The finding -- not yet replicated in people -- raises hope for developing a safer and more effective way to combat transmission of both diseases among humans.

"We're the first to show that you can use a sustained-release formulation of this antibiotic to completely inhibit both infections when transmitted simultaneously by ticks," said study author Dr. Nordin Zeidner, chief of the U.S. Centers for Disease Control and Prevention's Vector-Host Laboratory, in Fort Collins, Colo.

Zeidner stressed, however, that the treatment shouldn't be thought of as a vaccine for either disease but rather as a potentially novel method to inhibit infection following exposure.

"But this is, nevertheless, an important proof of concept," he added, "because we know that a lot of ticks infected with Lyme disease also carry this co-infection."

The study was published in the April issue of the Journal of Medical Microbiology.

Lyme disease is the most common tick-borne illness in the United States, with approximately 20,000 new cases diagnosed in 2006, according to the CDC. It's transmitted by blacklegged ticks infected with the bacterium Borrelia burgdorferi. The ticks are common in the upper Midwest and Northeastern regions of the United States and can also carry other diseases such as human granulocytic anaplasmosis, posing a risk for combined infections.

People infected with Lyme disease can experience flu-like fever, weakness, headache, fatigue, and skin rashes. If left untreated, the disease can spread to the joints, as well as to the heart and the nervous system. Symptoms of anaplasmosis can include fever, headache, lethargy, rashes and gastrointestinal problems, according to the CDC.

Efforts to develop a vaccine for either Lyme disease or anaplasmosis haven't met with much success. So, doctors stress prevention measures when outdoors, such as the use of insect repellants with DEET and covering up with clothing.

As for treatment, the CDC suggests that two to four weeks of repeated oral antibiotics -- such as doxycyline, amoxicillin, and cefuroxime axetil -- can effectively treat most patients, particularly when the infection is caught early.

But, some doctors and patient-advocacy groups have argued that chronic infections may require a much longer antibiotic regimen -- despite treatment guidelines issued in 2006 by the Infectious Disease Society of America that warned that long-term antibiotic use raises the risk for drug resistance and medical complications.

Searching for a way to address such concerns, Zeidner and his colleagues focused on the potential benefits of a single dose sustained-release version of the antibiotic doxycycline. They noted that a standard single oral dose of the drug is quickly cleared from the body (about eight hours) -- requiring continuous and repeated use. By contrast, the sustained-release version is injected and continues to circulate for approximately 19 days after delivery.

In their mice study, the researchers exposed 6-week-old female mice to ticks infected with both Lyme disease and anaplasmosis. Three days after infection, some mice were randomly assigned to receive a single dose of either oral or sustained-release injected doxycycline, while others were given just water or a non-antibiotic compound.

The results: 100 percent of the mice injected with the long-acting antibiotic were fully protected from developing either disease. Only 20 percent to 30 percent of the mice given the oral antibiotic were similarly protected, the researchers said.

"I want to emphasize, however, that this is an animal model of disease we're looking at, and this formulation is not ready to put in people tomorrow," Zeidner cautioned. "It will take some time before it's ready for the clinic."

Dr. Raphael B. Stricker, recent past president of the International Lyme and Associated Diseases Society, described the new research as "outstanding."

"This work is very interesting," he said, "because they've found a way to target both Lyme disease and another very significant disease that up until just four years ago wasn't even recognized. And since the current treatment could involve taking antibiotics for months at a time, a single shot like this -- giving long-term protection and maybe even treatment -- could certainly end up being preferable."

More information

For more on treating Lyme disease, visit the CDC.

MONDAY, March 24 (HealthDay News) -- The use of fluoroquinones to treat children with multidrug-resistant tuberculosis can lead to the development of drug-resistant invasive pneumococcal disease, including severe pneumonia and meningitis.

That finding emerged from a study by researchers at the National Institute for Communicable Diseases in South Africa.

They analyzed 21,521 cases of children with invasive pneumococcal disease and screened 19,404 isolates (90 percent of all cases) for resistance to ofloxacin (a fluoroquinone). Minimum inhibitory concentrations (MIC) for all isolates were measured, and levofloxacin resistance was defined as an MIC of 4mg/L or more. The researchers assessed nose and throat pneumococcal carriage in 65 children in two TB hospitals where invasive pneumococcal disease caused by levofloxacin-resistant Streptococcus pneumoniae had been detected.

Twelve cases of invasive pneumococcal disease were identified as levofloxacin-resistant, all in children younger than 15 years old. There were five deaths among the 11 patients whose outcomes were known.

The researchers found that invasive pneumococcal disease caused by levofloxacin-resistant S. pneumoniae was associated with a history of TB treatment. Eight out of nine (89 percent) children with non-susceptible isolates had a history of TB treatment, compared to 396 of 2,202 (18 percent) of children with susceptible isolates. Among the hospitalized children with nose and throat pneumococcal carriage, nearly 100 percent of the bacteria were levofloxacin resistant.

"Our data suggest that the use of fluoroquinones to treat multidrug-resistant tuberculosis in children has led to the emergence of invasive pneumococcal diseases caused by levofloxacin-non-susceptible S. pneumoniae and its nosocomial spread among children," the researchers concluded.

The study was published by The Lancet and released Monday to coincide with World TB Day.

More information

The U.S. National Foundation for Infectious Diseases has more about pneumococcal disease.

MONDAY, March 10 (HealthDay News) -- Children cared for by the same doctor during their first six months of life are more likely than those examined by different doctors to receive proper screening for lead poisoning, anemia and tuberculosis by age 2, a U.S. study finds.

The study looked at 1,564 infants covered by Medicare. All the children were born at three Philadelphia-area hospitals between July 1999 and March 2001, and received health care at more than 120 different primary-care offices.

Lead toxicity in infants can lead to low intelligence later in life, iron-deficiency anemia can cause movement problems and damage sight or hearing, and tuberculosis can have serious complications for children.

Children most at risk -- such as those from urban, low-income families -- often don't receive proper screening for these problems, the study authors noted.

"Continuity of care may be of particular importance to vulnerable pediatric patients, such as those insured through the Medicaid program," principal investigator Dr. Evaline Alessandrini, a pediatrician at the Children's Hospital of Philadelphia, said in a prepared statement. "All health-care visits, not just well-child visits, are important in establishing relationships with families and meeting children's health-care needs."

She and her colleagues said efforts to improve infant outcomes should focus not only on increasing the number of visits to a primary-care doctor, but also reducing the number of pediatricians who treat a child. It's also important to identify which children are most at risk of not receiving continuity of care.

"In 2008, there's a lot of discussion about the purpose of primary care and the benefits children achieve by having a regular doctor. We don't want to forget the basics and, if there are simple ways to ensure those aspects of primary care are met, then we should find ways to get them done," Alessandrini said.

The study was published in the March issue of Pediatrics.

More information

The March of Dimes has more about screening tests for infants.

Researchers found that the rate of latent TB infection (LTBI) in the U.S. population in 1999-2000 was 4.2 percent. This does not include homeless people or those in prison. The current infection rate would have to be 1 percent and decreasing for the United States to meet its goal of TB incidence of less than one per million by 2010.

"Persons with LTBI are not infectious and cannot transmit TB to others, and only 5 to 10 percent of individuals with LTBI will go on to develop active TB, which is infectious. But because the risk of progression to TB can be substantially reduced by preventive treatment, it is crucial that LTBI be detected and treated," said study author Dr. Diane Bennett, of the U.S. Centers for Disease Control and Prevention.

Of the 11.2 million people with LTBI in the country in 1999-2000, only one in four had been diagnosed, and only 13 percent had been prescribed treatment, the data analysis revealed.

"The LTBI rates among non-Hispanic whites, 1.9 percent, is close to that required for TB elimination, but the far higher rates among all other groups make U.S. TB elimination by 2010 unlikely," wrote Bennett and colleagues.

The LTBI rate among people living below the poverty level was 6.1 percent, compared with 3.3 percent for those living above the poverty level. The analysis also found that the TB infection rate among foreign-born people was 18.7 percent, compared to 1.8 percent among people born in the United States. Of those, 12 percent of the foreign-born and 16 percent of the U.S.-born had received treatment.

"The higher LTBI rates among some subgroups suggest that specific public health actions should be taken for and with immigrant communities, racial minorities and individuals living in poverty," Bennett said. "While LTBI is not infectious and latently affected individuals are not a threat to others, increased outreach for education, diagnosis and provision of appropriate preventive treatment could prevent many future cases of active TB."

The findings were published in the first issue for February of the American Journal of Respiratory and Critical Care Medicine.

More information

The U.S. Centers for Disease Control and Prevention has more about TB.

FRIDAY, Dec. 7 (HealthDay News) -- The oldest evidence of tuberculosis has been discovered in a 500,000-year-old human fossil from Turkey, a finding that contradicts the widely held belief that the disease emerged only several thousand years ago, according to a team of international researchers.

The discovery, made during investigation of the new specimen of the human species Homo erectus, lends support to the theory that dark-skinned people who migrated northward from low, tropical latitudes produced less vitamin D, which can have a negative effect on the immune system and the skeleton.

People with dark skin produce less vitamin D because the skin pigment blocks ultraviolet light from the sun.

"The production of vitamin D in the skin serves as one of the body's first lines of defense against a whole host of infections and diseases. Vitamin D deficiencies are implicated in hypertension, multiple sclerosis, cardiovascular disease and cancer," John Kappelman, a professor of anthropology at the University of Texas at Austin and a member of the international team, said in a prepared statement.

This specimen, believed to be a male, had a series of small lesions etched into the bone of the cranium. The shape and the location of the lesions are characteristic of a form of TB that attacks the lining of the brain.

The findings are published in the Dec. 7 issue of the American Journal of Physical Anthropology.

Before antibiotics were available, doctors prescribed plenty of sunshine and fresh air for TB patients.

"No one knew why sunshine was integral to the treatment, but it worked. Recent research suggests the flush of ultraviolet radiation jump-started the patients' immune systems by increasing the production of vitamin D, which helped to cure the disease," Kappelman said.

More information

The U.S. Centers for Disease Control and Prevention has more about tuberculosis.