Prevalence and associated risk factors of Linguatula serrata infection in definitive and intermediate hosts in Iran and other countries: A systematic review

Linguatula serrata is known as a cosmopolitan zoonotic parasite whose adult form inhabits the upper respiratory system, nasal airways and frontal sinuses of dogs, foxes, cats and other carnivores, which are recognized as its final hosts. Its immature form resides in mesenteric lymph nodes, liver, lungs and spleen of herbivorous and other ruminants, which serve as its intermediate hosts. Both adult and nymphal stages of L. serrata can infect humans, which typically occurs via ingestion of eggs of infected dogs or consumption of raw or undercooked infected viscera of contaminated herbivores. The most common form of infection in human is nasopharyngeal linguatulosis, also known as Halzoun syndrome or Marrara syndrome. This paper presents a review of previous studies on L. serrata conducted in Iran from 1969 to 2018 and other countries. It was found that despite the fact that many studies have been conducted in Iran, the rate of infection with this parasite has not been studied in some areas of the country. In addition, the rate of infection with L. serrata increased with the age of ruminant animals and it was significantly higher in some areas. The prevalence of L. serrata nymphal infections in most areas was higher in goats in comparison to the other animals which can be an important risk factor for human infection. Although there was no significant difference in the rate of infection among male and female animals, the prevalence of L. serrata in male animals was typically lower than females. There was no significant difference in the seasonality of nymph infection.