Human toxoplasmosis in the Czech Republic 1923-2023: From the first case through a massive outbreak to a long-term decline

When the Prague ophthalmologist Josef Janků in March 1922 noted and a year later described strange symptoms in a deceased newborn, he did not know that this would be the first documented case of toxoplasmosis in humans, moreover with congenital transmission and eye damage. Only the improvement of serological diagnostics revealed that toxoplasmosis was one of the most common serious parasitoses in the Czech Republic. The annual number of reported cases of clinical toxoplasmosis increased from one hundred in the early 1970s to 513-860 between 1983 and 1993. In 1994, the number of cases of clinical toxoplasmosis rose transiently to a total of 2056 cases as a result of an unusually widespread epidemic. Since then, the numbers have been steadily declining and have returned to one hundred cases in recent years.

The reasons for the decrease in the incidence of toxoplasmosis in the Czech Republic could be the gradual improvement of social and hygiene standards and education, control and supervision of food safety. The process of urbanisation has resulted in fewer outdoor activities. On the other hand, the growing popularity of organic food, organic farming and unconventional cooking practices could theoretically contribute to the spread of toxoplasmosis, as well as travelling to southern countries rich in stray cats.

However, seroprevalence data do not match such a significant decrease in toxoplasmosis. According to 37 studies performed on different groups of persons in the years 2002-2018, seropositivity in men can be found between 7.9-40.2% (average: 23,9%) and between 15.9-45,9% (average 28,9%) in women. This is not much less than the 26.3% of positive men and 34.1% of positive women found in surveys from 1971 to 1996. The declining reporting discipline associated with the skyrocketing administration can also be a problem.

Clinical toxoplasmosis in the past and present is reported twice as often in women as in men. The younger age categories predominate - men 10-24 years, women 20-34 years. The most common clinical forms are lymphadenitis (72.8%), ocular toxoplasmosis (6.0%), primary infection during pregnancy (5.4%), and congenital infection accounts for 0.6%.

The incidence is highly locally variable. The highest is in some districts of West Bohemia and Moravia, while the lowest number of cases is reported from Prague and the surrounding area.

Supported by MH CZ - DRO (The National Institute of Public Health – NIPH, 75010330)