Loiasis

Introduction 

Loiasis is a chronic filarial disease caused by infection with Loa loa (African eye worm) 

-the disease is found in the rainforests of West and Central Africa

-it is transmitted by the bite of the deer fly or mango fly called Chrysops 

-Infected larvae deposited by the bite of the deer fly crawl into the skin and develop into adults which migrate subcutaneously. Females produce microfilariae, which enter the blood 

-it is the adult worm rather than the microfilariae which produce clinical manifestations 

Symptoms & Signs 

Many infected persons are asymptomatic 

Skin: the characteristic finding of loiasis is the Calabar swelling, localized subcutaneous area of angioedema, erythema, pain and pruritis developing on the extremities due to migration of adult worms through subcutaneous tissues 

Eye: Adult worms crawling across the conjunctiva of the eye, scary but no loss of vision 

Blood: Peripheral eosinophilia, leukocytosis and elevated IgE levels 

Diagnosis 

Detection of microfilariae in the blood: peak circulation between 10 A.M and 2:00 P.M; so a daytime blood smear should be obtained 

Isolation of the adult worm from the eye or skin biopsy 

Treatment 

The treatment of choice is diethylcarbamazine

Worms in the eyes: surgical excision  


Onchocerciasis

Introduction

Onchocerciasis is a chronic parasitic disease caused by filarial nematode Onchocerca volvulus 

-it is transmitted by female blackflies near free-flowing rivers and streams 

-Most cases are in tropical Africa and Central America 

-Larvae deposited by the blackfly mature into adult worms in subcutaneous tissue and form skin nodules. Females produce microfilariae which migrate to the eyes and cause serious eye disorders. 

Symptoms & Signs 

Onchocerciasis is characterized by dermal, ocular and lymphatic manifestations

Dermal: Subcutaneous nodules over bony prominences (onchocercomata), intensely pruritic papular rash, skin atrophy, scaly dermatitis feeling like ‘lizard skin’ or ‘leopard skin’, loose pelvic skin described as ‘hanging groin’ 

Ocular: most serious manifestations of onchocerciasis; photophobia,   conjunctivitis, keratitis, uveitis, retinochoroiditis, iridocyclitis, optic atrophy, glaucoma, and blindness (river blindness) 

Lymphatic: Inguinal and femoral lymphadenopathy

Diagnosis 

Identification of microfilariae: in skin snips, in nodule biopsy or in the urine, but not in blood 

Eye: Slit-lamp examination revealing microfilariae in the eye 

Mazzotti test: Exacerbation of skin rash and pruritus after administration of diethylcarbamazine 

Other tests: PCR

Treatment 

-Ivermectin (drug of choice) kills microfilariae, not adult worms 

-Suramin kills adult worms 

Other agents: Moxidectin, doxycycline 


Lymphatic filariasis

Filarial infections are grouped into 3 categories of disease based on the location of disease: lymphatic, cutaneous, and body cavity

-Lymphatic filariasis is caused by three filarial nematodes: Wuchereria bancrofti (most common), Brugia malayi, and Brugia timori

-it is found mostly in South Asia and Africa 

-Humans are infected by the bites of infected mosquitoes

-Larvae move to the lymphatics and lymph nodes, where they mature into adult worms, which produce large numbers of microfilariae

Symptoms & Signs 

-Classical lesion: Lymphadenitis in the femoral area as a red, enlarged and tender lump spreading centrifugally down the lymphatic channels of the leg (centripetal spread in bacterial lymphangitis) 

-recurrent bouts of “filarial fevers” lasting 2 to 3 weeks

-High fever, transient local edema, lymphatic inflammation – Acute adenolymphangitis (ADL)

-Elephantiasis, thickening of the subcutaneous tissues, brawny edema

-Conjunctivitis, headache, photophobia, vertigo, scrotal pain, orchitis, epididymitis, elephantiasis of breasts, vulva 

Diagnosis 

Detection of microfilariae in peripheral blood, hydrocele fluid; Periodicity determines the best time for blood collection;  blood samples for Wuchereria and Brugia are only positive if drawn at night

Serology: Antigen assays, PCR 

High-frequency ultrasound: can show motile adult worms 

Treatment 

Effective agents: Diethylcarbamazine (Drug of choice), Albendazole, Doxycycline, ivermectin 

Diethylcarbamazine can cause hypersensitivity reaction with antigen liberation from dead microfilariae 


Anisakiasis

Introduction 

-Anisakiasis is a gastrointestinal parasitic disease caused by the larvae of the nematode, Anisakis simplex

-Transmission is due to ingestion of infective larvae from saltwater fish or squid that humans eat raw or undercooked sushi or sashimi or ceviche 

-it is most common in Japan

-Adult worms live in whales and dolphins 

Symptoms & Signs 

Acute infection can resemble appendicitis, and chronic infection can resemble gastrointestinal cancer

Severe epigastric or abdominal pain, nausea, vomiting, urticaria, angioedema, anaphylaxis 

Diagnosis 

Clinical: Acute abdomen after ingestion of raw fish 

Endoscopy: Direct visualization of larvae 

Biopsy: Eosinophilic granuloma with embedded larvae 

Treatment 

-No medical treatment is available 

-Surgical or endoscopic removal by extraction of the larvae 


Toxocariasis

Introduction 

Toxocariasis is due to human infection with Toxocara cati (an intestinal parasite of cats) or Toxocara canis (an intestinal parasite of dogs)

-Most commonly encountered among children 1 to 6 years of age 

-Transmission to humans by ingestion of eggs in soil, particularly in those with a history of pica

-Invading larvae migrate in human tissues and cannot mature to adult worms 

Symptoms & Signs 

A. Visceral larva migrans: it is due to disseminated systemic infection; It mostly affects the liver, lungs, heart, skeletal muscle and brain; eosinophilic granulomas surround parasite larvae

Pulmonary: Cough, wheezing, pulmonary infiltrates 

Abdominal: The most commonly affected organ is the liver; hepatomegaly, splenomegaly 

Heart: Myocarditis, pericarditis, cardiac arrhythmia

decreased visual acuity 

B. Ocular Larva Migrans

Unilateral posterior or peripheral inflammatory eye mass, granuloma formation, blurred vision, red eye, a whitish pupil due to loss of red reflex (leukocoria), unilateral strabismus

Diagnosis 

Labs: Leukocytosis with marked eosinophilia, anemia, and elevated liver function tests

Serology: ELISA, Western blot 

Liver biopsy: Demonstration of larva 

Treatment 

-It is usually a benign and self-limited illness 

-Severe disease: Albendazole, mebendazole, corticosteroids 


ANGIOSTRONGYLIASIS

Introduction 

Angiostrongyliasis is a parasitic disease caused by Angiostrongylus cantonensis and Angiostrongylus costaricensis

-They possess distinctive, coiled pattern due to their uterine tubes 

-Angiostrongylus cantonensis, the rat lungworm, is the most common cause of human eosinophilic meningitis

-it is transmitted between rats and mollusks (such as slugs or snails) in its natural life cycle

-Most cases of infection are diagnosed in Southeast Asia and the Pacific Basin,

-Humans acquire the Infection by ingesting raw or undercooked infected snails or slugs or foods contaminated by the slime of infected snails or slugs 

Symptoms & Signs 

Meningeal Angiostrongyliasis: Eosinophilic meningitis caused by Angiostrongylus cantonensis; headaches,nausea, vomiting, neck stiffness, cranial and extraocular nerve palsies, seizures, paralysis, lethargy 

Abdominal Angiostrongyliasis: caused by Angiostrongylus costaricensis; mimics appendicitis; nausea, vomiting, fever, abdominal pain  

Diagnosis 

Diagnosis is based on epidemiologic history, clinical features and labs 

Labs: Eosinophilia 

Epidemiologic history: History of travel to endemic regions, of eating snails and slugs 

Treatment 

There is no specific treatment for Angiostrongyliasis 


Trichinosis

Introduction

-Trichinosis is a parasitic disease caused by Trichinella spiralis and related species 

-it is the most common parasite of skeletal muscle

-it is spread by ingestion of undercooked meat, most commonly pork 

-Life cycle: Humans ingest undercooked meat containing encysted larvae, which mature into adults in the intestine. Female worms release larvae which enter blood and migrate to skeletal muscle or other organs, where they encyst

Symptoms & Signs 

-Most infections are asymptomatic

-Infection can be divided into two phases: 

Intestinal phase: fever, headache, chills, abdominal pain, nausea, vomiting, and diarrhea 

Muscular phase: Fever, facial edema, eyelid or periorbital edema, myalgia, weakness, maculopapular exanthem, subungual bleeding, conjunctivitis and subconjunctival hemorrhages, retinal hemorrhages, dry cough, dyspnea, dysphagia, painful movement of the eye muscles, involuntary movements, myocarditis, thromboembolic disease, and encephalitis

Diagnosis 

Labs: Eosinophilic leukocytosis, elevated serum muscle enzymes (creatine kinase, lactate dehydrogenase, aspartate aminotransferase), normal ESR 

-ELISA, serologic tests, muscle biopsy showing encysted larvae 

Treatment 

Albendazole is the drug of choice for trichinosis; Mebendazole 


Dracunculiasis

Introduction

-Dracunculiasis is caused by the nematode roundworm called Dracunculus medinensis, or Guinea worm.

-The Guinea worm is the largest tissue parasite of humans

-the disease is on the verge of being eradicated

-Humans are infected when they ingest water containing infective larvae from crustaceans like Cyclops 

Symptoms & Signs 

-Fever, periorbital edema, wheezing, urticaria, nausea, vomiting, diarrhea, dyspnea, blister formation, rupture of the blister with the worm emerging as a whitish filament in the center of a painful ulcer 

-Immersion in water relieves the pain

Diagnosis 

-identification of a typical skin ulcer with a protruding worm

Treatment 

-No drug is effective in treating dracunculiasis 

-Wet compresses, occlusive dressings

-Definitive treatment: Gradual extraction of the worm by sequentially rolling it over a small stick


Enterobiasis

Introduction

Enterobiasis is caused by a small intestinal parasite called Enterobius vermicularis 

-it is the most common intestinal nematode in the United States with highest prevalence in school-aged children 

-Transmission is by the fecal-oral route 

-Gravid female worms migrate nocturnally from the cecum to the perianal region to deposit large numbers of eggs 

Symptoms & Signs 

-Most individuals with pinworm infection are asymptomatic

-The most common symptom is perianal pruritis, which is most severe at night 

-Enuresis, restlessness, insomnia, perianal scratching, cellulitis, impetigo 

Diagnosis 

-Diagnosis can be made by “Scotch Tape” technique: Apply adhesive cellulose tape to the anal region and examine under thee microscope for ova 

-Eggs are football shaped with a thin outer shell

Treatment 

-The treatment of choice is albendazole

-Other effective agents: Mebendazole, Pyrantel pamoate 

-All family members may need treatment


Strongyloidiasis

Introduction

Strongyloidiasis is caused by S. stercoralis, a Nematode parasite

-Humans are the only hosts: It’s life cycle differs from that of most other helminths in that its entire life cycle may be completed within the human host 

-it is acquired by direct contact of skin with larvae or by ingestion of food contaminated with larvae 

-Life cycle: Filariform larvae (infectious) penetrate the skin, enter the blood, migrate to the lungs, move into alveoli, ascend up the trachea, swallowed, enter the colon, produce eggs which form rhabditiform larvae(non-infectious), which are passed in the feces

Autoinfection: Rhabditiform larvae can transform into filariform larvae in human host resulting in seeding of the perianal area with parasites; immunosuppression enhances risk of autoinfection  

-Of the common helminths, only  strongyloides may persist in the human host indefinitely

Symptoms & Signs 

Skin: A serpiginous urticarial rash in response to the migrating larvae; Generalized petechiae and reticular purpura of thee arms, legs, and abdomen with a characteristic thumbprint periumbilical distribution

Thumbprint sign: A unique pattern of periumbilical purpura resembling multiple thumbprints 

Larval currens: External autoinfection producing raised, red, serpiginous lesions over the buttocks, abdomen and back 

Pulmonary and intestinal manifestations can be like hookworm and Ascaris infections

Lungs: Cough, fever, eosinophilia

GI: Peptic-ulcer like pain, nausea, vomiting, diarrhea, constipation, malabsorption, weight loss

Hyperinfection: The most severe complication of Strongyloidiasis is hyperinfection

Immunodeficiency due to HIV,  human T-lymphotropic virus-1 (HTLV-1), has a stronger association with Strongyloides hyperinfection

Lung:  the most common extraintestinal manifestation of hyperinfection syndrome is pulmonary disease; Cough, wheezing, dyspnea, hemoptysis 

GI: Abdominal pain, diarrhea, ileus 

Other organs: liver, urinary tract, brain 

Diagnosis 

Larvae: Diagnosis depends on finding larvae, rather than eggs, in the stool

Serology: Serology via ELISA 

Labs: Eosinophilia 

Treatment 

Effective agents: Ivermectin (Drug of choice), Albendazole 


Hookworm disease

Introduction 

-Hookworm disease is caused by the Infection with the hookworms Ancylostoma duodenale and Necator americanus

-Adult hookworm possess two pairs of teeth in the buccal capsule 

-Male hookworm has a characteristic copulatory bursa 

-Infectious larvae present in soil penetrate the skin, enter bloodstream, reach the lungs, invade the alveoli, ascend the airways, are swallowed, reach the intestines, mature into adult worms, attach to the mucosa, and suck blood

Symptoms & Signs 

Most infected persons are asymptomatic

Skin: Initial skin infection by the larval penetration may cause a pruritic maculopapular rash (ground itch) and serpiginous tracks of subcutaneous migration (cutaneous larva migrans) 

Lungs: Pulmonary symptoms during larval migration through the lungs include fever, cough and wheezing 

Gastrointestinal: Abdominal pain, anorexia, nausea, vomiting, diarrhea, ascites 

Hematological: Hypochromic microcytic anemia, eosinophilia, hypoalbuminemia

Diagnosis 

Diagnosis is based on the identification of characteristic eggs in feces

Adult worms: Ancylostoma duodenale possesses four sharp tooth-like structures, whereas N americanus has dorsal and ventral cutting plates;  the males have a unique fan-shaped copulatory bursa

Labs: Microcytic anemia, occult blood in the stool, hypoalbuminemia, eosinophilia 

Treatment 

Effective agents: Albendazole, Mebendazole, Pyrantel pamoate 


Trichuriasis

Introduction

Trichuriasis is caused by whipworm Trichuris trichiura, a nematode parasite of the large intestine 

-Humans acquire the infection by eating foods contaminated with eggs. In the small intestine, the larvae hatch, mature and migrate to the colon 

– Unlike Ascaris, Trichuris does not have a migratory lung phase

-The adult worm has a ‘buggy whip’ appearance, hence the name whipworm 

Symptoms & Signs 

-Most infected persons are asymptomatic

-Abdominal pain, distention, cramps, nausea, vomiting, diarrhea, rectal prolapse, iron-deficiency anemia

Diagnosis 

-Diagnosis is based on finding the barrel-shaped or lemon-shaped eggs with a plug at each end 

-Adult worms may be seen in the prolapsed rectum

Treatment 

Effective agents: Albendazole, mebendazole, ivermectin, and oxantel pamoate


AscariASIS

Introduction 

Ascariasis is caused by Ascaris lumbricoides, the most common intestinal helminth and the largest intestinal nematode 

-it can reach up to 40 cm in length 

-it is particularly common in the Far East, India, and South Africa

-it is seen following ingestion of foods or vegetables fertilized by ‘night soil’ (human feces) or playing in the infected soil 

Life cycle: Humans ingest eggs, which form larvae in the gut, where after hatching, they migrate through the blood to the lungs, where they enter the alveoli,ascend the bronchial tree, and are swallowed. In the gut, they become adults and lay eggs that are passed in the feces. Adult worms can migrate to the appendix, bile duct or pancreatic duct, causing obstruction and inflammation 

Symptoms & Signs 

Most persons with Ascaris infection are asymptomatic

Lungs: migrating worms can cause fever, cough, chest pain, dyspnea, eosinophilia, or  “Löffler syndrome”

Gastrointestinal: Abdominal pain, obstruction, volvulus, perforation, appendicitis 

Biliary: Cholangitis, cholecystitis, obstructive jaundice, pancreatitis 

Diagnosis 

Adult worms: can be seen emerging from the mouth, nose, or anus or in stools 

Chest X ray: migratory pulmonary infiltrates 

ERCP: linear filling defects within the bile ducts 

Eggs in stool: egg is oval with an irregular surface with a typical “scalloped” edge 

Treatment 

Effective agents: Albendazole, mebendazole, ivermectin, or pyrantel pamoate 


Taenia solium infection

Introduction

Pork taeniasis is a disease caused by the tapeworm Taenia solium 

– it is particularly common in South and Southeast Asia, Africa, Latin America, and Eastern Europe

T solium inhabits the human jejunum 

-it possesses a rostellum armed with sucking disks and two rows of hooklets

-It can cause two distinct forms of infection in humans: adult tapeworms in the intestine (Taeniasis) or larval forms in the tissues (cysticercosis). 

-Taeniasis is acquired by eating raw or undercooked pork. Cysticercosis is acquired only by ingesting eggs in fecally contaminated food or water.

-Significant difference from beef tapeworm: Tissue cysticerci develop in swine and humans

Symptoms & Signs 

Taeniasis: Tapeworm in gut causes little damage. 

Cysticercosis: Cysticerci encyst in various human tissues, including skin, liver, muscle, heart, kidney,eye and brain 

Neurocysticercosis: fever, nausea, vomiting,headache, mental disturbances,  focal neurologic abnormalities, personality changes, visual disturbances, seizures, increased intracranial pressure, and hydrocephalus  

Diagnosis 

Adult worm is diagnosed from proglottids or eggs in stool 

Cysticercosis is diagnosed by imaging, biopsy, or serology 

Neuroimaging: Mass lesions; a scolex within a cystic lesion 

Treatment 

Intestinal worms: Praziquantel 

Cerebral cysticercosis: Praziquantel, albendazole,antiseizure medications 

Obstructive hydrocephalus: removal of the cysticercus via endoscopic surgery 


Taenia saginata

Introduction 

Beef Taeniasis is a parasitic infection by beef tapeworm called Taenia Saginata 

-it is prevalent in Latin America, Eastern Europe, Africa and Russia 

-Humans become infected when they eat raw or undercooked beef (“measly beef”) 

-Taenia saginata inhabits the human jejunum, grow to a maximum length of 10 m

-After ingestion, larvae attach to the gut wall and become adult worms with gravid proglottids. 

-Terminal proglottids pass in the feces and are eaten by cattle

Symptoms & Signs 

-Most persons infected with beef tapeworm are asymptomatic 

-Nausea, vomiting, headache, pruritus, abdominal pain, diarrhea, constipation and intestinal obstruction 

– In contrast to Taenia solium, cysticercosis does not occur

Diagnosis 

-Adhesive cellophane tape technique can detect eggs

-Gravid proglottids visible in stool or appear in the underclothing or bedsheets of infected patients

-Adult worm examination: Scolex has four suckers but no hooks

Treatment 

The drug of choice is praziquantel


Paragonimiasis

Introduction

Paragonimiasis is primarily a lung disease caused by the fluke paragonimus 

-it is prevalent in Southeast Asia, Africa, and South and Central America. 

-Human infection follows consumption of undercooked or raw crustaceans such as shellfish, crayfish and crabs 

-After consumption, larvae enter the gut and later burrow through diaphragm into lung parenchyma 

Symptoms & Signs 

Lung disease: Fever, cough, chest pain, hemoptysis with rusty, blood-tinged sputum containing Charcot-Leyden crystals, dyspnea, bronchitis, bronchiectasis, lung abscess,  urticaria, and eosinophilia

-Individuals may be mistaken for having tuberculosis 

Extrapulmonary involvement: Blindness, epididymitis, testicular inflammation, and seizures 

Diagnosis 

Diagnosis is made by finding the characteristic eggs in sputum, urine, or stool, or by identifying worms in biopsied tissues 

-Serologic tests help in making diagnosis and monitoring treatment response

Chest X-ray: small segmental infiltrates, round nodules, cystic rings with a crescent corona, fibrosis, abscesses and calcifications

Skull imaging in CNS disease: clusters of calcified cysts, ring-enhancing lesions

Treatment

The treatment of choice is praziquantel or triclabendazole.


clonorchiasis

Introduction

Clonorchiasis, due to Clonorchis sinensis and opisthorchiasis, due to Opisthorchis, occur in Southeast Asia and Eastern Europe

-Clonorchiasis and opisthorchiasis are clinically indistinguishable. 

-Humans are infected by eating raw, pickled, frozen, dried, salted, and smoked fish containing the encysted larvae (metacercariae)

-After excystation in the duodenum, immature flukes invade the biliary ducts and differentiate into adults 

Symptoms & Signs 

Most infections are asymptomatic

Fever, chills, abdominal pain, urticaria, eosinophilia, hepatomegaly, cholecystitis, cholangitis, pancreatitis, liver abscess, jaundice 

-Chronic infection is associated with increased risk of cholangiocarcinoma 

Diagnosis 

Definitive diagnosis is made by finding the typical brownish, small, operculated eggs in the stool 

-The eggs of Opisthorchis are indistinguishable from those of Clonorchis

– Imaging studies: Biliary tract dilatations with filling defects due to flukes 

Treatment 

The drug of choice is praziquantel

Other effective agent: Albendazole 


Fascioliasis

Fascioliasis is an infectious disease caused by Fasciola hepatica, the sheep liver fluke

-it is prevalent in sheep-raising areas 

-it results from ingestion of encysted metacercariae on aquatic vegetables or water plants such as watercress 

Symptoms & Signs 

Fever, malaise, abdominal pain, weight loss, urticaria, marked eosinophilia, leukocytosis, tender hepatomegaly, cholangitis 

CT and other imaging studies show hypodense migratory lesions of the liver. 

Diagnosis 

Definitive diagnosis: Identification of characteristic eggs in stool, duodenal or biliary aspirates 

CT/imaging studies: hypodense nodules in the liver; tracts or tunnels (representing the migration of larvae)  

Treatment 

The treatment of choice is triclabendazole

Other effective agents: Bithionol, emetine, dehydroemetine, nitazoxanide 

-it does not respond well to praziquantel


schistosomiasis

Introduction

Schistosomiasis is a disease caused by five species of the parasitic genus Schistosoma

Humans are infected with schistosomes after contact with freshwater containing cercariae released by infected snails

Symptoms & Signs 

Schistosomiasis has three stages of clinical symptomatology corresponding to the life cycle of the parasite in the human host 

Stage 1: Cercarial Dermatitis (“Swimmer’s Itch”)

The first stage is characterized by a very itchy maculopapular rash which occurs at the time of penetration 

Stage 2: Acute schistosomiasis (Katayama syndrome)

The second stage is characterized by a serum sickness like syndrome with elevated levels of immunoglobulin E and eosinophilia. 

-Fever,chills, myalgias, headache, cough, sweating, lymphadenopathy, hepatosplenomegaly, diarrhea, abdominal pain, and pulmonary infiltrates 

Stage 3: Chronic schistosomiasis

The third, chronic stage is characterized by granulomatous reactions to egg deposition in the intestine, liver, bladder, lung and CNS 

-Chronic diarrhea, abdominal pain, blood loss, portal hypertension, splenomegaly, bleeding esophageal varices, pulmonary hypertension, right-sided congestive heart failure, transverse myelitis, hematuria, bladder obstruction, hydroureter, and hydronephrosis

Diagnosis 

Diagnostic methods: Detection of schistosome eggs in stool or urine, ELISA, biopsy of the rectum, colon, liver or bladder 

-Eggs of Schistosoma haematobium possess a characteristic terminal spine

Treatment 

The drug of choice for treatment of schistosomiasis is praziquantel

Chemoprophylaxis with artemether has shown efficacy 


Trichomoniasis

Introduction 

Trichomoniasis is a disease caused by the flagellated protozoan parasite Trichomonas vaginalis which manifests as vaginitis in women and nongonococcal urethritis in men 

-It is the most prevalent nonviral sexually transmitted disease worldwide

-it is most often transmitted during sexual contact 

-risk factors include prostitution, multiple sexual partners 

-Females are more often affected and symptomatic than males

Symptoms & Signs 

Women: Vulvovaginal discomfort, pruritis, dysuria, dyspareunia, copious vaginal discharge, no foul smelling, frothy, yellow or green colored discharge pooled in the posterior vaginal fornix, punctuate hemorrhages over vaginal walls, A red, granular, friable endocervix (Strawberry cervix); symptoms worsen during menses and pregnancy; increased risk of preterm birth 

Men: Most infected men are asymptomatic; dysuria, dyspareunia, and scant urethral discharge 

Diagnosis 

T. vaginalis can be recovered from the urethra of both males and females 

-it is detectable in males after prostatic massage

-Diagnostic methods: Wet-mount microscopy, culture, molecular tests (Nucleic acid amplification tests) 

-Trichomonas vaginalsis has characteristic twitching movements, it contains 4 frontal and 1 larger back flagella, which is embedded into an undulating membrane

Treatment

All infected persons should be treated, even if asymptomatic to prevent reinfection and to limit the spread 

Effective agents: Metronidazole, tinidazole 


giardiasis

Introduction

Giardia lamblia is a flagellated protozoan parasite infecting the small intestine and biliary tree

-it is endemic around the world 

-risk factors: drinking contaminated water, hypochlorhydria, immunocompromise, unprotected sex, exposure to infected day care centers, camping sites, swimming areas

-After ingestion, cysts excyst in the small intestine and release flagellated trophozoites in the proximal small intestine. Both cysts and trophozoites are excreted in feces.  

-Chlorination does not destroy cysts; they can be eradicated from water by either boiling or filtration 

-In the United States and Europe, Giardiasis is the most common intestinal protozoan pathogen

Symptoms & Signs 

-the manifestations of infection range from asymptomatic carriage (most common) to chronic diarrhea and malabsorption 

Acute giardiasis: nausea, vomiting, abdominal pain, bloating, belching, flatus, diarrhea; The stool is greasy in appearance, foul-smelling, and floats. It is usually devoid of blood or mucus. 

Chronic giardiasis: can be episodic or continual; diarrhea, increased flatulence, sulfurous belching, weight loss, malabsorption,vitamin deficiencies,  growth retardation, dehydration; stools are foul smelling, greasy or frothy, without blood, pus or mucus. 

Diagnosis

-It can be diagnosed by detection of parasite antigens in the feces, by identification of cysts or trophozoites in the feces or by nucleic acid amplification tests 

-Cysts are oval and contain four nuclei; Trophozoites are pear-shaped and contain 

two nuclei and four pairs (8) of flagella; they have ventral sucking disks 

Treatment 

Effective agents: Metronidazole, tinidazole, quinacrine, furazolidone, nitazoxanide and paromomycin 

-Unlike metronidazole, tinidazole, furazolidone is safe in pregnancy 


Cyclosporiasis

Introduction

Cyclosporiasis is a disease caused by protozoan Cyclospora cayetanensis 

-Cyclospora can be transmitted through water or foods like raspberries, basil, and mesclun 

Symptoms & Signs 

-It can be self-limited or can persist for more than a month

-abdominal cramps, bloating,burping, flatulence, nausea, vomiting, watery, explosive diarrhea, fatigue, anorexia, and myalgia 

Diagnosis 

Diagnosis is made by detection of spherical oocysts in stool stained with acid-fast stains 

-The oocyst formula is  O.2.2 because one oocyst contains two sporocysts and each sporocyst contains two sporozoites 

Treatment 

Treatment is trimethoprim-sulfamethoxazole for 7 days