Status of Linguatula serrata infection in livestock: A systematic review with meta-analysis in Iran

Assessing the Prevalence and Histopathology of Linguatula serrata Infection of Camels and Cattle in Zabol County, Sistan and Baluchestan Province, Iran

BACKGROUND/OBJECTIVE

Linguatula serrata (L. serrata) is a worldwide zoonotic parasite and one of the most widespread pathogens. This study aimed to determine the prevalence of L. serrata in cattle and camels of Zabol County, Sistan and Baluchestan Province, Iran.

METHODS

From March 2014 to February 2021, 300 cattle (48 female and 252 male) and 300 camels (31 female and 269 male) were examined at the Zabol slaughterhouse, encompassing different age groups. The cattle breeds were indigenous (native Sistani breeds) and non-indigenous (breeds introduced from external regions), while all the camels were native breeds. To identify L. serrata nymphs, three samples of mesenteric lymph nodes (MLNs) were meticulously collected in phosphate-buffered saline immediately after slaughtering.

RESULTS

According to the results, 4.33% (13/300) of cattle were infected with L. serrata, with six females and seven males infected. There was a significant difference in the prevalence of infection between females (6/48, 12.5%) and males (7/252, 2.77%) of cattle (p = 0.009). Moreover, cattle older than 3 years had significantly more infections with L. serrata nymphs (16.07%, 9/56) than cattle of other ages (p < 0.001). Compared to other seasons, autumn showed a high prevalence of parasites (8.1%, 6/74) (p = 0.017). Regarding the camels, only 3.66% (11/300) were infected, and there was no significant difference in infection rates between male and female camels or between seasons (p > 0.05). The infection rate was higher in camels older than 3 years (n = 9) than in camels younger than 3 years (p < 0.05). The MLNs of infected cattle were edematous, red, enlarged and characterized by an eosinophilic granulomatous reaction with mononuclear inflammatory cells.

CONCLUSION

The present study had low rates of L. serrata infection because the farms were clean, and cattle and camels did not have contact with final hosts such as dogs and wild canids. This suggests that their management strategies, including secure and preventative measures, were effective.

Exploring the anatomy of Linguatula serrata using micro-computed tomography

Micro-computed tomography (micro-CT) is an emerging tool in parasitology that can assist in analysing morphology and host-parasitic interactions. It is a non-destructive, cross-sectional imaging technique that offers good resolution and the ability to create three-dimensional (3D) reconstructions. Here, we used micro-CT to study Linguatula serrata, which is a zoonotic pentastome parasite that infects dogs and ruminants throughout the world. The aims of this study were to describe the internal and external anatomy of adult L. serrata specimens using micro-CT, and to describe and compare specimens stained with 0.3% phosphotungstic acid (PTA) and 1% iodine (I2). Ten adult L. serrata specimens were subjected to micro-CT examination. The specimens were fixed in 70% ethanol and stained with 0.3% PTA or 1% I2. Both stains offered good tissue contrast. The main identifying external features of L. serrata (hooks, mouth, buccal cadre) were clearly visible. Virtual sections and 3D reconstructions provided a good overview of the coelomic cavity, with visualisation of the digestive tract, nervous system, and male and female reproductive organs. These micro-CT images and morphological descriptions may serve as an anatomical reference for L. serrata, in particular, the internal anatomy which has not been described in recent years.

Cancerogenic parasites in veterinary medicine: a narrative literature review

Parasite infection is one of the many environmental factors that can significantly contribute to carcinogenesis and is already known to be associated with a variety of malignancies in both human and veterinary medicine. However, the actual number of cancerogenic parasites and their relationship to tumor development is far from being fully understood, especially in veterinary medicine. Thus, the aim of this review is to investigate parasite-related cancers in domestic and wild animals and their burden in veterinary oncology. Spontaneous neoplasia with ascertained or putative parasite etiology in domestic and wild animals will be reviewed, and the multifarious mechanisms of protozoan and metazoan cancer induction will be discussed.

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.

Meat-borne parasites in the Arab world: a review in a One Health perspective

Meat-borne parasitic zoonoses are generally not well-monitored, and so understanding extent and overall prevalence is problematic. Without sufficient attention, their prevalence can become unexpectedly and unacceptably high. This review sheds light on meat-borne parasites in the Arab world, which includes all the Arab countries situated in the continents of Asia and Africa, with more than 400 million inhabitants distributed in 22 countries. Meat-borne parasites can be divided into two main categories-helminths and protozoa. The main helminths included in this review are Taenia saginata, Taenia solium, Taenia asiatica, Echinococcus spp., Fasciola spp., and Trichinella spiralis, while the meat-borne protozoan parasites are Toxoplasma gondii, Cryptosporidium spp., and Sarcocystis spp. In addition, Linguatula serrata, which belongs to the class Pentastomida, was included. Among those, the genus Taenia is the most frequently reported in the Arab world, particularly T. saginata. Many parasitic infections that are mainly transmitted through pork, although widespread in many parts of the world, are rare in the Arab countries, primarily due to religious proscriptions. The majority of the publications concerning meat-borne parasites were from Egypt, which contains the largest population in the Arab world and the highest population density, in addition to various economic, social, and environmental reasons.

Linguatulosis in small ruminants in southeastern Iran: Epidemiological, histopathological and phylogenetic findings and its public health importance

Linguatulosis, as a zoonotic disease, can infect most ruminants and cause accidental infections in humans. The objective of this study was to explore the epidemiological, histopathological and phylogenetic profiles of Linguatula serrata infection in sheep and goats and its public health importance during 2015-2018. Mesenteric lymph nodes (MLNs) and liver tissue of goats and sheep were selected randomly in Kerman slaughterhouse. Nymphal samples were used for DNA extraction, amplification and subsequently phylogenetic analysis using 18s rRNA and cytochrome C oxidase subunit 1 (cox1). Overall, of 828 examined livestock, 179 (42.4%) goats and 71 (17.5%) sheep were found to be infected with the nymphal stage of L. serrata. A significant difference was observed between linguatulosis and age. In the histopathological assessment, longitudinal and transverse sections of L. serrata nymphs were observed within the cyst-like spaces surrounded by a wall of fine fibrosis and compact lymphocytes. Moreover, comparing with the L. serrata reference sequences, we found only a single nucleotide change in our goat haplotype in 18s genetic region; while much nucleotide variations were observed in cox1 gene sequences. The results of the present study showed a high infection rate among goats and sheep in southeastern Iran. A better understanding of the disease could be achieved when the parasite species, their molecular characterization and the extent of infection in the area are determined. It is fundamental to select a comprehensive control program in order to take proper preventive and therapeutic measures against the infection.

Clinical manifestation and epidemiological findings of human linguatula serrate infection in Iran: systematic review

The aim of this study was to collect data and provide information on clinical diagnosis of disease, methods of dissemination, prevention and treatment of human linguatuliasis in order to increase people's awareness and health care. In this study case reports of individuals in Iran those infected with the Linguatula serrata were taken from the international databases (e.g., Medline (PubMed), Scopus, Iranmedex, Scientific Information Database, and Irandoc) and reviewed. The review covers the case reports of human tongue worm infection published either in Persian or in English between the years 1980-2018. An individual researcher undertook the bibliographic search and evaluation of articles based on inclusion/exclusion of specific criteria. Cases of infection have been reported in eight provinces of Iran. Dietary habits play the important roles in the transmission of the parasite. Clinical diagnosis was achieved by obtaining a patient's history, then completing a clinical examination of the mentioned patients. Symptoms of infection were mainly observed in the upper respiratory tract in most reports, the patient's status was improved by removing the parasite from the infected organ. Given that viscera of slaughtered livestock plays a significant role in the transmission of this infection to humans, Careful inspection of slaughtered livestock in slaughterhouses and Preventing the slaughter of livestock illegally and unsanitary, outside the slaughterhouse, is important. Accordingly, it is very important to train the employees working in the slaughterhouses and the people who consume these organs.

Linguatula serrata in cattle in southeastern Iran: Epidemiological, histopathological and phylogenetic profile and its zoonotic importance

This study aimed to determine the prevalence, histopathological observations, and phylogenetic analysis of L. serrata in cattle and its potential zoonotic and public health implications in southeastern Iran.The cross-sectional study was performed in cattle in southeastern Iran. Lymph nodes were collected from each cattle and examined by parasitological and histopathological techniques. A binary logistic regression and chi-square tests were implemented to analyze the data. Genomic DNA was randomly extracted from the nymphal stages of Linguatula isolates. Further characterization and phylogenetic relationships were done using two primers for amplification of partial DNA fragments of 18 s rRNA and cytochrome C oxidase subunit 1 (cox1), respectively.The results showed that 64 cattle of the total 404 were infected with L. serrata. There was no significant difference between linguatulosis infection and gender, while age was significantly different (P < 0.05). The cyst-like spaces containing the longitudinal and transverse sections of the L. serrata nymphs were surrounded by granulomatous reactions. The higher nucleotide variation in the cox1 region was supported by estimating the evolutionary divergence between L. serrata isolates and other Linguatula records of ruminants in Iran. The phylogenetic tree confirmed the close evolutionary relationships among all reported records of L. serrata in Iran.The high prevalence of linguatulosis caused by L. serrata declares the existence of a potential risk of FBPs for humans in southeastern Iran. This condition can advance more serious public health problems and requires a comprehensive control program and treatment strategies to prevent the disease.