Parasitic roundworms - Nematoda
Adult nematoda worms develope from larvae and have sepearte sexes (one can distinguish male from female).
Adult nematoda worms develope from ____ and have sepearte ____.
True
Adult nematoda worms: one can distinguish male from female. True / False ?
eggs
All nematodas produce....
Common name: large intestinal roundworm Disease: ascaridoses/ascariasis (intestinal helminth infection) --> intestinal parasite
Ascaris lumbricoides Common name: Disease:
• Worms may move toward upper gastrointestinal tract and become vomited. • In heavy infestation worms may ball up and cause intestinal obstruction and even perforation of the intestine. • Due to ectopic localization hepatic abscesses, acute pancreatitis, periotonitis can develop.
Complications: Ascaris lumbricoides
• Heavy infections in children may cause restlessness, irritability, anorexia, insomnia, nightmares, bed-wetting, nausea and vomiting. • Patients often complain on teeth grinding or abdominal pain. • Occasionally, wandering worms have been associated with appendicitis, vaginitis, and rarely, extra-intestinal granulomas in ectopic sites.
Complications: Enterobius vermicularis
• If the worms invade the central nervous system encephalitis or other severe neurologic pathology can develop. • Due to encephalitis, myocarditis or pneumonia, death may occur.
Complications: Trichinella spiralis
Heavy infections can show finger clubbing and due to tenesmus, prolapsed rectum. In children heavy infections may result in severe anemia, even growth retardation and cognitive delay.
Complications: Trichuris trichiura
1. Microscopy - eggs in stools. Eggs show typical morphology - barrel shaped with protein plugs at both ends. 2. Endoscopy - worms in the intestine; Adult worms may be seen hanging from the walls of the colon. 3. Blood test - high levels of eozinophilia (typical for all helminth infections) - anemia (typical for Trichiurosis / Whipworm infection) 4. Defecating proctogram; rectal prolapse can be seen.
Diagnosis : Trichuris trichiura
1. By symptoms (nonspecific); GI fullness, abdominal pains, vomitting - During migratory phase; Loeffler`s syndrome (dry, unproductive cough), which is typical for ascaridosis. 2. Blood tests are usefull; high eosinophilia can be detective, 20-40% (due to response of worm proteins). 3. Study eggs in feces in microscope (rough, brownish outer layer). 4. During migratory phase larvae in sputum can be observed; 1 - 2 mm, pale, transparent 5. CT; Small bowel (red arrows)representing adult ascaris. 6. US; Worm in gall bladder (ectopic location)
Diagnosis: Ascaris lumbricoides
1. By symptoms; Itching araund the anus is the most common symptom 2. By worms in the perianal region; To look for the worms 2 to 3 hours after the infected person is asleep. 3. By eggs on «sticky tape» ; Eggs are found in high quantitites on perianal region (not in feces). The eggs are then studied in microscope. 4. By eggs under fingernails; Infected person may have some pinworm eggs under the nails
Diagnosis: Enterobius vermicularis
1. Antibody test; IgG levels are high, but Ab test should be combined with symptoms. 2. Symptoms; e.g. fever, couighing, abdominal pain. If under the skin, it can be seen with naked eye. 3. Anamnesis (very important); history of exposure to cats and dogs.
Diagnosis: Toxocara sp.
1. Symptoms; specific symptoms which are compatible with trichinellosis. 2. Anamnesis; History of eating undercooked pork or wild game meat. 3.Antibody (ELISA)test; Antibodies(IgG), may not be detectable until 3 weeks after infection. 4. Muscle biopsy; shows encapsulated larvae
Diagnosis: Trichinella spiralis
prolaps can be seen
Diagnosis: Trichuris trichiura
Eggs of Trichuris trichiura require hot and humid environments to develop outside the host in the soil.
Eggs of Trichuris trichiura require ____ and ____ environments to develop outside the host in the _____.
Common name: Pineworm Disease: Enterobiosis --> Intestinal parasite
Enterobius vermicularis Common name: Disease:
Most common intestinal helminth infection in the world; more than one billion people worldwide. Children at age 4-14 are particular vulnerable. Risk infection exists wherever fecal disposal is improper, in countries of poor sanitation, low standard of personal hygiene. In many communities more than 80% of people are infected due to poor sanitation.
Epidemiology: Ascaris lumbricoides
Parasite has worldwide distribution, but appears to be more common in temperate than in tropical countries. Very common helminthic infection. Prevalence rates in some communities are 30-50%. The people most likely to be infected with pinworm are children under 18, people who take care of infected children and people who are institutionalized. In these groups, the prevalence can reach 50%. People can get this infection by ingesting eggs; eggs are deposited around the anus by the worm and can be carried to common surfaces such as hands, toys, bedding, clothing, and toilet seats.
Epidemiology: Enterobius vermicularis
About 30% of dogs and about 25 % of cats are infected with Toxocara sp. Toxocara is more prevalent in hot, humid regions where eggs are kept viable in the soil. People under 20 are more likely to be infected with Toxocara and if they own a dog or cat. This infection is more common in people living in poverty. Humans can be infected by accidentally ingesting Toxocara eggs especially if they work with dirt and accidentally ingest dirt containing eggs. The amount of people having toxocariosis is unknown, because many cases are asymptomatic or with mild symptoms.
Epidemiology: Toxocara sp.
Trichinella spiralis has a global distribution and is the species most commonly found in pigs, but in wild animals also. Worldwide, an estimated 10.000 cases of trichinellosis occur every year. The risk of trichinellosis from commercially raised and properly prepared pork is very low. However, eating undercooked wild game, particularly bear meat, puts one at risk for acquiring this disease. Homemade ham and sausage were the cause of many cases of trichinellosis reported in recent years. Currently>11 million people are infected globally.
Epidemiology: Trichinella spiralis
Common intestinal helminth infection in the world; around 500 million people in the world are infected with whipworm (higher prevalence than ascaridosis) Children (especially boys) are more commonly affected because of their high exposure risk. Infection often occurs in areas where human feces are used as fertilizer or fecal disposal is improper; in countries of poor sanitation and low standard of personal hygiene.
Epidemiology: Trichuris trichiura
For the development of the eggs conductive climatic conditions are necessary; - soil - humidity - temperature 25-30℃ - supply of oxygen
For the development of the eggs _____________ are necessary.
Cuticle protects parasite from environment
Function: Cuticle of Ascaris lumbricoides
used in mating.
Function: claspers
• Sexual dimorphism - Males are 1-4 mm long, posterior end curved ventrally - Females are 8-13 mm long, posterior end pointed • Very small in size!
General Characteristics: Enterobius vermicularis (pineworm)
--> General characteristics are very similar to all nematodes, especially Ascaris worms. • Sexual dimorphism • Cylindrical body, 20 - 25 cm in length • In males - curved posterior end • Cuticle • Muscles • Body cavity • Tube shaped internal organs
General Characteristics: Toxocara sp.
• Sexual dimorphism - Female 3-5 mm - Male ~1.5 mm • Very small nematode, but very dangerous for humans. • Male worms have claspers on its posterior end.
General Characteristics: Trichinella spiralis
• Sexual dimorphism - Males 30-45 mm long with a coiled posterior end - Females 35-50 mm long with a straight posterior end • Both sexes have a long, whip-like anterior end (very long and thin)
General Characteristics: Trichuris trichiura
Typical and very common nematoda. • Sexual dimorphism; - In males - curved posterior end. - In females - posterior end pointed • Cylindrical body, 20 - 25 cm in length; they are very big (even upto 49cm has been observed) - males are smaler • Cuticle (outerlayer) • Muscles • Body cavity; Tube shaped internal organs are located inside the cavity.
General characteristics: Ascaris lumbricoides
Some work on the worm's nerve ganglia --> paralyse the muscles within few minutes. Others act on tubulin formation in the worm cell, which disturb glucose uptake and normal digestion.
How does Antihelminthic drugs work?
1. Adult worms live in small intestine; Females produce eggs, eggs are passed with the feces. 2. Eggs can be fertilized (adaptive) and unfertilized, but fertile eggs embryonate and become infective; to become embryonated an egg (with larva inside), the egg must undergo cleavage (special type of mitotic division). 3. After eggs are swallowed, larva hatch in small intestine. 4. Larva invade intestinal mucosa, and via circulation are carried to the lungs. 5. The larva mature, penetrate the alveolar walls, crawl up to the throat and are swallowed. 6. Larva in small intestine develop into adult worms. →For the development of the eggs conductive climatic conditions are necessary - soil, humidity, temperature25-30℃, syply of oxygen.
Life cycle: Ascaris lumbricoides
embrynonated eggs are ingested. Larvae hatch in small intestine. Adult live in cecum. Gravid females migrates to perianal region at night and lay eggs. Eggs on perianal folds, mature within 4-6hours, and become infective. Eggs are again ingested, and life cycle continues.
Life cycle: Enterobius vermicularis
Eggs are embryonated (contain larvae; infective stage), and passed with dog feces. Humans can get infected: 1. by ingesting infected embryonated egg. 2. if rabbit ingest egg, the larava penetrate the gut, and migrate to tissue where larva and cysts ; human can get toxocara infection by ingesting the infected tissue of that animal. After ingestion of eggs or cysts; eggs hatch, larvae are release and penetrate intestinal wall, and ciruclate into tissue (liver, heart, lungs, brain, muscle and eyes). Larvae in the dogs/cats body develop into adult worm in small intestine; female worms lay eggs. Puppies can also acquire infection through placenta (transplacental way) and/or through milk (transmammary way); encysted larvae are reactivated in female dogs late in pregnancy, and can infect puppies. --> Life cycle of Toxocara cati is similar.
Life cycle: Toxocara canis.
After ingestion of contaminated meat, with encapsulated larvae, larvae are liberated by digestive fluids. Larva invade small intestine, and mature into adult worms. Adult worms populate, and female worms release newborn larvae ( about 1500 stk). Larvae migrate via circulation and find striated muscle cells, where they encapsulate. Different animals are involved, but humans are accidentally infected (by eating improperly processed meat).
Life cycle: Trichinella spiralis
1. eggs are passed in feces (female produces 20.000 eggs per day) 2. eggs embryonate (larva inside) - outside the host 3. embryonated eggs are ingested 4. larvae hatch in small intestine 5. adults in caecum (large intestine) and appendix; in heavy infected individuals can be present in more distal segments of GI - descending colon and rectum. --> Eggs require hot and humid environments to develop outside the host in the soil.
Life cycle: Trichuris trichiura
Larva developes inside eggs; hatches and continue development Embryonated eggs are the infectious stage for humans.
Morphology Nematoda: Embryonated eggs
barrel shaped with protein plugs at both ends.
Morphology: Eggs of Trichuris trichiura
1. Ascaris lumbricoides 2. Trichuris trichiura 3. Enterobius vermicularis 4. Toxocara sp. 5. Trichinella spiralis
Name 5 different species of Nematoda
Encapsulated larva in muscle cell.
Name infectious stage of Trichinella spiralis?
Rough, brownish outer layer
Name the specific characteristics of the Ascaris lumbriocoides eggs.
Nematoda eggs vary in size and shape , and are excreted with feces.
Nematoda eggs vary in ____ and ____, and are excreted with ____
Embryonated eggs
Nematoda: Infectious stage for humans
roundworms
Nematodas are ....
Parasite load and host immune response.
Pathogenesis and clinical symptoms of Toxocara sp. depend on...
1. Larvae migratory phase 2. Intestinal phase
Pathogenesis and symptoms: Ascaris lumbricoides Name the two phases in development of ascaris.
- Presence of adults in the intestin induces coarsening of mucosal folds, shortening of the crypt depth, ↓ mucus production and hyperthrophy of the intestinal muscle layers. - These problems associate with reduced food intake, gastrointestinal fulness, mild abdominal pains, abdomen rumbling , occasional vomiting, loose stools or constipation, impaired cognitive function in children.
Pathogenesis and symptoms: Ascaris lumbricoides, ascaridosis - Intestinal phase
- Antigenes released during molting process cause inflamation, peripheral eosinophilia and an antibody response (↑IgE levels). - Imobilized larvae results in formation of granulomas. - Movement of the larvae from the capillaries into the alveoli results in haemorrhage. - Oedema of the alveoli, exudate in alveolar sacks, increased mucus production results in Loeffler`s syndrome (dry, unproductive cough, high fever and bronchial asthma).
Pathogenesis and symptoms: Ascaris lumbricoides, ascaridosis - Larvae migratory phase
• Adult worms attach to the mucosa and feed on intestinal content, bacteria and possibly epithelial cells, causing minute ulcerations which may lead to mild catarrhal inflammation with diarrhea, eosinophilia and bacterial infection. • Host`s sensations and reactions to female worms depositing sticky eggs on the skin, cause intense perianal itching. • Patients scratch themselves that often cause skin damage, bleeding , very intense itching; there can be secondary bacterial infetion due to scrathing.
Pathogenesis and symptoms: Enterobius vermicularis
• Most people infected with Toxocara sp. do not have any symptoms. • People who are infected with high numbers of Toxocara sp. larvae or have repeated infections show symptoms such as fever, coughing, enlarged liver , pulmonary infiltrates , neurological signs. This form of toxocariasis is called visceral toxocariasis (VT) or visceral larvae migrans (VLM). • The larvae can also travel to the eye and cause ocular toxocariasis (OT) or ocular larvae migrans (OLM). Ocular toxocariasis occurs when Toxocara larva enters the eye and causes inflammation and scarring on the retina. OT typically occurs only in one eye and can cause irreversible vision loss.
Pathogenesis and symptoms: Toxocara sp.
Enteral/intestinal phase • After larvae hatch out, they develop into developing worms molt several times, damage epithelium depositing cuticula there. At that stage (1-2 days after infection) symptoms include diarrhea and gastric discomfort such as dyspepsia, nausea, vomiting. • At the onset of production of new born larvae, local inflammation consisting of infiltration by eosinophils, neutrophils is observed, villi become flattened and become less absorbent. • When larvae penetrate into circulation due to enteric flora, bacteremia may occur. Parenteral phase • Migrating newborn larvae randomly penetrate brain, liver, kidney, heart cells, but encapsulate only in striated muscle cells. Cell death is result of these events. Fever, muscle pain, edema (typically periorbital) and vasculitis are typical presentations of parenteral phase. Proteinuria may follow. Cardiomyopathies and CNS abnormalities are common
Pathogenesis and symptoms: Trichinella spiralis
• Trichuris trichiura buries its thin, threadlike anterior half into the intestinal mucosa and feeds on tissue secretions; it selectively uses large amounts of iron and B group vitamins. Due to tissue invasion occasional peripheral eosinophilia could be observed. Mechanical damage of the intestinal mucosa and toxicity of the parasites` wastes induce pathological changes such as hyperemia, edema, hemorrhage. • Loose stools may be present with minimal blood with the development of chronic anemia if bleeding is chronic. • Due to irritation of the rectum nocturnal stooling is quite common. • Light infection (< 100 worms) usually asymptomatic.
Pathogenesis and symptoms: Trichuris trichiura
Pathogenesis of ascaridosis is related to organ damage and host reaction to parasite proteins.
Pathogenesis of ascaridosis is related to ________ and host reaction to _______.
• Proper disposal of feces (treatment of excreta/feces with ovicides). • Good hygiene (hand washing before eating, handling food, after using bathroom). • Treatment of food before eating (wash fruits and vegetables). • Mass chemotherapy (treatment of all patients in a given population which are at risk)
Prevention: Ascaris lumbricoides
• Good hygiene (hand washing before eating, handling food, after using bathroom). • To stop the spread of pinworm and possible re-infection; people who are infected should bath every morning to help remove a large amount of the eggs on the skin; infected people should not co-bathe with others during their time of infection. • Infected people should cut fingernails regularly, and avoid biting the nails and scratching around the anus. • Changing of bed linens in the morning is a great way to prevent possible transmission of eggs in the environment and risk of reinfection; bed linens should not be shaken and carefully placed into a washer and laundered in hot water followed by a hot dryer .
Prevention: Enterobius vermicularis
• Regular your dog`s and cat`s treatment for worms, especially young animals. • Cleaning your pet's living area at least once a week. Feces should be either buried or bagged and disposed of in the trash. Wash your hands after handling pet waste. • Not allowing children to play in areas that are soiled with pet or other animal feces and covering sandboxes when not in use. • Teaching children that to eat dirt or soil is dangerous. • Hand washing with soap and warm water after playing with pets or, after outdoor activities, and before handling food.
Prevention: Toxocara sp.
• Preparation meat to safe temperatures. • Do not allow pigs or wild animals to eat scraps, or carcasses of any animals, including rats. • Freeze pork less than 15 cm thick for 20 days at 15°C to kill any worms.
Prevention: Trichinella spiralis
• Proper disposal of feces (treatment of excreta/feces with ovicides). • Good hygiene (hand washing before eating, handling food, after using bathroom). • Treatment of food before eating : wash, peel fruits and vegetables, especially that have been grown in soil that has been fertilized with manure (human feces).
Prevention: Trichuris trichiura
They are different from other nematodes ! 1. Larva; live in small intestine mucosa, and mature into adults 2. Encapsulated larva; they encapsulate in muscle cells, in very rigged collagen capsule (infectious stage). 3. Adult worms; live in small intestine mucosa, and females release newborn larvae ( NOT eggs! ).
Stages of development of Trichinella spiralis:
The muscles of Ascaris lumbricoides are responsible for the movement of the parastie, and they consists of smooth muscle cells.
The muscles of Ascaris lumbricoides are responsible for the ___ of the parastie, and they consists of _____.
dog worm
Toxocara canis is...
cat worm
Toxocara catis is...
Common name: Dog's / Cat's roundworm Disease: Toxocariosis --> Intestinal/tissue parasite
Toxocara sp. Common name: Disease:
• Antihelminthic drugs. • Symptomatic (antipruritic drugs). • Hygiene care. • Treating family members in the same household, whole group treatment in daycare centres, shools, hospitals, kindergartens.
Treatment Principles: Enterobius vermicularis
• Antihelminthic drugs (visceral toxocariasis). • Treatment of ocular toxocariasis consists of measures to prevent progressive damage to the eye. Patients with OT should see ophthalmologist for possible surgery.
Treatment Principles: Toxocara sp.
• Safe and effective prescription drugs. • Treatment should begin as soon as possible.
Treatment Principles: Trichinella spiralis
• Antihelminthic drugs. • Surgery may be used to control heavy infestation and ectopic localization of worms (infestation of biliary tract and obstruction of the intestine). • Sometimes non-antihelminthic drugs are necessary; in very massive infestation, toxins excreted by the worm causes toxicity in the patient --> patient needs intravenous infusions. • In some cases antimicrobial treatment is also needed
Treatment principles: Ascaris lumbricoides
• Antihelminthic drugs. • Anal surgery could be used for treating rectal prolapses.
Treatment principles: Trichuris trichiura
Common name: Trichina worm Disease: Trichinellosis --> Intestinal/tissue parasites
Trichinella spiralis Common name: Disease:
Trichinellosis is charaterised by 2 phases; 1. enteral/intestinal phase 2. parental phase
Trichinellosis is charaterised by ... phases. Name them.
Common name: whipworm Disease: Trichiurosis / Whipworm infection --> Intestinal parasite
Trichuris trichiura Common name: Disease:
"splincter" hemorrahges (blue hemorrhages) under the finger nails Conjunctivitis and pink eyes Periorbital edema Diarrhea and stomach cramps
Typicall symptoms of Trichinellosis
soil
What is necessary for the development of Toxocara canis/catis eggs?
Refers to cramping rectal pain.
What is tenesmus?
The life cycle of Trichuris trichiura does not include tissue migratory phase.
What is the difference in the life cycle of Ascaris lumbricoides and Trichuris trichiura?
Embryonated eggs
What is the infective stage of Toxocara canis/catis for dogs, small mammils (e.g rabbits) and humans?
Trichinella spiralis adult females release newborn larva, NOT eggs!
Whatt differs Trichinella spiralis from other nematodes?
1. Toxocara canis 2. Toxocara cati
Which Toxocara sp. cause toxocariosis?
1. Toxocara sp. 2. Ascaris lumbricoides
Which parasite spp. have tube shaped organs?
Trichinella spiralis, males.
Which sp. has claspers? And does female, male of both have them?
1. eggs 2. embryonated eggs 3. adult worm
Which three morphological forms do Nematoda exist in?
