Filariasis are parasitic diseases caused by nematodes living in human tissues, transmitted by blood-sucking insects. The disease occurs most often in people living in the subtropics, as well as in people traveling to these parts of the world. what are the symptoms of filariosis? How is filariasis treated?

Filariasis- parasitic diseases caused by nematodes - have been divided into 3 groups, depending on the clinical symptoms caused by particular parasites.

The cutaneous form of filariasis (Loa loa,Onchocerca volvulus ), the lymphatic form ( Wuchereria bancrofti ,Bruges malayi ,Brugia timori ), as well as the form of filariasis in which symptoms originating from body cavities dominate (nematode species from the groupMansonella ).

In clinical practice, cutaneous and lymphatic forms of filariasis are by far the most commonly observed. The larvae of nematodes enter the body through the bite of a mosquito or other blood-sucking arthropod, so it is important to ensure regular use of effective repellants when traveling to exotic countries.

The nematodes responsible for causing filariasis include parasitesWuchereria bancrofti ,Brugia malayi ,Brugia timori,Onchocerca volvulusand Loa loa. They are typically found in Asia, especially India and China, Indonesia, Africa, and South and Central America.

In Poland, these nematodes do not occur in the natural environment, but people suffering from filariosis more and more often visit an infectious disease specialist because of the growing popularity of exotic travels to tropical countries.

A specific feature of the parasites from the group of nematodes is that they travel through the lymphatic vessels. Then they cause a difficult outflow of lymph from the surrounding tissues, the accumulation of tissue fluid and, consequently, the formation of lymphoedema.

Contents:

  1. Filariasis: causes
  2. Filariasis: symptoms
  3. Filariasis: 4 main types
  4. Filariasis: diagnosis
  5. Filariasis: differentiation
  6. Filariasis: treatment
  7. Filariasis: prevention
  8. Filariasis: prognosis

Filariasis: causes

Vector of infectionfilariosis are mosquitoes of the generaCulex ,AedesandAnophelesor other blood-sucking insects, e.g. fluff or bitterns . They suck blood into their digestive tract infected with microfilariae (i.e. nematode larvae) after stinging a person suffering from filariosis.

In the body of the insect, the larvae undergo a series of changes and mature into a form capable of causing infection (it is exactly the 3rd larval stage, passing to the insect's stinging and sucking apparatus). By pricking and sucking the blood of a previously he althy person, infectious larvae pass through the skin into their peripheral blood and develop into an adult (filaria) form.

They enter the subcutaneous tissue, the lymphatic system and body cavities, and from there they release microfilariae into the peripheral blood, which are sucked in by blood-sucking insects - thus the development cycle of nematodes is closed.

Filariasis: symptoms

The clinical picture of a parasitic disease caused by nematodes depends mainly on the type of parasite that causes it and the location of its adult form. Sometimes, however, it is asymptomatic.

The symptoms of common filariasis presented by patients in the early, acute stage of infection include ailments caused mainly by microfilariae circulating in the human peripheral blood and the immune reaction of the organism to foreign antigens of the parasite.

Patients most often complain of troublesome itching of the skin, hives, nausea, enlarged lymph nodes, as well as swelling of the lower limbs or external genitalia.

In the advanced stage of the disease, when adults are located in the subcutaneous tissue, the lymphatic system, the organ of vision or the central nervous system, the symptoms presented by patients usually concern the affected organs.

They may be accompanied by general symptoms, such as fever, headaches and joint pains, indicative of an ongoing chronic inflammatory process in the body.

In the chronic stage of parasitic disease, treated inadequately or not at all, dead microfilariae and adults may calcify, form granulomas and nodules within the skin and subcutaneous tissue.

Filariasis: 4 main types

Wushereriosis

Vusheriosis is the most commonly described filariosis in humans, caused by nematodesWuchereria bancrofti , transmitted by mosquitoes. Adult nematodes feed in the vessels and lymph nodes, which in the advanced stage of the disease causes inflammation of the vessels and enlargement of the lymph nodes.

They may be tender, with limited mobility in relation to the surrounding tissues, the skin above them maybe altered, red and excessively warm. Changes in the lymphatic system are caused by the presence, development and death of filaria in the lymph nodes and vessels.

It is worth noting that mature female Wuchereria bancrofti are about 8-10 cm long.

Nematodes disrupt the flow of the lymph and the formation of typical lymphoedema. The most common late complication of recurrent genital lymphangitis in men is testicular hydrocele.

On the other hand, massive swellings that lead to distortion of the affected area are called elephantiasis. Most often it affects the lower limbs, abdominal cavity and external genitalia (scrotum in men, labia in women).

Accumulating tissue fluid and lymph cause chronic inflammation and lead to irreversible fibrosis of the connective tissue.

Permanent changes in the form of a huge swelling that make it impossible to function and move, hardening of the skin, as well as the appearance of bulges and growths within the affected area, ending with sensory disturbances and degenerative changes in the osteoarticular system are characteristic.

The affected skin is dry, calloused, tight, shiny, prone to cracks and the formation of difficult-to-heal erosions and ulcers, which become the gateway of infection.

Loajoza

Leolose is a filariosis caused by Loa loa nematodes, transmitted by bitterns of the genusChrysops . Symptoms of the disease usually concern three systems:

  • Skin symptoms

Loajoza belongs to the skin filariasis. Adult forms of the parasite may be located within the subcutaneous connective tissue, therefore the typical clinical symptoms for this disease entity are painful and itchy skin lesions. Pain most often occurs in the area of ​​the upper limbs and on the face.

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In addition, they form a massive swelling, which passes after some time (hours or even days), called Calabrian edema. These are periodic, painless changes around dead parasites.

  • Ocular symptoms

Adult forms of the nematode can also be found within the organ of vision. This can lead to reddening of the conjunctiva, tearing and reduced visual acuity. Without proper treatment, loajosis leads to retinopathy, retinal detachment, and eventually blindness.

  • Nervous system symptoms

Adult forms of Loa loa nematodes located in the central nervous system can cause sensory disturbances, peripheral neuropathy, epileptic seizures, as well as meningitis and encephalitis.

Onchocerkoza

Onchocercosis is a parasitic disease caused by the nematode Onchocerca volvulus, which is transmitted by various species of Simulium fluff. The symptoms of the disease most often concern organs and systems:

  • Ocular symptoms

Onchocerkoza is otherwise also called river blindness. Typical features of this parasitic disease are conjunctivitis, keratitis, inflammation of the iris, and also of the ciliary body.

The most dangerous and unfortunately the most common chronic complication of Onchocerca infection are cataracts (clouding of the lens) and glaucoma (increased pressure inside the eyeball), which may result in a gradual reduction in visual acuity over time, and even the development of complete blindness.

  • Skin symptoms

Itchy lumps and lumps appear on the surface of the skin of a person infected with the nematode, often located on the skin of the upper and lower limbs, trunk and buttocks, and on the head. They contain adult forms of the nematodeOnchocerca- one of the diagnostic methods of this disease is the detection of parasites in the nodules.

It is worth mentioning that adult femalesOnchocercareach a body length of 20-70cm, and males 3-12cm. Patients' skin is red, swollen, inflexible, with pigmentation disorders, dry and peels off easily.

  • Lymphatic symptoms

Enlarged lymph nodes and disorders in the drainage of the lymph from the genital area, caused by the presence of mature forms of nematodes in the vessels, may, in extreme cases, lead to the development of elephantiasis of the lower limbs and scrotum.

Sometimes, significant enlargement of the lymph nodes leads to the formation of large folds of inelastic and flaccid skin that hang around the groin ("hanging groin"), causing patients great discomfort.

Mansoneloza

Mansonellosis is a parasitic disease caused by nematodes from the groupMansonella , transmitted byCulicoides ,AedesiAnopheles .

This filamentous disease usually does not cause any characteristic symptoms. It can cause lymphadenopathy and allergic reactions related to the invasion of microfilariae. Patients report hives, itchy skin, presencetumors and lumps within it, as well as general flu-like symptoms, including fever, headache, joint pain and swelling, and abdominal pain.

Filariasis: diagnosis

The diagnosis of a parasitic disease is made by a physician specializing in infectious diseases based on the history and clinical picture, physical examination and the results of additional tests. It is very important to inform the doctor about exotic travels to nematode endemic countries.

A feature that draws attention to the possibility of a parasitic disease is eosinophilia found in blood counts, i.e. an increased percentage of eosinophils, as well as high levels of IgE immunoglobulins.

To establish the diagnosis, a specialized blood parasitological test is also used, which consists in viewing a thick smear of a fresh drop of peripheral blood of a patient stained with the Giemsa or hematoxylin method under a microscope. It consists in determining the presence of microfilariae in the tested sample.

It is worth remembering that blood for testing should be collected at the appropriate time of the day and night, depending on the daily activity of microfilariae produced by the tested parasite.

The microfilaries of Wuchererii bancrofti and Bruges malayi are active at night, while Loa loa are active during the day.

Special serological methods are also used for the detection of filariosis, which are based on the detection of specific antibodies against nematodes using immunoenzymatic methods, as well as molecular methods based on the detection of the genetic material of parasites using PCR.

The presence of microfilariae can also be tested in urine, skin nodule sections, and in the anterior chamber of the eye, depending on the type of nematode and filariasis. Sometimes, in the advanced stage of the disease, an ultrasound scan is used to reveal the adult parasites that are found in the lymph vessels and cause their obstruction.

Filariasis: differentiation

Infection with nematodes should be differentiated from other diseases that cause acute lymphangitis and lymphadenopathy, i.e. lymphadenopathy. There are sarcoidosis, tuberculosis and leprosy among them.

Lymphoedema and elephantiasis can be caused not only by parasites in the lymph vessels that prevent lymph flow, but also damage to lymphatic vessels during surgery, in the course of cancer, and circulatory failure.

Before the final diagnosis is made, it is also necessary to rule out the common cause of lower limb edema, i.e.thrombophlebitis.

Filariasis: treatment

The drug of choice for the treatment of filariasis is diethylcarbamazine, which is effective in destroying circulating microfilariae. However, it is worth remembering that the decaying larvae of the parasites can cause a strong allergic reaction in the patient and even lead to anaphylactic shock, therefore treatment is carried out only in specialized centers under strict medical supervision.

The therapy is started with low doses of the drug, gradually and slowly increasing them. Other drugs used in the treatment of filariasis are ivermectin, albendazole and suramin.

Anti-inflammatory and analgesic drugs can be used as supportive measures, but they will not fight the cause of the disease. In the advanced stage of the disease, especially elephantiasis, it is not possible to cure the patient, care should be taken to hygiene and good condition of the skin of the limbs, and to prevent the formation of difficult-to-heal erosions or ulcers.

It is worth taking care of daily physical activity, which improves the flow of lymph. Surgical treatment may be necessary in the advanced stage of the disease, especially in the treatment of testicular hydrocele.

Filariasis: prevention

The only known method of preventing filariasis is effective protection against mosquitoes and other blood-sucking insects during a stay in tropical countries. It is recommended to use repellants, mosquito nets and to wear clothes with long sleeves and legs, especially after dark.

Filariasis: prognosis

The prognosis of patients struggling with a parasitic disease such as filariosis is relatively good in the early stages of the disease. Effective treatment of permanent complications of the disease has not yet been discovered. elephantiasis, which is why it is so important to see a doctor early and start treatment.

Category:

Parasitic diseases