Global status of neglected human Linguatula infection: a systematic review of published case reports

Human linguatulosis is a rare but highly specialized pentastomid parasitic infection all around the world. The disease is caused by worm-like parasites which share some morphologic features of arthropods and annelids. The life cycle of Linguatula spp. is provided as an example of pentastomid biology. The adult forms of Linguatula spp. are found in the nasal passages and frontal sinuses of dogs and other canids, domestic animals, and humans. Infestation may occur in the viscera, where immature forms develop in the liver, spleen, lungs, eyes, and other organs, or in the nasopharyngeal area. This review includes previous studies on the genus Linguatula in Iran and other countries from 1940 to 2019. Considering a few reports of human infestation, a comprehensive search was performed on both English and Persian databases for publications reporting human cases all around the world. Finally, 30 papers of 62 human cases were included in this study. The mean age of the patients was 25.8 years (varied from 8 to 79 years). Altogether, 41 (66.1%) and 21 (33.9%) of the patients were female and male respectively. The maximum cases (n = 25) were from Sudan. Nasopharynx was the most frequently involved organ in human cases. Our findings offer that physicians should consider the Linguatula infection in patients with complaints like unexpected dysphagia, with coughing, sneezing, and vomiting, after consuming raw/undercooked contaminated ruminant's viscera.

Pathological characteristics of Linguatula serrata (aberrant arthropod) infestation in sheep and factors associated with prevalence in Iran

Linguatula serrata is a cosmopolitan zoonotic parasite in which carnivores and herbivores serve as final and intermediate hosts, respectively. The aim of this study was to compare the L. serrata nymphal infection rate and intensity of infection (mean number of nymphs ± standard error) to the appearance and pathological changes of mesenteric lymph nodes (MLNs) infected with L. serrata using sheep slaughtered in Tabriz, Iran. In addition, the effect of age, sex, and season on the prevalence of L. serrata infection was evaluated. For this purpose, over a four-year period, 31,078 MLNs from 3199 sheep were examined, with 4972 (15.99%) MLNs infected representing 518 (16.20%) sheep. Collected MLNs were categorized by color as normal, red or black and by consistency as normal, soft or hard. L. serrata were found in 8.88% of normal-colored MLNs, 14.45% of red (hemorrhagic) MLNs and 44.57% of black-colored MLNs, with the difference being significant for infection and infection intensity (P < 0.0001). In regards to MLN consistency, 7.98% of normal, 31.52% of soft and 5.42% of hard lymph nodes were found to be infected with the infection rate and intensity in soft nodes being significantly different (P < 0.0001). Pathological changes in MLNs infected with L. serrata nymph with normal color and consistency had calcification of the L. serrata nymph, granulomatous inflammation around the nymph and some neutrophils. Granulomatous inflammation around the L. serrata nymph, haemosiderophage, macrophage and lymph node depletion from lymphocytes were observed in MLNs infected with L. serrata nymph with soft consistency. In addition, MLNs infected with L. serrata nymph with hard consistency and black color contained neutrophils in the capsule's wall, caseous necrotic mass and L. serrata surrounded by a thick capsule. In regards to prevalence, age, sex and season (autumn) were significant (P < 0.0001, P < 0.01, respectively). These study results suggest that targeted meat inspection and targeted animal interventions could be used to decrease human exposure to L. serrata and animal infection.

Human pentastomiasis in Sub-Saharan Africa

Pentastomiasis is a rare zoonotic infection but it is frequently observed in Africa and Asia. Most human infections are caused by members of the Armillifer armillatus species. They are responsible for visceral pentastomiasis in Western and Central Africa. Humans may be infected by eating infected undercooked snake meat or by direct contact with an infected reptile. An increasing number of infections are being reported in Congo, Nigeria, and Cameroon. Despite an occasionally high number of nymphs observed in human viscera, most infections are asymptomatic and often diagnosed by accident during surgery or autopsy. The clinical presentation of pentastomiasis is quite varied and depends on infected tissues. The liver, lungs, and pleura are most frequently involved. Abdominal emergencies have been reported. Diagnostic delays always occur and diagnosis focuses on the patient's lifestyle and living environment. It is mainly based on the morphological description of the parasite's calcified cuticle, the site of the lesion, and the parasite's region of origin. Most patients do not require any treatment. Personal measures such as avoidance of contact with snake droppings are recommended to prevent transmission. Imported pentastomiasis has been observed in African migrants.

Imported Armillifer pentastomiasis: report of a symptomatic infection in The Netherlands and mini-review

We report a case of symptomatic visceral Armillifer pentastomiasis in a 23-year-old female Liberian immigrant to The Netherlands. The patient was referred to the gynecologist because of lower abdominal pain. During laparotomy, multiple adhesions were seen in the lower pelvis and a hydrosalpinx with an encapsulated Armillifer nymph, most likely Armillifer armillatus, was found. Key features of the parasite's cuticle which facilitate the diagnosis of pentastomiasis, are presented. Symptomatic pentastomiasis is uncommon, and most cases are diagnosed incidentally during surgery for other reasons, or at autopsy. With regard to increasing international migration, other imported pentastomiasis cases to Europe and North America are reviewed, and more cases are likely to be seen in the future.

Imaging features of pediatric pentastomiasis infection: a case report

We report here a case of pentastomiasis infection in a 3-year-old girl who had high fever, abdominal pain, abdominal tension and anemia. Ultrasound scanning of the abdomen revealed disseminated hyperechoic nodules in the liver and a small amount of ascites. Abdominal MRI showed marked hepatomegaly with disseminated miliary nodules of high signal intensity throughout the hepatic parenchyma on T2-weighted images; retroperitoneal lymphadenopathy and disseminated miliary nodules on the peritoneum were also noted. Chest CT showed scattered small hyperdense nodules on both sides of the lungs. The laparoscopy demonstrated diffuse white nodules on the liver surface and the peritoneum. After the small intestinal wall and peritoneal biopsy, histological examination revealed parenchymal tubercles containing several larvae of pentastomids and a large amount of inflammatory cell infiltration around them. The pathological diagnosis was parasitic granuloma from pentastomiasis infection.