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Populations of large wildlife are declining on local and global scales. The impacts of this pulse of size-selective defaunation include cascading changes to smaller animals, particularly rodents, and alteration of many ecosystem processes and services, potentially involving changes to prevalence and transmission of zoonotic disease. Understanding linkages between biodiversity loss and zoonotic disease is important for both public health and nature conservation programs, and has been a source of much recent scientific debate. In the case of rodent-borne zoonoses, there is strong conceptual support, but limited empirical evidence, for the hypothesis that defaunation, the loss of large wildlife, increases zoonotic disease risk by directly or indirectly releasing controls on rodent density. We tested this hypothesis by experimentally excluding large wildlife from a savanna ecosystem in East Africa, and examining changes in prevalence and abundance of Bartonella spp. infection in rodents and their flea vectors. We found no effect of wildlife removal on per capita prevalence of Bartonella infection in either rodents or fleas. However, because rodent and, consequently, flea abundance doubled following experimental defaunation, the density of infected hosts and infected fleas was roughly twofold higher in sites where large wildlife was absent. Thus, defaunation represents an elevated risk in Bartonella transmission to humans (bartonellosis). Our results (i) provide experimental evidence of large wildlife defaunation increasing landscape-level disease prevalence, (ii) highlight the importance of susceptible host regulation pathways and host/vector density responses in biodiversity-disease relationships, and (iii) suggest that rodent-borne disease responses to large wildlife loss may represent an important context where this relationship is largely negative.

Bats are natural reservoirs for a variety of pathogens (1). However, despite the risk to human health, persons around the world still intentionally handle bats, often without taking appropriate precautions. [...]

To the Editor: Human contact with wildlife is a leading cause of disease spillover. Bats, in particular, host numerous zoonotic pathogens, from henipaviruses to lyssaviruses (1). In Ghana, the straw-colored [...]

The human body louse and human head louse are generally recognized as 2 subspecies of Pediculus humanus (P. h. humanus and P. h. capitis, respectively) that have distinct ecologic preferences [...]

A tularemia outbreak, caused by Francisella tularensis type B, occurred among wild-caught, commercially traded prairie dogs. F. tularensis microagglutination titers in one exposed person indicated recent infection. These findings represent [...]

Plague, a disease caused by the bacterium Yersinia pestis, likely was transported to North America about 100 years ago via ship-borne rats and their fleas. The bacterium apparently was introduced [...]

More than 30 species of bartonellae that are highly prevalent in a wide variety of vertebrates have been described. Bartonella bacilliformis, B. henselae, and B. quintana are well-known human pathogens, [...]

Bartonella spp. are vector-borne bacteria associated with -D an increasing array of emerging zoonotic infections in humans and animals (1). Some Bartonella spp. are widely distributed among small mammals in [...]

Linking human disease events to likely sources of infection has been advanced by molecular epidemiology. However, isolates from several potential infection sources often are similar, and none may exactly match [...]

Abstract Background Bartonella tamiae, a newly described bacterial species, was isolated from the blood of three hospitalized patients in Thailand. These patients presented with headache, myalgia, anemia, and mild liver function abnormalities. Since B. tamiae was presumed to be the cause of their illness, these isolates were inoculated into immunocompetent mice to determine their relative pathogenicity in inducing manifestations of disease and pathology similar to that observed in humans. Methods Three groups of four Swiss Webster female mice aged 15-18 months were each inoculated with 106-7 colony forming units of one of three B. tamiae isolates [Th239, Th307, and Th339]. A mouse from each experimental group was sampled at 3, 4, 5 and 6 weeks post-inoculation. Two saline inoculated age-matched controls were included in the study. Samples collected at necropsy were evaluated for the presence of B. tamiae DNA, and tissues were formalin-fixed, stained with hematoxylin and eosin, and examined for histopathology. Results Following inoculation with B. tamiae, mice developed ulcerative skin lesions and subcutaneous masses on the lateral thorax, as well as axillary and inguinal lymphadenopathy. B. tamiae DNA was found in subcutaneous masses, lymph node, and liver of inoculated mice. Histopathological changes were observed in tissues of inoculated mice, and severity of lesions correlated with the isolate inoculated, with the most severe pathology induced by B. tamiae Th239. Mice inoculated with Th239 and Th339 demonstrated myocarditis, lymphadenitis with associated vascular necrosis, and granulomatous hepatitis and nephritis with associated hepatocellular and renal necrosis. Mice inoculated with Th307 developed a deep dermatitis and granulomas within the kidneys. Conclusions The three isolates of B. tamiae evaluated in this study induce disease in immunocompetent Swiss Webster mice up to 6 weeks after inoculation. The human patients from whom these isolates were obtained had clinical presentations consistent with the multi-organ pathology observed in mice in this study. This mouse model for B. tamiae induced disease not only strengthens the causal link between this pathogen and clinical illness in humans, but provides a model to further study the pathological processes induced by these bacteria.

The first molecular detection and finding on the prevalence of Bartonella in small mammals of several urban areas of Nepal is reported. The study identified genotypes belonging to seven known Bartonella species and five genotypes unknown in the species.

Fleas collected from rodents in the Negev Desert, southern Israel, are molecularly screened for Bartonella species, where two Bartonella gene fragments, corresponding to RNA polymerase B and citrate synthase (gltA), are targeted. The gltA analysis has shown that Bartonella genotypes are highly similar or identical to strains detected in rodent species from different parts of the world.

Twice a year in southwestern Nigeria, during a traditional bat festival, community participants enter designated caves to capture bats, which are then consumed for food or traded. We investigated the presence of Bartonella species in Egyptian fruit bats (Rousettus aegyptiacus) and bat flies (Eucampsipoda africana) from these caves and assessed whether Bartonella infections had occurred in persons from the surrounding communities. Our results indicate that these bats and flies harbor Bartonella strains, which multilocus sequence typing indicated probably represent a novel Bartonella species, proposed as Bartonella rousetti. In serum from 8 of 204 persons, we detected antibodies to B. rousetti without cross-reactivity to other Bartonella species. This work suggests that bat-associated Bartonella strains might be capable of infecting humans. [ABSTRACT FROM AUTHOR]