eMedicine Specialties > Pediatrics: General Medicine > Infectious Disease

Chorioretinitis

Author: Quoc V Nguyen, MD, Assistant Professor, Department of Pediatrics, New York State Health Department
Contributor Information and Disclosures

Updated: Aug 29, 2007

Introduction

Background

Chorioretinitis (CR) is an exudative inflammatory process that involves the retinal vessels and is usually caused by congenital viral, bacterial, or protozoan infections in neonates. Congenital toxoplasmosis (CTP) is the most common cause of infectious chorioretinitis in immunocompetent children. Congenital cytomegalovirus (CMV) infection is the second most common etiology. Fungal infections are more frequently identified, and emergent pathogens, including West Nile virus and lymphocytic choriomeningitis virus, have been described. In rare instances, chorioretinitis is part of a systemic noninfectious process.

In the older pediatric age group, chorioretinitis is diagnosed in diverse clinical conditions and can reflect newly acquired diseases or reactivation. Chorioretinitis can result from a dissemination of Toxocara or Baylisascaris in immunocompetent patients. In severely immunodeficient patients, including those with acquired immunodeficiency syndrome (AIDS), chorioretinitis may be associated with Epstein-Barr virus (EBV), CMV, varicella-zoster virus, various fungi (eg, Candida, Aspergillus, Fusarium, dimorphic fungi), and Toxoplasma.

Pathophysiology

Chorioretinitis causes an inflammation of the retinal vessels in reaction to a generalized infection that involves multiple organ systems. Congenital disseminated infections also manifest as intrauterine growth retardation, microcephaly, microphthalmia, cataract, uveitis, hearing defect, osteomyelitis, enlarged liver and spleen, lymphadenopathy, dermal erythropoiesis, carditis, and congenital heart disease. Vessel trauma caused by lodging Toxocara or Baylisascaris larvae may be associated with severe inflammatory responses.

Although chorioretinitis that is associated with congenital viral infections tends to be stable or improves in infancy, chorioretinitis associated with asymptomatic CTP progresses for years after birth and is more likely to be clinically significant at an older age.

Frequency

United States

CTP occurs much less frequently in the United States than in several European countries. Chorioretinitis is extremely rare in children, regardless of immunologic status.

Worldwide, chorioretinitis due to CTP is more common than chorioretinitis due to symptomatic congenital CMV. The seroprevalence rate in childbearing women is estimated at 14-30%, and the estimated incidence rate of CTP is 0.1 per 1000 births.

Statistically, chorioretinitis due to CMV is more common than chorioretinitis due to CTP in the United States. Chorioretinitis occurs in approximately 14% of infants born with symptomatic congenital CMV infection. However, severely affected infants represent fewer than 10% of those with congenital infections due to maternal primoinfection with viremia during the first half of pregnancy. Chorioretinitis affects only 2% of asymptomatic infants with congenital infection.
 
Toxocara canis –associated ocular larva migrans occurs in more than 60% of symptomatic seropositive children. This zoonosis is probably one of most commonly acquired childhood eyesight impairments because of the high prevalence of young pet dogs in the United States.

International

Seroprevalence rates for CTP in childbearing women are 50-80% in European countries, and the estimated incidence rate of CTP is 1-4 cases per 1000 births. However, acquired toxoplasmosis accounts for a much higher rate of ocular infections in late childhood worldwide. The prevalence of CMV seroconversion in many parts of the world reaches almost 100% in young adults. The incidence of CMV congenital infection is not well documented.

Mortality/Morbidity

• If left untreated or if the condition does not respond to treatment, severe chorioretinitis can result in partial or total loss of vision in the affected eye.
• Morbidity is due to concurrent damage to major organ systems, especially damage to the brain (eg, developmental delays, seizures). 
• Mortality due to chorioretinitis depends on the nature and progression of the basic illness.

Age

• Congenital chorioretinitis is usually evident at birth.
• Congenital chorioretinitis associated with CTP actively progresses after birth and manifests when the individual is aged 5 years.
• Acquired chorioretinitis occurs at any age, depending on the disseminated illness.

Clinical

History

• In most individuals with chorioretinitis, the history may not help in establishing causal agents. For example, in patients with chorioretinitis associated with congenital infections, eliciting the maternal history of primary viral or flulike illnesses during pregnancy is usually not easy. Dietary habits (preference of raw meat) and pet care (cleaning cat litter box) may imply toxoplasmosis, whereas the lack of rubella vaccination in an immigrant may warrant investigating. However, a pregnant woman with symptomatic West Nile viral meningoencephalitis may be readily diagnosed using historical, epidemiologic, and laboratory data. 
• Many maternal primary infections due to CMV, rubella, herpes simplex virus (HSV), and syphilis occur insidiously and are not clinically apparent. 
• In patients with acquired chorioretinitis, a history of illness that relates to toxoplasmosis (eg, handling kitten wastes, eating undercooked meat) may be present. Toddlers with exposure to puppy or raccoon waste have an increased risk of developing visceral larva migrans and ocular larva migrans.
• A recent history that includes strabismus, vision loss, and CNS involvement in a toddler exposed to raccoon waste or who has a newly acquired puppy suggests zoonotic roundworm larval infestation (Baylisascaris or Toxocara).

Physical

Chorioretinitis is an inflammation of the posterior uveal tract and involves the retina and the vitreous body. If the inflammation is unilateral, the child may squint, favor the "good eye," or report an inability to see objects. Older children with chorioretinitis may present with photophobia and clumsiness with poor walking balance. The "red eye" phenomenon in snapshots of a child with chorioretinitis may reveal incongruency.

• Include an ophthalmologic examination as part of a detailed physical examination. 
• A pediatric ophthalmologist should perform a thorough examination of all visible components of the eye in an infant in whom any congenital infection is suspected.
  • This examination is electively performed and is documented with photographs of the abnormalities in the lens, uvea, and retina and an age-appropriate assessment of vision, visual acuity, and fields. 
  • Ophthalmologic examination is an integral part of monitoring treatment efficacy and disease progress. 
  • Ophthalmologic examination can reveal exudative "cotton balls" (ie, focal atrophic and pigmented scars of the retina). Vitreous inflammations can manifest as transient floating opacities. However, these findings are common in all patients with chorioretinitis regardless of etiologies.
• Because chorioretinitis is usually associated with a congenital syndrome, all other abnormal physical findings should be documented; these include intrauterine growth retardation, microcephaly, microphthalmia, cataract, uveitis, hearing defect, osteomyelitis, enlarged liver and spleen, lymphadenopathy, dermal erythropoiesis, carditis, and congenital heart disease.
• CNS involvement may manifest as abnormal muscle tone, changes in reflexes, or both. A complete neurological examination is warranted.
• If amnionitis is suspected at delivery, thorough examination and culture of amniotic fluid and placenta may elicit the pathogen.

Causes

• Congenital infection
• In immunocompetent children, chorioretinitis is usually associated with congenital infection; acquired infection is a less likely cause.
• Toxoplasma gondii and CMV are the leading causes of congenital infections associated with chorioretinitis.
• Viral etiologies include vertical or perinatal infections, including HSV, rubella, varicella, EBV, lymphocytic choriomeningitis virus, and, possibly, flavivirus. Despite increasing rarity, congenital syphilis should still be considered in an infant born with chorioretinitis whose mother has human immunodeficiency virus infection and untreated or inadequately treated syphilis.
• Distinguishing these infections from perinatal transmission of other viral illnesses, including HIV, hepatitis B, and CMV, is important.
• The risk of intrauterine infection is highest in infants of women with primoinfection and is much less with recurrent infections.
• Acquired chorioretinitis in immunocompetent children: Some children who ingest embryonated T canis or Baylisascaris procyonis eggs develop visceral larva migrans or ocular larva migrans.
• Immunocompromised children
• Chorioretinitis may be associated with systemic infection due to a vast array of pathogens.
• General infections include congenital or acquired Lyme disease, Yersinia enterocolitica, and Mycobacterium tuberculosis (MTB).
• Invasive fungal infections may result from Candida and Cryptococcus species and histoplasmosis.
• A species of blackfly (Simulium species) can transmit onchocerciasis (in tropical Africa, Yemen, Saudi Arabia, and parts of Latin America).
• Noninfectious disease
• Systemic noninfectious disease, such as sarcoid, collagen vascular, and granulomatous diseases may cause chorioretinitis.
• Other possible noninfectious processes, which mostly occur in older children or young adults, include chronic granulomatous disease (CGD), sarcoidosis, Behçet disease, and juvenile rheumatoid arthritis.

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