striata, D. subdermata, D. sudanensis, D. tawila, D. tenuis, D. ursi) and 8 species of questionable validity (D. aethiops, D. andersoni, D. conjunctivae, D. desportesi, D. hystrix, D. schoutedeni, D. spinosa, D. subcutanea). Actually, 10 species of the genus Dirofilaria (D. asymmetrica, D. digitala, D. kuelzii, D. ochmanni, D. pauliani, D. roemeri, D. scapiceps, D. timidi, D. uniformis, D. websteri) are attributed to other genus.

[Human dirofilariasis in Italy: a new palpebral case with spontaneous healing in Abruzzo]. / Dirofilariasi umana in Italia: un nuovo caso palpebrale con guarigione spontanea in Abruzzo.

One case of human palpebral dirofilariasis by Dirofilaria repens, in Abruzzo, is described. It is the first case reported in this region. The parasite was released following the energetic rubbing of the palpebral area, with the result in the spontaneous recovery of the patient.

[Human subcutaneous dirofilariasis: 2 new cases in northern Italy]. / Dirofilariasi sottocutanea umana: due nuovi casi nell'Italia del Nord.

Two new cases of human subcutaneous dirofilariasis in Northern Italy are described. The first one occurred in a 56 year-old man living in Venezia Lido and was localised in the frontal region; the second one in a 52 year-old woman living in Modena and was localised in the sacrococcygeal region. Both lesions were associated with Dirofilaria repens. In the same geographical areas other cases of this zoonosis had occurred in the past.

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.