Environmental contamination with parasites in selected rural farms in the Philippines: impacts of farming practices on leafy greens food safety

Domesticated animal reservoirs of Cryptosporidium and Giardia in agricultural farms in Laguna and Quezon provinces, Philippines

Cryptosporidium and Giardia are recognized as significant etiological agents of diarrheal outbreaks in humans as these parasites may be transmitted through the ingestion of water and food contaminated with feces of human or animal origin. However, surveillance studies on the role of animal reservoirs in the transmission of Cryptosporidium and Giardia are deemed insufficient and the complete dimension of the problem contributing to contamination in an agricultural setting is unknown. This study aimed to assess the presence of Cryptosporidium and Giardia in domesticated animals from selected farms in the agricultural provinces of Laguna and Quezon in Southern Luzon, Philippines. Using immunofluorescence assay, an overall 85.7% incidence of protozoan infection was recorded among the animals (N = 161). Of these, 77.0 and 73.9% were positive for Cryptosporidium and Giardia, respectively. Highest incidence (95.83%) of Cryptosporidium was documented in swine and the highest incidence (89.47%) of Giardia was observed in ruminants. Analyses revealed significant differences in the incidence of the protozoan parasites among animals with different containment status, water source, age group, and sex. On the other hand, farm workers' knowledge on parasite transmission was negatively correlated (p = 0.001) to parasite incidence. With the scarcity of data about Cryptosporidium and Giardia in farm-raised animals in the Philippines, the information obtained from this study will be vital for protozoan source tracking and further control interventions against Cryptosporidium and Giardia infections.

From fox to fork? Toxocara contamination of spinach grown in the south of England, UK

BACKGROUND

Toxocara canis and Toxocara cati are intestinal parasites of dogs, cats and foxes, with infected animals shedding eggs of the parasite in their faeces. If humans accidentally ingest embryonated Toxocara spp. eggs from the environment, severe clinical consequences, including blindness and brain damage, can occur. Previous work has demonstrated the presence of Toxocara spp. eggs on vegetable produce grown in the UK, but only in small-scale community gardens. The aim of this study was to determine whether Toxocara spp. eggs are also present on vegetables grown on commercial farms in the UK, which supply produce to a greater number of people.

METHODS

A total of 120 samples (300 g each) of spinach (Spinacia oleracea) were collected across four farms in the south of England, UK. The samples were processed using a sieving approach followed by multiplex quantitative polymerase chain reaction analysis.

RESULTS

Overall, 23.0% of samples were positive for T. canis (28/120; 95% confidence interval 16.7-31.7%) and 1.7% for T. cati (2/120; 95% confidence interval 0.5-5.9%). There was a statistically significant difference in the number of positive samples between farms (P = 0.0064). To our knowledge, this is the first report of the isolation of Toxocara spp. from vegetables grown on commercial farms in the UK.

CONCLUSIONS

The results of this study highlight the requirement for the thorough washing of vegetables prior to their consumption, especially those such as spinach which may be eaten without first peeling or cooking, and effective farm biosecurity measures to minimise access to farmland by definitive host species of Toxocara spp.

Detection of Giardia duodenalis and Toxoplasma gondii in soil and water samples in the Quindío River basin, Colombia

Two zoonotic protozoan pathogens, Giardia duodenalis and Toxoplasma gondii, are important causes of waterborne infections in the Quindío region in Colombia. No previous data exist on how contamination occurs at the source for drinking water consumed by the human population in this region. Our aim was to describe the frequency of G. duodenalis and T. gondii DNA in 11 sampling points during a five-month period in water and adjacent soil at the Quindío River basin (Andean region in the central western part of Colombia). The study employed nested PCR for T. gondii, using the B1 gene as the amplification target, and single-round PCR for G. duodenalis assemblage A and assemblage B, amplifying the gdh gene, followed by DNA sequencing. In 50 soil samples, 28% (14/50) were positive for T. gondii. For G. duodenalis, distribution was in equal parts for assemblage A (8%; 4/50) and assemblage B (8%, 4/50). Genotyping of T. gondii sequences showed two soil samples with type I strain, another two samples of soil with type III strain, but most samples were of unidentified strains. In water samples, T. gondii was detected in 9.1% (5/55), G. duodenalis assemblage A in 34.5% (19/55), and G. duodenalis assemblage B in 12.7% (7/55). T. gondii DNA positivity was associated with lower soil temperature (p = 0.0239). Presence of G. duodenalis and T. gondii was evidenced in soil and water samples in the Quindío River basin, indicating soil as the potential source of contamination for the river that it is destined for human consumption. Monitoring these protozoa in drinking water is necessary to prevent public health risks in human populations.