Transboundary zoonotic diseases, several of which are vector borne, can maintain a dynamic focus, and have pathogens circulating in geographic regions encircling multiple geopolitical boundaries. Global change is intensifying transboundary problems including the spatial variation of the risk and incidence of zoonotic diseases. The complexity of these challenges can be greater in areas where rivers delineate international boundaries and encompass transitions between ecozones. The Rio Grande serves as a natural border between the US State of Texas and the Mexican States of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Not only millions of people live in this transboundary region but also a substantial movement of goods and people pass through it everyday. Moreover, it occurs over a region that functions as a corridor for animal migrations, and thus links the Neotropic and Nearctic biogeographic zones, with the latter being a known foci of zoonotic diseases. However, the pathogenic landscape of important zoonotic diseases in the south Texas-Mexico transboundary region remains to be fully understood. An international perspective on the interplay between disease systems, ecosystem processes, land use, and human behaviors is applied here to analyze landscape and spatial features of Venezuelan equine encephalitis, Hantavirus disease, Lyme Borreliosis, Leptospirosis, Bartonellosis, Chagas disease, human Babesiosis, and Leishmaniasis. Surveillance systems following the One Health approach with a regional perspective will help identifying opportunities to mitigate the health burden of those diseases on human and animal populations. It is proposed that the Mexico-US border, along the Rio Grande region be viewed as a continuum landscape where zoonotic pathogens circulate regardless of national borders.

Babesia bovis and Babesia bigemina are causative agents of bovine babesiosis, a tick-borne disease of cattle in tropical and subtropical regions. Babesia spp. infection adversely affects cattle health and can be fatal resulting in considerable economic loss worldwide. Under endemic stability conditions, herds contain high numbers of chronically infected, asymptomatic carrier animals, in which no parasitemia is detected by microscopic blood smear examination. In addition to bovines, also water buffaloes are infected by both Babesia spp. commonly leading to a subclinical infection. The infection rate (by nPCR) and herd exposure (by IFAT) of bovines and water buffaloes reared under similar field conditions in an area of endemic stability were determined and compared. In order to optimize direct parasite detection, highly sensitive nPCR assays were developed and applied, allowing the detection of as little as 0.1 fg DNA of each Babesia pathogen. Significantly lower percentages (p<0.001) of seropositive water buffaloes compared to bovines were observed for B. bovis (71.4% vs. 98%) and B. bigemina (85% vs. 100%). Interestingly, in comparison, differences noticed between water buffaloes and bovines were considerably larger with direct parasite detection by nPCR (16.2% vs. 82.3% and 24% vs. 94.1% for B. bovis and B. bigemina, respectively). As expected, bovines subjected to monthly acaricide applications exhibited a significant lower infection rate as determined by nPCR than bovines not subjected to these measures (B. bovis 33.3% vs. 90.7%, p<0.001; B. bigemina 80% vs. 96.5%, p<0.001, for treated vs. untreated animals). Interestingly no differences between these groups were observed with respect to seropositivity, suggesting similar rates of parasite exposure (B. bovis 100% vs. 97.7%, p<0.001; B. bigemina 100% vs. 100%, p<0.001). Importantly, a significantly higher number of water buffaloes as determined by nPCR were infected when reared jointly with bovines not subjected to tick control than when reared jointly with bovines subjected to tick control (B. bovis 31.6% vs. 9.5%, p<0.01; B. bigemina 42.1% vs. 9.5%, p<0.01, for water buffaloes reared with untreated vs. treated bovines) and/or when reared without bovines (B. bovis 31.6% vs. 11.6%, p<0.01; B. bigemina 42.1% vs. 20%, p<0.01). An accumulation of seropositivity and a decline of infection rates were observed in older animals, while differences observed with regard to gender may warrant further investigation. In summary, our findings suggest that water buffaloes are much more capable to limit or eliminate Babesia infection, possibly due to a more capable immune defense. Furthermore, an increased Babesia spp. parasite reservoir of bovines seems to increase the infection rate of water buffaloes when both are reared on the same pasture.

ObjectiveTo determine the prevalence of infection with intestinal parasites in 101 dogs in an animal shelter in Veracruz, Mexico, and investigate whether any general characteristics of the dogs were associated with infections.MethodsParasitological examination of fecal samples from the dogs was performed by means of centrifuge-flotation using Sheather's sucrose and zinc sulfate flotation media. In addition, hematocrit was determined in each canine blood sample.ResultsIntestinal parasites were found in 99 (98.0%) of the 101 dogs studied. About five different intestinal parasites were identified: Ancylostoma caninum in 89 dogs (88.1%), Giardia canis in 46 (45.5%), Uncinaria stenocephala in 43 (42.6%), Trichuris vulpis in 19 (18.8%) and Strongyloides canis in 16 (15.8%). Multivariate analysis showed: 1) Giardia infection was associated with young age and mixed breed; 2) Ancylostoma was associated with young age and no rabies vaccination; and 3) Strongyloides was associated with no rabies vaccination. Uncinaria and Trichuris infections were not associated with the variables assessed.ConclusionsA high prevalence of intestinal parasites was found in the dogs studied. This suggests that the environment is highly contaminated with intestinal parasites. Preventive and therapeutic measures should be taken against infection with intestinal parasites in dogs in this region