Taeniasis and Diphyllobothriasis: Causes, Symptoms, and Prevention
Taeniasis Saginata (Beef Tapeworm)
Eggs are eliminated with bowel movements. In the environment, proglottids disintegrate, and under appropriate conditions, eggs can remain viable and infective for several months. They are disseminated by wind and contaminate pastures. Cattle become infected by eating grass contaminated with T. saginata eggs.
In the animal, gastric juices disintegrate the egg, releasing the hexacanth embryo. This embryo penetrates the mucosa, enters lymphatic vessels and the bloodstream, and migrates to muscle and fatty tissue. After approximately 75 days, it develops into the larval stage, Cysticercus bovis.
Human infection occurs by eating raw or undercooked beef.
Clinical Manifestations of Human Taeniasis Saginata
General Symptoms: Headaches, fatigue, weight loss, appetite changes.
Nervous System Symptoms: Altered character.
Allergic Symptoms: Nasal itching and urticarial reactions.
Gastrointestinal Symptoms: Nausea, vomiting, colicky abdominal pain, and expulsion of gravid proglottids.
Treatment
Praziquantel and niclosamide are effective treatments.
Prophylaxis
- Individual: Consume thoroughly cooked beef (above 60°C).
- Veterinary medical inspection of meat.
- Avoid eating meat of dubious origin.
- Purchase meat only from established businesses.
- Irradiation or freezing at slaughter plants.
Epidemiology
Taeniasis caused by T. saginata is more frequent than that caused by T. solium, and its frequency is higher in urban than in rural areas. This is related to the difficulty of visualizing Cysticercus bovis in beef muscle or differentiating it from accumulations of fatty tissue.
Diphyllobothriasis (Diphyllobothrium latum)
Fish tapeworm.
Diphyllobothrium pacificum
The adult worm develops in the small intestine of sea lions, marine fish, and occasionally humans. Its intermediate hosts are planktonic crustaceans and some marine fish.
Diphyllobothrium dendriticum
The adult worm develops in the small intestine of dogs, cats, and fish-eating birds. Its intermediate hosts are freshwater crustaceans and salmonid fish.
Morphology
The scolex is long and spatula-shaped, approximately 3 mm long, with two bothria. The strobila consists of trapezoidal proglottids. Gravid proglottids have a central rosette-shaped uterus, full of eggs. Eggs are oval, brown, with a lid or operculum, and are non-embryonated when eliminated.
Diphyllobothriasis Cycle
The worm releases eggs and proglottids with eggs (oval-shaped with an operculum). For egg development, they need to reach fresh water. At an ideal temperature, eggs begin to mature, forming a ciliated embryo that exits through the operculum and is called a coracidium. The coracidium swims and is consumed by copepods (crustaceans), which become infected. The coracidium develops into a procercoid larva in the copepod’s gut. Fish, like trout, consume infected copepods, and the procercoid perforates the fish’s intestine and migrates to the musculature, developing into a plerocercoid larva. Once ingested by humans, the plerocercoids reach the stomach and then the small intestine.
The worm’s action in children can cause vitamin B12 deficiency, leading to megaloblastic anemia. It may involve the central and peripheral nervous systems, causing demyelination.
Diagnosis
Serial parasitological examination of stools (PSD) to search for eggs and gravid proglottids.
Treatment
- First Option: Praziquantel 150 mg tablets.
- Second Option: Niclosamide in tablets of 500 mg.
Prophylaxis
- Consume well-cooked salmonids (above 60°C).
- Proper disposal of human excreta: Do not dispose of waste into rivers or lakes.
- Freeze salmonids to -18°C for 24 hours or -10°C for 72 hours.
- Plerocercoids are not destroyed by smoking or lemon juice.