Dirofilariasis - Causes, Symptoms and Treatment .MF .

August 12, 2017 17:52 | Infectious Diseases

Dirofilariasis refers to geohelminthiasis that affects mainly animals (dogs, cats rarely), the main point of application is the heart muscle.Although the disease zoospetsifichnost all cases of human infestation longer occur due to the presence of a special transporter larvae from animals - the mosquito.Data on morbidity among people of different and very low because of the low detectability and the lack of official registration of the parasitosis.

Dirofilariasis (Dirofilariasis) - a parasitic disease that affects mainly animals but also occurring in humans caused by the larval stage of threadlike nematode genus Dirofilaria, characterized by lesions of the organs of vision, as well as other organs and systems with mainly chronic course.

Background dirofilariasis consists in the constant presence of obligate sources of disease - animals - close to the man and his dwellings, widespread dirofilyary both in animals and in general, in natural conditions, low awareness of health care providers and contact th

ese patients not on the profile, namely,, to the doctors of different specialties.For example, the majority of patients with heartworm passes the doctors with diagnoses such as boil, abscess, atheroma, tumors, fibroids, cysts, and others.

dirofilariasis first description dates back to 1855 year, when the steps for removing the worm from the eye sick girl Portuguese Lusitanian Dr. Amato.Then, at a certain frequency described similar cases in France, in Italy.In Russia, the first case of heartworm eye is described in 1915 in Ekaterinodar doctor and scientist Vladychensky APAlready since 1930 the founder of the school helminthological KIScriabin and students work closely on this issue.

Dirofilariasis, upper eyelid

Geographically dirofilariasis a certain frequency is found in Central Asia, Georgia, Armenia, Kyrgyzstan, Kazakhstan, Azerbaijan, Ukraine, the Russian Federation is quite rare, especially in the south of its regions (Volgograd Region, Krasnodarregion, Rostov region, Astrakhan region, and others).However, analysis of the incidence of recent years has shown that a certain frequency of the disease is present and in areas with a temperate climate (Moscow region, Tula, Ryazan region, Lipetsk region, the Urals, Siberia, Bashkortostan, and others).In one year the average recorded up to 35-40 cases of heartworm in Russia, and in some areas (eg, Rostov) - up to 12 cases per year.

also disease at different rates is recorded in North America, Brazil, India, Australia, in Africa, in Europe (Italy, Spain, France) Sri Lanka as well as in Canada and Japan.The most disadvantaged by dirofilariasis considered Iran and Greece.

What causes heartworm disease

name comes from the Latin «diro, filium», which means "evil thread."
causative agent in humans - larval stage (microfilariae) threadlike nematode (class of Roundworms) genus Dirofilaria, which in the human body does not reach sexual maturity (more in the development cycle).

There are several types of dirofilyary:
1) Dirofilaria repens, Dirofilaria immitis (parasites in dogs and cats),
2) Dirofilaria ursi (brown bear and Siberian tiger),
3) Dirofilaria tenuis (raccoons),
4) Dirofilaria subdermata(porcupine),
5) Dirofilaria lutrae et spectans (Brazilian and North American otters),
6) Dirofilaria striata (American wild cat).

vast majority of cases it is caused by D. repens and D. Immitis, remaining pathogens are found sporadically.


mature individuals of up to 30cm and a width of 1.5 mm, a filamentary shape with narrowed
ends.The female has her mouth, esophagus, intestines, nerve ring, vulva, fallopian tubes, uterus, and ovaries, in males - papillae and spicules.

larvae (microfilariae or) as microscopically small - up to 320 m long and 7 m wide, are thread-like appearance with a blunt front and a pointed posterior end.However, due to their size can reach with a current CROI and lymph "the most remote corners of the human body."

source of infection with heartworm - obligate or compulsory source - a pets (dogs in the majority, at least the cat - D. repens and D. immitis), isolated cases of the disease are found among wild animals.Prevalence different urban dogs of 3.5 to 30% depending on the region.

Dirofilariasis, the source of infection - the dog

intermediate host mosquito genus Culex, Aedes, Anopheles - they carry invasive larvae (microfilariae) from animals to each other, as well as to man.Mosquito larvae infestation different - from 2,5% (Anopheles) and 30% (Aedes).Do not rule out the role in the transmission of larvae and other blood-sucking insects - fleas, lice, horseflies, ticks.Man is a casual and atypical dirofilyary host for the larvae.

Dirofilariasis, a carrier of the infection - mosquitos

mechanism of human infection - transmissive (through the bite of blood-sucking insects - mosquitoes and other), resulting in the larvae of the animals enter the body.

universal human susceptibility.No, depending on age and gender, but the majority of patients in the age group from 30 to 40 years.There is a greater risk of infection in certain groups of people who have direct contact with carriers of heartworm - mosquitoes.The risk group includes:
- fishermen, hunters, gardeners,
- owners of animals (dogs and cats),
- living near rivers, lakes, swamps,
- tourism lovers,
- forestries workers fisheries.

There is a seasonal infection most larvae dirofilyary - spring and summer.The rise of the disease recorded in two waves: in April-May and October-November.

cycle of dirofilyarii

mature individuals resides in the cavity of the right ventricle, and right atrium, pulmonary artery, the hollow veins, bronchi animals.Dirofilyarii secrete into the blood stream a large number of larvae (microfilariae-1).Larvae to 320 microns in length and 7 mm in width, that is microscopically small.The larvae are blood and lymph penetrate into the small vessels in various organs and tissues, as well as transmitted from mother to fetus.It is because of the blood bloodsucking mosquito and other insect larvae ingest when bloodsucking.During the day the microfilariae-1 are kishenike mosquito, and then penetrate into the cavity, where they are moulting (microfilariae-2), then reach mosquito lower lip and ripen to an invasive stage (microfilariae-3).The duration of maturing in the mosquito, on average 17 days.Then the mosquito sticks or skin of an animal, or a man and vpyskivaet microfilariae-3.Within 90 days, the larvae continue their development at the site of the bite (primary affect) - is subcutaneous fat, which molt twice, which ultimately leads to the formation of microfilariae-5.Thereafter, it enters the bloodstream and spreads throughout the body, can settle in organs and tissues (most often the heart, the pulmonary artery), which ripen and mature to the stage for a further 3 months.Thus, the entire development cycle lasts up to 8 months.The blood circulating microfilariae can host up to 3 years.

Dirofilariasis, development cycle

dirofilyarii full development cycle tested in animals.Man is a casual and a dead-end host larvae, most of which are still in contact with dies.The man rarely parasites once and males and females, so the possibility of fertilization in the female, and no, respectively, separating larvae.Also in humans are rare, and there is microfilaremia (ie larvae in the blood).These moments allow epidemiologically to say that man is not the source of infection.

dirofilyary Pathogenic action on the human body

Most often a person is revealed only one individual dirofilyary.Because fertilization is practically excluded, the growth of the adult takes time about 8-9 months, the parasite rarely leaves the place of primary localization (ie the node in the subcutaneous fat layer).

main pathogenic effect dirofilyary - primary affect (on the site of a mosquito bite) - an inflammatory response in the form of changes in subcutaneous fat in the form of seals, inflammation, the appearance of dense formations of up to 4 cm or more, accompanied by pain and pruritus.Pathomorphological node is a cavernous formation of a sero-purulent contents, inside of which is the microfilariae, and then dirofilyariya surrounded by a connective tissue capsule.Content site "rich" inflammatory cells and connective tissue (neutrophils, white blood cells, eosinophils, macrophages, fibroslasty) and protein abundance.Often, the parasite dies, gradually decomposing.

Clinical symptoms of heartworm

incubation period (from the time of infection to onset of symptoms) last from 30 days to several years, depending on the state of the human immune system.

Forms dirofilariasis:

a) Cutaneous is fairly common form in humans.In place of introduction
larvae (it coincides with the place sucking mosquitoes) appears small seal, painful to the touch.About half of patients complain of movement (migration) of the seal of the parasite under the skin.That is, during the day the seal location on the changes of 10-30 cm, and in the previous location is completely disappears.When cutaneous patients complain of a feeling of crawling parasites, wiggling in different areas of the body, but always within the node, as well as "phantom" paresthesia (tingling sensation on the imaginary body) that has more to do with a neurosis.The disease with cutaneous form undulating, ie periods of exacerbation changing periods of remission (calm).In the future, in the absence of medical care within the unit may form an abscess, in which there are strong jerking pain in the hearth, redness of the skin over it.
Sometimes scratching strong knot can reveal, and the parasite emerges.

b) Eye form is also one of the most common in humans (50% of all cases).It
with this form, patients will seek treatment.The parasite is localized under the skin of the eyelids, conjunctiva sometimes under the eyes, at least in the eyeball.Usually the affected area affects the eyelids, the mucous membrane - the conjunctiva, the anterior chamber of the eye and the sclera.The patient has the feeling of a foreign body in the eye, swelling and redness of the eyelids, pain in the commission of oculomotor movements, inability to completely lift the eyelids (blepharospasm), excessive tearing, itching in the affected eye.Externally, the process is similar to an allergic angioedema.Visual acuity remained unchanged.As with the skin form, with an eye patients complain of a feeling of perturbation in the affected eye.Locally - under the skin of age there is a small tumor formation or nodule (granuloma), and when viewed from the conjunctiva can be seen very dirofilyariyu.With the defeat of the eyeball may cause diplopia (split), exophthalmos (bulging eyes).

Dirofilariasis, eye shape

If any of the forms of heartworm placing the majority of patients and the general complaints - weakness, irritability, anxiety, sleep disorders, headaches.

described in the literature are rare cases of heartworm - omentum, pleura, male genitals (scrotum, testicles), the fallopian tubes.Cases of lung lesions dirofilyariyami, in the human heart are extremely rare.

Diagnostics dirofilariasis

1) Primary diagnosis of heartworm clinical and epidemiological .However, as a rule,
collection of epidemiological history (presence of dogs near the shelter, mosquito bites, exploring the woods, fishing, garden plots) little information in terms of diagnosis.Pay attention should be on the patient's stay in the endemic areas during periods of high mosquito activity.Also, important information is seasonal: during a short incubation (up to 3 months after infection) the occurrence of the disease in June-July and October-November, and after prolonged incubation (up to 8 months) - occurrence of the disease in the following year after infection.
main role is played by the complaints of patients: the appearance of subcutaneous nodules, which during the day can be migrated at a distance of 10-30 cm, inside which there is a sense of "creeping", as well as other typical complaints described above.The differential diagnosis spend with erythema nodosum, boils, carbuncles, abscesses, allergic reactions, conjunctivitis, holyazionami (consequences of the "barley" eyes) and other diseases.

2) Laboratory diagnosis includes:
- complete blood count (eosinophilia up to 10-11%);
- macroscopic study of the parasite helminth after surgical removal of the focus (node): detection of threadlike parasite with a rounded front and rear ends pointed.It also investigates and internal organs of the parasite, the presence of microfilariae in the uterus of the female.
- Morphological study of the remote host or granuloma: at the cut visible foci of chronic inflammation of the capsule from the outside, inside which is a thin round parasite, rolled into a ball.Distinguishing features - the presence of "cuticular spines" - the so-called peaks of longitudinal ridges on the cuticle of the parasite.
- specific serological tests for the detection of the parasite antigen in the blood:
this ELISA for the detection of somatic antigen dirofilyary PCR diagnostics to determine repeated patterns of one DNA species or cuticular dirofilyary other antigens, immunoblot method for detecting antigens adults and larvae.

Dirofilariasis, microscopically

3) Diagnostics (ultrasound study of formations and units with the detection of parasites inside rolled into a ball, X-ray and X-ray, MRI, CT).

Treatment dirofilariasis

Tactics of treatment is determined by the form of the disease.Most often it is parasitism a single individual, and immature, so toxic antiparasitic treatment is rare.

main method of treatment - surgical - removal of formations, units, granulomas with subsequent morphological study of education.In order to prevent migration of the parasite during the day before surgery ditrazin administered.

Drug therapy is rarely used and ivermectin, diethylcarbamazine, but in the course of therapy, possible allergic reactions.

Concomitant therapy: non-steroidal anti-inflammatory drugs, steroids, antihistamines, sedatives, and others.When

eye shape dirofilariasis main method of therapy - surgical removal of helminth iz
under the eyelid skin, conjunctiva, followed by the appointment of disinfectant and anti-inflammatory drugs: chloramphenicol drops, sulfatsil sodium kolbiotsina followed by laying the ointment (erythromycin, tetracycline).A number of patients required the appointment of a drop of dexamethasone to reduce inflammation.The whole period of therapy supported the appointment of antihistamines (Zyrtec, Claritin, Aerius, diazolin and others).

Preventing heartworm

- struggle with the growth of the population of stray animals (dogs, cats);
- individual protection against blood-sucking insects (repellents, protective clothing);
- deworming pet dogs and cats to prevent in the spring-summer period (vermitan, levamisole, ivermectin, selamectin, dektomaksom, novomek);
- in the centers of parasitosis - treatment ponds to reduce the number of mosquitoes (delarvatsiya).

infectious disease doctor Bykov NI