How does dirofilariasis appear in humans?
Mar 22, 2018
Dirofilariasis - a natural focal parasitic disease of dogs, cats, wild animals Canidae and Felidae family that is able to be transmitted to humans.It is believed that the disease is typical for areas with a humid and warm climate: these are the countries of Asia, Africa, southern Europe.In Italy, France, Greece, Sri Lanka, the incidence remains practically constant.And sporadic cases are recorded every year in Spain, Israel, Japan and Hungary.But in recent years, there has been an increase in the incidence of dirofilariasis in countries for which this disease is not entirely characteristic.So, in the territory of the post-Soviet countries, every year more new cases of the disease are registered.Contents: Pathogen heartworm Symptoms Symptoms of subcutaneous heartworm Symptoms internal dirofiljarioza Diagnosis Treatment Prevention Fighting mosquito Identification of heartworm in dogs Preventing contact of humans and animals mosquito
Dirofilariasis Latin is translated as "wicked string" suchThe analogy is caused by the appearance of the parasite.Dyrofilarias are white helminth helminths belonging to the class of nematodes.There are about twenty kinds of dirofilaria, but for a person are the danger of Dirofilaria repens and Dirofilaria immitis.Dirofilaria repens mature female can reach a length of 13-15 cm and Dirofilaria immitis 25-30 cm. Width helminth ranges 0,03-1,2 mm.
person infected with heartworm by the bite of infected mosquitoes of the genus Culex, Aedes, Anopheles.The final hosts of the dyrofilaria are animals of the family of dogs, cats, and also wiverworms.In an infected animal, microfilariae circulate in the blood, which are not contagious to humans or to other animals.When bitten by a mosquito of a sick animal, the insect infects.And already in the mosquito the microfilariae are transformed into an invasive larva.Then the infected insect bites the person and thereby infects it with dirofilaria.The larva in the tissues of the human body grows, but does not turn into a sexually mature individual.Therefore, it remains unable to reproduce in the human body.
Often when infected, one larva enters the human body, less often two, even less often two or four.
Dirofilaria repens and Dirofilaria immitis cause different forms of the disease.The first - is the cause of subcutaneous dirofiljarioz, the second - visceral.In the territory of post-Soviet countries, it is subcutaneous dirofilariasis.And the visceral form is characteristic for such countries as Japan, USA, Canada, Australia, Southern Europe.
Symptoms subcutaneous dirofiljarioza
The incubation period lasts from a month to a year.The first symptom of the disease can be considered the appearance under the skin or mucous membrane of a tumor-like formation, which is accompanied by reddening, itching in this part of the body.Education itself can be painful or not bring any unpleasant sensations.A characteristic sign of the disease is the migration of the helminth, which is marked externally as the movement of education along the body.For two days the larva is able to overcome the distance of thirty centimeters.
Often discovering on the body a tumor-like formation, people go to a surgeon who suggests a diagnosis of lipomas, fibromas, atheromas, etc.But during the operation the doctor discovers an unexpected finding in the form of a helminth.
The dirofilaria has its "favorite" places in the human body. These are the parts of the body( as the incidence decreases):
- Neck and trunk;
- Mammary glands;
Dysphilia also exhibits nonspecific symptoms in the form of weakness, headache, nausea, fever, pain in the larva's site, which can radiate along the nerve fibers.
Approximately in half the case, the dirofilaria is localized in the eyes and surrounding envelopes.The eyelids, the conjunctiva, the anterior chamber of the eye, the sclera, the tissue of the eye fossa are affected.
Such patients may experience a foreign body sensation in the eye, reddening of the eyelid skin, ptosis, blepharospasm.A tumor forms under the skin.
When a conjunctiva is affected, severe pain, lacrimation and itching caused by movement of the helminth are noted.Conjunctiva thus is hyperemic, through it sometimes it is possible to see the helminth itself.
When dirofilaria penetrates into the orbital tissue around the helminth, granuloma forms, which entails the development of exophthalmos and diplopia.The defeat of the eyeball is even worse, accompanied by a deterioration in vision.In this case, the injured person can even see a moving parasite.
A specific symptom of the disease is the sensation of a parasite moving inside the subcutaneous( submucosal) seal.It is worth noting that the migration of the parasite is enhanced when the skin is exposed to heat with the help of UHF or warming compresses.
In many patients, dyrofilariasis manifests itself as a recurrent course with periods of exacerbation and extinction of the disease.If the helminth is not removed in time, inflammation in the soft tissues may develop, as well as the formation of an abscess.
Symptoms of internal dirofilariasis
With this form of the disease the lungs are most often affected.After infection of the person, the larva enters the left ventricle of the heart, and from there into the pulmonary arteries.Here at the site of the localization of the parasite, a fibrous capsule is formed.
This form of dirofilariasis often does not occur asymptomatically.Sometimes patients may experience chest pain, coughing, hemoptysis.
Disease is found in most cases suddenly during chest radiographs or even during surgery on the lungs if a malignant process is suspected.On X-ray images in the lungs, nodules 1-2 cm in diameter are identified.
The only way to confirm the diagnosis is a parasitological examination of a seized helminth.By studying the parasite in detail under a microscope, the doctor will be able to determine whether or not it is a dystrophilia by characteristic features.
The auxiliary diagnostic method can be referred to as ELISA.At a dirofiljarioze in a blood in the person antibodies to migrating larvae( toksokar) can be found out.A positive ELISA result can not be the only correct one to determine the final diagnosis.
In addition, the pre-operative stage can be used methods of ultrasound and computed tomography.The obtained images can detect a small formation of an oval or spindle-like shape.
It is noteworthy that eosinophilia in the clinical analysis of blood with dirofilariasis is not typical and is observed only in 10% of all cases.
The main method of treatment is complete removal of helminth from the human body.Before the operation, the doctor can prescribe dytrazine in order to immobilize the parasite.
In cases where the dyrofilaria constantly migrates, it is difficult to catch, but there is a threat of damage to the eye, drugs containing albendazole( vormil, medizol) may be prescribed.
According to the indications, desensitizing therapy is performed.
During the screening activities it was found that in different regions of Russia approximately 4-30% of dogs are infected with microfilaria.While in Greece and Iran, this figure reaches 25-60%.It is noteworthy that the intensity of human invasion depends on the season.Dirofilariasis in humans is registered throughout the year, but most cases develop precisely in the spring-summer period and less in the autumn-winter, which is probably associated with exacerbation of dyrophilia in dogs.
Prevention of the disease consists of three directions:
- Fighting mosquitoes;
- Detection of dirofilaria in dogs with subsequent treatment;
- Prevention of human and animal contact with mosquitoes.
It is known that the foci of dirofilariasis are formed next to reservoirs near populated areas.Here, state and medical structures carry out measures to combat insects.
In addition, in the basement of multi-storey buildings, mosquitoes Culex can live almost all year round.Insects penetrate the ventilation system into apartments, where people bite, as well as animals.Therefore, appropriate measures should be carried out in the basements of houses.
Detection of dirofilariasis in dogs
A home pet needs to regularly carry out antihelminthic prophylactic measures with the use of drugs such as albendazole, ivermectin, levamisole, etc.
It is possible to suspect dirofilariasis in dogs by certain signs.At the forefront are changes on the skin: baldness, pigmentation, rashes, non-healing wounds, itching.
Gradually, the cardiovascular system of the dog is affected by microfilaria.The pet becomes sluggish, passive, appetite disappears, the temperature rises, even with minimal physical exertion a cough appears.Often the dog limps, there may be cramps.
Prevention of human and animal contact with mosquitoes
When visiting reservoirs, forest areas, repellents should be used and the body areas should not be covered with uncovered clothing.There are also animal repellents, with the same purpose can use special collars.
In settlements with a large number of mosquitoes, you should limit walks with the dog in the evening and at night.
Grigorova Valeria, medical reviewer