Identificación morfológica y molecular de filarías caninas en una comuna semi-rural de la Región Metropolitana, Chile / Morphological and molecular identification of canine filariae in a semi-rural district of the Metropolitan Region in Chile

Introduction: To date, there has been no definitive confirmation of the presence of zoonotic dirofilariasis in dogs in Chile. Objectives: To study the presence of dirofilarias in blood samples from dogs collected in a semi-rural district near Santiago and to compare their frequency in dogs with and without dermatological manifestations. Methods: We examined 100 blood samples for dog filariae infections using microscopic methods (modified Knott technique). 50 dogs presented dermatological symptoms or signs compatible with filarial infections and 50 were asymptomatic. ITS-2 and 12s rDNA gene amplification by PCR and sequencing were performed in samples microscopically positive for microfilariae. Results. We observed microfilariae in 22 dogs (22%). Of these, 16/50 (32%) were symptomatic and 6/50 (12%) were asymptomatic (p = 0.02). Morphologically, the majority of micro-filariae were similar to Dirofilaria repens, although many had a bigger size than previously described. Nucleotide sequencing of the amplified genes showed no more than 95% homology with the D. repens sequences available for comparison. D. reconditum and D. dracunculoides infections were also identified. Conclusions: These features might indicate the presence of new species of Dirofilaria or a D. repens close related variant in Chile.

Introducción: A la fecha no hay datos concluyentes en Chile respecto a la presencia de dirofilariasis zoonótica en perros. Objetivos: Identificar la presencia de dirofilarias en sangre de perros de una comuna semi-rural cercana a Santiago y comparar su frecuencia en animales con y sin manifestaciones dermatológicas. Materialy Métodos. Se examinó un frotis sanguíneo de 100 perros en busca de microfilarias mediante observación microscópica (técnica de Knott modificada). Cincuenta perros presentaban síntomas o signos dermatológicos que se han asociado a esta parasitosis y 50 eran asintomáticos. Se amplificaron los genes ITS-2 y 12s ADNr de filarías en las muestras con microfilarias al frotis, secuenciando los fragmentos amplificados. Resultados: Se observaron microfilarias en 22 perros (22%), 16/50 (32%) sintomáticos y 6/50 (12%) asintomáticos (p = 0,02). Morfológicamente, la mayoría de las microfilarias observadas fueron similares a D. repens; sin embargo, una gran proporción mostró un tamaño mayor al descrito para esta especie. Las secuencias nucleotídicas de los genes amplificados mostraron una homología no mayor al 95% con las secuencias de D. repens disponibles para comparación. Se identificaron además dos especies poco patógenas, D. reconditum por morfología y secuenciación genética y D. dracunculoides por morfología. Conclusiones: Los resultados indican la existencia de una nueva especie de Dirofilaria cercanamente relacionada a D. repens o de una variante de esta especie.

[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.

Three new cases of human infection with Dirofilaria repens, one pulmonary and two subcutaneous, in the Egyptian governorate of Assiut.

Human dirofilariasis caused by Dirofilaria repens is a parasitic infection, currently considered to be an emerging zoonosis, that has been observed in many areas of the Old World. Dogs are the main 'reservoir' host. In humans, D. repens can cause inflammatory nodules, most commonly in the subcutaneous tissues or in the subconjunctival space. Lung involvement, which is the most common of the non-cutaneous and non-ocular manifestations, is frequently mis-diagnosed as a primary or metastatic lung tumour. Two new subcutaneous cases and one new pulmonary case, all observed in the Egyptian governorate of Assiut, are described here. This represents the first report of human pulmonary dirofilariasis caused by D. repens on the African continent. All the worms collected from the cases, including a living worm from the left lung of the pulmonary case, were identified morphologically, and the identity of the lung parasite was confirmed by PCR.

[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.

Dirofilarial infection presenting as a facial mass: case report of an emerging zoonosis.

Dirofilariasis is a parasitic infection caused by nematodes. Human infection remains rare but is increasing in scope, particularly in endemic areas. Dirofilariasis typically presents as a subcutaneous mass or with pulmonary nodules. Here, we present the case of a 73-year-old woman whose asymptomatic facial mass was caused by dirofilarial infection. The pathophysiology, diagnosis, and treatment of dirofilariasis of the head and neck will be discussed. In endemic areas, dirofilariasis must be considered in the differential diagnosis of facial masses.

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.

Serological assays on eight cases of human dirofilariasis identified by morphology and DNA diagnostics.

Specimens of Dirofilaria sp. removed from eight Italian patients were identified as D. repens by morphology and confirmed as such by a PCR-based method of DNA analysis. Blood samples were also drawn from the patients so that two serological tests (ELISA and western blot), one based on the recognition of molecular markers recently identified in the somatic antigenic complex of D. repens, could be evaluated. The antigenic complex used in the ELISA only gave a weak sensitivity. However, the western-blot assays, based on the polypeptide molecular markers, were found to have greater sensitivity and should be useful in detecting human cases of dirofilariasis.

Human infection with Dirofilaria repens in Malaysia.

Human dirofilariasis is a rare infection in Malaysia. Thus far, only two human cases have been reported viz. Dirofilaria immitis and D. (Nochtiella) repens and in both instances, adult worms were recovered from infected patients. The two cases reported in the present study, one from Melaka and the other from Penang, were diagnosed histologically. Based on the diagnostic criteria for identifying Dirofilaria in tissue sections, the parasites were identified as D. (Nochtiella) repens.

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.

[Human dirofilariasis in southern Italy. II. The Calabria Region]. / La dirofilariasi umana nel sud d'Italia. II: Regione Calabria.

A new case of subcutaneous Human Dirofilariasis, in a 42-year-old woman from the province of Cosenza, is described. It is the first reported in Calabria. The nematode, an immature female of Dirofilaria repens, was clinically diagnosed as a "Fibrolipoma". In a collateral research on dogs in different areas of the same province, microfilariae of D. repens in 2 out 134 individuals were detected.

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.

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.

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.

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.