Rift Valley fever (RVF) is a re-emerging vector-borne zoonotic disease that causes outbreaks in humans and animals across Africa. To better understand RVF at human–animal interfaces, a prospective longitudinal survey of people, livestock, and mosquitoes was conducted from 2016 to 2018, in two regions of Tanzania, with distinct climatic zones (Iringa and Morogoro). Molecular and serological tools for testing (RT-qPCR and IgM/IgG ELISA) for RVF virus (RVFV) were used to assess infection and exposure in people and animals. Mosquitoes were collected quarterly from 10 sentinel locations. In total, 1385 acutely febrile humans, 4449 livestock, and 3463 mosquito pools were tested. In humans, IgM seroprevalence was 3.75% (n = 52/1385), and overall seroprevalence (IgM and/or IgG positive) was 8.30% (n = 115/1385). People from Iringa had a higher exposure risk than those from Morogoro (aOR 2.63), and livestock owners had an increased risk compared to non-owners (aOR 2.51). In livestock, IgM seroprevalence was 1.09%, while overall seroprevalence was 10.11%. A total of 68.4% of herds had at least one seropositive animal. Sentinel animal follow-up revealed that the probability of seroconversion was significantly higher in Morogoro. Low-level RVFV RNA was detected in 8 human and 22 mosquito pools. These findings indicate active transmission among vectors, livestock, and people during the study period, highlighting the need for One Health surveillance approaches for RVFV and other arboviruses.

The case study summarizes our team’s engagement with communities in the Ruaha Landscape of Tanzania, a landscape with abundant protected areas that provides habitat for a wide variety of wildlife and frequent opportunities for human-wildlife interaction through daily livelihood activities, such as agriculture, livestock production, and hunting and wild meat consumption. The study was implemented by the Health for Animals and Livelihood Improvement (HALI) project, a One Health research and capacity-building program investigating health at human-animal-environment interfaces in Tanzania.We applied an integrated multidisciplinary and participatory approach with extensive community engagement to explore wild meat consumption and the associated value chain in several villages bordering protected areas. Working with communities, we investigated factors driving wild meat consumption and trade and designed participatory wildlife sampling approaches for species confirmation and infectious disease testing, including establishing safe sample collection and transport from remote field environments to our university laboratory. Through collaborations with local community members, wild meat samples were opportunistically collected for virus testing and interviews were conducted to explore hunting practices, trade, and socioeconomics in an environment where subsistence hunting and poaching were under considerable legal pressure in the wake of anti-poaching policies. Our findings correlated commonly hunted wildlife species with collected tissue samples and identified risks for transmission of zoonotic diseases associated with hunting practices. Furthermore, we collaborated with stakeholders from participating villages in developing and implementing educational outreach programs aimed at improving awareness of the risks of wild meat to human health through the transmission of zoonotic diseases.© The Authors 2023

In endemic African areas, such as Tanzania, Brucella spp. cause human febrile illnesses, which often go unrecognized and misdiagnosed, resulting in delayed diagnosis, underdiagnosis, and underreporting. Although rapid and affordable point-of-care tests, such as the Rose Bengal test (RBT), are available, acceptance and adoption of these tests at the national level are hindered by a lack of local diagnostic performance data. To address this need, evidence on the diagnostic performance of RBT as a human brucellosis point-of-care test was reviewed. The review was initially focused on studies conducted in Tanzania but was later extended to worldwide because few relevant studies from Tanzania were identified. Databases including Web of Science, Embase, MEDLINE, and World Health Organization Global Index Medicus were searched for studies assessing the diagnostic performance of RBT (sensitivity and specificity) for detection of human brucellosis, in comparison to the reference standard culture. Sixteen eligible studies were identified and reviewed following screening. The diagnostic sensitivity (DSe) and specificity (DSp) of RBT compared to culture as the gold standard were 87.5% and 100%, respectively, in studies that used suitable “true positive” and “true negative” patient comparison groups and were considered to be of high scientific quality. Diagnostic DSe and DSp of RBT compared to culture in studies that also used suitable “true positive” and “true negative” patient comparison groups but were considered to be of moderate scientific quality varied from 92.5% to 100% and 94.3 to 99.9%, respectively. The good diagnostic performance of RBT combined with its simplicity, quickness, and affordability makes RBT an ideal (or close to) stand-alone point-of-care test for early clinical diagnosis and management of human brucellosis and nonmalarial fevers in small and understaffed health facilities and laboratories in endemic areas in Africa and elsewhere.

Background Many ecologically important plants are pollinated or have their seeds dispersed by fruit bats, including the widely distributed African straw-colored fruit bats (Eidolon helvum). Their ability to fly long distances makes them essential for connecting plant populations across fragmented landscapes. While bats have been implicated as a reservoir of infectious diseases, their role in disease transmission to humans is not well understood. In this pilot study, we tracked E. helvum to shed light on their movement patterns in Tanzania and possible contact with other species. Methods Tracking devices were deployed on 25 bats captured in the Morogoro Municipal and Kilombero District area near the Udzungwa Mountains of Tanzania. Nightly flight patterns, areas corresponding to foraging bouts and feeding roosts, and new day roosts were determined from bat movement data and characterized according to their proximity to urban built-up and protected areas. Sites for additional environmental surveillance using camera traps were identified via tracking data to determine species coming in contact with fruits discarded by bats. Results Tracking data revealed variability between individual bat movements and a fidelity to foraging areas. Bats were tracked from one to six nights, with a mean cumulative nightly flight distance of 26.14 km (min: 0.33, max: 97.57) based on data from high-resolution GPS tags. While the majority of their foraging locations were in or near urban areas, bats also foraged in protected areas, of which the Udzungwa Mountains National Park was the most frequented. Camera traps in fruit orchards frequented by tracked bats showed the presence of multiple species of wildlife, with vervet monkeys (Chlorocebus pygerythrus) observed as directly handling and eating fruit discarded by bats. Conclusions Because we observed multiple interactions of animals with fruits discarded by bats, specifically with vervet monkeys, the possibility of disease spillover risk exists via this indirect pathway. With flight distances of up to 97 km, however, the role of E. helvum in the seed dispersal of plants across both protected and urban built-up areas in Tanzania may be even more important, especially by helping connect increasingly fragmented landscapes during this Anthropocene epoch.

Deer mice (Peromyscus maniculatus) are abundant and widely distributed rodents in North America that occupy diverse habitats, including agricultural landscapes. Giardia and Cryptosporidium are common parasites in wildlife including deer mice, which may play a role in on-farm contamination of produce. An important step in assessing the risk of produce contamination by Cryptosporidium and Giardia shed by deer mice is to determine the prevalence, levels, and genotypes of (oo)cysts in mouse feces. A total of 63 (30.3%) and 53 (25.5%) of 208 deer mice trapped on 12 farms on the California Central Coast were positive for Cryptosporidium and Giardia, respectively. Of these mice, 41 (19.7%) contained both parasites. The odds of Cryptosporidium shedding were 2.5 to 5 times higher for mice trapped in autumn than for mice trapped in summer or spring. Female mice had a higher prevalence and two- to threefold higher levels of Cryptosporidium and Giardia compared with male mice. Female adults and female juveniles had the highest rates of contamination of the environment with Cryptosporidium and Giardia, respectively. We estimated that 20 infected deer mice inhabiting 1 ha of a typical leafy green produce farm in the study region could shed approximately 5.3 × 108 Cryptosporidium and 10.5 × 108 Giardia, respectively, per day into the environment. The small-subunit rRNA gene loci from a subset of protozoan isolates were sequenced and compared with existing sequences in GenBank. Multiple genotypes of Cryptosporidium and Giardia were found, and BLAST analyses suggest that Giardia and the majority of Cryptosporidium genotypes in deer mice circulate within various rodent populations, but some Cryptosporidium isolates possess zoonotic potential.

Significance Fresh produce has become the primary cause of foodborne illness in the United States. A widespread concern that wildlife vector foodborne pathogens onto fresh produce fields has led to strong pressure on farmers to clear noncrop vegetation surrounding their farm fields. We combined three large datasets to demonstrate that pathogen prevalence in fresh produce is rapidly increasing, that pathogens are more common on farms closer to land suitable for livestock grazing, and that vegetation clearing is associated with increased pathogen prevalence over time. These findings contradict widespread food safety reforms that champion vegetation clearing as a pathogen mitigation strategy. More generally, our work indicates that achieving food safety and nature conservation goals in produce-growing landscapes is possible.

ABSTRACT Recent outbreaks of food-borne illness associated with the consumption of produce have increased concern over wildlife reservoirs of food-borne pathogens. Wild rodents are ubiquitous, and those living close to agricultural farms may pose a food safety risk should they shed zoonotic microorganisms in their feces near or on agricultural commodities. Fecal samples from wild rodents trapped on 13 agricultural farms (9 produce, 3 cow-calf operations, and 1 beef cattle feedlot) in Monterey and San Benito Counties, CA, were screened to determine the prevalence and risk factors for shedding of several food-borne pathogens. Deer mice ( Peromyscus maniculatus ) were the most abundant rodent species trapped (72.5%). Cryptosporidium species (26.0%) and Giardia species (24.2%) were the predominant isolates from rodent feces, followed by Salmonella enterica serovars (2.9%) and Escherichia coli O157:H7 (0.2%). Rodent trap success was significantly associated with detection of Salmonella in rodent feces, while farm type was associated with fecal shedding of Cryptosporidium and Giardia . Seasonal shedding patterns were evident, with rodents trapped during the spring and summer months being significantly less likely to be shedding Cryptosporidium oocysts than those trapped during autumn. Higher rodent species diversity tended to correlate with lower fecal microbial prevalence, and most spatiotemporal pathogen clusters involved deer mice. Rodents in the study area posed a minimal risk as environmental reservoirs of E. coli O157:H7, but they may play a role in environmental dissemination of Salmonella and protozoa. Rodent control efforts that potentially reduce biodiversity may increase pathogen shedding, possibly through promotion of intraspecific microbial transmission.

A bstrAct : Outbreaks of foodborne illness associated with the consumption of leafy green produce from California and across the United States have heightened the need to identify vertebrate sources of these microbial hazards. Concern has focused on wildlife species that have direct access to the produce production environment and irrigation water supplies. Recent fecal surveys of California wildlife, feral animals, and livestock and companion animals are allowing regulators to compare the food safety risks of such pathogens as E. coli O157:H7 and Salmonella from these various animal species. In order to make valid food safety risk comparisons between wildlife, livestock, and companion animals, a variety of methodological and epidemiological issues need to be addressed in order to avoid substantial biases. For example, the amount of feces tested per animal can vary up to a 1000-fold, substantially biasing the probability of testing positive for large fecal contributors (e.g., cattle) compared to smaller wildlife (e.g., deer mice). Many wildlife species intrude and forage as a group in fields of produce, which can lead to in-field defecation, substantially, elevating the risk of microbial contamination compared to many larger animal species that do not have direct access to produce fields due to fencing. This paper highlights the technical challenges of making valid quantitative comparisons of microbial food safety risks from wildlife compared to other domestic animals. Proc. 25 th Vertebr. Pest Conf. (R. M. Timm, Ed.) Published at Univ. of Calif., Davis. 2012 . Pp. 100-103.

Outbreaks of foodborne illness associated with the consumption of leafy green produce from California and across the United States have heightened the need to identify vertebrate sources of these microbial hazards.Concern has focused on wildlife species that have direct access to the produce production environment and irrigation water supplies.Recent fecal surveys of California wildlife, feral animals, and livestock and companion animals are allowing regulators to compare the food safety risks of such pathogens as E. coli O157:H7 and Salmonella from these various animal species.In order to make valid food safety risk comparisons between wildlife, livestock, and companion animals, a variety of methodological and epidemiological issues need to be addressed in order to avoid substantial biases.For example, the amount of feces tested per animal can vary up to a 1000-fold, substantially biasing the probability of testing positive for large fecal contributors (e.g., cattle) compared to smaller wildlife (e.g., deer mice).Many wildlife species intrude and forage as a group in fields of produce, which can lead to infield defecation, substantially, elevating the risk of microbial contamination compared to many larger animal species that do not have direct access to produce fields due to fencing.This paper highlights the technical challenges of making valid quantitative comparisons of microbial food safety risks from wildlife compared to other domestic animals.

A year-long study was conducted to determine the fecal prevalence of Escherichia coli O157:H7 in three sheep ranches. Strain diversity and persistence were compared with multiple-locus variable-number tandem repeat analysis and pulsed-field gel electrophoresis. Ranch C, a feedlot, consisted of young sheep raised predominantly on a high-grain diet. The other two sites consisted of sheep raised on native pasture and a combination of native and irrigated pasture. Forty fecal samples were collected every month from each ranch. Samples were examined for E. coli O157:H7 by immunomagnetic separation and culture of the magnetic beads onto selective media. Detection of virulence markers in positive isolates was determined by PCR. E. coli O157:H7 was isolated from 100 (22.7%) of 440 fecal samples collected from ranch C. On ranch B, 9 (1.9%) of the 480 fecal samples were positive for the pathogen, while none of the samples from ranch A were positive. On ranch C, the odds of detecting E. coli O157:H7 was 3.2 times greater during the warmer months compared with the cooler months of the year. There was no association between days spent in the feedlot and fecal prevalence of the pathogen (P = 0.62). Most multiple-locus variable-number tandem repeat analysis types were isolated only once from ranch C (14 of 23), but several strains were isolated over 4 to 6 months, often in many intervening negative months. This study revealed that the prevalence of E. coli O157:H7 can be high in some sheep ranches in California, especially in feedlots where young sheep are fed predominantly high-grain rations.