Abstract
Purpose :
Toxoplasmosis, a disease caused by T. gondii, is the most important cause of posterior retinochoroiditis worldwide. The outbreaks of toxoplasmosis are opportunities to further investigate this disease. During and after the outbreak, patients with atypical ocular clinical presentation, can be diagnosed and better evaluated. The objective of this study is to perform a comprehensive review of ocular toxoplasmosis in worldwide outbreaks and to establish a protocol to study typical and atypical presentations worldwide.
Methods :
A comprehensive review was performed using the keywords “toxoplasmosis outbreak” on PUBMED. A total of 213 articles between 1950 – 2019 were found. Excluded articles include outbreaks in animals (64), pure epidemiological studies (15), prospective studies (13), case reports and reviews (40), congenital toxoplasmosis (2), simultaneous other infections (32), and only follow up studies (29). Eligibility criteria included: complete clinical information, clinical manifestations of the ocular disease, IgG and IgM titles for toxoplasmosis, mode of transmission, and the possible toxoplasmosis strain involved in the outbreak. A total of 21 studies were entered in this comprehensive review.
Results :
The toxoplasmosis outbreaks occurred in Brazil, Canada, India, Korea, Panama, Suriname, Turkey and USA, affecting 1,183 individuals. IgM was positive in 95.1% (1,125) of them. The main sources of contamination were undercooked meat and water; in 10 studies the strain was identified (type I). Seven studies specified urban or rural zone. The most common symptom was lymphadenopathy (556) followed by fever (401), arthralgia (298), fatigue (288) and malaise (281). Forty-three individuals were asymptomatic or complained of vague ocular pain. From the 1,183 patients, 310 (26%) were diagnosed with ocular toxoplasmosis and 13 presented with an atypical form of the disease.
Conclusions :
Toxoplasmosis outbreaks are an opportunity to diagnose (IgM positivity) and further study the ocular involvement. A protocol should include: 1) The percentage of ocular involvement, 2) The mode of contamination, 3) The toxoplasmosis strain, 4) IgM and IgG levels, 5) Complete ophthalmological examination including clinical pictures and imaging (OCT), 6) Complete description of the atypical ocular presentations. The unusual complaint of ocular pain by several patients in these studies deserves a further investigation.
This is a 2020 ARVO Annual Meeting abstract.