Rickettsialpox

Rickettsialpox is caused by the bacteria, Rickettsia akari. It is commonly found in the United States in New York City and other city areas. It also has been seen in Europe, South Africa, Korea, and Russia.

The bacteria are spread by the bite of a mite that lives on mice.

The disease begins at the site of the mite bite as a painless, firm, red lump (nodule). The nodule develops into a fluid-filled blister that bursts and crusts over. This lump may be up to 1 inch (2.5 centimeters) wide. These lumps usually appear on the face, trunk, arms, and legs. They do not appear on the palms of hands and soles of feet. Symptoms usually develop 6 to 15 days after coming in contact with the bacteria.

Other symptoms may include:

• Discomfort in bright light (photophobia)
• Fever and chills
• Headache
• Muscle pain
• Rash that looks like chickenpox
• Sweating
• Runny nose
• Sore throat
• Cough
• Enlarged lymph nodes
• Loss of appetite
• Nausea or vomiting

The rash is not painful and usually clears within a week.

The health care provider will do an examination to look for a rash similar to the one in chickenpox.

If rickettsialpox is suspected, these tests will likely be done: 

• Complete blood count (CBC)
• Tests of blood serum (serologic studies)
• Swabbing and culture of the rash

The goal of treatment is to cure the infection by taking antibiotics. Doxycycline is the drug of choice. Treatment with antibiotics shortens the duration of symptoms usually to 24 to 48 hours.

Without treatment, the disease usually resolves within 7 to 10 days.

A full recovery is expected when antibiotics are taken as instructed.

There are usually no complications if the infection is treated.

Contact your provider if you or your child has symptoms of rickettsialpox.

Controlling mice helps prevent the spread of rickettsialpox.

Rickettsia akari

Elston DM. Bacterial and rickettsial diseases. In: Callen JP, Jorizzo JL, Zone JJ, Piette WW, Rosenbach MA, Vleugels RA, eds. Dermatological Signs of Systemic Disease. 5th ed. Philadelphia, PA: Elsevier; 2017:chap 32.

Fournier P-E, Raoult D. Rickettsia akari (Rickettsialpox). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 187.

Updated by: Charles I. Schwartz MD, FAAP, Clinical Assistant Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.