Dirofilariasis

Description:

Dirofilariasis (Dirofilariasis, from armor. "diro, filum" — "evil thread") — the disease caused by parasitizing of a nematode of the sort Dirofilaria in a human body. It is the helminthosis which is characterized by slow development and a long chronic current.
Infection of the person occurs in the transmissible way through stings of the blood-sicking mosquitoes infected with invasive larvae of dirofilyariya. A source of infection of mosquitoes usually are the infested domestic dogs, and also cats, wildings are more rare.
The problem of a dirofilariasis is caused by broad circulation of the activator in the environment and lack of appropriate measures for identification and deworming of the infected animals — obligate definitivny owners (domestic dogs and cats). True incidence of people of a dirofilariasis is unknown as official registration is not conducted it. Owing to insufficient knowledge of doctors the dirofilariasis often passes under various diagnoses of not parasitic etiology.

Dirofilariasis symptoms:

The probability of an invasion does not depend on age of the person, and depends mostly on a possibility of contact with the infected mosquitoes in which peak of activity there is the greatest number of infections.
The period of a clinical incubation depends on reactivity of an organism and growth rate of a parasite and makes from one month to several years. In most cases the only individual — an immature female therefore microfilarias at people are not described is found, but are not excluded completely.
Approximately 6 months later after infection the parasite reaches the maximum sizes and is located in the inflamed node. As a rule, helminth is located in the connective tissue capsule containing serous and purulent exudate, protein and eosinophilic and neutrophilic leukocytes, which an infiltrirovana a fatty tissue with addition of macrophages and fibroblasts. Parasites are in absolute majority of cases under skin or mucous though messages on damage of lungs and a pleura meet. The worm can die and gradually collapse.
Usually several days later after a sting small consolidation of the size of the prosyany grain which sometimes is followed by an itch arises the infected mosquito on site of a sting. Soon the itch and consolidation can disappear, however further consolidation appears again and increases, reaching diameter of 0,5-4,0 cm. Skin over consolidation is usually slightly hyperemic, moderate puffiness is sometimes noted. The developing secondary inflammatory process leads to emergence of an itch from moderated to very strong, to pains both at rest and at a palpation.
Characteristic symptom of a dirofilariasis is migration of the activator — movement of consolidation or the helminth under skin which is noted at 10-40% infested. The distance to which the dirofilyariya moves makes several tens of centimeters, movement speed — to 30 cm in 1-2 days. Movement of a parasite from skin of the right hypochondrium through the left supraclavicular area and the left part of a mandible to a conjunctiva of the left eyeglobe is described. At migration of a parasite in hypodermic cellulose after each his movement on the new place there is a new consolidation, and on the old place of its stay there is no trace left. Strengthening of migration happens at impact on skin UVCh currents at physical therapy, and also after warming up by compresses or the warming ointments.
Specific character of a dirofilariasis are feelings of stir and crawling of live "worm" in consolidation, a tumor or a hypodermic node. At many patients the invasion has a recurrent current with phases of a zatikhaniye and an aggravation of process. During untimely removal of helminth there can be a development of abscess in the place of its localization.
In some cases patients take helminth at skin raschyosa, or as a result of spontaneous opening of an abscess helminth comes to light independently.
The fact that right-hand localization of helminth prevails is interesting.
The headache, nausea, weakness, the increased temperature, severe pains in the place of localization of helminths with irradiation on the course of nervous trunks can be other symptoms of a disease. The eosinophilia of peripheral blood unlike many other helminthoses is not characteristic of a dirofilariasis.
After extraction of helminth at the person usually clinical signs disappear.
Defeats of organs of sight.
About 50% of all registered cases are the share of a dirofilariasis with localization of the activator under skin a century, in a mucous membrane and under a conjunctiva, is more rare — in an eyeglobe. Adult individuals — females come to light, males are more rare. At an eye dirofilariasis eyelids, a conjunctiva, an anterior chamber, a sclera, an eye-socket are surprised. At damage of skin of eyebrows and the century develops swelled as Quincke, connected with parasitizing of a female/male of a dirofilyariya in hypodermic cellulose. Eyelids are sharply edematous, pastozna, are slow-moving, close an eye, the itch of different intensity and dacryagogue from moderated to very strong, pain at rest and at a palpation is sometimes noted. Some patients have a feeling of a foreign body in an eye, stirs in the field of consolidation and protrusion of an eye. A dermahemia the century, a ptosis and a nictitating spasm are characteristic. Under skin dense small knots, a granuloma or a tumor are formed. Some patients notice presence of a dirofilyariya at an eye conjunctiva, looking in a mirror. Visual acuity usually does not decrease. Intraocular pressure can sometimes increase.
At defeat of a conjunctiva and a conjunctival sac conjunctivitis which as a result of the movement of helminth is followed by strong thermalgias, dacryagogue and itch develops. The conjunctiva is edematous, hyperemic within several days, through it the gyrose body of helminth is visible. All phenomena completely disappear after it migrates in an eye-socket or is removed surgically.
Defeat of an anterior chamber of an eye arises at penetration into it of an adult dirofilyariya which is found on the characteristic movements. Damage of an eye-socket is promoted by development and formation of a granuloma around helminth that can lead to an exophthalmos and a diplopia (doubling of the image). Defeat of an eyeglobe proceeds more hard, is followed by decrease in visual acuity, at the same time "the moving worm, a bloodsucker" is sometimes marked out before an eye.
Local secondary inflammatory processes belong to complications of an eye dirofilariasis. Two cases of amotio of a retina at patients with localization of parasites in a sclera and a vitreous with decrease in visual acuity with 1,0 to 0,2 are described.

Dirofilariasis reasons:

The activator of a dirofilariasis belongs to the class of roundworms of Nematoda, Spirurina group, Spiruromorpha suborder, the Filarioidea family, the sort Dirofilaria. In total several species of worms from which the greatest distribution have D. repens, D. immitis are described. The absolute majority of cases of the person therefore will be described below the disease caused by these two species of parasites is caused by them.
Activators of an invasion D. repens and D. immitis are obligate parasites of carnivorous families Canine and Cat's. D. tenuis strikes raccoons, D. ursi occurs at brown bears and the Amur tiger, D. subdermata strikes porcupines, D. lutrae and D. spectans North American and Brazilian otters respectively, with D. striata — wild American cats.
Dirofilaria repens.
Also in various sources synonyms of D. repens meet [5]: Filaria palpebralis Pace, 1867; F. peritonaei Babes, 1880; F. conjunctivae Addario, 1885; Loa extraocularis Skrjabm, 1917; D. acutiuscula (Molin, 1858; Chitwood, 1935); Dirofilaria sp. Kotlan, 1951
Widespread activators of an invasion D. repens and D. immitis are obligate parasites of carnivorous families Canine and Cat's.
Female of D. repens.
The body is narrowed by the ends. A cuticle white with accurate longitudinal and gentle cross striation. Roth simple, the oral capsule is rudimentary. Length of a body is 140 — 150 mm, width is 0,447 - 0,552 mm. A gullet — 1,05-1,53 mm, a front muscular part of 0,49-0,54 mm. The gullet is separated from intestines by three valvules. The nervous ring is located at distance of 0,305-0,368 mm from the head end. Cervical nipples and an excretory opening are not found. The vulva is bordered with slightly acting lips and located at distance of 1,84-1,92 mm from the head end. The vagina is long, about 3,42 mm. At some copies of parasites the vagina and oviducts describe numerous loops which last at first forward, then are wrapped back and connect to the uterus occupying almost all perigastrium. The twisted ovaries are located in back department of a body. Small intestine, more or less direct. The anus is located almost terminalno. The tail with a stupid tip, is slightly bent ventrally.
Male of D. repens.
Length of a body is 58 mm, the maximum width is 0,41 mm. Body width in the field of the end of a gullet reaches 0,38 mm, and at the level of a foul place — 0,36 mm. Length of a gullet reaches 1,74 mm. The nervous ring will be spaced from the head end at distance 0,26 mm. Behind a nervous ring, at distance of 0,34 mm from the head end, cervical nipples are located. On the head there are no ornamentation, only speakers submedian head nipples (4 pieces) are noticeable. The tail end is rounded stupidly off. The opening of a foul place will be spaced from the tail end on 0,38 mm. Sexual nipples are asymmetric: 4 large preanalny nipples and two post-proctal are on the right side noticeable; on the left side there are 3 preanalny nipples, and post-proctal are absent. Spicules of unequal size and unequal structure. The left spicule reaches 0,448 mm of length. The proximal end of the left spicule has width of 0,0312 mm; gradually the spicule is narrowed and gets a zhelobovidny form. At distance of 0,214 mm from the proximal end the spicule is split as if on 2 departments connected with each other by a membrane which soon again connect together. The distal end of the left spicule is pointed. The right thick and short spicule reaches 0,176 mm of length with the maximum width of 0,0273 mm. It has the trench form, gradually утончающегося towards the back. Its distal end is rounded stupidly off.
Microfilarias.
Microfilarias without cap, the front end their stupid, back pointed, threadlike. The nuclear column does not reach the end of a body. Microfilaria length (on Lent, Freitas, 1937) 0,30-0,36 mm, width is 0,006-0,008 mm. The sizes of the microfilarias painted on Giemsa found in blood of dogs of Sri Lanka make 0,290±0,015 × 0,006≠0,002 mm, on other authors their sizes — 0,200-0,360 × 0,005-0,008 mm.
Dirofilaria immitis.
Length of a body of a puberal female makes 180 — 300 mm, a male of 100 — 110 mm.

Treatment of the Dirofilariasis:

As usually in a body of the person only one worm, in most cases immature which does not otrozhdat a microfilaria parasitizes, use of microfilaricidal drugs is not shown.
Some authors recommend use of antigelminnty drugs: an ivermectin dose, and then 3 doses of a dietilkarbamazin if it is possible to make the authentic diagnosis without surgical intervention. However, in most cases the final diagnosis of a dirofilariasis is established after carrying out operation on morphological studying of the withdrawn parasite. And in case of death of a parasite after chemotherapy at the patient toksiko-allergic reactions are possible.
Optimum method of treatment — full surgical removal of helminth.
No special diets, or restrictions of mobility are required.
Medicines.
As the parasite biochemical differs from the person, influence by drugs, toxic for parasites, their eggs and larvae is possible. Mechanisms of influence can be the following:
Braking of polymerization of a tubulin;
Neuromuscular blockade;
Cholinesterase inhibition;
The increase in permeability of a cellular membrane leading to loss of intracellular calcium.