Is reactivation of toxoplasmic retinochoroiditis associated to increased annual rainfall?

Abstract

Background: Reactivation of toxoplasmic retinochoroiditis is the most frequent form of uveitis in Misiones, Argentina. Fluctuations in the number of patients consulting with this type of uveitis were detected during the last decade. Since the province was consecutively exposed to rainy and dry periods over the last years, we decided to explore whether a relationship between reactivation of toxoplasmic retinochoroiditis and rain might be established according to the data registered during the 2004–2010 period. Results: The frequency of toxoplasmic reactivation episodes increases when precipitation increases (mostly in second and fourth trimesters of each year). Analysis of the independent variables demonstrates that precipitation is a significant predictor of the frequency of reactivation episodes. Although registered toxoplasmic reactivations were more frequent during the third trimester of the year, the association between the third trimester and the reactivation episodes did not reach statistical significance. Conclusion: Prolonged and intense rainfall periods were significantly associated with the reactivation of toxoplasmic retinochoroiditis. Changes promoted by this climatic condition on both the parasite survival in the soil as well as a putative effect on the host immune response due to other comorbidities are discussed.

Colombian Ocular Infectious Epidemiology Study (COIES): Ocular Toxoplasmosis Incidence and Sociodemographic Characterization, 2015-2019

“…The relationship between rainfall and toxoplasmosis has become a particularly relevant topic, as a Colombian multicentric study found a statistically significant association between congenital toxoplasmosis seropositivity and the mean annual rainfall (Gómez-Marin et al, 2011). Additionally, pluviosity has been related to an increase in the frequency of toxoplasmic reactivation episodes in humans (Rudzinski et al, 2013) and the risk of seroconversion for Tg in cats (Afonso et al, 2010). However, with our data is not possible to establish the relationship between rainfall and toxoplasmosis.…”

“…Regarding geographical variation, one Colombian study found an association between the high prevalence of congenital toxoplasmosis and pluviosity (Gómez-Marin et al, 2011). Another study found an association between pluviosity and toxoplasmosis reactivation (Rudzinski et al, 2013).…”

Exploring the association between precipitation and population cases of ocular toxoplasmosis in Colombia

“…Regarding congenital infection, Go ´mez-Marin's et al study [10] found a statistically PLOS NEGLECTED TROPICAL DISEASES significant association between annual rainfall and congenital toxoplasmosis. With respect to OT relapses, a study carried out in Argentina found that the frequency of toxoplasmic reactivation episodes increases when precipitation increases and that the mean annual rainfall could be a predictor of the frequency of reactivations; for every mm of rainfall, there was a 2% increase in the reactivation episodes (OR = 1.002, 95% CI = 1.000-1.003, P = 0.019) [11].…”

“…A previous study has shown that the mean annual rainfall significantly correlates with the incidence of congenital toxoplasmosis [ 10 ]. Furthermore, another study found a positive correlation between the annual precipitation and toxoplasmic retinochoroiditis reactivation rate [ 11 ]. This correlation could exist because oocyst survival is higher in humid, warm soil than under dry conditions [ 12 ].…”

“…The literature describing the effect of precipitation and risk of OT is limited; however, it is hypothesized that higher rainfall is associated with increased rates of congenital toxoplasmosis and OT recurrences [ 10 , 11 ]. Therefore, considering that Colombia is one of the rainiest countries worldwide [ 14 ], this study aimed to investigate the relationship between precipitation and new cases of OT from 2015 to 2019 in our country.…”