Schistosoma haematobium in China, ex-Africa: new populations at risk?

Patented technologies for schistosomiasis control and prevention filed by Chinese applicants

BACKGROUND

Many valuable and productive patented technologies have been developed to control schistosomiasis in China in the past 70 years. We conducted a research to analyse patented technologies for schistosomiasis control and prevention filed by Chinese applicants for determining the future patent layout.

METHODS

The patent databases of China National Intellectual Property Administration and Baiten were comprehensively searched, and patented technologies for schistosomiasis control and prevention, published between January 1950 and December 2020 filed by Chinese applicants were sorted on 30 December 2020. The patent types, technical fields, and patent development trends were analysed using patent indexing.

RESULTS

There are 184 valid schistosomiasis control technology patents, among them 128 invention patents. The patents related to schistosomiasis control and prevention technology have gone through the germination, growth, and maturity stages. These phases correspond with three phases in schistosomiasis control in China. The main technical aspects were fundamental research (n = 37), detection (n = 13), chemotherapy (n = 61), and armamentarium/devices (n = 73), of which the number of patents for detection for diagnosis was smaller. The top three specialised technical fields for patents subgroups, focusing on antiparasitic agents, DNA or RNA, vectors and medicines, of which schistosomicides are the major dominant subgroup.

CONCLUSIONS

We recommend that technologies to be patented for schistosomiasis control and prevention be focused on detection, preliminary studies for molecular detection methods should be significantly enhanced, and patent layout must be performed, which will, in turn, promote accuracy of early diagnosis, not only in humans but also in livestock. It is necessary to develop more anti-schistosomal drugs safely and effectively, exceptionally eco-friendly molluscicides and herbal extracts anti-schistosomes, improve treatment, develop vaccines for use in humans.

Toxicity of a molluscicide candidate PPU07 against Oncomelania hupensis (Gredler, 1881) and local fish in field evaluation

Schistosomiasis japonica caused by Schistosoma japonicum infection is recognized as a considerable economic and public health concern in Asia. Oncomelania hupensis is the sole intermediate host of S. japonicum. The only molluscicide recommended by World Health Organization (WHO) since 1960s is relative toxic to other aquatic species. In this article, we evaluated the novel molluscicide PPU07 in field trials on their efficiency against O. hupensis and toxicity for local fish. 25% PPU07 sulfate WP exhibited similar molluscicidal effect at 2.0 g/m² and 2.0 g/m³ in the spraying and immersion trials with the WHO recommended molluscicide niclosamide (1 g/m² and 1 g/m³). The mortality rates reached 95% and 96%, respectively. Moreover, little toxicity was observed for local fish and other aquatic organisms at the effective molluscicidal concentrations. In all, 25% PPU07 sulfate WP is a promising molluscicide for snail control, particularly in semi-commercial or commercial aquaculture ponds.

Yellow fever cases in Asia: primed for an epidemic

There is currently an emerging outbreak of yellow fever in Angola. Cases in infected travellers have been reported in a number of other African countries, as well as in China, representing the first ever documented cases of yellow fever in Asia. There is a large Chinese workforce in Angola, many of whom may be unvaccinated, increasing the risk of ongoing importation of yellow fever into Asia via busy commercial airline routes. Large parts of the region are hyperendemic for the related Flavivirus dengue and are widely infested by Aedes aegypti, the primary mosquito vector of urban yellow fever transmission. The combination of sustained introduction of viraemic travellers, an ecology conducive to local transmission, and an unimmunized population raises the possibility of a yellow fever epidemic in Asia. This represents a major global health threat, particularly in the context of a depleted emergency vaccine stockpile and untested surveillance systems in the region. In this review, the potential for a yellow fever outbreak in Asia is discussed with reference to the ecological and historical forces that have shaped global yellow fever epidemiology. The limitations of surveillance and vector control in the region are highlighted, and priorities for outbreak preparedness and response are suggested.

Design, synthesis, and cercaricidal activity of novel high-efficient, low-toxic self-spreading PEG-N-salicylanilide derivatives against cercariae larvae of Schistosome Japonicum floating on the water surface

Novel cercaricides of PEG-N-salicylanilide derivatives that could self-spread and float on the water surface were designed and synthesized according to the particular habit of cercariae larvae of Schistosome japonicum. The structures of the cercaricides were characterized by the infrared spectra (IR), magnetic resonance ((1) H NMR), and mass spectrum (MS). The images of the floating cercaricides on the water surface were investigated by the Brewster angle microscopy (BAM). When the cercaricides were dropped on the water surface, they could spread along the air-water interface automatically and form thin membranes floating on the water surface immediately. The lethality rate of cercariae for 5a and 6a was more than 90% in 120 min at a surface concentration of 0.008 mg/cm(2) . The non-ionic surfactant-cercaricides not only showed strong cercaricidal activities against the cercariae larvae but also exhibited low toxicities, which offered an effective and environment-friendly approach for the reduction of population infection rate and the realization of schistosome control.

Improving the management of imported schistosomiasis haematobia in China: lessons from a case with multiple misdiagnoses

Background

Human Schistosoma haematobium infection that causes urinary schistosomiasis occurs in Africa and the eastern Mediterranean, and China is only endemic for S. japonicum. In this report, we reported an imported case with S. haematobium infection returning from Angola to Shaanxi Province, northwestern China, where S. japonicum is not endemic.

Findings

The case was misdiagnosed as ureteral calculus, invasive urothelial carcinoma and eosinophilic cystitis in several hospitals, and was finally diagnosed by means of serological assay followed by microscopic examination of the urine sediment. The patient was then treated with praziquantel, and a satisfactory outcome was obtained.

Conclusions

As S. haematobium is not indigenous to China, most Chinese doctors and medical technicians are unfamiliar with this introduced parasitic disease, therefore, they need to increase the awareness of its existence when they encounter persons who have visited or resided in endemic areas, and the techniques for detection of the parasite, so as to reduce the misdiagnosis. In addition, health education should be given to those who will go to the endemic areas to improve their knowledge and awareness on prevention and control of schistosomiasis haematobia, thereby reducing the risk of exposure to the infested freshwater.