Taenia species (tapeworm)

Test code: X0061 - Ultrasensitive qualitative detection of common Taenia species by real time PCR

Taenia is a genus of parasitic flatworms known as tapeworms, within the class Cestoda, that infect the intestines of various mammals, including humans, livestock, dogs, cats, and wild carnivores. There are several Taenia species that can be transmitted from animals to humans, such as Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), and Taenia asiatica (Asian tapeworm). Other Taenia species infect pets and wildlife. For example, dogs can acquire Taenia species such as T. pisiformis, T. hydatigena, T. crassiceps, and T. serialis by eating infected prey such as rabbits or rodents. Cats can be infected with T. taeniaeformis by eating infected mice or rats.

These tapeworms have segmented bodies and require both a definitive host (where the adult worm lives) and an intermediate host (where larval stages develop) to complete their life cycle. When the intermediate host ingests the eggs through contaminated food, water, or soil, the eggs hatch into oncospheres (embryos). The oncospheres penetrate the intestinal wall and enter the circulatory or lymphatic system and migrate to muscles, liver, brain, or other tissues, where they develop into metacestodes or cysticerci. A cysticercus becomes infective after several months. The definitive host becomes infected by consuming raw or undercooked tissue from the intermediate host, which contains viable cysticerci. In the small intestine of the host the cysticerci evaginate and attach to the intestinal mucosa via their scolex, or head. The cysticerci mature into adult tapeworms over 2-12 weeks, depending on the species. Adult worms can survive in the intestine for years and keep producing new proglottids to perpetuate the cycle.

Taenia infection is sometimes asymptomatic in intermediate hosts, but if the parasite load is heavy, tissue damage may occur. In definitive animal hosts, such as dogs or cats, infections are often mild, with possible irritation from passing segments or minor digestive upset. In human infections, symptoms vary depending on cyst location, number, and the host's immune response. Symptoms may not appear for weeks to years. Some infected people may remain asymptomatic, but in others, infection of the nervous system can lead to serious symptoms.

Diagnosis of Taenia infection is traditionally through microscopic examination of feces and tissue, but this method has low sensitivity. Polymerase chain reaction is increasingly used in diagnosis of this infection and in environmental surveillance due to its high specificity and sensitivity (Cuttell et al., 2013; Nunes et al., 2003).

Utilities:

• Help confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of Taenia infection
• Help ensure that herds are free of Taenia
• Early prevention of spread of Taenia between animal species
• Environmental monitoring for Taenia
• Minimize human exposure to Taenia

References:

Cuttell L, Owen H, Lew-Tabor AE, Traub RJ. Bovine cysticercosis--development of a real-time PCR to enhance classification of suspect cysts identified at meat inspection. Vet Parasitol. 2013 May 1;194(1):65-9.

Nunes CM, Lima LG, Manoel CS, Pereira RN, Nakano MM, Garcia JF. Taenia saginata: polymerase chain reaction for taeniasis diagnosis in human fecal samples. Exp Parasitol. 2003 May-Jun;104(1-2):67-9.

Specimen requirement: 2 ml feces; or rectal swab; or 10 ml soil; or 10 ml water, or used water filter media; or environmental swabs or swipes; or 0.2 ml fresh, frozen or fixed tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected