Social evolution: Diverse divisions of labor in trematode parasites.

Some animal societies solve problems, like foraging or defense, by cooperatively dividing labor. A new discovery highlights that trematodes are unique in forming different societies at multiple parts of their complex life cycle with distinct divisions of labor to solve different problems.

Potential for Emergence of Foodborne Trematodiases Transmitted by an Introduced Snail (Melanoides tuberculata) in California and Elsewhere in the United States.

We document that 3 human-infectious trematodes and their introduced first intermediate host snail (Melanoides tuberculata) are widespread throughout southern California. We surveyed 41 fishing localities, 19 of which harbored snails infected with zoonotic trematodes. Two of the parasites, Haplorchis pumilio and Centrocestus formosanus, are fishborne intestinal trematodes recognized as being important human pathogens in other areas of the world; the third, Philophthalmus gralli, can infect the human eye. An additional 5 species detected infecting M. tuberculata are likely of little direct threat to people; however, they may be recently introduced to the Americas, highlighting the risk that additional pathogenic trematodes transmitted by the snail in its native range could be introduced to the United States. The current, possible human-infection risk in California clarifies the need to consider the introduced snail and its parasites from a public health perspective anywhere in the United States the snail has been introduced.

We report that 3 human-infecting trematodes and their introduced intermediate host snail are widespread in southern California freshwater fishing localities. Eating undercooked or underfrozen fish is the way people get infected by 2 of the parasite species, which are recognized as important human pathogens in other areas of the world. We also found 5 non­human-infectious trematodes carried by the snail that may be cointroduced, highlighting the possibility that other dangerous pathogens transmitted by the snail where it is native could arrive later or already be present in the United States. The common presence of the human-infecting fishborne trematodes at fishing localities, the widespread popularity of eating uncooked fish (eg, as sashimi, sushi, poke, or ceviche), and the potential for additional human-infecting trematodes to also be introduced, all justify consideration of the introduced snail and its parasites from a public health perspective in California and other areas in the United States where the parasites or the host snail have already been reported.

Evidence gaps and diversity among potential win-win solutions for conservation and human infectious disease control.

As sustainable development practitioners have worked to "ensure healthy lives and promote well-being for all" and "conserve life on land and below water", what progress has been made with win-win interventions that reduce human infectious disease burdens while advancing conservation goals? Using a systematic literature review, we identified 46 proposed solutions, which we then investigated individually using targeted literature reviews. The proposed solutions addressed diverse conservation threats and human infectious diseases, and thus, the proposed interventions varied in scale, costs, and impacts. Some potential solutions had medium-quality to high-quality evidence for previous success in achieving proposed impacts in one or both sectors. However, there were notable evidence gaps within and among solutions, highlighting opportunities for further research and adaptive implementation. Stakeholders seeking win-win interventions can explore this Review and an online database to find and tailor a relevant solution or brainstorm new solutions.

Lynnia grapsolytica n. gen, n. sp. (Ciliophora: Apostomatida: Colliniidae), a Deadly Blood Parasite of Crabs with a Novel Pseudocytopharynx.

We describe a new genus and species of blood-dwelling apostome ciliate, Lynnia grapsolytica n. gen., n. sp. (Apostomatida: Colliniidae). A distinct kinety "hook" pattern on the tomite's posterior ventral face, coupled with its marine habitat and use of a decapod host, readily distinguishes this ciliate from all known colliniids. We detected the parasite in ~12% of Pachygrapsus crassipes (Brachyura: Grapsidae) crabs in a California estuary and confirmed its presence at a Baja California rocky intertidal site. As existing methods failed to adequately stain this ciliate, we developed a new miniaturized silver carbonate impregnation staining method that produced excellent somatic and nuclear stains in all five observed cell types. A possibly unique trait is the active invagination of the tropho-tomont's anterior to form a temporary "pseudocytopharynx," likely used for feeding. Histological examination revealed that the ciliate invaded and damaged skeletal muscle, the heart, connective tissues, and gonads. Survivorship analysis indicated that infected crabs experienced 2.6 times greater daily mortality than uninfected crabs. Laboratory and field experimental infection attempts failed, suggesting a complex life cycle with outside-host development. Phylogenetic analysis at the 18S and COI loci confirmed the ciliate's placement in the Colliniidae. We emend the diagnosis of Family Colliniidae.