Also known as the rat tapeworm, H. diminuta adults live and mate in the bowels of rats. Eggs of H. diminuta are excreted by the rats in droppings, which are frequently consumed by beetles. Once inside the beetle, the eggs mature into a cysticercoid. The juvenile tapeworms claw their way out of the beetle gut into the circulatory system by means of their three pairs of hooks. There, they wait for a rat to ingest the host beetle, where they mature to adult form, lay eggs, and restart the entire cycle. Beetle manipulation
H. diminuta has an effective mechanism for interspecies transfection. Beetles prefer to ingest rat droppings infected with tapeworm eggs, because of their odor. It is not known if the odor is produced specifically by the eggs or the droppings. H. diminuta also sterilizes its beetle host, if female. This is so the beetle does not waste energy in its reproductive system, allowing H. diminuta to further exploit the beetles metabolic resources. H. nana
H. nana is a tapeworm, belonging to the class Cestoidea, phylum Platyhelminthes. It consists of a linear series of sets of reproductive organs of both sexes; each set is referred to as a genitaluim and the area around it is a proglottid. New proglottids are continuously differentiated near the anterior end in a process called strobilation. Each segment moves toward the posterior end as a new one takes its place and, during the process, becomes sexually mature.
Hymenolepiasis is infestation by one of two species of tapeworm: Hymenolepis nana or H. diminuta. Alternative names are dwarf tapeworm infection and rat tapeworm infection. The disease is a type of helminthiasis which is classified as a neglected tropical disease. Symptoms and signs
Hymenolepiasis does not always have symptoms, but they usually are described as abdominal pain, loss of appetite, itching around the anus, irritability, and diarrhea. However, in one study of 25 patients conducted in Peru, successful treatment of the infection made no significant difference to symptoms. Some authorities report that heavily infected cases are more likely to be symptomatic.Symptoms in humans are due to allergic responses or systematic toxaemia caused by waste products of the tapeworm. Light infections are usually symptomless, whereas infection with more than 2000 worms can cause enteritis, abdominal pain, diarrhea, loss of appetite, restlessness, irritability, restless sleep, and anal and nasal pruritus. Rare symptoms include increased appetite, vomiting, nausea, bloody diarrhea, hives, extremity pain, headache, dizziness, and behavioral disturbances. Occasionally, epileptic seizures occur in infected children.Examination of the stool for eggs and parasites confirms the diagnosis. The eggs and proglottids of H. nana are smaller than H. diminuta. Proglottids of both are relatively wide and have three testes. Identifying the parasites to the species level is often unnecessary from a medical perspective, as the treatment is the same for both. Complications
Abdominal discomfort and, in case of prolonged diarrhea, dehydration are possible complications.In 2015 an unusual complication was noted in a man whose immune system had been compromised by HIV.