Pentachlorophenol (PCP) was used in large quantities, and mainly for killing the intermediate host snails of schistosome in China, thereby resulting in ubiquitous PCP residue in the environment. However, studies considering the carcinogenicity of PCP for humans mainly focused on occupational workers, and the actual carcinogenicity of PCP for general population is uncertain. To investigate the association between cancer risks and PCP exposure in a community population, an ecological study was conducted in three contaminated areas along the Yangtze River. Standardized rate ratio (SRR) was calculated to represent the risk of cancer incidence, by using incidence in the low PCP exposure category as the reference group. A total of 15,962 cancer records were collected, and 76 water samples and 213 urine samples in three areas were examined. Our findings suggested that compared with the low PCP group, the high PCP group had significantly excessive incidences of various cancers related to different organs including lymph (SRR = 19.44, 95% CI = 15.00–25.19), blood (SRR = 17.24, 95% CI = 12.92–23.01), nasopharynx (SRR = 3.97, 95% CI = 3.75–4.21), gallbladder (SRR = 3.46, 95% CI = 3.09–3.87), pancreas (SRR = 3.41, 95% CI = 3.07–3.79), respiratory system (SRR = 3.41, 95% CI = 3.27–3.57) and liver (SRR = 3.31, 95% CI = 3.09–3.56). Taken together, our present study provides evidence that general community population exposed to high level of PCP exhibits a broader spectrum of increased cancer risks as compared to occupational groups.

It is a common method to analyse physiological mechanisms of organisms – commonly referred to as biomarkers – to indicate the presence of environmental pollutants. However, as biomarkers respond to a wide range of stressors we want to direct the attention on natural stressors, i.e. on parasites. After two years maintenance under controlled conditions, roach (Rutilus rutilus) revealed no influence on levels of metallothionein by the parasite Ligula intestinalis. The same was found for Gammarus fossarum infected with Polymorphus minutus. However, the heat shock protein (HSP70) response was affected in both host-parasite systems. While the infection of roach resulted in reduced levels of HSP70 compared to uninfected roach, the infection in G. fossarum led to higher levels of HSP70. We also analysed the effect of a 14 days Cd exposure (4 μg/L) on the uninfected and infected gammarids. The exposure resulted in induced levels for both, metallothionein and HSP70 whereas the combination of stressors, parasite and exposure, revealed a decrease for levels of HSP70 in comparison to the metal exposure only. Accordingly, parasites as natural parts of aquatic ecosystems have to be considered in ecotoxicological research.

Global warming and the associated climate changes are predictable. They are enhanced by burning of fossil fuels and the emission of huge amounts of CO₂ gas which resulted in greenhouse effect. It is expected that the average global temperature will increase with 2–5 °C in the next decades. As a result, the earth will exhibit marked climatic changes characterized by extremer weather events in the coming decades, such as the increase in temperature, rainfall, summertime, droughts, more frequent and stronger tornadoes and hurricanes. Epidemiological disease cycle includes host, pathogen and in certain cases intermediate host/vector. A complex mixture of various environmental conditions (e.g. temperature and humidity) determines the suitable habitat/ecological niche for every vector host. The availability of suitable vectors is a precondition for the emergence of vector-borne pathogens. Climate changes and global warming will have catastrophic effects on human, animal and environmental ecosystems. Pathogens, especially neglected tropical disease agents, are expected to emerge and re-emerge in several countries including Europe and North America. The lives of millions of people especially in developing countries will be at risk in direct and indirect ways. In the present review, the role of climate changes in the spread of infectious agents and their vectors is discussed. Examples of the major emerging viral, bacterial and parasitic diseases are also summarized.

A wide range of endocrine disruptor compounds are routinely discharged to the ecosystem. Water contaminated with these compounds has a potential effect on the reproductive physiology of aquatic organisms as well as humans. In the present study, we tested the effect of the steroid estrogen, 17β-estradiol, on Biomphalaria alexandrina, a snail species that is widely distributed in Egypt and that acts as an intermediate host for the human blood fluke, Schistosoma mansoni. The effects of exposure to 0.3 mg/L and 1 mg/L 17β-estradiol on fecundity (MX) and reproductive rate (R₀) of B. alexandrina were recorded. In addition, levels of steroid sex hormones and antioxidants in the hemolymph and ovotestis (OT) of exposed snails were measured. Histopathological changes in the OT of B. alexandrina were also investigated. Exposure to 0.3 mg/L and 1 mg/L 17β-estradiol caused a significant increase in the number of egg masses per snail after 3 weeks and 1 week of exposure for the two tested concentrations compared with unexposed controls. An increase in the levels of progesterone hormone was recorded in the hemolymph of exposed snails in comparison with unexposed controls. Additionally, levels of the antioxidant enzyme glutathione (GSH) were increased in the hemolymph and OT tissues of snails after 2 and 4 weeks of exposure. Histopathological sections in the OT revealed an increase in the oocyte and a decrease in the sperm densities after 2 weeks and this effect was restored to normal conditions after 4 weeks of exposure to both tested concentrations. The current results indicate that B. alexandrina is sensitive to 17β-estradiol and can therefore be used as bioindicator and model organism for the assessment of water pollution with endocrine disruptor compounds.

Schistosomiasis is one of the neglected tropical diseases. It is a snail-borne trematode infection, and Biomphalaria alexandrina snails are the intermediate host of Schistosoma mansoni in Egypt. The objective of this study is to evaluate the molluscicidal activity of the aqueous seed extract of Moringa oleifera against B. alexandrina snails. The results showed that this aqueous extract was lethal for B. alexandrina snails (LC₅₀ 0.27 g/l; LC₉₀ 0.41 g/l). Exposure of snails to the sublethal concentrations of this aqueous extract caused a considerable reduction in survival rates and hatchability rates of eggs of these snails. Moreover, it negatively affected some biochemical aspects, where it increased the levels of transaminases (ALT and AST), while it decreased the concentrations of total protein, albumin, and globulin concentration. Histological examinations of the digestive gland of snails exposed to the sublethal concentrations of aqueous seed extract of M. oleifera revealed severe damage in the digestive cells, where they lost their tips and some were degenerated, while the secretory cells increased in number. Regarding the hermaphrodite gland, there were losses of connective tissues and irregular sperms, and the eggs were degenerated. These findings prove the potent activity of aqueous seed extract of M. oleifera against the intermediate hosts of Schistosoma mansoni and provide a considerable scope in exploiting local indigenous resources for snails’ molluscicidal agents.