Case Report: Human Bertiellosis in Brazil

ABSTRACT.

The Anoplocephalidae family comprises a group of parasites that affect reptiles, birds, and mammals. Humans can be accidentally infected by ingesting contaminated mites. We present a case of human bertiellosis in Brazil. Our report reinforces the importance of correctly identifying the parasite to provide adequate treatment.

INTRODUCTION

Cestodes of the Anoplocephalidae family include parasites that affect reptiles, birds, and mammals from various regions of the world. These cestodes are heteroxenous and require an intermediate and a definitive host to complete their life cycles. Parasites of the genus Bertiella have definitive hosts, particularly primates, rodents, Australian marsupials, and dermapterans. Bertiella genus is the only anoplocephalid group infecting humans.^1,2

The life cycle begins when Oribatida mites (intermediate hosts) found in the soil feed on cestode eggs amid the feces from infected mammals. After infecting mites, the embryos develop into the cysticercoid larvae, and when ingested, they can infect the intestine of wild animals. This parasite may infect humans through ingestion of contaminated food or water.³ Infection risk increases when humans come into contact with definitive hosts.⁴

Bertiellosis is an extremely rare human infection. Here, we describe a child infected with Bertiella sp. living in a rural area with forest fragments that are home to several primate species. The Human Research Ethics Committee of Centro Universitário do Espírito Santo (Colatina, Brazil) approved this study in accordance with Agreement No. 968.561. The patient’s mother provided written informed consent before the examination.

CASE REPORT

A 7-year-old boy from the municipality of Pancas, Espírito Santo state (19°13′27′ S, 40°51′4″ W), Brazil, was seen at a health center after relatives detected “worms” in the stools. No other clinical symptoms or signs were reported. Fecal examination by spontaneous sedimentation method revealed helminth eggs that were identified as Ascaris lumbricoides. Mebendazole (5 mL) twice a day was prescribed for 3 consecutive days and repeated after 10 days. However, stool examination revealed eggs after treatment. Administering metronidazole (5 mL) every 8 hours for 5 consecutive days could also not clear the infection (giardiasis infection was also presumed). With the evidence for treatment failure, the mother administered a single dose of liquid albendazole (10 mL) for 3 consecutive days in combination with ivermectin (6 mg) without clearance of the infection.

The patient developed symptoms including abdominal pain and weakness 2 years after the initial detection of helminth eggs. Several tests were performed during these 2 years, with persistence of the parasitic structures in feces. The patient’s mother brought stool samples to our laboratory for parasitological examination. Macroscopically, cestode-imbricated proglottids were macroscopically identified (Figure 1A), with unilateral, irregularly alternating genital pores. Microscopy revealed the presence of 44- × 55-μm eggs with a rough outer membrane and a hexacanth embryo with a bifurcated piriform apparatus (Figure 1B), leading to identification of Bertiella sp. After diagnosis of bertiellosis, niclosamide (1 g) was prescribed with successful outcome.

Figure 1.

Human bertiellosis in Brazil. (A) Proglottids measuring 1.7 cm in length and 1.0 cm in width recovered from the patient’s stool (200×). (B) An egg showing morphological characteristics of Bertiella sp. The egg measured approximately 44 μm × 55 μm, with a rough outer membrane and a hexacanth embryo with a bifurcated piriform apparatus inside (400×). Monkeys belonging to (C) Callicebus personatus, (D) Alouatta guariba clamitans, and (E) Callithrix geoffroyi were observed around the infected child’s home.

The parasite samples were sent to the Laboratory of Clinical Parasitology at the Federal University of Alfenas, Brazil, to confirm the identification and for molecular examination. Unfortunately, the low amounts and poor quality of extracted parasite DNA prevented sequencing and molecular species identification.

A visit to the patient’s residence was conducted to describe the environmental and ecological aspects that were favorable for the patient’s infection and counsel the family members on prophylactic measures to be taken to prevent the spread of infections.

DISCUSSION

The origin of the infection could not be confirmed in this case. The patient lived in a rural area surrounded by fragments of the Atlantic Forest. The forest fragments house several monkey species, including Callicebus personatus (Figure 1C), Alouatta guariba clamitans (Figure 1D), and Callithrix geoffroyi (Figure 1E), which are potential hosts for the parasite and could have contaminated the soil with their feces, enabling the infection of mites. The mother confirmed that her child frequently fed the monkeys. Contamination of the peridomicile with infected mites facilitated the accidental transmission to the child, whose frequent direct contact with the soil might have facilitated oral ingestion of mites.

Human infections by Bertiella sp. have been reported in several regions of the world.⁵ This is the seventh reported human case in Brazil and the first in Espírito Santo state, located in southeastern Brazil. In this study, we have documented the lack of knowledge among practitioners in recognizing the worm and the delay in establishing a correct diagnosis and treatment. The quality of the training in helminthology has declined in the medical microbiology curriculum, and several rare species of zoonotic cestodes have fallen into obscurity. Even among specialist practitioners, knowledge of human intestinal cestode infections is often limited to three genera: Taenia, Hymenolepis, and Dibothriocephalus.² Bertiella, Dipylidium, Raillietina, Inermicapsifer, and Mesocestoides sp. may cause persistent gut infections in human beings.² The lack of experienced laboratory personnel may contribute to the underreporting of these infections.

Generally, humans and primates infected by Bertiella sp. are asymptomatic; however, in some cases, especially in children, weight loss, constipation, anorexia, diarrhea, and severe abdominal pain and vomiting can occur.⁴

The diagnosis can be made by analyzing distinctive eggs and/or proglottids. In addition, history of exposure to nonhuman primates and their environment should be investigated in the diagnostic workup.

DNA techniques are important to confirm the species identification. Samples must be fixed in 70% ethanol for extraction and sequencing.² Unfortunately, polymerase chain reaction analysis was not possible in the present study due to inadequate fixation of the samples.

Controlling and preventing this zoonosis is challenging because intermediate hosts are cosmopolitan and have a wide territorial distribution.⁴ In addition, definitive hosts such as primates, rodents, and marsupials are considered synanthropic animals that facilitate contact with humans.⁶ In addition, increased deforestation in 2020 was reported according to Agricultural and Forestry Defense Institute of Espírito Santo, which increases contact with wild animals. Inappropriate soil use is frequent in the municipality due to agriculture without technology, which also contributes to deforestation, according to the Capixaba Research Institute Technical Assistance and Rural Extension.

CONCLUSION

In summary, our study documents the risk of infection by Bertiella sp. in Brazil and stresses the necessity of correctly identifying parasite structures for adequate treatment and prevention measures. This report also highlights the importance of zoonotic infections and “one-health” approaches both in research and clinical practice.