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416 
 

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Published Online: December 31, 2019 

 

 

Case Report 

Urinary Canthariasis Due to Tenebrio molitor Larva in a Ten-Year-Old Boy 
 

Mohammad Hassan Aelami1; Alireza Khoei2; Hamidreza Ghorbani3; Farrokh Seilanian-

Toosi4; Elham Poustchi5; Bibi Razieh Hosseini-Farash5,6; *Elham Moghaddas5 

 
1Department of Pediatrics and Hand Hygiene and Infection Control Research Center, Imam Reza Hospital, 

Mashhad University of medical Sciences, Mashhad, Iran 
2Department of Pathology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 

3Kidney Transplantation Complications Research Center, Mashhad University of Medical Sciences,  

Mashhad, Iran 
4Department of Radiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 

5Department of Parasitology and Mycology, Faculty of Medicine, Mashhad University of Medical Sciences, 

Mashhad, Iran 
6Cutaneous Leishmaniasis Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 

 
(Received 10 Aug 2018; accepted 26 Oct 2019) 

 

Abstract 
Canthariasis is a human disease caused by infestation of beetle larvae. We report here an unusual cause of urogenital in-

fection due to Tenebrio molitor in a 10-year-old boy suffering from severe and intermittent suprapubic pain from Nehban-

dan City, Northeastern Iran in 2018. After 9 months, three larvae were excreted. Keratinization of bladder wall was ob-

served in histopathology. All laboratory evaluations were normal except for presence of microscopic hematuria. This re -

port implicated that T. molitor could infest bladder accidentally and cause canthariasis and clinical symptoms that may 

lead to severe pain and bladder inflammation and hyperemia.  

 

Keywords: Canthariasis; Bladder; Human; Child  

 
Introduction 
 

Canthariasis is a parasitic disease caused by 

beetle larvae, either humans or animals (1). Can-

thariasis in humans and animals due to Teneb-

rio molitor is an uncommon phenomenon. The 

reports are very rare and pathological effects 

are poorly known (2). 

The first and only report on canthariasis due 

to T. molitor in bladder was reported about 375 

years ago in a book entitled “Observations Medi-

cae” (3). Moreover, T. molitor has invaded um-

bilicus and tonsils (4). However, the majority 

of reported cases of T. molitor larva in hu-

mans have been related to gastrointestinal tract 

(2, 5). Recently accidental ulcer infestation due 

T. molitor has been reported in a case with 

HIV/AIDS and skin ulcers (6).  

Tenebrio molitor is a yellow mealworm 

commonly found as a stored-product pest. The  

 

 
life cycle of this organism comprises four stages 

including egg, larva, pupa and adult forms. The 

entire life cycle lasts approximately one year. 

Adult and the larvae feed on grains (hence the 

name mealworm), meat or decomposing ani-

mals including birds, spiders, rodents, lizards 

and some other beetles. Human is infected by 

the ingestion of eggs or larvae of T. molitor (7). 

Tenebrio molitor can also promote allergic re-

actions in exposed individuals (8). 

Epidermolysis bullosa (EB) is the name for 

a group of rare genetic skin disorders that 

cause fragility in skin. Any trauma or friction 

to the skin can cause painful blisters (9). 

 In this case report, we describe an unusu-

al case of canthariasis due to T. molitor in a 

10-year-old boy with EB.  

*Corresponding author: Dr Elham Moghaddas, 
E-mail: moghaddase@mums.ac.ir 

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Published Online: December 31, 2019 

 

 

 Case presentation 
 

The patient was a 10-year-old boy (23kg) 

who had epidermolysis bullosa (EB) disorder 

referred from a local clinic from Nehbandan 

City in 2018, Northeastern of Iran. He suffered 

from periodic painful episodes in urinary sys-

tem for the past 9 months. Symptoms were in-

termittent, and urine contained brown sediments 

similar to bladder stones (Fig. 1). There were 

no signs of gross hematuria and fever during 

the mentioned time. Complete medical exami-

nations including urine analysis, urine culture, 

urine and blood biochemistry, hematology, Im-

munoassays for autoimmune diseases, thyroid 

function tests and renal ultrasound were per-

formed.  

Ultrasound was performed after observa-

tion of the excreted brown sediment from ure-

thra for finding kidney stones. Kidney and blad-

der appeared normal in ultrasound. Urinalysis 

revealed no abnormality except for occult blood. 

Urinary culture was negative. Blood cell count 

and creatinine levels showed the normal rang-

es. Moreover, urine biochemistry was normal. 

Erythrocyte sedimentation rate (ESR) was 21 

mm/1h.  

The boy’s mother found three larvae in his 

urine more than two weeks after symptoms start. 

Morphologically, the larvae had six short legs 

close together near the head. The head has a 

pair of short hooks and was creamy white in 

color. The larvae had 26mm length and 0.5 

mm width. They had three pairs of feet on the 

belly near the head and with each foot had 4 

sections and nodes hocks curved claws (Fig. 

2). Based on the characteristics, the larva was 

diagnosed as T. molitor.  

Debris, hyperemia and inflammation were 

identified in bladder and in the urethra cystos-

copy (Fig. 3). However, no larva was seen in 

bladder and urethra. A single dose of 3mg of 

ivermectin was orally administrated. The pa-

tient recovered after oral Ivermectin therapy. 

Following treatment, high volume of insect 

shells was repulsed (Fig. 4). In addition, the 

abdominal pain completely resolved within a  

 

 

few months following treatment. Histopathol-

ogy of excreted particles from urethral duct 

showed keratinizing squamous metaplasia af-

ter treatment.  

Informed consent was taken from the pa-

tient’s parents. This study was reviewed and 

approved by the Ethics Committees of Mash-

had University of Medical Sciences, Iran. 

 

 
 

Fig. 1. Brown sedimentations excreted via urethra 

 

 
 

Fig. 2. Macroscopic examination of the larva 

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418 
 

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Published Online: December 31, 2019 

 

 

 
 

Fig. 3. Cystoscopy finding including debris, hypere-
mia and inflammation 

 

 
 

Fig. 4. Disposal shell of insect after treatment by 
ivermectine 

 
Discussion 
 

This case was initially misdiagnosed as kid-

ney stones because the shedding of stone like 

substance without excretion of any larva from 

the urethra. Ultrasonography failed to detect the 

larva probably because the initial request was 

ordered for checking of kidney or urinary tract 

stones. Unlike most stones that are hard, the ob-

served particles from this patient had soft struc-

ture. This beetle has 9–20 instars, the brown sed-

imentations were probably larvae shells during 

molting (https://en.wikipedia.org/wiki/Mealworm). 

On the other hand, we could speculate that the 

class of the scanner for determination of lar-

vae was inadequate.  

Beetle larvae have been recovered from hu-

man organs including tonsils (4), nose and blad-

der (10), umbilical cord (11), the gastrointesti-

nal tract (4, 5), as well as from subcutaneous 

tissue in wild bird (1).  

Canthariasis is a rare ectoparasitic condition. 

Among the reported cases, most of them were 

gastrointestinal. No previous cases in HIV/AIDS 

patients have been reported, neither associated 

with skin ulcers. Beetles could be found in hous-

es where dried grains are stored, particularly 

this is case for T. molitor. Adult Tenebrio laid 

eggs on the skin of our patient. Females lay eggs 

and larvae develop within few weeks at necrotic 

tissue. In fact, scars attract the beetle and its lar-

vae are fed on a variety of dried plant or ani-

mal matter and are known to scavenge on car-

casses of dead animals. 

Moreover, canthariasis has been reported in 

a case with HIV/AIDS patients associated with 

skin ulcer (6). Ulcers in HIV patients and other 

diseases related to skin damages could increase 

susceptibility to a wide range of infections such 

as canthariasis.  

The present case had EB is a genetic dis-

order that result in easy blistering of the skin 

and mucous membranes. The patients with EB 

are susceptible to infection due to damage in 

skin physical barrier (9). 

Beetles are a common household pest found 

in stored grain and stored food products. Adult 

of T. molitor laid eggs on the in or around the 

urogenital opening of our patient when he was 

resting. Then, the eggs hatch and larvae mi-

grate along the urethra with consequent cantha-

riasis. Some previous studies suggested this route 

of transmission for urinary myiasis (12,13)  

This larva is unable to dwell in subsequently 

of the bladder wall. Because of this, our patient 

showed no macroscopic hematuria, and the blad-

der wall thickness was also normal (3mm). How-

ever, because of long stimulation time, wall 

bladder showed pathological changes. There 

were no lesion(s) in radiographic investigation. 

Tenebrio molitor can be the intermediate 

hosts of the rat tapeworm, Hymenolepis diminu-

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https://en.wikipedia.org/wiki/Mealworm


J Arthropod-Borne Dis, December 2019, 13(4): 416–419                                              MH Aelami et al.: Urinary Canthariasis … 

419 
 

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Published Online: December 31, 2019 

 

 

ta (4). On the other hand, human is the acci-

dental host of H. diminuta by ingestion of bee-

tles or meal worms containing metacestode. Up 

to now, seven human patients have been re-

ported from Iran to be infected with H. diminuta 

(14). Therefore, unintentional swallowing of T. 

molitor may be a possible route of transmission.  

 
Conclusion 
 

Infection with T. molitor can present as an 

emergency condition with acute pain episodes 

in urinary system. Understanding of this infec-

tion should be considered when there are no ev-

ident signs for stones in urinary system in 

routine management. 

 
Acknowledgements  

 

We appreciate the patient's parents and 

their child for their support at all stages of the 

diagnosis of disease. 

The authors declare that there is no con-

flict of interests. 

 
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