Diagnosis is the same as with liver flukes: examination of feces or other samples and immunoassay. Praziquantel is used to treat infections caused by intestinal flukes.
- How are flukes transmitted?
Helminthic gastrointestinal infections
Numerous helminths are capable of colonizing the GI tract. Many such infections are asymptomatic, but others may cause signs and symptoms ranging from mild GI stress to severe systemic infection. Helminths have complex and unique life cycles that dictate their specific modes of transmission. Most helminthic infections can be treated with medications.
Resolution
Carli’s doctor explained that she had bacterial gastroenteritis caused by Salmonella bacteria. The source of these bacteria was likely the undercooked egg. Had the egg been fully cooked, the high temperature would have been sufficient to kill any Salmonella in or on the egg. In this case, enough bacteria survived to cause an infection once the egg was eaten.
Carli’s signs and symptoms continued to worsen. Her fever became higher, her vomiting and diarrhea continued, and she began to become dehydrated. She felt thirsty all the time and had continual abdominal cramps. Carli’s doctor treated her with intravenous fluids to help with her dehydration, but did not prescribe antibiotics. Carli’s parents were confused because they thought a bacterial infection should always be treated with antibiotics.
The doctor explained that the worst medical problem for Carli was dehydration. Except in the most vulnerable and sick patients, such as those with HIV/AIDS, antibiotics do not reduce recovery time or improve outcomes in Salmonella infections. In fact, antibiotics can actually delay the natural excretion of bacteria from the body. Rehydration therapy replenishes lost fluids, diminishing the effects of dehydration and improving the patient’s condition while the infection resolves.
After two days of rehydration therapy, Carli’s signs and symptoms began to fade. She was still somewhat thirsty, but the amount of urine she passed became larger and the color lighter. She stopped vomiting. Her fever was gone, and so was the diarrhea. At that point, stool analysis found very few Salmonella bacteria. In one week, Carli was discharged as fully recovered.
Go back to the previous Clinical Focus box.
Key concepts and summary
- Helminths often cause intestinal infections after transmission to humans through exposure to contaminated soil, water, or food. Signs and symptoms are often mild, but severe complications may develop in some cases.
- Ascaris lumbricoides eggs are transmitted through contaminated food or water and hatch in the intestine. Juvenile larvae travel to the lungs and then to the pharynx, where they are swallowed and returned to the intestines to mature. These nematode roundworms cause ascariasis .
- Necator americanus and Ancylostoma doudenale cause hookworm infection when larvae penetrate the skin from soil contaminated by dog or cat feces. They travel to the lungs and are then swallowed to mature in the intestines.
- Strongyloides stercoralis are transmitted from soil through the skin to the lungs and then to the intestine where they cause strongyloidiasis .
- Enterobius vermicularis are nematode pinworms transmitted by the fecal-oral route. After ingestion, they travel to the colon where they cause enterobiasis .
- Trichuris trichiura can be transmitted through soil or fecal contamination and cause trichuriasis . After ingestion, the eggs travel to the intestine where the larvae emerge and mature, attaching to the walls of the colon and cecum.
- Trichinella spp. is transmitted through undercooked meat. Larvae in the meat emerge from cysts and mature in the large intestine. They can migrate to the muscles and form new cysts, causing trichinosis .
- Taenia spp. and Diphyllobothrium latum are tapeworms transmitted through undercooked food or the fecal-oral route. Taenia infections cause taeniasis . Tapeworms use their scolex to attach to the intestinal wall. Larvae may also move to muscle or brain tissue.
- Echinococcus granulosus is a cestode transmitted through eggs in the feces of infected animals, especially dogs. After ingestion, eggs hatch in the small intestine, and the larvae invade the intestinal wall and travel through the circulatory system to form dangerous cysts in internal organs, causing hydatid disease .
- Flukes are transmitted through aquatic plants or fish. Liver flukes cause disease by interfering with the bile duct. Intestinal flukes develop in the intestines, where they attach to the intestinal epithelium.
Fill in the blank
Short answer
Why does the coughing up of worms play an important part in the life cycle of some helminths, such as the roundworm Ascaris lumbricoides ?