Symptoms

Tickborne rickettsial diseases (TBRD) may be very difficult to diagnose in the early stages, even by experienced physicians who are familiar with the diseases. The early clinical presentations of TBRD may resemble nonspecific signs and symptoms of various other infectious and non-infectious diseases. The majority of patients with TBRD visit a physician during the first 2--4 days of illness, after an incubation period of approximately 5--10 days after a tick bite. (Although patients with anaplasmosis might seek medical care later (4—8 days after fever onset).

Initial Signs and Symptoms

Initial symptoms generally include fever, chills, severe headache, malaise, and muscle aches. Diarrhea might occasionally occur. Sensitivity to light might be observed in adult patients.

Initial Signs and Symptoms of Tickborne Rickettsial Diseases
Anaplasmosis	Ehrlichiosis		Rocky Mountain spotted fever
Anaplasma phagocytophilum (anaplasmosis)	Ehrlichia chaffeensis (ehrlichiosis)	Ehrlichia ewingii infection	Rickettsia rickettsii
Fever	Fever	Fever	Fever
Headache	Headache	Headache	Headache
Malaise	Malaise	Malaise	Malaise
Muscle aches	Muscle aches	Muscle aches	Muscle aches
Vomiting		Vomiting	Vomiting
		Nausea	Nausea
			Loss of appetite

In patients with Rocky Mountain spotted fever, a rash first appears 2-5 days after the onset of fever, but may not present or may be very subtle when the patient is initially seen by a physician. Younger patients usually develop the rash earlier than older patients. Most often it begins as small, flat, pink, non-itchy spots (macules) on the wrists, forearms, and ankles. These spots turn pale when pressure is applied and eventually become raised on the skin.

The red, spotted (petechial) rash of Rocky Mountain spotted fever is usually not seen until the sixth day or later after onset of symptoms and occurs in 35-60% of patients with the infection. The rash may involve the palms or soles of the feet.

In contrast to Rocky Mountain spotted fever, rash is relatively uncommon in adult patients with ehrlichiosis, and is rarely reported with anaplasmosis. However, rash has been described in approximately 60% of pediatric patients infected with E. chaffeensis.

 

Description of Rash in Tickborne Rickettsial Diseases
Anaplasmosis	Ehrlichiosis		Rocky Mountain spotted fever
Anaplasma phagocytophilum (anaplasmosis)	Ehrlichia chaffeensis (ehrlichiosis)	Ehrlichia ewingii infection	Rickettsia rickettsii
Rare	Rash in <30% of adults and approximately 60% of children	Rare	Maculopapular rash approximately 2-4 days after fever onset in 50%-60% of adults (and >90% in children); might involve palms and soles

Hospitalization

A substantial number of patients with TBRD require hospitalization. Severe manifestations of these diseases may involve the respiratory system, central nervous system, gastrointestinal system, or renal system. Rocky Mountain spotted fever is the most commonly fatal rickettsial disease in the United States. See table for the case fatality rates of the tickborne rickettsial diseases.

Case fatality rate of tickborne rickettsial diseases
Anaplasmosis	Ehrlichiosis		Rocky Mountain spotted fever
Anaplasma phagocytophilum (anaplasmosis)	Ehrlichia chaffeensis (ehrlichiosis)	Ehrlichia ewingii infection	Rickettsia rickettsii
<1%	2-3%	No documented fatalities	5-10%

Long-term Health Problems

Long-term health problems following acute Rocky Mountain spotted fever infection include partial paralysis of the lower extremities, gangrene requiring amputation of fingers, toes, or arms or legs, hearing loss, loss of bowel or bladder control, movement disorders, and language disorders. These complications are most frequent in persons recovering from severe, life-threatening disease, often following lengthy hospitalizations.

Special Groups

Infection in Children

Children with ehrlichiosis infection may experience nausea, vomiting, and loss of appetite as seen more commonly seen with Rocky Mountain spotted fever. Other frequently observed signs and symptoms in children with either RMSF or ehrlichiosis are abdominal pain, altered mental status, and conjunctival (eye) injection. Abdominal pain might be severe enough to mimic appendicitis or other causes of acute abdominal pain.

Immune-compromised Individuals

The severity of TBRD may be related in part to the immune status of the patient. Persons with compromised immunity caused by immunosuppressive therapies (e.g., corticosteroids or cancer chemotherapy), HIV infection, or splenectomy appear to develop more severe disease, and case-fatality ratios for these individuals are characteristically higher than case-fatality ratios reported for the general population.

G6PD Deficiency

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) is a sex-linked genetic condition affecting approximately 12% of the U.S. black male population. Deficiency of this enzyme is associated with a high proportion of severe cases of Rocky Mountain spotted fever. This is a rare clinical course that is often fatal within 5 days of onset of illness.