Surgery for a thoracic gunshot wound reveals pleural infection with dirofilaria repens Case Report Journal of Clinical Images and Medical Case Reports

Abstract

Dirofilaria repens (D. repens) is a vector-borne filaroid helminth of carnivores, with dogs representing the major reservoirs of infestation. Humans are accidental hosts in which D. repens usually do not reach sexual maturity but may induce local inflammation, mainly in subcuta- neous or ocular tissues. Here, we present the rare case of an incidental pleural D. repens infection in a young patient with a gunshot wound to the right upper chest. During thoracoscopy to remove the bullet from the dorsal chest wall, a small solitary worm was discovered in the pleu- ral cavity on the diaphragm and later identified as D. repens. Our pa- tient was asymptomatic regarding the parasite. D. repens is considered an emergent zoonotic pathogen in northern and central Europe and may be increasingly relevant for animals and human health. Spreading of the parasite is facilitated by climate changes and globalization.

Full text

Open Access, Volume 5
Surgery for a thoracic gunshot wound reveals pleural infecon
with dirolaria repens
Case Report
www.jcimcr.org
Journal of
Clinical Images and Medical Case Reports
Received: Mar 01, 2024
Accepted: Mar 27, 2024
Published: Apr 03, 2024
Archived: www.jcimcr.org
Copyright: © Moneke I (2024).
DOI: www.doi.org/10.52768/2766-7820/2961
*Corresponding Author: Isabelle Moneke
Department of Thoracic Surgery, Medical Centre,
University of Freiburg, Faculty of Medicine, Univer-
sity of Freiburg, Germany.
Email: Isabelle.moneke@uniklinik-freiburg.de
ORCID: 0000-0002-1019-5214.
ISSN 2766-7820
Introducon
Human dirolariasis is a zoonoc vector-borne helminth dis-
ease caused by two species of Dirolaria: Dirolaria repens (D.
repens) and Dirolaria immis (D. immis). Human dirolariosis
is mostly asymptomac, however it can become clinically ap-
parent by nodules that appear when pre- adult/adult worms are
arrested in a pulmonary artery branch in the case of D. immis
(pulmonary dirolariosis) or in subcutaneous or ocular ssue
in the case of D. repens (subcutaneous or ocular dirolariosis),
causing coagulaon necrosis and inammatory cells inltraon
[1]. Dirolaria are mosquito-transmied nematodes primarily
using domesc and wild canids, and to a lesser extent felines as
principal reservoirs [2]. D. immis has a world-wide distribuon
[3] and may cause severe and potenally fatal disease (heart
worm disease) in dogs and other carnivores but rarely in hu-
mans [3,4]. Despite humans being accidental hosts for both Di-
rolaria species, D. repens shows higher zoonoc potenal [5].
Over the last 2 decades, the prevalence of the clinically less no-
ceable D. repens has increased in its endemic areas and its dis-
tribuon range has expanded to previously unaected regions
in northern and central Europe [3,6]. Thus, D. repens infecon
has become increasingly relevant, not only for animals, but also
for human health. Humans are accidental hosts, and while the
Abstract
Dirolaria repens (D. repens) is a vector-borne laroid helminth of
carnivores, with dogs represenng the major reservoirs of infestaon.
Humans are accidental hosts in which D. repens usually do not reach
sexual maturity but may induce local inammaon, mainly in subcuta-
neous or ocular ssues. Here, we present the rare case of an incidental
pleural D. repens infecon in a young paent with a gunshot wound to
the right upper chest. During thoracoscopy to remove the bullet from
the dorsal chest wall, a small solitary worm was discovered in the pleu-
ral cavity on the diaphragm and later idened as D. repens. Our pa-
ent was asymptomac regarding the parasite. D. repens is considered
an emergent zoonoc pathogen in northern and central Europe and
may be increasingly relevant for animals and human health. Spreading
of the parasite is facilitated by climate changes and globalizaon.
Keywords: Dirolaria repens; Human; Thoracic manifestaon; Gun-
shot wound.
Isabelle Moneke1*; Anastasiya Kornyeva1; Leonie Braun3; Frederik Kukla3; Fabian Kohn4; Bernward Passlick1; Laurin Titze1
1Department of Thoracic Surgery, Medical Centre, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany.
2Department of Microbiology, Medical Centre, University of Freiburg, Faculty of Medicine, University of Frei-burg, Germany.
3Veterinary Laboratory Freiburg, Germany.
4Department of Anaesthesiology and Crical Care Medicine, Medical Centre, University of Freiburg, Faculty of Medicine, Univer-
sity of Freiburg, Germany.

www.jcimcr.org Page 2
Citaon: Moneke I, Kornyeva A, Braun L, Kukla F, Kohn F, et al. Surgery for a thoracic gunshot wound reveals pleural infecon
with dirolaria repens. J Clin Images Med Case Rep. 2024; 5(4): 2961.
parasite does not normally reach adult stage in humans, it may
live for several years [7]. In most cases, only 1 parasite develops
[6] and the infecon usually remains asymptomac. D. repens
mostly presents as subcutaneous or ocular dirolariasis [7,9].
Rarely, local infecon may appear, accompanied by a mild sys-
temic reacon, e.g., fever or mild eosinophilia [10]. Even more
rare are severe systemic immunoreacons [7]. However, in
cases of sexual maturity, it may cause larva migrans syndrome
and migrate to other organs, such as the abdominal cavity or
the lungs [7,9]. The denite treatment is surgical removal of the
parasite. Pharmacological treatment is usually not necessary
[8], unless systemic infecon is present and/or the worm can-
not be surgically removed.
Case report
A 13-year-old male was admied to our terary trauma cen-
ter with a gunshot wound to the right upper chest caused by
an air rie accident. The CT-scan showed a penetrang gunshot
wound with entry point of the projecle in the 4th ICR and con-
secuve traumac injury to the right upper lobe with resulng
hematopneumothorax (Figure 1). There was no evidence of ac-
ve bleeding in the CT-scan, and the paent was hemodynami-
cally stable. However, the bullet was stuck in the dorsal part
of the chest wall. Therefore, we performed right-sided video-
assisted thoracoscopy. First, we evacuated the hematoma and
inspected the gunshot wound area in the dorsolateral chest
wall. The projecle was divided into two parts which were stuck
in the parietal pleura and could be recovered in total. The lung
did not require suturing as the injury was supercial. Aer ev-
erything was cleaned up and the chest tube about to be placed,
a winding formaon suddenly appeared on the diaphragm, just
below the right lower lobe. Upon closer inspecon it was re-
vealed to be a small translucent worm. The worm was removed
alive and later idened as Dirolaria repens by microscopic
and molecular diagnosis at the veterinary reference instute
(Figure 2). The paent was asymptomac regarding the para-
site. He was treated with mebendazole, a broad spectrum an-
thelminc, for 3 days unl the parasite was idened to be D.
repens and the treatment was stopped. There was no evidence
of a systemic reacon, e.g., no blood eosinophilia, or further
clinical manifestaon of D. repens. The paent made a full re-
covery and was discharged aer 5 days. He had a history of trav-
eling to Thailand and Italy for vacaon a few months prior to the
accident, however, the origin of the parasite remained unclear.
Discussion
To our knowledge, human D. repens manifestaon in the
pleural cavity is very rare. The current literature mostly consists
of care reports and a few case series. Nematodes such as D.
repens typically locate anywhere in the subcutaneous ssue or
cause ocular dirolariasis [3,9,11,12]. In the case of our paent,
the pre-adult worm might simply have migrated as larva to end
up in the pleural cavity, where it stayed. There was no indica-
on for microlaremia, although this cannot be ruled out, as we
did not perform qPCR of a whole blood sample. Most human
cases of dirolariasis are asymptomac and detected inciden-
tally, just like in our paent. Over the last decade, an increasing
number of cases was reported in previously unaected areas in
northern and central Europe [10,11,13]. Whether the number
of cases has truly increased, or whether the detecon of D. re-
Figure 1: Computed tomography (A+B) and 3D reconstrucon of
the thoracic skeleton (C) showing the locaon of the bullet and the
resulng hemopneumothorax.
Figure 2: (A) Thoracoscopic discovery of D. repens (black arrow) on
the diaphragm. (B) D. repens in a petri dish, shortly aer recovery.
(C+D) Morphological analysis under the microscope, the small ar-
rows in D point to the longitudinal ridges, which are characterisc
for D. repens.
pens became signicantly beer, cannot be fully answered [2],
however, there are several factors in favour of an actual spread-
ing of the parasite. First and foremost, the climate change af-
fecng mosquito vectors as well as globalizaon plays an im-
portant role in this expansion [7,9,14]. A higher annual mean
temperature may contribute to accelerang the development
of D. repens within the vector [7]. While our paent had trav-
elled to Thailand and Italy for vacaon within the last 2 years,
he may very well have acquired the parasite in Germany. Many
regions have already reached a periodically suitable climate for
D. repens microlariae to develop into infecous larvae, which
might then be transmied by mosquitoes [7].
Moreover, the import of dogs and the travel of dogs to en-
demic countries may contribute to the spread of the parasite,
especially since many infected dogs remain undetected due to
the subclinical nature of the disease [7,15]. Measures to control
this infecon should be focused on dogs and humans, as well as
mosquitoes [8].

www.jcimcr.org Page 3
Conclusion
In conclusion, this case demonstrates an exceedingly rare
case of pleural D. repens infecon in a human. The available
data are scarce and likely underesmate the number of cases,
since dirolariasis is usually not a noable disease [13]. Thus,
further epidemiological studies are warranted to esmate the
prevalence and incidence of D. repens infecon in dogs, hu-
mans, or other hosts. Veterinarians as well as clinicians should
become familiar with clinical manifestaon of this emergent
pathogen, because there will most likely be an increased num-
ber of cases in the future which may pose a relevant public
health problem.
Declaraons
Author contribuons: IM and AK wrote the manuscript with
input from LB, FK, FKu, BP and LT. FKu performed the morpho-
logical analysis of D. repens. All authors have read and approved
the manuscript.
Paent consent statement: The paent’s and the paent’s
parents’ informed consent for publicaon of the case report
was obtained. Both parents both signed the wrien consent
form provided by the university clinic, which is in accordance
with the guidelines of the local ethics commiee. A separate
vong is not needed.
Data availability statement: On reasonable request to the
corresponding author the data used in this arcle will be shared.
Potenal conicts of interest: The authors have no nancial
conict of interest or relevant disclosures related to this case
report.
References
1. Gonzalez-Miguel J, Rosario L, Rota-Nodari E, Morchon R, Simon
F. Idencaon of immunoreacve pro-teins of Dirolaria im-
mis and D. repens recognized by sera from paents with pul-
monary and subcutaneous dirolariosis. Parasitol Int. 2010; 59:
248-56.
2. Kondrashin AV, Morozova LF, Stepanova EV, Turbabina NA,
Maksimova MS, Morozov AE, Anikina AS, Morozov EN. Global
Climate Change and Human Dirolariasis in Russia. Int J Environ
Res Public Health. 2022; 19.
3. Genchi C, Kramer L. Subcutaneous dirolariosis (Dirolaria re-
pens): an infecon spreading throughout the old world. Parasit
Vectors. 2017; 10: 517.
4. Brindicci G, Santoro CR, Signorile F, Leone A, Di Ciaula G, Monno
L, Angarano G. Subcutaneous Human Dirolariosis By D. Repens
In South Italy: A Case Report. New Microbiol. 2019; 42: 234-6.
5. Gabrielli S, Mangano V, Furzi F, Oliva A, Vita S, Poscia R, Fazii P,
Di Paolo J, Marocco R, Mastroianni CM, Bruschi F, Maucci S.
Molecular Idencaon of New Cases of Human Dirolariosis
(Dirolaria repens) in Italy. Pathogens. 2021; 10.
6. Biasizzo H, Soba B, Ilovski F, Harlander M, Lukin M, Blatnik O,
Turel M, Srpcic M, Kern I, Beovic B. Severe and Rare Case of Hu-
man Dirolaria repens Infecon with Pleural and Subcutaneous
Manifestaons, Slovenia. Emerg Infect Dis. 2022; 28: 2504-7.
7. Capelli G, Genchi C, Baneth G, Bourdeau P, Brian E, Cardoso L,
Danesi P, Fuehrer HP, Giannelli A, Ionica AM, Maia C, Modry D,
Montarsi F, Krucken J, Papadopoulos E, Petric D, Pfeer M, Savic
S, Otranto D, Poppert S, Silaghi C. Recent advances on Dirolaria
repens in dogs and humans in Europe. Parasit Vectors. 2018; 11:
663.
8. Redon-Soriano M, Blasco A, Gomila B, Gonzalez-Sanchez M, Si-
mon F, Esteban JG. Subconjuncval human dirolariasis by Di-
rolaria repens in the Mediterranean Basin. Am J Ophthalmol
Case Rep. 2022; 26: 101570.
9. Miterpakova M, Antolova D, Ondriska F, Gal V. Human Diro-
laria repens infecons diagnosed in Slovakia in the last 10 years
(2007-2017). Wien Klin Wochenschr. 2017; 129: 634-41.
10. Mateju J, Chanova M, Modry D, Mitkova B, Hrazdilova K, Zam-
pachova V, Kolarova L. Dirolaria repens: emergence of autoch-
thonous human infecons in the Czech Republic (case reports).
BMC Infect Dis. 2016; 16: 171.
11. Salaman RV, Pavlikovska TM, Sagach OS, Nikolayenko SM, Ko-
rnyushin VV, Kharchenko VO, Masny A, Cielecka D, Konieczna-
Salaman J, Conn DB, Golab E. Human dirolariasis due to Diro-
laria repens in Ukraine, an emergent zoonosis: epidemiological
report of 1465 cases. Acta Parasitol. 2013; 58: 592-8.
12. Balendran T, Yatawara L, Wickramasinghe S. Human Dirolaria-
sis Caused by Dirolaria repens in Sri Lanka from 1962 to 2020.
Acta Parasitol. 2022; 67: 628-39.
13. Deksne G, Jokelainen P, Oborina V, Lassen B, Akota I, Kutanovaite
O, Zaleckas L, Cirule D, Tupits A, Pim-anovs V, Talijunas A, Kru-
mina A. The Zoonoc Parasite Dirolaria repens Emerged in the
Balc Countries Estonia, Latvia, and Lithuania in 2008-2012 and
Became Established and Endemic in a Decade. Vector Borne
Zoonoc Dis. 2021; 21: 1-5.
14. Geissler N, Ru J, Walochnik J, Ludwig W, Auer H, Wiedermann
U, Geissler W. Autochthonous Human Dirolaria repens Infec-
on in Austria. Acta Parasitol. 2022; 67: 1039-43.
15. Genchi C, Kramer LH. The prevalence of Dirolaria immis and
D. repens in the Old World. Vet Parasitol. 2020; 280: 108995.