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Bartonella spp. are facultative intracellular vector-borne bacteria associated with several emerging diseases in humans and animals all over the world. The potential for involvement of ticks in transmission of Bartonella spp. has been heartily debated for many years. However, most of the data supporting bartonellae transmission by ticks come from molecular and serological epidemiological surveys in humans and animals providing only indirect evidences without a direct proof of tick vector competence for transmission of bartonellae. We used a murine model to assess the vector competence of Ixodes ricinus for Bartonella birtlesii. Larval and nymphal I. ricinus were fed on a B. birtlesii-infected mouse. The nymphs successfully transmitted B. birtlesii to naïve mice as bacteria were recovered from both the mouse blood and liver at seven and 16 days after tick bites. The female adults successfully emitted the bacteria into uninfected blood after three or more days of tick attachment, when fed via membrane feeding system. Histochemical staining showed the presence of bacteria in salivary glands and muscle tissues of partially engorged adult ticks, which had molted from the infected nymphs. These results confirm the vector competence of I. ricinus for B. birtlesii and represent the first in vivo demonstration of a Bartonella sp. transmission by ticks. Consequently, bartonelloses should be now included in the differential diagnosis for patients exposed to tick bites.

The reported number of cases of Lyme disease, Borrelia burgdorferi sensu lato, is thought to have increased in the UK over the past decade, but consistent surveillance data are lacking. Here the prevalence of B. burgdorferi in ticks attached to pet dogs was examined – using them as sentinels for human disease risk. Dogs give a good indication of the exposure of their human owners to infected ticks, since they largely share the same environment and visit the same outdoor areas. PCR was used to test 739 tick samples collected from 3534 dogs selected at random as they visited veterinary practices over a period of six months. Overall, the prevalence of infected ticks on all dogs was 0.5% giving an estimated 481 infected ticks per 100,000 dogs. The data suggest that the prevalence of Borrelia in the UK tick population is considerably higher than most recent estimates indicate.

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Tick-borne babesiosis is a less well known but potent disease
By Maia Smith
January 25, 2012

Babesiosis is about the closest most Americans will ever come to experiencing malaria, and like malaria its symptoms range from crippling to lethal to none at all. Both are vector-borne diseases (mosquitoes in the case of malaria and deer ticks for babesiosis).
Both diseases infect the spleen and liver; the symptoms are similar; the pathogens are closely related and are treatable by the same drugs. However, babesiosis is one of the lesser known tick-borne diseases: not that it doesn’t occur, but doctors outside of tick hotspots may not know much about it or know when to look for it.
It’s not too surprising that I came down with babesiosis last summer; what is surprising, is that I got cured. For that, I credit the Red Cross.
Although there is no FDA-licensed test to screen blood for babesiosis at this time, the Red Cross does selectively test blood donations and conducts research studies. A few weeks after I donated, I got a letter in the mail, informing me that I had tested positive for babesiosis.
I hadn’t felt particularly sick; sure there were times I’d felt better, but there were also times I’d felt worse and still had to go to school. I called up Island Health Care, who squeezed me in for a blood test that same day.  They prescribed atovaquone, a drug known as malarone when it’s used to treat malaria. I took the drug, felt better, and two months later tested clean.
Just because I didn’t look sick, doesn’t mean I didn’t have the disease. If my blood had been given to someone who was already sick from something else, it could have killed them. Old people are especially susceptible; so are HIV patients, little kids and people without a spleen. Since 1979, transfused babesiosis has infected at least 70 people, of whom 12 died, according to the Red Cross.

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It has long been known that ticks harbor Bartonella and that humans who have Lyme disease may also have Bartonellosis. However, the actual transmission of Bartonella from tick to host has not been demonstrated until a mouse study by Drs Reis and colleagues was published in May 2011. The study is available free on line for those interested. “This work represents the first in vivo demonstration of a Bartonella sp. transmission by ticks. It . . . corroborate[s] a prospect that ticks play a role in the natural cycles of some of the bartonellae including those pathogenic for humans. Consequently, bartonelloses should be included in the differential diagnosis for patients exposed to tick bites.”
The study also found that transstadial transmission is high.  This means that bartonella  survive in the tick through the molt from one life stage to another, for example from nymphal ticks to adult ticks. It had been thought that the possible mechanism of transmission of bartonella might be through contaminated tick feces. funded a study at UC Davis pursuing this theory. However, this study confirms that transmission to the host occurs with saliva and not through contaminated feces.

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