Investigating seagrass in Toxoplasma gondii transmission in Florida (Trichechus manatus latirostris) and Antillean (T. m. manatus) manatees

A systematic review, meta-analysis and meta-regression of the global prevalence of Toxoplasma gondii infection in wild marine mammals and associations with epidemiological variables

Toxoplasma gondii infection in wild marine mammals is a growing problem and is associated with adverse impacts on marine animal health and public health. This systematic review, meta-analysis and meta-regression estimates the global prevalence of T. gondii infection in wild marine mammals and analyzes the association between T. gondii infection and epidemiological variables. PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure, and Wanfang Data databases were searched until 30 May 2021. Eighty-four studies (n = 14,931 wild marine mammals from 15 families) were identified from literature. The overall pooled prevalence of T. gondii infection was 22.44% (3,848/14,931; 95% confidence interval (CI): 17.29% - 8.04%). The prevalence in adult animals 21.88% (798/3119; 95% CI: 13.40 -31.59) was higher than in the younger age groups. North America had a higher prevalence 29.92% (2756/9243; 95% CI: 21.77 - 38.77) compared with other continents. At the country level, the highest prevalence was found in Spain 44.26% (19/88; 95%CI: 5.21 - 88.54). Regarding climatic variables, the highest prevalence was found in areas with a mean annual temperature >20°C 36.28% (171/562; 95% CI: 6.36 - 73.61) and areas with an annual precipitation >800 mm 26.92% (1341/5042; 95% CI: 18.20 - 36.59). The subgroup and meta-regression analyses showed that study-level covariates, including age, country, continent, and mean temperature, partly explained the between-study heterogeneity. Further studies are needed to investigate the source of terrestrial to aquatic dissemination of T. gondii oocysts, the fate of this parasite in marine habitat and its effects on wild marine mammals. This article is protected by copyright. All rights reserved.

Recent epidemiologic and clinical importance of Toxoplasma gondii infections in marine mammals: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. T. gondii causes mortality in several species of marine mammals, including threatened Southern sea otters (Enhydra lutris) and endangered Hawaiian monk seals (Monachus schauinslandi). Marine mammals are now considered sentinels for environmental exposure to protozoan agents contaminating marine waters, including T. gondii oocysts. Marine mammals also serve as food for humans and can result in foodborne T. gondii infections in humans. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, and genetic diversity of T. gondii infecting marine mammals in the past decade. The role of genetic types of T. gondii and clinical disease is discussed.

Using Ecological Modelling to Assess the Long-Term Survival of the West-Indian Manatee (Trichechus manatus) in the Panama Canal

There is evidence of a thriving population of West-Indian manatee (Trichechus manatus) in the Panama Canal, although it is not clear if they are descendants of a small group of introduced manatees or if manatees have entered the Canal from the Caribbean through the Canal locks. This study describes the development and application of an individual-based model to assess the survival of a population of West-Indian manatees in the Panama Canal. In addition, we seek to determine the effects of isolation, predation, and mortality on long term survival. The model was parameterized using empirical data collected from the literature to every extent possible. A sensitivity analysis was performed to evaluate the model’s sensitivity to changes in the used parameters. Four scenarios were modeled to understand under which conditions the original population could have been maintained over time. Our results show that the manatee population would have collapsed quite quickly after its initial introduction and that only through the addition of several individuals into the lake over the years could the population have survived until the present day. Our results have important implications for the long-term conservation of this endangered species.