Hymenolepis diminuta infection in a child from urban area of North India: A rare case report.

Hymenolepis diminuta, also known as rat tapeworm, infects humans uncommonly. The diagnosis is based on the demonstration of characteristic eggs in the feces. We present a case report of H. diminuta infection in a 6-year-old female child from an urban area of India who presented with fever and seizures and also had complaints of intermittent abdominal pain, vomiting, and loss of appetite, without an apparent history of contact with rodents. The infection was treated with albendazole and showed clinical and parasitological cure. More awareness is required for a better understanding of epidemiology and transmission routes of this rare zoonosis.

INTRODUCTION

Hymenolepis diminuta, also known as rat tapeworm, is primarily a rodent parasite and rarely infects humans. Infection is acquired accidentally by ingesting infected arthropods containing the cysticercoid larvae. Till date, more than 20 different species of arthropods, including beetles and fleas, have been identified as intermediate hosts.[1] Inside the arthropod, the hexacanth embryo emerges from the egg and develops into cysticercoid larva. Once the arthropod containing the cysticercoid is ingested by the definitive host, i.e., rat or rarely human, it grows into the adult form in the small intestine, and its eggs are passed out in the feces. H. diminuta infection is reported to be more common among children than adults.[2] The diagnosis is based on the demonstration of characteristic eggs in the stool specimen. There are few case reports of human infections from different parts of the world. In India, cases have been reported from Odisha, Uttarakhand, Tamilnadu, and other places.[3456789] Here, we present a case in a 6-year-old female child from an urban area of North India. Informed consent was obtained from the patient.

CASE REPORT

A 6-year-old female child presented in pediatric emergency with complaints of high-grade fever followed by one episode of generalized tonic–clonic seizures. She was a known case of typical febrile seizures and mild persistent asthma for the past 3 years. She also complained of intermittent abdominal pain, vomiting, and loss of appetite for the past 6 months. Since previous 3 days of getting admitted to the hospital, she had been passing loose motions. The clinical examination and routine blood investigations were within normal limits, and she was completely immunized. No other family member had similar complaints. For febrile seizures, she was administered intravenous paracetamol and sodium valproate and was stabilized.

Investigations

A stool sample was submitted for bacterial culture and parasites. The bacterial cultures did not show growth of any pathogens. On microscopy, there were no pus cells or red blood cells in the stool sample. A few spherical, thick-shelled, yellow-colored eggs with six central hooklets without any polar filaments were seen.

Diagnosis and treatment

Eggs found in stool were characteristic of H. diminuta [Figure 1]. These eggs were differentiated from those of Hymenolepis nana by their larger size (70 μm) and absence of polar filaments. A repeated stool sample after 2 days showed the same microscopic findings. Due to unavailability of praziquantel, she was prescribed albendazole 400 mg for 3 days.

Figure 1

Hymenolepis diminuta egg from stool sample (under ×40 magnification)

Outcome and follow-up

Two weeks posttreatment, another stool sample for microscopic examination was submitted and was found negative for any parasite. Simultaneously, her gastrointestinal symptoms also subsided. Health education regarding proper sanitation was given to the family.

DISCUSSION

H. diminuta has a ubiquitous distribution worldwide; however, it is rarely found in humans. The definitive host as well as natural reservoirs of H. diminuta are rodents, i.e., rats and mice. Children and adults from poor socioeconomic group are more prone to infection because of unhygienic practices; however, our patient was from an urban area of North India, and no history of rat infestation in the house could be elicited. The infection with H. nana is much more common than H. diminuta because its transmission does not need any intermediate host; however, cases of H. diminuta infection, though less commonly reported, seem to be on a rise. About 500 cases of H. diminuta infection had been reported worldwide,[10] and survey reports from different populations have shown an incidence of 0.001%–5.5% of H. diminuta parasitism.[3] There are few cases of human infections have been reported from Thailand, Indonesia, Malaysia, Italy, Spain, Jamaica, and other places.[11] In India, almost a century ago, in a survey of 10,000 stool samples by Chandler, 23 cases of H. diminuta infection were reported.[12] In addition, there are few case reports from Tamil Nadu, Odisha, and Haryana [Table 1].[3456789] Foods such as cereals contaminated with infected insects are reported as the chief sources of infection in India.[7] The demonstration of H. diminuta eggs in the stool is the essential diagnostic tool.[2] Most of the time this condition may be asymptomatic; however, vague abdominal pain and extraintestinal manifestations such as pruritus, irritation, and eosinophilia may be present.[7] Similar symptoms were present in our case. Although eosinophilia is a characteristic finding in this infection, surprisingly it was not there in our patient, as also noted by Tiwari et al.[6] Schulte et al. have suggested that eosinophilia is mainly seen during tissue-invasive stages of parasite.[13] Although praziquantel is the drug of choice, however, due to nonavailability, our patient was administered albendazole and responded to the therapy. The efficacy of albendazole for the treatment of H. nana has been reported ranging from 28% to 100% at a dosage of 400 mg per day for 3 days.[14]

Table 1

Previous case reports of Hymenolepis diminuta infection from India

Here, we have reported an uncommonly encountered parasite H. diminuta especially in an urban setting. The mode of infection could not be traced back to any apparent contact with rodents, thus opening a possibility of some other indirect transmission mechanism. Majority of the cases are asymptomatic, and the prevalence of infection in the community may be underestimated. Therefore, more effort should be put into improving our knowledge of the epidemiology and transmission routes of this uncommon human infection.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.