Jiangsu Province has had especially high malaria transmission in the last century; the malaria cases once reached more than 10 million a year, which is almost one-fourth of the total population of the entire province [14]. After concerted efforts from the national to regional levels, malaria transmission has been well controlled recently, and only hundreds of malaria cases have been reported in Jiangsu annually [15,16,17], despite fluctuations after a re-emergence of vivax malaria in central China from 2004 to 2006 [18]. No additional local malaria cases have been observed and reported since 2011; however, the total number of malaria cases increased markedly in the last several years because of oversea laborers who export and trade in China but have contact with areas of endemic malaria [4]. Nantong Prefecture was selected in this study because it shows a pattern of malaria spread that this similar to that of the entire province and is a good current representative.
The “1–3-7” strategy for the surveillance of and response to malaria elimination was produced by Jiangsu Province and was recently adopted as the national policy for malaria elimination in China [19, 20]. This strategy is defined as the reporting of malaria cases within one day, their confirmation and investigation within three days, and the appropriate public health response to prevent further transmission within seven days. Reporting of information is the first and one of the most important steps for malaria elimination. The correct diagnosis, including malaria infection and detailed parasite species classification, plays very important roles in case verification and focal treatment. A misdiagnosis of a malaria species might lead to the use of inappropriate antimalarial drugs and secondary transmission by local malaria vectors in the absence of timely vector control measures such as IRS activity [21]. In this study, a relatively low reporting accuracy was found in terms of the P.v species from 13 prefectures in Jiangsu Province, and Anopheles sinensis, one of the most effective malaria vectors, especially for transmitting vivax species in China, is widely distributed in the entire province [22]. When the infection source accumulates without the correct foci treatment due to malarial case misdiagnosis, the infection can re-emerge. An impressive lesson demonstrating a re-emerging infection was observed in Greece, where a vivax malaria outbreak occurred in 2009 after malaria was declared eliminated in 1973 [23], in addtion, more countries including Italy, Cyprus and Costa Rica have reported the re-emerging infection recently (https://www.cdc.gov/malaria/).
In China, a public health system network has been established and covers public health from the national to the most basic levels in rural villages. For example, each village has a village clinic with at least one doctor, where patients suspected of having malaria are advised to transfer to hospitals for parasite assessment and treatment as soon as possible, and there are specific sections/departments that are responsible for public health care, including malaria control and elimination, at health care institutions at the township and upper governmental levels. However, a lack of sufficient technology and ability has always affected the staff in malaria-associated departments, especially at lower levels. Furthermore, because the number of malaria cases is decreasing, less attention or financial support is directed to malaria control and elimination, making disease control worse at a basic level. In this study, there was a relatively high percentage of parasite species corrected by a provincial microscopy center from the cases that were reported by the sub-provincial organizations in Jiangsu in 2013 and 2014 (Table 1). In addition, many patients (23.14%) went to township and village hospitals but did not receive a confirmed diagnosis of malaria (Fig. 4), which indicates that capacity for diagnosis, including microscopy examination skills, should be improved.
The quality of microscopic malaria examination is dependent on the competence and performance of laboratory technicians, including blood smear preparing, staining, and interpreting. In this study, staff with higher education levels were more likely to be found at upper county levels than in townships. This study shows that staff at a county level, including county CDCs and county hospitals, exhibited much better skills than staff from township hospitals or PHCs in terms of parasite interpretation. In fact, a small percentage of the staff at township hospitals and PHCs could not differentiate falciparum from other species, which could place the current malaria elimination surveillance system at risk. In addition, the ability to prepare slides was also closely related to educational background. For example, microscopists with a bachelor degree had better blood smear preparation skills than those who graduated from a 2-year specialized secondary school. Consequently, it is imperative to encourage more young and promising graduates with a higher education level to join the malaria control and elimination network.
In elimination settings, a village clinic doctor or township PHC workers are responsible for malaria case management and subsequent investigations. In this study, a substantial number (more than 20%) of the malaria patients went first to the township or lower level to seek medical treatment because of febrile or other malaria-related symptoms. However, none of these patients received a confirmed diagnosis at the township and village level. This inability to diagnose malaria might represent the situation in the entire province, because similar results were found from reporting data in other cities in Jiangsu Province: a zero or a very low percentage of patients received malaria confirmation at the township or village level. The main reason for this lack of confirmation might be due to inadequate ability in the lower-level staff to microscopically distinguish plasmodium parasites from artifacts. In addition, because the staff in township hospitals in particular are responsible for many disease diagnoses and treatments, it is difficult to perform well under time constraints and a heavy workload, and poor quality blood smear preparation might result. Accordingly, periodic refresher training, frequent supervision, and the establishment of a testing program should be provided by a provincial reference laboratory to lower level personnel, especially in townships in the province, to maintain microscopic skills and ability. Additionally, an alternative approach, such as RDTs, should also be considered for use, particularly at the township and village levels, to avoid potential misdiagnoses and missed diagnoses of malaria, which may cause death in falciparum malaria cases due to the lack of timely and appropriate diagnosis and treatment.
