Acariasis is a group of infectious diseases caused by arachnids. Pathognomonic symptoms for invasive pathologies are organ dysfunctions, for external ones – inflammatory phenomena on the skin and appendages. With high sensitization, allergic symptoms come to the fore. Diagnostics is based on the detection of the pathogen in various biological materials, determination of the IgE level. Complex treatment is carried out using etiotropic acaricidal drugs, anti-inflammatory and desensitizing drugs, local and symptomatic effects.
Acariases (acaroses) are a heterogeneous set of nosologies in structure, which includes superficial and deep lesions, allergization of the body by the products of pathogens. Reports on the influence of some representatives of domestic ticks on human health have been recorded since 1778, in 1972 it was suggested about the role of acariasis in the structure of cases of sudden infant death syndrome, Kawasaki disease. The prevalence is not reliably known due to the difficulties of diagnosis. It is believed that 36-45-year-olds are more susceptible to the disease, there is a predominance of male patients. Sensitization is determined in 90% of patients with bronchial asthma.
The sources of the disease are a large group of arachnids belonging to various species. The most common lesions are caused by the superfamilies Analgoidea, Glycyphagoidea and Acaroidea. Ticks often lead a parasitic lifestyle, being on the outer covers of their hosts-animals, less often plants, in internal organs. A person usually gets involved by accident. The causative agents of acariasis can be conditionally divided into domestic ones living inside a human dwelling, and those located in places where grain, dry hay, flour, and bulk food are stored.
The ways of infection are diverse, the contact method of infection prevails when using common items of clothing, bedding and underwear, in cramped living conditions. Ticks get inside by inhalation – by inhaling dust containing pathogens and their waste products. Infection is described when eating contaminated food, water, when introducing parasites into the external auditory canal, into the eyes when bathing in a pond. Urogenital infection most likely occurs in an ascending way from the mucous membrane of the genitals, urethra, with unprotected sexual intercourse.
The main risk factors are working with animals and plants that are hosts of parasites, immunodeficiency of various nature. According to some studies, up to 4-6% of the Asian population secrete eggs, larvae and mature individuals with feces and urine. Symptoms of acariasis are often detected among representatives of such professions as agricultural workers, granaries and bakeries, trainers, gardeners, zookeepers, Pathology is often found in people living in unsatisfactory social and hygienic conditions.
The pathogenesis of systemic manifestations of acariasis is practically not studied. An idea of the pathophysiological mechanisms of the action of ticks on the body can be obtained from the description of the mechanism of pathological properties of the causative agent of widespread superficial acariasis – scabies. Sarcoptes scabiei (itchy itch) damages the epithelium of the human skin, releasing antigens and epithelial cell processing products in the course of its vital activity, thereby activating the work of the complement system.
It is believed that the peritrophin molecule, located inside the intestinal walls of the tick, stimulates the activation of the lectin complement pathway. However, on the surface of the insect’s body there is a set of serine proteases (SMIPP-Ss) that allow the pathogen to evade the effects of the immune system. These proteins have the ability to bind the complement component C1q, mannose-binding lectin, properdin and inhibit all three immune response pathways simultaneously. Also, the protective tick protein can indirectly suppress phagocytosis.
The defeat of organs and tissues in acariasis is manifested by a variety of symptoms. Representatives of arachnids are found both at home and in the wild. The classification of pathology is based on varying degrees of parasite invasion, but this process is usually random and nonspecific. Manifestations also do not have strict criteria that characterize acariasis, this is associated with the complexity of the diagnosis of nosologies.
- Surface acariasis. They are caused by temporary ecto- and exoparasites of mammals and birds, randomly involving humans in the infectious process. They include scabies, demodecosis, and other nonspecific symptoms of invasion: itching, rashes, dermatitis, conjunctivitis.
- Deep acariasis. Pathogens enter the internal organs transiently, some are capable of completely anaerobic reproduction. Lesions of the lungs by ticks are more often recorded in East Africa and Korea, the intestines – Spain and China, the urinary system – in Canada, South Africa and Romania. In Taiwan, Thailand, infections of the auditory canal are detected.
- Acariasis allergies. It is believed that up to 10% of the world’s population is sensitized to domestic mites living in mattresses, pillows, upholstered furniture, granaries and medicinal herbs. Often the first signs are bronchial asthma and allergic rhinitis.
Symptoms of acariasis
The incubation period of infection depends on the type of invasion. Skin symptoms develop 10-24 hours after the introduction of the pathogen; visceral pathologies are detected after a longer stay of ticks in the human body – up to several months. Clinical manifestations depend on the depth of parasite invasion, the most frequent localization is the skin. The most common superficial acariasis are demodecosis and scabies.
The main symptoms of acne infection – redness, itching, greasy shine and acne – are common in the face, sometimes the external auditory canal. There is peeling in the area of eyebrows and eyelashes, less often their loss, puffiness of the eyelids and discharge from the eyes, especially noticeable in the morning. Scabies look like whitish lines with a black dot at the beginning, most often found in areas with thin skin: in the interdigital spaces, the penis area, on the inside of the wrists and forearms. Then the lesion spreads to the areas of friction and constant contact with clothing.
Anaphylaxis with tick-borne acariasis occurs suddenly, begins with symptoms of a sharp lack of air, numbness of the lips, tongue, transparent copious discharge, nasal congestion. Pulmonary manifestations of acariasis manifest with fever of more than 38.5 ° C, prolonged dry cough (sometimes paroxysmal), episodes of hemoptysis and pain behind the sternum. Intestinal signs may include prolonged subfebrility, diffuse abdominal cramps, nausea, vomiting, stool disruptions, impurities of pus and blood in the stool, weight loss, burning around the anus.
Symptoms of damage to the outer ear include unbearable itching, the feeling of a crawling insect, severe pain. The symptoms of acariasis invasion of the reproductive system depend on the gender of the patient. With vaginal acariasis, itching occurs, pain in the lower abdomen and lower back, abundant whitish discharge. In men, itchy ulcers and warts form on the head of the penis, foreskin, scrotum. The defeat of the urinary tract is manifested by frequent painful urination, lumbar pain, periods of increased body temperature above 37.5 ° C, chills.
The main complications of acariasis are suppuration, the symptoms of which occur after the addition of secondary bacterial flora. With a prolonged undiagnosed course, invasive acariasis leads to chronic inflammatory pathologies of the urinary and reproductive systems, violation of reproductive functions, contribute to the development of tissue-organ hyperplastic processes, ulcerative-necrotic changes in the mucous membrane of the gastrointestinal tract, bronchial asthma, chronic bronchitis, external otitis. The possible connection of demodecosis with the onset of melanoma symptoms is being actively investigated.
Diagnostics of acariasis
Timely detection and treatment of symptoms of acariasis requires consultation with an infectious disease specialist. The examination of a parasitologist, allergist-immunologist is shown. It is important to collect epidemiological, labor history, clarification of living conditions. Other specialists are involved for clinical indications. The basic laboratory and instrumental diagnostic signs of the disease are:
- Physical data. With an objective examination, it is possible to detect combs, papules, vesicles, urticary rashes on the skin, sometimes perianal. Palpation of the abdomen reveals rumbling, diffuse sensitivity, rarely hepatomegaly. Auscultatively, hard breathing, dry wheezing, sometimes local weakening of breathing and dulling of percussion sound are listened to. A visual assessment of the nature of sputum, feces and urine is mandatory.
- Laboratory tests. The general blood test has no specific manifestations except for moderate eosinophilia. Biochemical parameters correspond to the norm; an increase in ALT and AST activity is rarely detected. In the general clinical analysis of urine – leukocyturia, erythrocyturia. Sputum in visceral acariasis contains eosinophilic accumulations. In the vaginal smear, leukocytes are detected, in the coprogram – erythrocytes, pus.
- Identification of infectious agents. The proof of acariasis is the detection of ticks in biological fluids (sputum, eye, ear, vaginal secretions, urine) by microscopy. Avidin-biotin system of solid-phase enzyme immunoassay (ABC-ELISA) has been developed to identify pathogens in feces. Bacteriological examination of the material (sowing) is mandatory.
- Instrumental techniques. Chest x-ray in lung acariasis confirms the expansion of the basal zone, the strengthening of the pulmonary pattern. The details of the changes are carried out during CT. Abdominal ultrasound often identifies signs of hepatitis, cholecystitis, pyelonephritis, cystitis. Colonoscopy in the intestinal form can reveal ulcerative-necrotic lesions of the large intestine, duodenitis.
Differential diagnosis is carried out with a migrating larva having serpiginous passages, fungal skin lesions with characteristic peeling and plaques. Depending on the organ into which the invasion occurred, acariasis is differentiated with pulmonary tuberculosis (the final diagnosis is established only by the results of the detection of mycobacteria), genital herpes, which has specific vesicular rashes, schistosomiasis, in the clinic of which hematuria and dysuria predominate; amoebiasis, occurring with periods of remission and a stool resembling “raspberry jelly”.
Treatment of acariasis
For the treatment of symptoms of cutaneous forms, isolation of the patient in the hospital is necessary. Careful personal hygiene is important. The place of treatment of systemic acariasis depends on the severity of clinical manifestations, the epidemiological basis for hospitalization. Bed rest is prescribed for severe course, burdened with a premorbid background. Dietary recommendations depend on the form of infection. Given the allergogenicity of tick waste products, potential food allergens should be limited. In the absence of contraindications, it is necessary to increase the use of liquid.
Treatment of acariasis is most studied on the example of superficial forms of the disease (especially scabies and demodecosis). Therapy of visceral types of acaroses is difficult due to the complexity, lack of alertness of medical specialists; in the vast majority of cases, local remedies are prescribed. Oral, injectable and infusion medications are indicated for people with sensitive skin, systemic diseases, and various immunodeficiency conditions. The traditional treatment of acariasis is the use of:
- Etiotropic medications. Specialists in the field of modern infectology usually prefer a combination of metronidazole with doxycycline, ornidazole. Known dosage forms prescribed for organ invasions are ivermectin, chloroquine, nystatin, neomycin. Treatment with locally acting ointment etiotropic agents containing macrolides, benzyl benzoate, is indicated for skin symptoms of acariasis.
- Pathogenetic agents. An important area of therapy is desensitization of the body, for this purpose, calcium preparations, antihistamines, less often systemic glucocorticosteroids are recommended. Anti-inflammatory (NSAIDs) and detoxification medications based on acesol, glucose-salt and succinate-containing solutions are used almost exclusively for organ lesions. Local treatment is performed with antipruritic ointments, talkers.
- Symptomatic therapy. If systemic anaphylaxis occurs, the administration of adrenaline, prednisone, and resuscitation measures are indicated. The dysfunction of the digestive system determines the need to take enzymatic, antiemetic agents, sorbents, sometimes proton pump blockers. The addition of a pyogenic infection, especially with pulmonary acariasis, requires the use of antibacterial drugs.
In the study of the effectiveness of the treatment of acarodermatitis with ornidazole, satisfactory elimination of the pathogen and an increase in the inflammatory reaction, weakly suppressed by antihistamines, were noted. As a result, a combined treatment was proposed – the appointment together with an etiotropic preparation of the main recombinant bovine fibroblast growth factor (“bovine” gel) for topical use, as well as the injectable glucocorticosteroid betamethasone intramuscularly.
The local use of pilocarpine gel has shown a good acaricidal effect only with prolonged use, which creates a danger of systemic side effects of the drug (muscarine-like effect). Some researchers suggest a combination of camphor oil and metronidazole as an antipruritic agent. Ivermectin, when taken orally, has a pronounced clinical effect on refractory blepharitis, papulo-pustular lesions of the scalp.
Prognosis and prevention
The prognosis with timely detection is favorable. No fatal cases have been recorded. Currently, there is no vaccine; the main measures to counteract infection with acariasis are early diagnosis, isolation and treatment of patients, deratization and disinsection of habitats of pathogens, as well as wild animals imported from endemic zones – exotic birds, cats, elephants, etc. For preventive purposes, wet cleaning is recommended with the treatment of books, carpets, soft toys and other things that are areas of tick accumulation, the use of respirators when working in dusty conditions.