Search USGS⌕ Search
Home/Archive/USGS

USGS · 1013893

Control methods for snail-borne zoonoses

G. L. Hoffman
View original source ↗Export metadata ↓

Abstract

All trematodes which cause infections and diseases in humans (zoonoses) require snails for their first intermediate host. Some have additional intermediate hosts such as crustaceans, fishes and frogs. In this paper I have discussed the use of various procedures for controlling snail populations thereby reducing the population of trematodes whose cercariae penetrate the skin of man, or which are acquired by eating raw aquatic vegetation such as watercress, or which cause pathology in fish. Biological, chemical, and physical snail control techniques are discussed. The most promising molluscucides are copper compounds, Bayluscide, biocidal rubber and molluscicidal bait.

Explore related subjects

Journal of Wildlife DiseasesArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

G. L. Hoffman. 1970. Control methods for snail-borne zoonoses. https://doi.org/10.7589/0090-3558-6.4.262

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Fipronil baits as emerging tools for flea control and plague mitigation: Experiments with cricetid mice on prairie dog colonies

Plague is a zoonotic disease of mammalian hosts and flea vectors. Wildlife biologists most commonly mitigate plague by controlling flea populations. We evaluated the efficacy of edible baits for systemic flea control with two cricetid species on colonies of black-tailed prairie dogs ( Cynomys ludovicianus ): the western deer mouse ( Peromyscus sonoriensis ) and the northern grasshopper mouse ( Onychomys leucogaster ). We tested grain bait with 0.005% fipronil by weight and “FipBit” pellets with 0.46–1.52 mg of fipronil/pellet. Flea prevalence was assessed via combing of live-trapped mice. In one experiment with fipronil grain bait and FipBits ( n =564 combings), flea prevalence declined from 74% (grain) and 45% (FipBits) before treatments to 0% for both treatments from 30–44 d and from 324–413 d after treatments. During a second experiment with FipBits ( n =299 combings), flea prevalence declined from 13% to 32% before treatments to 0% from 11–15 d after treatments, but increased to 29–56% from 349–378 d after treatments. Results herein suggest annual fipronil bait treatments may be most effective for flea control.

Journal of Wildlife Diseases↗
USGS2026

Toxoplasma gondii: Challenges and perspectives in interpreting longitudinal seroprevalence data for a chronic parasitic infection

Toxoplasma gondii —the causative agent of toxoplasmosis—is a zoonotic pathogen of warm-blooded hosts. Infection causes mild-to-severe symptoms, including lethargy, fever, muscle pain, abortion, ocular disease, and encephalitis. Toxoplasma affects many vertebrate species, although felids are the only known definitive hosts. Seroprevalence in wildlife is often assessed using cross-sectional data, but few studies have tracked individual-level infections through time. We present a 4-yr dataset from white-tailed deer ( Odocoileus virginianus ) with repeated sampling of individuals that highlights challenges associated with assigning serostatus to individuals. Using a modified agglutination test, we observed seroconversion from seronegative to seropositive within individuals, as expected. Although toxoplasmosis is known to be a chronic disease, we also found reversion from seropositive to seronegative. Accurate assignment of serostatus is necessary for evaluating effects of infection on behavioral and physiologic outcomes. However, longitudinal data from individuals whose titers oscillate around the positive threshold present novel challenges. Therefore, we discuss the implications for assigning serostatus for chronic toxoplasmosis infection for three proposed approaches: 1) ever positive, always positive; 2) negative until positive and then always positive; and 3) status by sampling period. Clarifying which approach is used to assign serostatus when analyzing longitudinal T. gondii data may enable more meaningful comparisons across systems and studies.

Journal of Wildlife Diseases↗
USGS2025

Mortality events in Yuma myotis (Myotis yumanensis) due to white-nose syndrome in Washington, USA

The impacts of white-nose syndrome (WNS) on many bat species in eastern North America have been well documented because of the length of time that the causative agent, Pseudogymnoascus destructans ( Pd ), has been present and the ability to monitor bat hibernacula in that region. However, the disease outcomes for bat species in western North America are less known because of the more recent arrival of Pd and the challenges associated with monitoring hibernating bat populations in parts of the western US. We report on mortality events involving Yuma myotis ( Myotis yumanensis ) bats at two locations in King and Benton counties, Washington, US, that were attributed to WNS during the late winters of 2020–21 and 2024, respectively. All bats that were grossly examined had depleted subcutaneous white adipose tissue, tested positive for the presence of Pd , had histopathologic lesions consistent with WNS, and did not exhibit evidence of other disease processes that may have contributed to death. Mortality was likely higher than what was documented because the locations of the Pd -contaminated hibernacula from which the bats originated were inaccessible or unknown and thus could not be surveyed. These findings indicate that Yuma myotis may be highly susceptible to WNS, and close monitoring is warranted to understand how WNS will affect population trends in this (and other) western bat species.

Washington↗