Prevalence of Parasitic Infections in a Tertiary Hospital in China: A 12-Year Retrospective Study

Parasitic infections represent a worldwide public health issue in many developing countries. Few epidemiological studies regarding parasitic infections and the evolution of infection spectrum in China have been reported up to date. It is necessary to investigate the epidemiological feature of parasitic infection during recent years. Three hundred and thirty-six cases of parasitic infections were retrospectively enrolled and analyzed. Electronic medical records of the enrolled parasitic patients from were retrieved from the Electronic Medical a China. Demographic characteristics and data of laboratory tests were exported in and analysis were performed using Graphpad


Abstract
Background Parasitic infections represent a worldwide public health issue in many developing countries. Few epidemiological studies regarding parasitic infections and the evolution of infection spectrum in China have been reported up to date. It is necessary to investigate the epidemiological feature of parasitic infection during recent years.

Methods
Three hundred and thirty-six cases of parasitic infections were retrospectively enrolled and analyzed. Electronic medical records of the enrolled parasitic patients from January 1, 2010 to May 31, 2021 were retrieved from the Electronic Medical Record System of a tertiary hospital in China. Demographic characteristics and data of laboratory tests were exported in Excel and analysis were performed using Graphpad Prism 5.

Conclusions
Our study demonstrated the prevalence of parasitic infection over the latest 12 years in a single center of China. The trend of parasitic infection rate reached the peak in 2018 with the dominating parasitic species changed from soil origin to foodborne. Furthermore, with the emergence of various dietary habits and the development of living conditions, unclean diets especially eating raw meat had become the main route of transmission for parasites, which alarmed that food safety education for public should be strengthened and enlarged. Although eosinophil elevation and IgE is reliable indicators for initiating screening of parasitic infection but enough for diagnosis, novel diagnostic kits for parasites should be devepoled.

Background
In the early 1960s, there were many parasitic diseases that seriously affected the health of people worldwide, especially in China and poor countries. Parasitic infection was used to be a troublesome problem that hindered social and economic development [1,2]. Though exceptional achievements have been accomplished in ghting parasites in the past 60 years, parasitic infections in China still account for a large percentage of the global burden [3]. Soil-transmitted parasites and foodborne parasites (FBPs) are the two dominant species of parasites. FBPs exist in animal meat or aquatic products, and these parasites would be transmitted to human body by eating raw or uncooked food containing eggs or larvae [4].
Soil-transmitted parasites (also named soil-transmitted nematodes) do not require an intermediate host, and its eggs or larvae in the outside world (mainly refers to the soil) could directly infect human [5]. Altered routes of transmission can re ect the current situation of economic development of a country to a certain extent. For the rapid advance of economy and sanitary conditions, the species spectrum of parasites has been changed for years.   (Figure 1b). Cases from other regions were less than 10: 9 from Guizhou, 8 from Henan, 8 from Heilongjiang, 5 from Jilin, 5 from Sichuan, 4 from Fujian, 4 from Hubei, 4 from Chongqing, 3 cases from Guangdong, 3 from Hunan, 3 from Liaoning, 3 from Shanxi, 2 from Guangxi, 2 from Inner Mongolia, 2 from Shandong, 2 from Xinjiang, 1 from Beijing, 1 from Hainan, 1 from Qinghai, 1 from Shanxi, 1 from Xizang, 1 from Yunnan and 2 from America. The pro le of every-year parasitic infections was displayed in Figure 3b, showing that the FBPs (clonorchis sinensis, paragonimus westermani, cysticercus, sparganum mansoni) became the dominated parasitic species. Cysticercus

The Periods Of Parasitic Infections Before Diagnosis
The periods of infection before the time of diagnosis of the top four parasites (clonorchis sinensis, paragonimus westermani, cysticercus and sparganum mansoni) were summarized in Table 2. Surprisingly, 38.57% patients infected with paragonimus westermani were diagnosed after more than 6 months' infection. Similarly, patients with cysticercus and sparganum mansoni diagnosed after more than 6 months' infection accounted for 25.00% and 28.30% respectively (Table 2). Moreover, symptoms of 6 cases infected with sparganum mansoni had appeared over 10 years since they were children. Of the 6 cases, 3 cases were diagnosed owing to epileptic seizure, but other patients were unfortunately wrongly diagnosed as rheumatoid arthritis. Therefore, etiological treatments for many parasitic patients were delayed because of delayed diagnosis of parasites infection. controlling the prevalence of parasitic diseases. This study only showed the parasitic infection of a single center in east China, however, there is a non-negligible fact that in some areas of the parasite endemic areas in the west, south and northeast of China are still enlarging [7]. Therefore, consolidation of the achievements for parasitic prevention and control remains challenging worldwide especially in this period of coronavirus diseas (COVID-19) pandemic [8]. Based on the present survey, three points could be recommended for future control and prevention of parasitic diseases.
First of all, parasitic infection can't be ignored in clinical work. The present investigation recorded period of infection before diagnosis for foodborne parasitic diseases demonstrating an important actual situation that many cases were not diagnosed timely at the rst visit in local hospitals. Three possible reasons are displayed here. Firstly, lack of speci c diagnostic kits for parasites in some areas may be the dominant reason, as the diagnostic kits for parasites are only available in CDC. Secondly, specialized disease outpatient departments for parasitic diseases have not been set or closed in many hospitals for the declined prevalence of parasitic infection. Moreover, most foodborne parasitic diseases with non-speci c clinical symptoms are easily confused with other medical diseases, and the epidemiological history collection is incomplete or lacks speci city, enhancing the di culty of diagnosis [9]. All these possible reasons alert us that though the prevalence of parasites has declined or even disappeared for years, parasitic infection remains. With the pro le of parasitic diseases changed with the improvements of economic and living conditions, diagnosis of parasitic diseases should be taken into consideration for many clinicians as an optional choice accordingly. Setting up specialized disease outpatient departments for parasitic diseases in some regions is necessary and urgent.
In addition, system of therapeutic effect evaluation and speci c indicators for the outcome should be developed.
Praziquantel as a broad-spectrum antiparasitic agent speci c for parasitic infection has been widely applied for about forty years since it was found in 1970s [10]. Patients with parasitic infection were usually administered praziquantel according to the course. However, medical history of many patients in our study manifested that the lack of sensitive and speci c prognostic biomarkers results in a fact that it is impossible to accurately evaluate the therapeutic effects and the outcome of antiparasitic treatment. Consequently, some patients had been repeatedly admitted to the hospitals because of relapse and becoming worse or chronic. Thus, standardized system for evaluation of therapeutic effect should be set and biomarkers for accurately monitoring the outcome need to be developed for delicacy management.

Consent for publication
All participants enrolled in this study consent to submission.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.