A long parasite can invade our intestines and cause this disease.
Taeniasis: a meter-long living being inside us
Taeniasis is the product of an infection following the consumption of contaminated meat or contact with material that has been exposed to the feces of a sick animal. Knowing the parasite in question is the first of the barriers to preventing contagion, so below we show the most general characteristics of the Taenia genus.
giant parasites
The cestodes Taenia solium and Taenia saginata are the cause of taeniasis. It is important to know that the first named species can also give rise to cysticercosis, a much more serious pathology that we will discover in later sections.
Tapeworms or tapeworms have a flat, wormy shape, and their body is divided into multiple segments or proglottids. Each one of these compartments has a complete hermaphroditic reproductive system, and it is curious to know that the final segments full of eggs usually completely detach from the tapeworm without causing any type of damage.
One of the most striking features of tapeworms is their extraordinary size for the parasitic lifestyle they display. Taenia solium measures from 4 to 8 meters, while T. Saginata can reach 12 meters in length without much difficulty. Can you imagine having a living being of such proportions inhabiting your small intestine? As grotesque as it may seem, as we will see later, this disease is much more silent than is believed .
They also have a cephalic organ called the scolex, made up of suckers and crowns of hooks. This complex head serves as a point of attachment to the intestinal mucosa of the vertebrates they parasitize, where they feed and carry out their vital functions. Next, we present the life cycle of the parasite that gives rise to taeniasis in humans.
A simple life cycle
Taeniasis is a pathology linked to the presence of pigs and cows in unhealthy environments , as these are the main hosts of the parasite. Next, we summarize the life cycle of tapeworms in a simple way:
- The spherical eggs, 30 to 45 micrometers in diameter, are passed with the feces of the infected human.
- These oncospheres can remain in the medium for days to months, and livestock animals become infected by eating contaminated vegetables.
- Taenia solium infects pigs, while Taenia saginata has cattle species as intermediate hosts.
- Once in the animal, the eggs hatch and the larvae migrate to the animal’s muscle tissues, giving rise to cysticerci.
- The person becomes infected by consuming meat with cysticerci.
- These larvae, once in the human body, migrate to the small intestine, where the hermaphrodite adult capable of reproducing develops.
As we have been able to observe, in this case the human being is the definitive host of the parasite, because without us, its life cycle could not be closed. Taeniasis is the pathology produced by the presence of the adult tapeworm in the small intestine . Another case is that of cysticercosis, much more lethal and serious.
When a person accidentally consumes Taenia solium eggs, either by putting something contaminated with human feces or other means of transmission into their mouth, the tapeworm larvae become confused. These believe that they are in their intermediate host (cow or pig) and migrate to human tissues generating cysts known as cysticerci. When the larvae encyst in the brain (neurocysticercosis), things get even worse.
Clinical approach to taeniasis and cysticercosis
Once we have described the parasites that cause this curious disease, it is time to analyze taeniasis from a clinical and epidemiological point of view.
1. Causes
Tapeworms are cosmopolitan parasites with a higher incidence in places where it is customary to eat raw or poorly cooked pork or beef. The places with the highest incidence are Latin America, Southern Africa, India or China, among others.
A curious study carried out at European level in 2012 collected data on taeniasis recorded over 20 years. These were the results:
- Of the 846 registered cases, 522 were autochthonous and 324 imported.
- 70.1% of autochthonous cases were registered in Portugal between 1983 and 1994.
- 74% of imported cases were by migrants and the rest by travelers within Europe.
- Most of the imported cases came from South America.
- Most of the imported cases occurred in Spain (47.5%), France and Italy.
As we can see, taeniasis is not a disease that only affects low-income countries . It is also present in European countries, either by indigenous or imported infections, mostly from Latin America.
Another story is when we look at the presence of these parasites in countries such as Brazil. In this case, a study showed that the prevalence (number of infected individuals) among cattle in this region was 5.5%:
In Latin America, it is estimated that cases of neurocysticercosis (the worst pathology caused by Taenia solium) is 100 infected per 10,000 inhabitants, affecting a total of 350,000 people. Taking into account the seriousness of this pathological variant, we are faced with exorbitant numbers.
2. Symptoms
As strange as it may seem, the symptoms of taeniasis are mild or even absent. That’s right, a person can have a 10-meter animal in their intestine for years and barely even notice it . Even so, studies collect the most common clinical manifestations of this pathology. Among more than 3,000 people with the disease surveyed, the following symptoms were collected:
- 35% reported having abdominal pain.
- 34% had recurrent nausea.
- More than 20% experienced weakness and weight loss.
- Less than 20% experienced other symptoms, such as headaches , constipation, vertigo, diarrhea or itching in the anal region.
All these symptoms are a product of the activity of the adult tapeworm in the small intestine. After all, it is a meter-long parasite that is continuously feeding on the nutrients provided by the human diet.
Cysticercosis presents in a much more aggressive way, and the clinical picture depends a lot on the organs that the larvae have infected. The case of neurocysticercosis is the most striking, because having encysted in the brain itself, they generate symptoms such as headaches, memory loss, seizures and even death.
3. Diagnosis and treatment
The search for eggs in the stool of the suspected patient is the most common detection method, although not the most effective, detecting less than half of the cases when a single stool sample is analyzed. That is why samples are collected from patients for at least three days.
According to the World Health Organization (WHO), taeniasis is effectively treated with the administration of praziquantel or niclosamide in a single dose . For its size, killing the parasite is surprisingly easy.
Treating neurocysticercosis is more complex, since the elimination of the larval cysts can produce an inflammatory response orchestrated by the immune system of the affected person. For this reason, the aforementioned medications are used for a longer period of time, in addition to corticosteroids, antiepileptics, and in some cases surgical interventions.
Conclusions
Taeniasis and cysticercosis are pathologies that occur due to irregular operations in the branches of veterinary medicine, public health and the environment.
As the sources of infection are found in fecal material and contaminated meat , applying the maximum number of hygiene measures is essential for its eradication. This includes better inspection of meat products, identification and treatment of cases of taeniasis in humans and cysticercosis in cattle, and improvement of general sanitation in the environment.
Bibliographic references
- Pfuetzenreiter, MR, & Pires, FDD Á. (2000). Epidemiology of teniasis/cysticercosis by Taenia solium and Taenia saginata. Rural Science, 30(3), 541-548.
- Meza-Lucas, A., & Rebolledo, F. A. (2002). Human taeniasis due to Taenia solium. Mexican Journal of Clinical Pathology and Laboratory Medicine, 49(2), 92-99.
- Taeniasis, CDC. Retrieved July 16 at https://www.cdc.gov/dpdx/taeniasis/index.html
- Zammarchi, L., Strohmeyer, M., Bartalesi, F., Bruno, E., Muñoz, J., Buonfrate, D., … & COHEMI Project Study Group. (2013). Epidemiology and management of cysticercosis and Taenia solium taeniasis in Europe, systematic review 1990–2011. PloS one, 8(7), e69537.
- Taeniasis and cysticercosis, World Health Organization (WHO). Collected on July 16 at https://www.who.int/es/news-room/fact-sheets/detail/taeniasis-cysticercosis#:~:text=sistema%20nervioso%20central.-,Treatment,2%20a %C3%B1os%3A%20500%20mg ).
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.
