Apolipoprotein-ε4 is associated with higher fecundity in a natural fertility population.

In many populations, the apolipoprotein-ε4 (APOE-ε4) allele increases the risk for several chronic diseases of aging, including dementia and cardiovascular disease; despite these harmful effects at later ages, the APOE-ε4 allele remains prevalent. We assess the impact of APOE-ε4 on fertility and its proximate determinants (age at first reproduction, interbirth interval) among the Tsimane, a natural fertility population of forager-horticulturalists. Among 795 women aged 13 to 90 (20% APOE-ε4 carriers), those with at least one APOE-ε4 allele had 0.3 to 0.5 more children than (ε3/ε3) homozygotes, while those with two APOE-ε4 alleles gave birth to 1.4 to 2.1 more children. APOE-ε4 carriers achieve higher fertility by beginning reproduction 0.8 years earlier and having a 0.23-year shorter interbirth interval. Our findings add to a growing body of literature suggesting a need for studies of populations living in ancestrally relevant environments to assess how alleles that are deleterious in sedentary urban environments may have been maintained by selection throughout human evolutionary history.

Effect of Urbanization on Neospora caninum Seroprevalence in White-Tailed Deer (Odocoileus virginianus).

The protozoan Neospora caninum is transmitted between domestic and wildlife species. Urbanized environments and deer density may facilitate this transmission and play a critical role in the spillover of N. caninum from domestic animals to wildlife. White-tailed deer (Odocoileus virginianus; WTD) are an important intermediate host for maintaining the sylvatic cycle of N. caninum in the USA. Here, we assayed serum samples from 444 WTD from a nature reservation across a suburban to urban gradient in Ohio, USA. Antibodies to N. caninum were found by using a recombinant NcGRA6 ELISA in 23.6% (105/444). Significant risk factors for seropositivity were age class and urbanization. Deer from urbanized environments were at greater odds of being seropositive (89/323, 27.6%) than those from suburban habitats (16/121, 13.2%), and this difference persisted when adjusting for age and sex. Age was also a significant risk factor with adults at greater odds to be seropositive than fawns and yearlings. We speculate the main route of exposure in WTD is ingestion of N. caninum oocysts from contaminated environments and urbanized habitats facilitate this exposure.

Seroprevalence of Toxoplasma gondii in White-Tailed Deer (Odocoileus virginianus) and Free-Roaming Cats (Felis catus) Across a Suburban to Urban Gradient in Northeastern Ohio.

Felids serve as the definitive host of Toxoplasma gondii contaminating environments with oocysts. White-tailed deer (WTD; Odocoileus virginianus) are used as sentinel species for contaminated environments as well as a potential source for human foodborne infection with T. gondii. Here we determine the seroprevalence of T. gondii in a WTD and felid population, and examine those risk factors that increase exposure to the parasite. Serum samples from 444 WTD and 200 free-roaming cats (Felis catus) from urban and suburban reservations were tested for T. gondii antibodies using the modified agglutination test (MAT, cut-off 1:25). Antibodies to T. gondii were found in 261 (58.8%) of 444 WTD, with 164 (66.1%) of 248 from urban and 97 (49.5%) of 196 from suburban regions. Significant risk factors for seroprevalence included increasing age (P < 0.0001), reservation type (P < 0.0001), and household densities within reservation (P < 0.0001). Antibodies to T. gondii were found in 103 (51.5%) of 200 cats, with seroprevalences of 79 (51%) of 155 and 24 (53.3%) of 45 from areas surrounding urban and suburban reservations, respectively. Seroprevalence did not differ by age, gender, or reservation among the cats' sample. Results indicate WTD are exposed by horizontal transmission, and this occurs more frequently in urban environments. The difference between urban and suburban cat densities is the most likely the reason for an increased seroprevalence in urban WTD. These data have public health implications for individuals living near or visiting urban areas where outdoor cats are abundant as well as those individuals who may consume WTD venison.