Sparganosis – An Esoteric Infection

Sparganosis is one of the most bizarre and mysterious parasitic diseases ever described, caused by a pseudophyllidean cestode known as Spirometra. The majority of the world’s cases of sparganosis are in China, Japan, South Korea, Thailand, and southeast Asian nations.[1-3] In South America, Europe, and Africa, there are isolated examples. Sporadic cases have been recorded from different parts of India, and they could develop into a serious public health issue. Due to the rarity of this illness, the treating physician may overlook the potential of sparganosis in the differential diagnosis if he or she has little to no expertise with this larval ailment.[4] Spirometra belongs to the Diphyllobothriidae family, and its lifecycle has been well documented.[5] The most common species in the genus Spirometra include S. mansoni, S. ranarum, S. mansonoides, S. erinacei, and the aberrant Sparganum proliferum. Adult worms living in the intestines of carnivore animals, for example, dogs and cats, and freshwater copepods serve as the first intermediate host. Infected copepods are ingested by the second intermediate hosts, including fish, reptiles, and amphibians, in which larvae develop into plerocercoid (L3 stage), which is called sparganum. Man acts as an accidental host and acquires infection by either ingestion of undercooked reptiles and fish containing plerocercoid larva (L3 stage) or drinking contaminated water that contains infected copepods containing procercoid larva (L2).[5] Sparganum penetrates the intestinal wall and migrates to subcutaneous tissues, muscles, lymphatics, and visceral organs like the brain, eyes, breast, lungs, pleural cavity abdominal viscera, and urinary tract and can cause varied presentations depending on the final location. It gets encysted to form fibrous nodules measuring 2 cm associated with pruritis and urticaria. Ocular sparganosis is a serious manifestation and presented as edematous swelling of the eyelids. Sparganosis caused by Sparganum proliferum was recently termed proliferative sparganosis because in this rare cestode infection, several asexually multiplying plerocercoids invade various tissues and organs, leading to a poor prognosis.[6] The disease types can be categorized into cutaneous proliferative sparganosis and internal proliferative sparganosis.[7] Most infections are asymptomatic; only the more obvious or severe cases are diagnosed, for instance, people who have a fever and neurological symptoms such as seizures, mild hemiplegia, a progressively worsening headache, and altered level of consciousness.[8] Clinically, sparganosis is frequently misinterpreted as glioma because of its unusual characteristics, irregular intracranial location, and atypical epidemiology. Due to the parasite’s capacity to affect the host’s immune response, long-term parasite survival is feasible. The recovery of sparganum from infected tissues is typically used to make the diagnosis. A sparganum is diagnostic; therefore, species-level identification is typically not necessary. Imaging techniques like MRI also play a major role, which aids in the diagnosis. Identification of spargana using macro- and microscopic techniques is one of the laboratory procedures for diagnosing sparganosis. Macroscopically, spargana resemble a thin, white solid flatworm that ranges in length from a few millimeters to several centimeters and is covered in inflammatory exudates and a gliotic wall. In contrast to other cysticerci, spargana exhibit a solid, non-cavitated body without a bladder wall, hooked scolex, or suckers. Finding a distinctive deep-folded tegument and calcareous corpuscles as well as other histological characteristics allows for the identification of Spirometra. Strong peripheral eosinophilia may be detected by biochemical testing.[6,8] In cases where spargana are invisible, such as in pleural sparganosis, or where biopsy or removal of spargana is problematic, serological assays provide an alternate method for diagnosing sparganosis.[7] In fact, a sensitivity of 100% and a specificity of 99% were achieved by employing recombinant cysteine protease from sparganum plerocercoids as an antigen. Human sparganosis has been classified as a surgical condition that solely hinges on finding larvae in the lesions. Although praziquantel has also been used, it has been used with sporadic success; surgical excision is still thought to be and will continue to be the mainstay of the treatment because there is no evidence to support the proven benefit of medical treatment.[9,10] In India, sparganosis appears to be a significant food-borne zoonosis associated with drinking contaminated water or consumption of infected raw or undercooked meat. However, there may be underreporting of these cases because it may be difficult to accurately quantify the issue due to a lack of adequate knowledge of its existence in the medical community, which could result in an incorrect diagnosis of this parasitic condition. Although parasite extraction continues to be the cornerstone of diagnosis, all suspected cases must be thoroughly tested for substitute indicators such as absolute eosinophil levels. In order to have some notion of the scope of the problem, it may also be scientifically very sensible to survey populations from high-risk locations using a reliable, well-validated serological test like the sparganosis immunoglobulin ELISA. Data availability statement Nil. Author contribution Contributor 1: Literature search, manuscript preparation, manuscript editing, manuscript review; Contributor 2: Manuscript review; Contributor 3: Manuscript editing; Contributor 4: Study design, literature search, manuscript preparation, manuscript editing, corresponding author. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.