From stillness to motion: 80 years after the first description of Taenia solium oncosphere hatching
© Mendlovic et al.; licensee BioMed Central Ltd. 2014
Received: 25 November 2013
Accepted: 27 November 2013
Published: 16 January 2014
Human neurocysticercosis (NCC) is a considered public health problem in many underdeveloped and developing countries. Because of the enormous increase in international tourism and migration, NCC nowadays is also found in some developed countries. Our group was the first to demonstrate that tapeworm carriers in the household are the main risk factor for acquiring cysticercosis in humans and pigs, since the disease results from the ingestion of microscopic tapeworm eggs.
We had the opportunity to film the liberation of the embryo from the oncospheral membrane after the hatching of the egg, which is the activation process required for intestinal wall invasion by the onchosphere. Yoshino (J Formosa Med Ass 32:139-142, 1933) described with great detail in diagrams and photographs this process eighty years ago after he infected himself with three living cysticerci in order to study the life cycle of Taenia solium. Other authors further described this process. Nevertheless it has never been filmed before. The purpose of this paper is to shift from stillness to motion since we can now show for the first time a movie of an activated oncosphere and its release from the oncospheral membrane.
Oncospheral activation is the requisite for T. solium embryos to invade the intestinal mucosa and develop into cysticerci. This process has been amply described but here it is shown for the first time in motion; thus it may be of interest for readers of the journal and useful for educational purposes towards the control of NCC.
The life cycle of T. solium includes the human being as the definitive host that harbors the intestinal tapeworm and the pig as the intermediate host in which the larval stage or cysticercus develops. Definitive hosts acquire the disease after ingesting undercooked infected pork meat, while cysticercosis is produced after swine consume infected human feces that contain tapeworm gravid proglottids full of eggs. In addition, accidental ingestion of these eggs can cause human neurocysticercosis (NCC), a public health problem in many developing countries and an emerging infectious disease in some developed ones[1–3]. NCC is a neglected tropical disease that is underfinanced and caused 25,341 disability adjusted life years (DALYs) in Mexico during 2005 due to epilepsy (90%) and severe chronic headaches (10%) associated to NCC. Improvements in research, diagnosis, treatment and control have been achieved in Mexico, suggesting that NCC may no longer be a public health problem in this country. This approach should be taken into consideration for the control of zoonoses and marginalized infectious diseases of poverty recently reviewed.
Our group was the first to demonstrate that patients with NCC are found mainly where a tapeworm carrier is part of the household, thus the egg is one of the main targets for the control of NCC. The morphology of tapeworm eggs has been described and illustrated in photographs and diagrams as early as 1933 by Yoshino, and afterwards by other authors[9–13]. Eggs measure between 26 and 34 μm and have a radial appearance because of the embryophore that surrounds and protects the oncosphere that is covered by the oncospheral membrane.
Additional file 1: Movie S1: The movie was filmed under an optic microscope and speeded-up 5 times. It shows the activation of a Taenia solium oncosphere. (MP4 14 MB)
Oncospheral activation is the requisite for T. solium embryos to invade the intestinal mucosa and develop into cysticerci. This process has been amply described but here it is shown for the first time in motion, thus it may be of interest for readers of the journal and useful for educational purposes towards the control of NCC.
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