The Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) recommend using insect repellents to prevent infections transmitted by mosquitoes and ticks. Insect repellents applied to exposed skin should be used in conjunction with other preventive measures such as wearing pants and long-sleeved shirts and avoiding outdoor activities during peak mosquito-biting times. Mosquitoes can transmit diseasecausing pathogens, including Zika, chikungunya, dengue, West Nile, eastern equine encephalitis, and yellow fever viruses, and the malaria parasite. Ticks can transmit the bacteria that cause Lyme disease, the rickettsia that cause Rocky Mountain spotted fever, and viruses such as Powassan virus. Some insect repellents containing EPA-registered active ingredients are listed in Table 1.

Lyme disease in the US is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans by Ixodes scapularis (blacklegged [deer] tick) and I. pacificus (western blacklegged tick). Most cases of Lyme disease occur in late spring and early summer in northeastern and mid-Atlantic states, the upper Midwest, and in northern California. B. mayonii, which is also transmitted by I. scapularis, has been shown to cause a similar illness in the upper Midwest.

Use of insect repellents is strongly recommended by the Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) to prevent infections transmitted by mosquitoes and ticks. Insect repellents applied to exposed skin should be used in conjunction with other preventive measures such as wearing pants and long-sleeved shirts, and avoiding outdoor activities during peak mosquito-biting times. Mosquitoes can transmit Zika, chikungunya, dengue, West Nile, eastern equine encephalitis, and yellow fever viruses, as well as malaria. Ticks can transmit Lyme disease, rickettsial diseases such as Rocky Mountain spotted fever, and viruses such as Powassan virus.

Use of insect repellents is strongly recommended by the CDC and the EPA to prevent Zika virus infection and other mosquito- and tickborne diseases. Mosquitoes can transmit chikungunya, dengue, West Nile, and yellow fever viruses, and malaria. Ticks can transmit Lyme disease and rickettsial diseases such as Rocky Mountain spotted fever.

A reader commenting on our Treatment of Lyme Disease article (Med Lett Drugs Ther 2016; 58:57) objected to a footnote in the table advising against use of doxycycline in children <8 years old. This warning has been included in the labeling of all tetracyclines since 1970 when it was recognized, after decades of use, that these drugs caused permanent staining and enamel hypoplasia of developing teeth. The CDC recently stated that short courses of doxycycline, which was first marketed in the US in 1967 and has less affnity for calcium than other tetracyclines, have not been shown to cause tooth staining.1 That statement was prompted by the discovery that children <10 years old have a disproportionately high fatality rate from rickettsial diseases, particularly Rocky Mountain spotted fever, for which doxycycline is the drug of choice and chloramphenicol is the only proven alternative.

The main evidence supporting the CDC's statement was a retrospective cohort study consisting of a record review and dental examination of 271 children living on a Native American reservation. No staining was detected in any of the 58 children who had been treated with doxycycline before the age of 8 years or in any of the 213 children who had not been exposed to the drug. Enamel hypoplasia was present in 4% of children in both cohorts.2

Lyme disease, unlike Rocky Mountain spotted fever, is seldom fatal and can be treated with antibiotics other than doxycycline. A single dose of doxycycline is recommended for prophylaxis after a tick bite. Given the CDC's statement about its safety, it would seem reasonable to use doxycycline for prophylaxis in all age groups. When longer treatment courses (10, 14, or 28 days) are recommended for the various clinical manifestations of Lyme disease in children <8 years old, alternative antibiotics generally could be used instead.

1. HM Biggs et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever and other spotted fever group Rickettsioses, Ehrlichioses, and Anaplasmosis – United States. MMWR Recomm Rep 2016; 65:1.
2. SR Todd et al. No visible dental staining in children treated with doxycycline for suspected Rocky Mountain spotted fever. J Pediatr 2015; 166:1246.

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Most cases of Lyme disease in the US occur between May and September in the Northeastern, Mid-Atlantic, and North Central states.

Most cases of Lyme disease in the US occur between May and September in the Northeastern, Mid-Atlantic and North Central states.

The text below reviews some common bacterial infections and their treatment. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

Hyperbaric oxygen (HBO₂) therapy, breathing 100% O₂ while exposed to increased atmospheric pressure, has been used for years to treat refractory wounds, especially diabetic foot ulcers.

Most cases of Lyme disease in North America occur between May and September. In 2005, 12 states (CT, DE, ME, MD, MA, MI, NH, NJ, NY, PA, VA, WI) reported about 95% of all the Lyme disease in the US, but some cases occurred in all states except AR, CO, HI, MS, MT and OK. New guidelines for treatment of Lyme disease have been published.

Information about empirical treatment of bacterial infections, emerging trends in antimicrobial resistance, new drugs and new data about older drugs continue to become available. Usual pathogens and empiric treatment for some common types of infections are summarized in the text and a table listing the drugs of choice and alternatives for each pathogen begins on page 40. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

Lyme disease in North America is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans by Ixodes scapularis or pacificus ticks. These ticks may also carry other pathogens; coinfection with Babesia microti or Anaplasma phagocytophilum (formerly Ehrlichia) has been reported.1 In 2001 and 2002, 12 states (CT, DE, ME, MD, MA, MI, NH, NJ, NY, PA, RI, WI) reported about 95% of all the Lyme disease in the US, but cases occurred in all states except HI, MT and OK. Most Lyme disease in North America occurs between May and September.

New drugs for bacterial infections and new information about older drugs continue to become available. Empirical treatment of some common bacterial infections is discussed in this article. A table listing the drugs of choice and alternatives for each pathogen begins on page 18. These recommendations are based on results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants. Local resistance patterns should be taken into account. Trade names are listed on page 24.

New drugs for treatment of bacterial infections and new information about older drugs continue to become available. Empirical treatment of some infections is discussed and a table listing the drugs of choice and alternatives for each pathogen are contained in this article. These recommendations are based on results of susceptibility studies, clinical trials and opinions of Medical Letter consultants. Local resistance patterns should be taken into account.

Lyme disease is caused by the spirochete Borrelia burgdorferi and transmitted to humans by Ixodes ticks. These ticks may also carry other pathogens; co-transmission of Babesia and Ehrlichia species has been reported.

Since The Medical Letter last reviewed the choice of drugs for treatment of bacterial infections, a few new drugs and some new information about older drugs have become available.

Lyme disease, a multisystem infection transmitted by ixodid ticks and caused by the spirochete Borrelia burgdorferi is the most common vector-borne illness in the USA. Cases have been reported in 44 states, and also in Canada and many countries in Europe and Asia (ME Falagas and SL Gorbach, Infect Dis Clin Pract, 5:217, 1996).

Lyme disease, a multisystem infection transmitted by ixodid ticks and caused by the spirochete Borrelia burgdorferi the most common vector-borne illness in the USA. It occurs, mainly in the northeast, upper midwest, and California, but cases have been reported in 48 states, and also in Canada and many countries in Europe.

Lyme disease, a multisystem bacterial transmitted by Ixodid ticks, particularly in early summer, continues to be a common problem in the USA and many other countries. Since last year (Medical Letter, 30:65, 1988), some new information has become available, but data on the choice, dosage and duration of antibiotic therapy are still available, but data on the choice, dosage and duration of antibiotic therapy are still limited.

Lyme Disease, a multisystem inflammatory disorder transmitted by lxodid ticks and caused by the spirochete Borrelia burgdorferi, is now the most common tick-transmitted illness in the USA. It has been reported in 32 states and on all other continents except Antarctica. Infected ticks have been found not only in wooded areas, but also on well-maintained suburban lawns (RC Falco and D Fish, Am J Epidemiol, 127:826, April 1988). Optimal treatment for this newly discovered disease is still being determined, but some recommendations based on published experience and work in progress can be made.