More than 300,000 persons in the United States are infected; more common in immigrants from Mexico and Central or South America, and in those who have visited endemic areas

Transmission is most often vector-borne (triatomines), congenital, or via blood transfusion or organ transplantation

Blood donations are screened for the disease; donors whose blood tests positive cannot donate again

Typically four to eight weeks after infection; usually asymptomatic; nonspecific febrile illness, swelling around the bite site

20% to 30% of persons develop symptoms, including cardiac and gastrointestinal manifestations; increased risk of stroke

Usually asymptomatic; anemia, hepatosplenomegaly, low Apgar scores, low birth weight, thrombocytopenia; rarely, meningoencephalitis, myocarditis

Direct microscopy of peripheral or umbilical cord blood to detect parasites; polymerase chain reaction testing also available

No or few parasites in the blood; multiple serologic tests with varying sensitivity and specificity are available; at least two positive results on serologic tests required for diagnosis

Infection is lifelong without treatment; persons with acute or congenital infection should be treated, as should immunocompromised persons with reactivated infection; pregnant women and persons with severe renal or hepatic insufficiency should not be treated; for chronic disease, treatment is recommended in persons younger than 18 years and in those younger than 50 years who do not have severe cardiomyopathy; all others should be treated on a case-by-case basis

Treatment options include nifurtimox or benznidazole (available through the Centers for Disease Control and Prevention)

More common in children, pet owners, and persons with geophagia; estimated serologic prevalence in the United States is 13.9%

Transmission occurs by ingesting Toxocara eggs in soil contaminated with feces from an infected dog or cat, or by eating undercooked meat from an infected animal

Usually asymptomatic

Abdominal pain, anemia, anorexia, coughing, eosinophilia, fatigue, fever, hepatomegaly, hypergammaglobulinemia, meningoencephalitis, wheezing

Peripheral granuloma with traction bands, posterior pole granuloma, strabismus, subretinal granulomatous mass, unilateral vision loss

More common in immigrants from Central and South America, but can occur in persons who have not traveled outside the United States

Transmission occurs by ingesting eggs excreted in the feces of a tapeworm carrier; transmission does not occur by eating undercooked infected pork

May be asymptomatic; seizures are the most common manifestation; chronic meningitis, cranial nerve abnormalities, headache, and intracranial hypertension or hydrocephalus may also occur

Muscular cysticerci are usually asymptomatic; ocular cysticerci may cause blurry vision

Combination of serologic testing and computed tomography or magnetic resonance imaging; number, location, and viability of cysticerci should be determined

Symptom control is priority; decision to treat with anthelminthic drugs should be individualized; coadministration of corticosteroids may decrease inflammatory response

Persons with cysticercosis and close contacts should be screened for tapeworm infection

More than 60 million persons in the United States are infected; symptomatic infection is more common in immunocompromised persons and in children with congenital infection

Transmission is most often foodborne, zoonotic (from cat feces), or congenital

Spiramycin should be used before amniocentesis to assess fetal infection in pregnant women who acquire infection in the first or early second trimester

Pyrimethamine (Daraprim), sulfadiazine, and leucovorin should be used in infants with congenital infection, in pregnant women who acquire infection in the late second or third trimester or who acquire the infection earlier and transmit it to the fetus, in immunosuppressed patients, and in immunocompetent patients with severe symptoms