Two recombinant Taenia solium oncosphere antigens, designated TSOL18 and TSOL45-1A, were investigated as vaccines to prevent transmission of the zoonotic disease cysticercosis through pigs. Both antigens were effective in inducing very high levels of protection (up to 100%) in three independent vaccine trials in pigs against experimental challenge infection with T. solium eggs, which were undertaken in Mexico and Cameroon. This is the highest level of protection that has been achieved against T. solium infection in pigs by vaccination with a defined antigen. TSOL18 and TSOL45-1A provide the basis for development of a highly effective practical vaccine that could assist in the control and, potentially, the eradication of human neurocysticercosis.

A survey to detect human taeniasis and cysticercosis was conducted in a community in Yucatan state, Mexico, an area endemic for Taenia solium. Information on the environmental, demographic and risk factors associated with transmission of T. solium within the community was recorded on questionnaires. Although no Taenia eggs or proglottides were found in the initial faecal samples collected from each of the 475 subjects, the results of a capture-ELISA for T. solium coproantigen were positive for 10 of the subjects (of both genders and various ages). After treatment with niclosamide, proglottides were detected in purge samples from seven of these 10 subjects. The prevalence of parasitologically confirmed taeniasis was therefore 1.5% (seven in 475). The other three ELISA-positive cases delayed supplying faecal material post-treatment, and it is nuclear whether they had expelled proglottides before providing the samples. All 10 ELISA-positive subjects became ELISA-negative after treatment. Seroprevalence of human cysticercosis, based on the detection in immunoblots of antibodies to antigens of 8- and 26-kDa from a crude saline extract of T. solium metacestodes, was 3.7% (i.e. five positives out of 134 subjects). None of the seropositive cases demonstrated clinical symptoms of infection. Again, the positive cases were of both genders and various ages. Although tongue palpation indicated that 17 (23%) of 75 pigs kept within the community had T. solium cysticercosis, the results of immunoblotting demonstrated antibodies to the 8- and/or 26-kDa antigens of T. solium in 26 (35%). The pigs allowed to roam throughout the community were far more likely to have cysticercosis than those kept in pens (odds ratio = 42, with a 95% confidence interval of 5.05-920.2; P < 0.00001). Not surprisingly, the risk factors associated with human taeniasis and cysticercosis included the eating of infected pork and close proximity to a carrier of T. solium. The main risk factor identified for porcine cysticercosis was free-range husbandry, permitting access to human faeces. This is the first comprehensive report of taeniasis and cysticercosis in a rural population from the Yucatan peninsula of Mexico.

Experimental results showed that the gill monogenean Cichlidogyrus sclerosus and its host, the Nile tilapia Oreochromis niloticus, exhibited significant numerical and physiological responses after exposure to sediments polluted with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and heavy metals in comparison with control fishes. After 15 days of exposure, C. sclerosus abundance significantly increased in treatments with low to fairly high sediment pollutant concentrations, but declined at high sediment pollutant concentrations. Hypertrophy and hyperplasia in secondary gill lamellae and the spleen melanomacrophage centers were significantly higher at extremely high sediment pollutant concentrations compared with the controls. Spleen lymphocyte and monocyte counts were significantly lower at extremely high sediment pollutant concentrations and were significantly correlated with high fluorescent aromatic compound concentrations measured as PAH exposure indicators. A multivariate redundancy analysis showed significant statistical association between sediment pollutant concentration, C. sclerosus abundance, and tilapia physiological variables. The polluted sediments negatively affected monogenean abundance and induced immunosuppression in hosts, consequently increasing histological damage in hosts and allowing persistent C. sclerosus infection. This study documents evidence suggesting that C. sclerosus and its host are indeed excellent models to test environmental quality in tropical freshwater ecosystems.

SummaryTaenia solium, a human cestode parasite endemic throughout most of South-east Asia, causes a number of public health and economic problems. The parasite is endemic in Bali due to a mix of cultural and religious practices. Immunoepidemiological investigation of three rural communities revealed a taeniasis prevalence of 0.72% (3/415). One of the three cases was due to Taenia solium, the other two to Taenia saginata. A further nine cases of Taenia infection were identified from patients from villages surrounding the chosen communities, suggesting that prevalence levels may be higher in other areas. Seroprevalence of human cysticercosis by immunoblot was 1.65% (6/363), though all cases were detected within a single community (6/115; prevalence 5.22%). Several other cases of subcutaneous cysticercosis were identified from local clinics, suggesting continued transmission of Taenia solium in the region. Other intestinal helminth parasites identified within the communities were Ascaris lumbricoides (29.9%), Trichuris trichiuria (33.9%) and hookworm (8.2%).

Caribbean spiny lobsters Panulirus argus are socially gregarious, preferring shelters harboring conspecifics over empty shelters. In laboratory trials, however, healthy lobsters strongly avoided shelters harboring lobsters infected with the highly pathogenic Panulirus argus Virus 1 (PaV1). Because PaV1 is transmitted by contact, this behavior may thwart its spread in wild lobsters. In a field experiment conducted from 1998 to 2002 in a shelter-poor reef lagoon (Puerto Morelos, Mexico), densities of juvenile P. argus increased significantly on sites enhanced with artificial shelters (casitas) but not on control sites. Because PaV1 emerged in this location during 2000, we reexamined these data to assess whether casitas could potentially increase transmission of PaV1. In 2001, PaV1 prevalence was 2.5% and the cohabitation level (percentage of healthy lobsters cohabiting with diseased lobsters) was similar between natural shelters (3.5%) and casitas (2.4 %). The relative lobster densities in casita sites and control sites did not change significantly before (1998-1999) or after (2001-2002) the disease emergence. In late 2006, data from casita sites showed a significant increase in prevalence (10.9%) and cohabitation level (29.4%), but no significant changes in lobster density. In May 2006, casitas were deployed on shelter-poor sites within Chinchorro Bank, 260 km south of Puerto Morelos. In late 2006, prevalence and cohabitation level were 7.4 and 21.7%, respectively. Our results are inconclusive as to whether or not casitas increase PaV1 transmission, but suggest that across shelter-poor habitats, lobsters make a trade-off between avoiding diseased conspecifics and avoiding predation risk.