Merck Manual

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Some Rickettsial and Related Infections

Some Rickettsial and Related Infections

Infection

Infecting Organism

Host

Areas Where Infection Occurs

Description

Typhus

Epidemic typhus (lice-borne typhus)

Brill-Zinsser disease (a recurrence of epidemic typhus, sometimes years after the first infection)

Rickettsia prowazekii, transmitted by lice or by unknown methods when the hosts are flying squirrels

People and flying squirrels

Throughout the world (uncommon in the United States, but occasionally occurs in people who have had contact with flying squirrels)

About 7 to 14 days after the bacteria enter the body, symptoms begin suddenly, with fever, headache, and extreme fatigue (prostration). A rash appears on the 4th to 6th day. Untreated, the infection may be fatal, especially in people older than 50.

Murine typhus

Rickettsia typhi or Rickettsia felis, transmitted by fleas

Cats, rodents, and opossums

Throughout the world

About 8 to 16 days after the bacteria enter the body, symptoms begin and are similar to those of epidemic typhus but are less severe.

Scrub typhus

Scrub typhus

Orientia tsutsugamushi (formerly, Rickettsia tsutsugamushi), transmitted by mite larvae (chiggers)

Mites (mites are both the transmitter and the host)

Asia-Pacific area, bounded by Japan, Korea, China, India, and northern Australia

About 6 to 21 days after the bacteria enter the body, symptoms begin suddenly, with fever, chills, headache, and swollen lymph nodes. A black scab may develop at the site of the chigger bite. A rash appears on the 5th to 8th day.

Spotted fever

R. rickettsii, transmitted by ticks

Rodents

The Western Hemisphere, including most of the United States (except for Maine, Hawaii, and Alaska) and Central and South America

About 3 to 12 days after the bacteria enter the body, symptoms begin.

Rickettsia africae, transmitted by ticks

Cows

Sub-Saharan Africa and West Indies

About 4 to 10 days after the bacteria enter the body, symptoms begin. A black scab usually develops at the site of the tick bite.

Mediterranean spotted fever (boutonneuse fever)

Rickettsia conorii, transmitted by dog ticks

Dogs

Africa, India, southern Europe, and the Middle East area around the Mediterranean, Black, and Caspian Seas

About 5 to 7 days after the bacteria enter the body, symptoms begin. A black scab may develop at the site of the tick bite.

Rickettsia sibirica, transmitted by ticks

Rodents

Armenia, central Asia, Siberia, Mongolia, and China

A black scab may develop at the site of the tick bite.

Rickettsia australis, transmitted by ticks

Rodents

Australia

A black scab may develop at the site of the tick bite.

Rickettsia parkeri, transmitted by ticks

Rodents

Southern United States and South America

About 2 to 10 days after the bacteria enter the body, symptoms begin. A black scab usually develops at the site of the tick bite.

Rickettsia akari, transmitted by mites

House mice

First observed in New York City

Other areas of the United States and Russia, Korea, and Africa

A small black scab appears at the site of the mite bite. It develops into a small sore that leaves a scar when it heals. About 1 week later, fever, headache, muscle pains, and a widespread rash develop.

Pacific Coast tick fever

R. philipii (364D)

Pacific Coast tick (Dermacentor occidentalis)

California

A black scab usually develops at the site of the tick bite, followed by fever, swollen lymph nodes, headache, muscle pains, and fatigue. Rash is a less common than with the other spotted fevers.

Monocytic ehrlichiosis

Ehrlichia chaffeensis, transmitted by ticks, mainly the lone star tick

White tail deer and other mammals

Southeastern and south central United States

About 12 days after a tick bite, symptoms usually begin. They include fever, chills, muscle aches, weakness, nausea and/or vomiting, cough, headache, and a general feeling of illness. A rash may develop on the torso, arms, and legs.

Granulocytic anaplasmosis

Anaplasma phagocytophilum, transmitted by ticks

Mainly mice and other small rodents

In the United States, the Northeast, mid-Atlantic, upper Midwest, and West Coast

Europe

About 12 days after a tick bite, symptoms usually begin. They include fever, chills, muscle aches, weakness, nausea and/or vomiting, cough, headache, and a general feeling of illness (malaise).

Q fever

Coxiella burnetii, transmitted by inhaling infected airborne droplets containing the bacteria or by consuming contaminated raw milk

Sheep, cattle, and goats

Throughout the world

About 9 to 28 days after bacteria enter the body, symptoms begin suddenly. They include fever, severe headache, chills, extreme weakness, muscle aches, loss of appetite, sweating, an unproductive cough, chest pain, and shortness of breath (caused by pneumonia), but no rash.