Annals of African Medicine Annals of African Medicine Society ISSN: 1596-3519 Vol. 10, Num. 1, 2011, pp. 59-62

Annals of African Medicine, Vol. 10, No. 1, January-March, 2011, pp. 59-62

Case Report

Severe pentasomide Armillifer armillatus infestation complicated by hepatic encephalopathy

Ademola A Adeyekun¹, Ikechukwu Ukadike¹, Victor A Adetiloye²

¹ Department of Radiology, University of Benin Teaching Hospital, PMB 1111 Benin City, Nigeria
² Department of Radiodiagnosis, Obafemi Awolowo University Teaching Hospital PMB 1153 Ile-Ife, Nigeria

Correspondence Address: Ademola A Adeyekun, Department of Radiology, University of Benin Teaching Hospital, PMB 1111 Benin City, Nigeria, adeyekun@yahoo.com

Code Number: am11013

PMID: 21311159

DOI: 10.4103/1596-3519.76592

Abstract

Keywords: Armillifer armillatus , hepatic encephalopathy, snake meat consumption

Introduction

Armillifer armillatus is a type of worm belonging to the phylum Pentastomida. Pentastomiasis, also known as porocephalosis or tongue worm infestation, is a rare infection that is generally limited to the tropics and subtropics. The worm normally inhabits the respiratory tract of snakes and reptiles and only occasionally infects humans.

The radiological literature on pentastomiasis is sparse. Linguatula serrata and A. armillatus account for more than 99% of all reported human cases. ^[1] When the parasite load is low, the overwhelming majority of cases are asymptomatic and are generally discovered only incidentally during autopsy, routine x-ray examination, or surgery.

A case of heavy A. armillatus infestation with derangement of hepatic function is presented in this article; we report this case because of the unusual presentation.

Case Report

A 57-year-old farmer, was referred to the medical outpatient department with a 6-month history of mood disturbance, occasional confusional state, depression, pruritus, and altered sleep pattern. The pruritus was more pronounced at night. Her past medical history revealed that she had been treated on several occasions for pneumonia. About 2 ½ years earlier she had been treated for pulmonary tuberculosis at a peripheral hospital. She had had several episodes of upper abdominal pain associated with vomiting and the passage of watery stool, but these attacks had all been managed conservatively. There was no previous history of blood transfusion or regular usage of sharp objects like piercing needles. There was associated weight loss.

On examination, she looked chronically ill and was emaciated. She was pale and mildly icteric, but was not dehydrated. There was finger clubbing. The other positive findings included a musty breath odor, mild flapping tremor (mild asterixis), and features of muscle rigidity. The chest, abdominal, and cardiovascular examinations were all normal. Her blood pressure was 130/90 and her pulse rate was 92 beats per minute. A working diagnosis of possible grade 1 hepatic encephalopathy, secondary to chronic liver disease, was made and radiological and laboratory investigations were requested.

Among the laboratory investigations, liver function test revealed increased alkaline phosphatase (ALP) of 55 U/l (normal 5-35 U/l). The enzymes GGT and 5′-nucleotidase were not assayed because of lack of facilities. The serum total bilirubin was 2.3 mg/dl (normal 0.5-1.5 mg/dl) and conjugated bilirubin was 1.2 mg/dl (normal <0.05 mg/dl). The serum total protein was low at 5.0 mg/dl (normal range 5.5-6.9 mg/dl), albumin was low at 2.2 mg/dl (normal 3.5-5.0 mg/dl). The urea level was 6.1 mg/dl (normal 10-50 mg/dl). The hemoglobin level was low (9.2 g/dl). Hepatitis B surface antigen (HbsAg) was negative. She did not give consent for liver biopsy.

Chest x-ray revealed multiple crescentic, comma-shaped, calcific opacities distributed in both hemithoraces [Figure - 1], with marked concentration of these opacities in the right hemidiaphragmatic region. A diagnosis of A. armillatus parasitic infestation was made based on the typical shape of the opacities. On further questioning, the patient confirmed that snake meat had been a regular part of her diet for many years and that she always prepared the meat herself.

A thoraco abdominal CT scan was done subsequently. The scanogram showed multiple crescentic, comma-shaped, calcific densities distributed over the entire abdomen, with predominance in the hepatic region [Figure - 2]. Transverse non-enhanced slices showed overwhelming hepatic involvement by the calcific deposits, with gross distortion of the liver parenchyma [Figure - 3]. The deposits were also concentrated in the spleen. The bowels, mesentery, and the urinary bladder were also affected [Figure - 4]. A radiologic diagnosis of severe A. armillatus infestation with liver parenchyma involvement was made.

She was managed as a case of grade 1 hepatic encephalopathy secondary to severe liver parenchymal parasitic infestation. She was placed on a high-carbohydrate, low-protein diet and treated with antibiotic (metronidazole), antihistamines, and lactulose.

On follow-up 3 weeks later at the outpatient clinic she showed significant clinical improvment.

Discussion

The first human infection by a pentastomid was described by Prunner in Cairo in 1847. ^[2] Two species, A. armillatus and Linguatula serrata, account for more than 99% of all reported human cases. ^[1] Among the four species of Armillifer, armillatus is found most commonly in West Africa, where the infection rate may be as high as 23% and the radiological incidence about 1.4%. ^[3] Infestation by A. armillatus was diagnosed radiologically in this woman. The other species of Armillifer which can also be recognized radiologically is A. monniliformis, which causes porocephalosis. It is not common in West Africa but is found in South and East Asia. Prathap et al. found a 45% incidence during autopsies in Malaysian aborigines. ^[4] This disease is commoner in males than in females as documented by Nzeh et al., ^[5] with a male: female ratio of 2:1. Our patient too was a female.

Infection with pentastomids is mostly asymptomatic in humans, being especially seen in those who regularly consume snake meat. Our patient admitted to having regularly eaten snake meat for several years. The larvae usually die and calcify within 2 years of infection of a human host. ^[6] However, pentastomids have the potential to cause harm, and, in rare cases, even to cause medical emergencies. ^[7] In heavy infestation, as in this case, the migration of many live larvae beneath the peritoneum or pleura may cause sufficient irritation to mimic an acute abdominal condition or pleurisy. ^[7] The encysted larvae can cause abdominal pain, vomiting, constipation, and diarrhea. The presence of extremely high numbers of cysts in some locations can even cause death. ^[8] Pneumonitis, bronchitis, pleuritis, pericarditis, hepatitis, and peritonitis, have all been noted in patients with severe infection. ^[3] Our patient, according to her past medical history, had been treated several times for pneumonitis and abdominal discomfort; it is likely that the heavy infestation was responsible for those illnesses. She had also been treated for primary pulmonary tuberculosis and this too may have been a misdiagnosis of the pneumonitis and granulomas caused by the worm infestation.

Our patient presented with features of grade 1 hepatic encephalopathy, which was likely the result of extensive hepatic parenchymal destruction due to severe granulomatous reaction. A study in Ibadan, Nigeria, by Smith et al. ^[8] found pentastomiasis to be the third most common cause of hepatic fibrosis after tuberculosis and schistosomiasis. This form of presentation may be as a result of the accumulation of neurotoxic substances that would normally have been metabolized by the liver. Our patient also had mild jaundice which, from the laboratory investigations, was obstructive in nature. This may also be as a result of fibrosis around the porta hepatis due to the extensive granulomatous reaction. Liver biopsy could have confirmed the diagnosis but was not done because patient did not consent to the procedure.

The diagnosis of pentastomiasis is mostly made incidentally at surgery, at autopsy or during radiographic examinations. The serological test for Armillifer is rarely used in clinical practice ^[9] and is often not available. Hence, it was not done in this patient. Laboratory investigations for this woman revealed elevated ALP and total bilirubin, which was suggestive of cholestasis. Her clinical presentation and response to therapy supported the diagnosis of hepatic encephalopathy.

Because pentastomiasis is mostly asymptomatic, it is often detected during radiological examination for other conditions. The diagnosis in our patient was made when chest radiography was done as part of her workup at admission to the hospital. The calcified dead larvae of armillifer are almost always localized to the abdomen and chest and are rarely seen at other sites, as demonstrated in this case. They are always multiple and are most commonly seen in the liver but can also involve the intestinal walls, peritoneum, mesentery, and lungs. ^[3],[9] The liver in this woman had the highest concentration but almost all the intra-abdominal structures were affected. The calcifications are described as crescentic, horseshoe, or comma-shaped. ^[3],[10] This pattern of calcification was noted in our patient also.

CT scan was helpful in the radiological investigation of this patient. The gross hepatic parenchymal distortion was well delineated. Also, it helped to outline the calcific crescentic deposits in almost all the intra-abdominal structures.

Treatment of this larval pentastomiasis is usually conservative, as the majority of the cases are asymptomatic. Antibiotics or surgical therapy is rarely needed. Our patient was also managed conservatively.

Conclusion

A case of heavy infestation of A. armillatus, with significant pulmonary and hepatic involvement is presented in this article. Health education should discourage the consumption of snake meat and arthropods.

References

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