Toxoplasmosis, Emergency Medicine

Basics

Description

Toxoplasma gondii " ”intracellular protozoan parasite:
- 3 forms:
  - Tachyzoite: Asexual invasive form
  - Tissue cyst: Persists in tissues of infected hosts during chronic phase
  - Oocyst: Contains sporozoites and produced during sexual cycle in cat intestine
Transmission:
- Ingesting tissue cysts or oocysts:
  - Ingesting undercooked meat
  - Vegetables contaminated with oocysts
  - Contact with cat feces, through cat or soil
- Transplacental
- Blood product
- Organ transplantation

Etiology

70% of adults seropositive
Asymptomatic in most immunocompetent patients
Worldwide; cats are the common host
Incubation is 7 days with a range of 4 " “21 days

Diagnosis

Signs and Symptoms

4 types of infection ‚
Immunocompromised Host ‚

CNS:
- Subacute presentation (90%)
- Encephalitis
- Headache
- Altered mental status
- Fever
- Seizures
- Cranial nerve palsies
- Spinal cord lesions
- Cerebellar signs
- Meningitis-like symptoms
- Movement disorders
- Neuropsychological symptoms:
  - Psychosis
  - Paranoia
  - Dementia
  - Anxiety
  - Agitation
Pulmonary:
- Pneumonitis
- Prolonged febrile illness
- Nonproductive cough
- Dyspnea

Immunocompetent Host ‚

90% are asymptomatic
Lymphadenopathy, usually cervical
Fever
Malaise
Mononucleosis-like syndrome with macular rash and hepatosplenomegaly
Headache
Sore throat
Night sweats
Maculopapular rash
Urticaria
Usually, self-limited process; resolves in 2 " “12 mo
Rarely presents with pneumonitis or encephalitis

Ocular Toxoplasmosis ‚

Blurred vision
Scotoma
Pain
Photophobia
Retina:
- Small clusters of yellow-white cotton-like patches
- Chorioretinitis; affects 85% of young adults with untreated congenital infection

Congenital Toxoplasmosis ‚

Results from an asymptomatic acute infection during pregnancy
1st trimester:
- Spontaneous abortion
- Stillbirth
- Severe disease up to 25% of the time
2nd or 3rd trimester:
- 50 " “60% chance of acquiring congenital toxoplasmosis
- 2% fatal
Most asymptomatic at birth
Delayed onset. 70 " “90% asymptomatic at birth:
- CNS disease
- Ocular disease (blindness months to years later)
- Lymphadenopathy
- Hepatosplenomegaly
- At birth, may have maculopapular rash, lymphadenopathy, hepatomegaly, splenomegaly, jaundice, thrombocytopenia

Essential Workup

Diagnose via:
- Isolation of organism:
  - Blood
  - CSF for encephalitis
  - Bronchoalveolar lavage for pneumonitis
  - Amniotic fluid
  - Aqueous humor
- Detection of tachyzoites in tissues or body fluids
- Demonstrating characteristic lymph node pathology
Thorough ocular exam:
- Retinal exam
- Visual acuity

Diagnosis Tests & Interpretation

Lab

LDH >600/UL associated with toxoplasmosis
CBC:
- Atypical lymphocytes
ABG/pulse oximetry for pulmonary symptoms
IgG antibodies:
- High number of false-positive and false-negative results
- Common tests:
  - Sabin " “Feldman dye test
  - Indirect fluorescent antibody
  - Agglutination
  - Enzyme-linked immunosorbent assay test
Immunoglobulin M (IgM) antibodies:
- Absence excludes diagnosis in immunocompetent host
- Reference labs may be helpful, such as Remington (650-853-4828 Toxoplasma Serology Laboratory) (www.pamf.org/serology)
- Diagnoses acute infection
- Appear in 5 days
- Disappear in weeks to months
- Neonatal testing differentiates from maternal infection

Imaging

Chest radiograph for pulmonary symptoms:
- Pneumonitis associated with reticulonodular pattern
CT head with contrast:
- Multiple bilateral hypodense ring-enhancing lesions
MRI brain:
- High signal abnormalities on T2-weighted images
Serial fetal ultrasonography can be useful in exploring congenital infection of the CNS or other signs.

Diagnostic Procedures/Surgery
Brain biopsy for encephalitis " ”definitive diagnosis ‚

Differential Diagnosis

Cryptococcal meningitis
CNS lymphoma
Pneumocystis carinii pneumonia
Cytomegalovirus retinitis
Mycobacterial infection

Treatment

Initial Stabilization/Therapy

Treat seizures in standard fashion with diazepam and phenytoin.
Initiate oxygen if hypoxia due to pneumonitis.

Ed Treatment/Procedures

Immunocompetent
Toxoplasmic lymphadenitis: ‚

No antibiotics unless symptoms severe and persistent
Treat symptomatic patients with pyrimethamine and folinic acid plus sulfadiazine or clindamycin for 3 " “4 wk
Clindamycin may be a useful alternative to sulfadiazine because of the side effects of the latter and in those who are hypersensitive to sulfa
Pyrimethamine and sulfadiazine (Eon Labs 800-526-0225) is available as a combination drug.
Corticosteroids may be useful for ocular complications and CNS disease.
Reassess to determine if longer therapy needed.

Immunocompromised

Confirmed acute infection by serology/symptoms:
- Treat with pyrimethamine and folinic acid + sulfadiazine or clindamycin for 4 " “6 wk after resolution of symptoms.
- Alternative medications:
  - Trimethoprim " “sulfamethoxazole
  - Pyrimethamine and folinic acid + dapsone
CNS symptoms + a lesion on CT or MRI:
- Treat empirically with pyrimethamine and folinic acid + sulfadiazine or clindamycin.
- Brain biopsy or CSF to confirm diagnosis
- Administer anticonvulsants only if confirmed prior seizures:
  - Poorer outcome for patients on anticonvulsants
Chronic asymptomatic infection:
- No therapy required
- Prophylaxis options for toxoplasmosis in AIDS and immunosuppressed patients:
  - Trimethoprim " “sulfamethoxazole; lifelong prophylaxis should be considered in HIV patients after consultation.
  - Pyrimethamine (75 mg/wk) and dapsone (200 mg/wk) and leucovorin 10 " “25 mg with each dose pyrimethamine

Ocular

Treat with pyrimethamine and sulfadiazine for 1 mo.
May add clindamycin
Administer systemic steroids with macular or optic nerve involvement.

Acute Acquired Infection in Pregnancy

Initially treat with spiramycin pending confirmatory tests and consultation (FDA, Division of Special Pathograns and Transplant Drug Products 301-796-1600 or CDC at 404-718-4745).
After the infection is documented, initiate treatment after consultation:
- Spiramycin in the 1st 17 wk
- Pyrimethamine and sulfadiazine after 17 wk
Spiramycin may reduce congenital transmission but does not treat fetus if infection is in placenta; maternal therapy may decrease severity of congenital disease.
Treat congenital infection with sulfadiazine, pyrimethamine, and folinic acid for 12 mo.
Prevention of exposure in seronegative pregnant women is important when contacting cats or their excrement.

Medication

Clindamycin:
- 600 mg (peds: 20 " “40 mg/kg/24 h) IV q6h
- 300 mg (peds: 8 " “20 mg/kg/24 h) PO q6h
- Useful if patient hypersensitive to sulfa
Dapsone: 50 mg PO per day or 200 mg PO per week (child >1 mo: 2 mg/kg PO per day)
Folinic acid: 5 " “25 mg PO daily in conjunction with pyrimethamine therapy
Pyrimethamine: 100 mg BID on 1st day loading dose, then 25 " “50 mg PO per day
Spiramycin: FDA authorization required
Sulfadiazine: 500 mg " “2 g (peds: 100 " “200 mg/kg/24 h div. BID) PO q6h
Trimethoprim " “sulfamethoxazole: 5 mg/kg of trimethoprim component IV or PO q12h

Follow-Up

Disposition

Admission Criteria

Acute infection with severe systemic symptoms
Immunocompromised patients with:
- Toxoplasmosis encephalitis
- Pneumonitis
- Sepsis

Discharge Criteria

Immunocompetent patients with:
- Mild symptoms
- Ocular
Maternal/congenital infection with mild symptoms

Issues for Referral
Infectious disease consultant ‚

Additional Reading

American Academy of Pediatrics. Red Book 2012 Report of the Committee on Infectious Diseases. Elk Grove, IL: AAP; 2012.
Centers for Disease Control and Prevention. Guidelines for prevention and treatment of opportunistic infections in HIV infected adults and adolescents. MMWR. 2009;58:1 " “207. http://www.cdc.gov/mmwr/pdf/rr/rr58e324.pdf.
Jones ‚ JL, Dargelas ‚ V, Roberts ‚ J, et al. Risk factors for Toxoplasma gondii infection in the United States. Clin Infect Dis. 2009;49:878 " “884.
Kaplan ‚ JE, Benson ‚ C, Holmes ‚ KK, et al. Guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: Recommendations from CDC, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. MMWR Recomm Rep. 2009;58:1 " “207.
Sciammarella ‚ J. Toxoplasmosis. Available at http://www.emedicine.com/emerg/topic601.htm. Accessed on July 6, 2002.

Codes

ICD9

130.0 Meningoencephalitis due to toxoplasmosis
130.4 Pneumonitis due to toxoplasmosis
130.9 Toxoplasmosis, unspecified
130.1 Conjunctivitis due to toxoplasmosis
130.2 Chorioretinitis due to toxoplasmosis
130.7 Toxoplasmosis of other specified sites
771.2 Other congenital infections specific to the perinatal period

ICD10

B58.2 Toxoplasma meningoencephalitis
B58.3 Pulmonary toxoplasmosis
B58.9 Toxoplasmosis, unspecified
B58.00 Toxoplasma oculopathy, unspecified
B58.89 Toxoplasmosis with other organ involvement
P37.1 Congenital toxoplasmosis

SNOMED

187192000 Toxoplasmosis (disorder)
192701001 Toxoplasma encephalitis (disorder)
187196002 Toxoplasma pneumonitis (disorder)
416481006 Ocular toxoplasmosis
73893000 Congenital toxoplasmosis (disorder)

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