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UDC 616.99-078-08
DIROFILARIASIS. HUMAN AS A SECONDARY DEFINITIVE HOST (CLINICAL CASE)
Altai State Medical University, Barnaul
M.V. Goryacheva, O.O. Mikheyeva, L.A. Churilova, T.S. Frolova, V.D. Ragulina, A.G. Mikhailov, S.I. Koltakova, M.V. Sorokina
In recent decades, cases of dirofilariasis have become more frequent in Russia. From 1996 to 2001, 152 cases of invasion were identified. In the temperate climate zone, the authors first established the case of sexual reproduction of Dirofilaria repens in a human body. The article describes the clinical cases of dirofilariasis in Altai Krai. Key words: dirofilariasis, invasion, Dirofilaria repens.
Recent years in Altai Krai have been marked by an increase of human cases of dirofilariasis- an obligate-transmissible dog helminthiases caused by Dirofilaria repens. In the Russian Federation, the disease had long been considered rare. Since the middle of 1990s of the XX century, there has been observed an increase of the number of registered dirofilariasis cases in human and the growth of attention to this problem. For the period of 1996 - 2001, there had been registered 152 cases, primarily in the residents of endemic territories of the South [1].
However, the analysis of morbidity of the recent years showed that a particular frequency of the disease is present in the regions with moderate climate (Moscow, Tula, Ryazan, Lipetsk Oblasts, the Urals, The Republic of Bashkortostan, etc.). The disease was also registered in Saratov, Samara and Nizhny Novgorod Oblasts, the Republic of Kalmykia. By the beginning of 2014, there had been registered 850 D.repens-infested people on the territory of 42 entities of the RF [2]. The hotbeds of invasion in the zone of moderate climate are determined up to 55-57°N (twenty years ago the Northern border was considered 53-54°N) [3]. Thus, at the present time, there is a tendency not only to the increase of the stated pathology, but also to the broadening of its areal to the Northern regions, which is probably connected with the rise of the average annual temperature.
In Altai Krai dirofilariasis has been registered since 1989. For the period from 1989 to 2011, there were detected 39 cases. Over the last 10 years, dirofilariasis morbidity grew nearly by four times. Thus, from 1989 to 1998, there were registered 8 cases, from 1999 to 2011 - 31 case [4], which can be considered as an outbreak of the disease on the territory of Altai Krai.
People become infected with dirofilariasis by agricultural works, during outdoor recreation from May to September, in the places with considerable populations of mosquitos and infected animals [1].
Dirofilariasis is caused by the class of filar-ial nematodes (roundworms), order Spirurida,
suborder Filariata, superfamily Filariidae, genus Dirofilaria. The agents of invasion in the territory of the Russian Federation D.repens and D.immitis are obligate parasites of the carnivorous families of Dogs and Cats, D. ursi of the brown bear and the Amur tiger. Mature females D. repens reach the body length of 135-150 mm, D. immitis
- 180300 mm, D. ursi - 120-225 m. Males, respectively, reach 50-58 mm, 100-110 mm, 51-85 mm. Larval stages - microfilariae - without a cap, with a blunt front end, pointed and filiform back end. The length of microfilaria - 0,30-0,36 mm, the width
- 0,006-0,008 mm (comparable to the erythrocyte diameter).
Dirofilarias, after the period of larvae migration through the blood channel, go through the stage of deposit in liver and spleen, which continues up to half a year, then settle in the subcutaneous connective tissue of dogs or, in case of larvated penetration, into a secondary optional host - human. The carriers of microfilariae of the helminths of Filariidae family are mosquitos of Culex, Aedes, and Anopheles genera. On the territory of the region there are indicated 25 species of mosquitos carrying dirofilarias, including 17 species and 2 subspecies p. Aedes, 1 species and 3 subspecies p.Culex, 1 species p. Anopheles (maculipennis). The domineering species are p.Aedes: A. communis A. vexans [4]. According to modern concepts, human is an optional dead-end host of the parasite, as females do not reach maturity in the human's organism, sexual reproduction does not occur and microfilar-iae do not sprout into the blood.
However, in recent years, there have appeared separate works denoting the fact, that the possibility of microfilaremia cannot be totally excluded. The sources of literature describe the cases of larvae occurrence in human blood. V.G. Su-pryaga and coauthors (2004) were the first to detect in the territory of Russia (Vladimir and Samara Oblasts) the patients with microfilariae in the punctate of the subcutaneous tumor [5-7].
Dirofilariasis is met in persons of both genders, in the age groups from 3 to 75 years. In human, mature forms of filariae localize in the area
of limbs, low neck zone, under the skin of eyelids in the subcutaneous connective tissue. There are described the cases of migration of parasites under the skin in the area of head - neck - upper limbs, which is the sign of «larva migrans cutanea» phenomenon.
The first manifestation of the disease is the appearance of a painful tumor, the area of which can be characterized by pruritis or urtication of various intensity. In some cases there can be observed headache, nausea, fatigue, high temperature. Eosino-philia of peripheral blood is not typical of dirofil-ariasis, but in several cases it can constitute 8-11%. The optimal method of treatment - surgical resection of the focus of chronic inflammation together with the helminth, around which there can form a connective-tissue capsule [8, 9].
Clinical case. In April 2014 the 56-year-old female patient N. was admitted to the Department of bone skin and soft tissue tumors №2 of the FS-BHI AROH with complaints of the tumor in the left breast, which she had found in November 2013. At the same time she had pains in the area of the tumor, which became less intensive in 1,5 months and were registered only by pressing.
Objectively: by observation of the area of the left breast, on the border of lower quadrants, there is observed a postoperative scar, 0,3*7sm (in 1999 - sector resection for fibroadenoma). By palpation the scar is soft, atrophic, in its projection there is determined a tumor of 3sm in diameter of firm texture with indistinct boundaries, soldered by surrounding tissues, moderately painful by pressing. No nipple discharge. Regional lymphatic nodes not distinctly palpated.
Mammography of 27.02.2014 - on the border of lower quadrants, there is observed an area of stroma induration with indistinct boundaries of inhomogeneous structure, size 3,5*2sm. Conclusion: Nodular fibrosis, suspected left breast cancer.
Ultrasonic examination of breast of 06.03.2014 - on the border of lower quadrants in the projection of the postoperative scar, there is located a hypo-isoechoic round inhomogeneous formation with a distinct wavy border, size 23,4*16,9*20,0mm, with a visible blood flow in the center and peripherally by CDI. Conclusion: Suspected left breast cancer.
Thin-needle aspiration biopsy of the left breast tumor of 26.02.2014.
Cytological conclusion - signs of purulent inflammation, macrophages, cubical epithelium cells.
Diagnosis before surgery: Chronic mastitis. Suspected left breast cancer.
The patient is planned to undergo sectoral resection of the left breast with the urgent histolog-ical test, by cancer diagnosis - Madden's mastectomy.
By the urgent histological test during the operation there was detected a parasite, presumably, dirofilaria.
Macroscopic examination - the sector of breast tissue 5,0x3,0x3,0 sm, on the section - cyst cavity with yellowish fluid, in the center - a filiform white circinated formation, by touching with forceps -active movement. By expansion - the formation 3,5 sm long, diameter - 1,0 mm, one of the ends is clublike thickened up to 2,5 mm. The mature helminth was resected together with the connective tissue membrane of the capsule and cyst cavity.
Consultation by the specialist of the clinical lab-oratorial diagnostics - Dirofilaria repens.
Pathomorphological examination - the internal capsule surface is presented by granulation tissue with a large number of lymphocytes. The fibrous part of the capsule includes the breast tissue with focal plasma cell infiltration and separate granulomas surrounded by fibrous tissue with single foreign body giant cells. Inside granulomas there are observed assemblies of microfilariae (longitudinal and cross sections) (Figure 1).
Final clinical diagnosis - dirofilariasis of the left breast. Mature and larval stage. State after surgical treatment.
After further curation of the patient it was stated, that the tumor did not relapse. No return visits for operative treatment were registered. The lack of neoplasm recurrence allows to assume, that the observed microfilariae had been formed as a result of Dirofilaria repens sexual reproduction.
In March 2017 in Altai Krai, there has already been registered two cases of dirofilariasis. Female patient P. from Kamen-na-Obi, 1959 year of birth, was admitted to FSBHI "Altai Regional Clinical Hospital" with a helminth localized in the right region of the neck (Figure 2). Helminth was resected and identified as Dirofilaria repens. Biopsy with further microscopy of surrounding tissues was not conducted. Final clinical diagnosis - dirofilariasis of the right region of the neck.
Patient N. applied to the "Pavlovsk Central District Hospital" with a formation on the front surface of the abdominal wall accompanied by itching and compression. Provisional diagnosis - lipoma of the front surface of the abdominal wall. By operative treatment there was resected a capsulated helminth of white color more than 3 sm longwise, which was also identified as Dirofilaria repens. Biopsy with further microscopy of surrounding tissues was not conducted. Final clinical diagnosis -dirofilariasis of the front surface of the abdominal wall.
Both cases of dirofilariasis are local. The patients did not leave the territory of Altai Krai during the recent year, in summer they were exposed to mosquito bites. The patients applied for medical help in several months since the disease onset.
By the first reference to a doctor, the established diagnosis was not connected with parasitic etiology.
According to our observations and the literature data, the majority of patients apply for med-
ical help on the subject of subcutaneous tumors disturbing them for several days or even months during spring (March - May).
Figure 1.
Cross sections of microfilariae inside granulomas in the breast tissue
Figure 2.
Helminth in the right region of the neck
Unfortunately, nowadays the monitoring of animal (dog) dirofilariasis morbidity is not carried. Thus, the "Barnaul Animal Health Center" does not possess statistical information on the dirofilariasis morbidity among dogs after the first outbreak in the 1990s of the XX century. The degree of prevalence of the disease in dogs of Altai Krai, in which dirofilariasis is a serious disease affecting not only subcutaneous fat, but also heart, is unknown. Consequently, it does not seem possible to estimate the possible risks for human health.
Conclusion
The case of Dirofilaria repens sexual reproduction in human organism was firstly established within the boundaries of the Siberian region (Altai Krai) in the zone of moderate climate. On the basis of possible inclusion of human in the group of secondary definitive hosts of Dirofilaria repens, it is recommended to revise the principles of transmissible invasions (filariasis) prevention on the territory of Altai Krai from the perspective of interruption of the invasion transmission - extermination of mosquitos, detection and dehelminthization of pets, prevention of mosquito contact with pets and human.
References
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Contacts:
Corresponding author - Goryacheva Marina Vlad-imirovna, Doctor of Biological Sciences, Associate Professor, Head of the Department of biology, histology, embryology and cytology of the FSBEI HE Altai State Medical University of the Ministry of Health of the Russian Federation, Barnaul. 656038, Barnaul, Papanintsev Ulitsa, 126. Tel.: (3852) 566927. Email: [email protected]
