Brugiosis is a chronic biohelminthiasis from the group of filarioses with a transmissive transmission mechanism. The clinical picture in the acute phase of the disease is characterized by the presence of signs of desensitization of the body, the development of lymphangitis and lymphadenitis. Repeated relapses of the pathological process lead to the formation of elephantiasis of the limbs. The main diagnostic method is microscopy of a blood smear with the detection of microfilariae. Additionally, serological methods are used to identify parasitic markers. Diethylcarbamazine and ivermectin are used as etiotropic drugs. To correct the general condition of the patient, symptomatic treatment is prescribed.
The endemic areas for brugiosis are the countries of Southeast Asia: India, China, Indonesia, the Philippines, Thailand, Vietnam. Seasonality is uncharacteristic, however, an increase in sporadic morbidity is noted during the rainy period. The susceptibility is universal, mainly men and the population living in swampy areas are ill. The lesion is up to 60%, clinical manifestations are formed in 14% of infected. In the acute phase, bruguiosis is carried by immigrants. The local population often suffers from erased forms due to repeated infections and circulation of specific antibodies in the blood.
The causative agent is the nematodes Brugia malayi and Brugia timori. The length of the female is 50-60 mm, the male is up to 25 mm. The helminth life cycle proceeds with a change of hosts. The final hosts are humans, some primate species, lizards and cats, and the intermediate hosts are mosquitoes of various species. Mature individuals live in the structures of the lymphatic system, and larvae live in blood vessels. In the daytime, microfilariae are localized in the vessels of internal organs, at night they go to the periphery.
The source of infection is a parasite carrier. At the moment of the mosquito bite, the larvae penetrate into the insect’s body. After 2-3 weeks, microfilariae turn into invasive forms and begin to enter the proboscis of the arthropod. Thus, with each new bite, a new organism is infected. In the body of the final host, the larvae turn into adults after 3-18 months. The life expectancy of mature nematodes is about 17 years.
The pathogenesis of brugiosis is based on the development of inflammatory and allergic reactions and the formation of irreversible obstruction of lymph outflow. Penetrating into the body, the larvae enter the blood vessels, and then into the lymphatic structures. During the circulation of microfilariae, metabolic products are isolated. This is associated with the occurrence of symptoms in the form of allergic reactions of a presumably immediate type. Morphological changes in lymphatic vessels are characterized by constant reactivation of inflammation in the vascular wall, endothelial proliferation and subsequent sclerosis.
Due to the obturation of the lumen, the outflow of lymph is disrupted, the vessels expand and rupture, fistulas form with the expiration of lymph either in the cavities and tissues of the body, or on the surface of the body. Relapses of the process lead to the formation of dermatitis, cellulitis of the subcutaneous tissue of the affected limbs, elephantiasis develops. The bodies of dead helminths dissolve or calcify, becoming covered with a fibrous capsule. Such foci can become a place of attachment of a secondary infection.
The incubation period is about 3 months. The stages of the disease are characteristic. There are acute and chronic phases of infection. Clinical manifestations of the acute stage of brugiosis are local allergic reactions in the form of the appearance of urticaria rash, general intoxication, eosinophilia. In addition, there are signs of activation of the inflammatory process. Painful lymphangitis of the upper and lower extremities is formed, inguinal and axillary lymph nodes are enlarged. These symptoms are accompanied by fever up to 39 ° C, chills, profuse sweating.
Such attacks last for several days, then acute phenomena begin to fade, ending with clinical recovery. The frequency of exacerbations ranges from 1-2 attacks per year to monthly reactivation. The severity of the flow can be different. Fatal cases are mainly associated with the addition of a secondary infection and the development of complications. After 5-7 years of recurrent course, brugiosis turns into a chronic stage.
Due to a violation of the outflow of lymph, the lymphatic vessels varicose expand and often burst, trophic ulcers form. The result of persistent inflammation is sclerosis of lymphostructures. Elephantiasis is observed, cellulite and dermatitis of the affected limb occur. The skin is covered with warty growths with many folds. The limb is disfigured, its size increases significantly. With brugiosis, elephantiasis of the legs is most often formed. The defeat of the genitals is rare.
A separate variant of brugiosis is tropical pulmonary eosinophilia or “eosinophilic lung” syndrome. This type of disease is characterized by the localization of microfilariae in the tissues of the host organism. Eosinophilic reaction with the formation of granulomas and fibroids is characteristic. There is an increase in lymph nodes, splenomegaly, the appearance of coughing attacks, nocturnal bronchospasms. On an X-ray of the chest organs, signs of a miliary lesion are determined. During spirometry, a restrictive type of violation of the ventilation capacity of the lungs is detected.
The most common complication of brugiosis is the attachment of bacterial infection at the site of damage to the lymphatic vessel with the development of thrombophlebitis, sepsis. Rupture of the lymphatic vessels of the kidneys and bladder with the presence of hiluria in brugiosis is rarely observed. Violation of the integrity of intestinal lymphostructures contributes to the occurrence of chyletic diarrhea. The constant outflow of lymph provokes the formation of pronounced protein deficiency, cachexia.
Dead helminths covered with a capsule are aseptic abscesses. The introduction of microbial flora leads to suppuration of these foci with the appearance of peritonitis, pleural empyema, purulent arthritis, and subsequently – fibrotic ankylosis. Constant maceration of the disfigured skin provokes the maintenance of chronic inflammation, which, in turn, is a predisposing factor for the development of atherosclerosis, rheumatoid arthritis and other diseases.
If you suspect brugiosis, you need to consult a parasitologist, an infectious disease specialist. During an objective examination, the doctor pays attention to the appearance of a specific rash on the skin, there is an increase in peripheral lymph nodes, mainly axillary and inguinal, hyperemia of the skin, soreness along the affected lymph vessels. Similar phenomena are characteristic of the acute phase of brugiosis during the period of exacerbation.
In the chronic stage of the disease, the presence of disfigured limbs, mainly legs, of enormous size, covered with rough skin with papillomatous growths, folds, cracks and trophic ulcers is detected. Involvement in the pathological process of the genitals and mammary glands in women is rarely observed. The following clinical and laboratory methods are used to diagnose infection:
- Clinical studies. In the blood test, hypereosinophilia is determined, at the time of activation of inflammation – leukocytosis, a shift of the formula to the left. In a biochemical study, a decrease in total protein is noted. In the analysis of urine, when the lymphatic structures of the kidneys are damaged, hiluria is detected. For the diagnosis of “eosinophilic lung”, chest radiography and spirometry are additionally prescribed.
- Detection of the pathogen. Thick and thin blood smears are made with their subsequent microscopy. Blood for analysis is collected at night or during the day after a provocative test with diethylcarbamizine, which promotes the exit of larvae into peripheral blood vessels. Microfilariae are identified in ascitic fluid, pleural effusion. Adults can be detected by biopsy of lymph nodes, but such a procedure contributes to impaired lymphatic drainage.
- Serological diagnostics. Indirect hemagglutination and immunofluorescence, enzyme immunoassay, rapid immunochromatography, flocculation test with bentonite are used to determine specific parasitic markers of brugiosis. Immunological tests do not always give reliable results. High IgE titers are detected in the blood of a patient with tropical pulmonary eosinophilia.
Differential diagnosis is carried out with lesions of the lymphatic system of bacterial etiology. It is important to distinguish pulmonary eosinophilia from tuberculosis, allergic aspergillosis and Leffler syndrome. With the development of splenomegaly, it is necessary to exclude lymphocytic leukemia. Manifestations of the late stage of brugiosis in the initial stages may resemble venous and heart failure, hereditary forms of elephantiasis.
An important stage of conservative treatment of brugiosis is hospitalization and isolation of the patient in order to prevent the spread of infection. For etiotropic treatment, ivermectin and diethylcarbamazine are used, albendazole and doxycycline may additionally be prescribed. The decay products of helminths after the start of taking medications can cause allergic reactions. Antihistamines, glucocorticosteroids are used to correct the condition.
Symptomatic therapy includes antipyretic and painkillers, intravenous infusions. The doctor’s further tactics depend on the development of complications and the stage of the disease. In the acute period before the formation of elephantiasis, a cure and complete release from the pathogen occurs. To improve lymph flow, physiotherapy, physical therapy, massage and wearing compression knitwear are additionally recommended. In the chronic phase, the pathogen is eliminated, but irreversible changes in the limbs and lymphatic apparatus persist.
Surgical intervention serves as a palliative therapy option, indicated in the late stages with severe lymphostasis. The main methods are lymphatic drainage operations, dermolipofasciectomy (excision of altered subcutaneous fat, fascia with affected lymphatic structures), liposuction (aspiration removal of altered fiber) and their combination. The choice of the surgical method of correction remains with the surgeon.
Prognosis and prevention
The prognosis is more often favorable. The appointment of conservative therapy in the early stages contributes to the cure. Elephantiasis leads to permanent disability, a decrease in the quality of life and disability. Fatal cases are associated with the formation of complications. Non-specific measures for the prevention of brugiosis include the destruction of mosquito breeding sites, the use of protective nets and repellents, and wearing long-sleeve clothing. In countries endemic to vuhereriosis and brugiosis, diethylcarbamazine is used as an additive to salt to prevent the development of infection.