180: The Rickettsiosis, Erlichioses and Anaplasmoses Flashcards
1
Q
What are the common symptoms associated with Rickettsial infections?
A
Common symptoms include: Fever, Headache, Myalgia, Malaise, Rash (common in rickettsia, occasional in ehrlichia, rare in anaplasmosis)
2
Q
What is the primary vector for Rocky Mountain Spotted Fever?
A
The primary vectors for Rocky Mountain Spotted Fever are: Dermacentor variabilis (dog tick), Dermacentor andersoni (wood tick), Rhipicephalus sanguineus
3
Q
What is the gold standard for diagnosing Rickettsial infections?
A
The gold standard for diagnosing Rickettsial infections is the Indirect Immunofluorescence Assay (IFA), which detects convalescent antibodies with a diagnostic titer of: ≥64 IgG, ≥32 IgM. This test is seldom diagnostic before the seventh day of illness.
4
Q
What are the treatment options for Rickettsial infections?
A
The drug of choice for Rickettsial infections is Doxycycline. Key points include: Effective for all ages, including during pregnancy. Limited use in children during the first 6-7 years has negligible effects on permanent incisors. Chloramphenicol may be used if tetracyclines are contraindicated due to allergies, but it has side effects like aplastic anemia and gray baby syndrome.
5
Q
What preventive measures can be taken against Rickettsial diseases?
A
Preventive measures against Rickettsial diseases include: Avoiding tick exposure, Wearing protective clothing, Performing regular tick checks in tick-infested areas, Proper tick extractions, Using chemical repellents like DEET in concentrations up to 35% (safe for adults and children)
6
Q
What is the likely diagnosis and first-line treatment for a patient with fever, headache, and a rash that started on the wrists and ankles?
A
The likely diagnosis is Rocky Mountain Spotted Fever (RMSF). The first-line treatment is doxycycline.
7
Q
What is the likely diagnosis and gold standard diagnostic test for a patient with fever, headache, and a rash, with laboratory findings showing thrombocytopenia, anemia, and mild hyponatremia?
A
The likely diagnosis is Rocky Mountain Spotted Fever (RMSF). The gold standard diagnostic test is the Indirect Immunofluorescence Assay (IFA).
8
Q
What is the likely diagnosis and clinical triad for a patient with fever, headache, and a rash that is blanchable and started on the wrists and ankles?
A
The likely diagnosis is Rocky Mountain Spotted Fever (RMSF). The clinical triad is fever, headache, and rash.
9
Q
What is the likely diagnosis and vector for a patient with fever, chills, and a petechial rash that started on the wrists and ankles?
A
The likely diagnosis is Rocky Mountain Spotted Fever (RMSF). The vector is the Dermacentor variabilis (dog tick) or Dermacentor andersoni (wood tick).
10
Q
What is the significance of early empiric treatment with doxycycline in suspected Rickettsial infections?
A
Early empiric treatment with doxycycline is crucial to prevent severe sequelae and mortality, especially when rickettsial infection is suspected but not yet confirmed.
11
Q
How do the spotted fever group and typhus group differ in terms of pathogen habitat and transmission?
A
The spotted fever group pathogens inhabit the cytoplasm or nucleus of host cells and are transmitted via the saliva of feeding ticks. In contrast, the typhus group pathogens live entirely within the cell cytoplasm and are transmitted through feces of infected human body lice or fleas.
12
Q
What are the major surface proteins of Rickettsia rickettsii and their roles?
A
Rickettsia rickettsii has two major surface proteins: Outer membrane protein A (OmpA) and Outer membrane protein B (OmpB). These proteins play roles in adhesion and immune evasion during infection.
13
Q
What are the common laboratory findings in patients with Rocky Mountain Spotted Fever?
A
Common laboratory findings include septic vasculitis, dermal edema, and perivascular lymphocytic infiltrate with extravasated RBCs. Other findings may include lymphocytic exocytosis and capillary wall necrosis.
14
Q
What are the clinical manifestations of severe Rickettsial infections?
A
Severe clinical manifestations of Rickettsial infections can include hypovolemia, purpura, and pulmonary and cerebral edema, resulting from the proliferation of bacteria within the vascular endothelium.
15
Q
What are the epidemiological characteristics of Rocky Mountain Spotted Fever?
A
Rocky Mountain Spotted Fever is caused by R. rickettsii, most frequently reported in the US, particularly in the South Central states during spring and early summer. It has the highest incidence in persons aged 60-69 years and a high case-fatality rate among children younger than 10 years.
16
Q
What is the causative agent of Mediterranean Spotted Fever (MSF)?
A
The causative agent of Mediterranean Spotted Fever (MSF) is Rickettsia conorii.
17
Q
What is the classic cutaneous hallmark of Rickettsia conorii infection?
A
The classic cutaneous hallmark of Rickettsia conorii infection is tache noir, which occurs at the site of inoculation as an erythematous, indurated papule with a central necrotic eschar.
18
Q
How can African Tick Bite Fever (ATBF) be distinguished from Mediterranean Spotted Fever (MSF)?
A
African Tick Bite Fever (ATBF) can be distinguished from Mediterranean Spotted Fever (MSF) by: 1. Multiple tick bites, 2. Multiple eschars (seen in 50% of patients with ATBF), 3. Lymphadenitis.
19
Q
What are the common systemic symptoms that appear after the primary lesion of Rickettsia akari infection?
A
Common systemic symptoms that appear approximately 7 days after the primary lesion of Rickettsia akari infection include: Fever, Chills, Diaphoresis, Myalgia, Erosions on the tongue, palate, and pharynx, Photophobia, Generalized lymphadenopathy, GI symptoms.
20
Q
What is the preferred method to identify Rickettsia akari?
A
The preferred method to identify Rickettsia akari is swabbing the eschar or vesicles of patients with rickettsioses, allowing DNA detection by PCR.
21
Q
What is the first-line therapy for non-RMSF spotted fevers?
A
The first-line therapy for non-RMSF spotted fevers is Doxycycline, which is effective even for the pediatric age group.
22
Q
What are the laboratory findings commonly associated with Rickettsia akari infection?
A
Laboratory findings commonly associated with Rickettsia akari infection include: Thrombocytopenia (common during the acute febrile illness), Mild leukopenia with a relative lymphocytosis.
23
Q
What is the typical resolution time for Rickettsia akari infection without antibiotics?
A
Rickettsia akari infection is typically self-limited and will resolve without antibiotics within 2 weeks.
24
Q
What is the likely diagnosis and hallmark cutaneous feature for a patient with a history of tick exposure who develops a painless, erythematous, indurated papule with a central necrotic eschar?
A
The likely diagnosis is Mediterranean Spotted Fever (MSF). The hallmark cutaneous feature is the tache noir.
25
What is the likely disease and etiologic agent for a patient with a history of rodent exposure who develops a painless bite lesion that progresses to an eschar?
The likely disease is Rickettsialpox. The etiologic agent is Rickettsia akari.
26
What is the likely diagnosis and distinguishing features for a patient with a history of tick exposure who presents with fever, chills, and multiple eschars?
The likely diagnosis is African Tick Bite Fever (ATBF). It can be distinguished from MSF by the presence of multiple eschars and lymphadenitis.
27
What is the likely diagnosis and preferred method to identify the organism for a patient with fever, chills, and a painless eschar, with histopathology showing perivascular macrophages as the target cells?
The likely diagnosis is Rickettsialpox. The preferred method to identify the organism is swabbing the eschar or vesicles for DNA detection by PCR.
28
What are the classic cutaneous hallmarks of Mediterranean Spotted Fever (MSF) caused by Rickettsia conorii?
The classic cutaneous hallmark of MSF is the **tache noir**, which occurs at the site of inoculation as an erythematous, indurated papule with a central necrotic eschar. This occurs in 13% to 68% of R. conorii infections.
29
What are the common differential diagnoses (DDx) for Mediterranean Spotted Fever (MSF)?
Common differential diagnoses for MSF include: **Brown recluse spider bite**, **Cutaneous anthrax**, **Scrub typhus**, **Rickettsialpox**, **Aspergillosis**, **Mucormycosis**.
30
What is the significance of the Weil-Felix test in diagnosing Rickettsial infections?
The Weil-Felix test and complement fixation tests have **inferior sensitivity and specificity** compared to newer diagnostic methods and are generally supplanted by more reliable tests.
31
What is the incubation period for Mediterranean spotted fever?
The incubation period for Mediterranean spotted fever is **5 to 7 days**.
32
What are the risk factors associated with Rocky Mountain spotted fever?
The risk factors for Rocky Mountain spotted fever include: **Males**, **Adults aged 40 to 64 years**, **Children under 10 years of age**, **Rural dwelling**.
33
What is the first-line treatment for Mediterranean spotted fever in adults?
The first-line treatment for Mediterranean spotted fever in adults is **doxycycline 200 mg by mouth q12h for 1 day or 100 mg by mouth q12h for 2 to 5 days**.
34
What is the prognosis for Rickettsialpox?
The prognosis for Rickettsialpox is **excellent**.
35
What are the primary vectors for Rocky Mountain spotted fever and their geographical distribution?
The primary vectors for Rocky Mountain spotted fever are: | Vector | Geographical Distribution | |--------|-------------------------| | Dermacentor variabilis (American dog tick) | Widespread in the United States, concentrated in South Atlantic and South-Central states | | Dermacentor andersoni (Rocky Mountain wood tick) | Widespread in the United States, concentrated in South Atlantic and South-Central states |
36
What is the prognosis for Rickettsialpox?
The prognosis for Rickettsialpox is excellent.
37
What are the primary vectors for Rocky Mountain spotted fever?
The primary vectors for Rocky Mountain spotted fever are:
- Dermacentor variabilis (American dog tick): Widespread in the United States, concentrated in South Atlantic and South-Central states.
- Dermacentor andersoni (Rocky Mountain wood tick): Widespread in the United States, concentrated in South Atlantic and South-Central states.
- Amblyomma americanum (lone star tick): Widespread in the United States.
- Rhipicephalus sanguineus (brown dog tick): Widespread in the United States.
- Amblyomma cajennense: Central and South America.
- Haemaphysalis leporispalustris: Widespread in the United States.
38
What is the incubation period for Mediterranean spotted fever?
The incubation period for Mediterranean spotted fever is 5 to 7 days.
## Footnote
Associated risk factors include exposure to dogs, higher incidence in children, and severe disease more common in individuals with alcoholism, elderly age, and G6PD deficiency.
39
What is the prognosis for Rickettsialpox and its associated risk factors?
The prognosis for Rickettsialpox is excellent.
## Footnote
Associated risk factors include males, urban dwellers (likely from mice exposure), and IV drug users.
40
What are the first-line treatments for Rocky Mountain spotted fever in adults and children?
The first-line treatments for Rocky Mountain spotted fever are:
- Adults: Doxycycline 100 mg by mouth q12h for 5 to 10 days.
- Children: Doxycycline 2.2 mg/kg by mouth q12h for 5 to 10 days.
41
What are the second-line treatments for Mediterranean spotted fever?
The second-line treatments for Mediterranean spotted fever include:
- Tetracycline 500 mg by mouth q6h for 10 days or ciprofloxacin 750 mg q12h for 8 days.
- Azithromycin 500 mg by mouth daily for 3 days.
42
What are the risk factors associated with severe disease in Rocky Mountain spotted fever?
The risk factors associated with severe disease in Rocky Mountain spotted fever include:
- Males
- Adults aged 40 to 64 years
- Children under 10 years of age
- Rural dwelling
- Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency
- Those with rapid decompensation or fulminant disease.
43
What is the prognosis for Mediterranean spotted fever in children?
The prognosis for Mediterranean spotted fever in children is generally mild, with good outcomes.
## Footnote
However, severe disease can occur in children with alcoholism, elderly age, G6PD deficiency, and delayed diagnosis and treatment.
44
What is the incubation period for Rickettsialpox?
The incubation period for Rickettsialpox is approximately 7 days (eschar) and can range from 7 to 24 days for systemic symptoms and rash.
## Footnote
Its geographical distribution includes the United States (mainly eastern seaboard), South Africa, Korea, Ukraine, Croatia, and sporadic cases.
45
What are the first-line treatments for Mediterranean spotted fever in adults and children?
The first-line treatments for Mediterranean spotted fever are:
- Adults: Doxycycline 200 mg by mouth q12h for 1 day or 100 mg by mouth q12h for 2 to 5 days.
- Children: Doxycycline 2.2 mg/kg by mouth q12h for 5 to 10 days.
46
What are the second-line treatments for Rickettsialpox?
The second-line treatments for Rickettsialpox include:
- Doxycycline can be used for severe cases.
47
What are the primary causes of endemic typhus and its vector?
Endemic typhus is primarily caused by Rickettsia typhi and, to a lesser extent, Rickettsia felis. The vector for endemic typhus is the Xenopsylla cheopis flea, which is associated with rats serving as the reservoir.
48
What are the clinical findings associated with epidemic typhus?
Clinical findings of epidemic typhus include:
1. Abrupt onset of intractable headache, fever, chills, and myalgia.
2. Rash begins in the axillary folds and upper trunk on the fifth day, becoming papular and petechial over several days.
3. Complications may include acral gangrene, cerebral thrombosis, and multiorgan system failure.
4. Laboratory findings often show thrombocytopenia and elevated transaminases.
49
What is the recommended treatment for scrub typhus?
The recommended treatment for scrub typhus includes:
1. Doxycycline for 14 days, as it is effective against the infection.
2. Alternatives include azithromycin, rifampin, and ciprofloxacin if doxycycline resistance is suspected.
50
What preventive measures can be taken against endemic typhus?
Preventive measures against endemic typhus include:
- Regular bathing and clothes washing.
- Delousing with agents such as permethrin, malathion, or DDT to eliminate fleas and lice.
51
What is the incubation period for epidemic typhus?
The incubation period for epidemic typhus is 1-2 weeks.
## Footnote
Common complications include seizures, meningoencephalitis, acute hepatitis, splenic rupture, respiratory failure, and thrombocytopenia.
52
What is the likely disease and causative agent for a patient with fever, chills, and a rash that spares the face, palms, and soles?
The likely disease is Epidemic Typhus. The causative agent is Rickettsia prowazekii.
53
What is the likely diagnosis and gold standard diagnostic test for a traveler returning from Southeast Asia with fever, chills, and an eschar?
The likely diagnosis is Scrub Typhus. The gold standard diagnostic test is the Indirect Fluorescent Antibody (IFA) test.
54
What is the likely diagnosis for a patient with fever, headache, and a rash that started on the chest?
The likely diagnosis is Endemic Typhus (Murine Typhus).
55
What is the likely diagnosis and primary vector for a patient from a refugee camp with fever, chills, and a rash?
The likely diagnosis is Epidemic Typhus. The primary vector is the body louse (Pediculus humanus var. corporis).
56
What is the likely diagnosis and primary vector for a patient with fever, chills, and a rash that began on the chest?
The likely diagnosis is Endemic Typhus (Murine Typhus). The primary vector is Xenopsylla cheopis (rat flea).
57
What are the primary causes of Endemic Typhus and its main vector?
Endemic Typhus is primarily caused by Rickettsia typhi and, to a lesser extent, Rickettsia felis. The main vector is the Xenopsylla cheopis flea, which is associated with rats serving as the reservoir.
58
What are the common clinical findings in patients with Epidemic Typhus?
Common clinical findings in Epidemic Typhus include:
1. Abrupt onset of intractable headache, fever, chills, and myalgia.
2. Rash that begins in the axillary folds and upper trunk on the fifth day, becoming papular and petechial.
3. Complications such as acral gangrene, cerebral thrombosis, and multiorgan system failure.
59
What is the incubation period for Scrub Typhus?
The incubation period for Scrub Typhus is **1-2 weeks**.
60
What are the initial symptoms of Scrub Typhus?
Initial symptoms include:
- **Erythematous papule** appearing within 2 days of the chigger bite, which may ulcerate with eschar formation in 1/3 of patients.
- **Sudden onset** of high fever, chills, headache, cough, myalgia, and gastrointestinal symptoms such as nausea and diarrhea.
61
How is Epidemic Typhus diagnosed?
Epidemic Typhus is diagnosed using **IFA (Immunofluorescence Assay)**, which is the most widely used method.
62
What laboratory findings are expected in Epidemic Typhus?
Expected laboratory findings include:
- **Thrombocytopenia**
- **Elevated transaminases**
- **Elevated lactate dehydrogenase**
- **Leukocytosis**
63
What treatment options are available for Endemic Typhus?
Treatment options for Endemic Typhus include:
- **Doxycycline**, typically resolving symptoms within 2-3 days after starting.
- **Spontaneous recovery** can occur within 2 weeks in untreated patients.
- Prior infection with **R. typhi** provides lifelong immunity to subsequent infections.
64
What preventive measures can be taken against Scrub Typhus?
Preventive measures against Scrub Typhus include:
- **DEET** applied to the skin or impregnated into clothing to prevent transmission.
- **Chemoprophylaxis** with weekly doxycycline when traveling to endemic areas.
- **Rodent control** to manage the natural host of chiggers, although it may paradoxically increase the risk of human disease.
65
What are the complications associated with Endemic Typhus?
Complications associated with Endemic Typhus can include various severe health issues, but specific details were not provided in the text.
66
What are the complications associated with Endemic Typhus?
Complications can include: Seizures, Meningoencephalitis, Acute hepatitis, Splenic rupture, Respiratory failure, Thrombocytopenia and hyponatremia.
67
What is the significance of Brill-Zinsser disease in relation to Epidemic Typhus?
Brill-Zinsser disease (BZD) is a recrudescent infection that can occur in survivors of Epidemic Typhus, even decades after the initial infection. It highlights the potential for long-term latent asymptomatic infection and the need for awareness in previously infected individuals.
68
What are the key differences in the rash presentation between Endemic and Epidemic Typhus?
Key differences in rash presentation are:
| Type of Typhus | Rash Presentation |
|----------------|------------------|
| Endemic Typhus | Rash develops in **50-60%** of cases, begins on the chest and spreads to sides and back, rarely involves palms and soles. |
| Epidemic Typhus | Rash begins in **axillary folds** and upper trunk, spreads centrifugally, and spares the face, palms, and soles. |
69
What is the gold standard for diagnosing Scrub Typhus?
The gold standard for diagnosing Scrub Typhus is **IFA (Immunofluorescence Assay)**, which requires a fourfold increase in titer of paired samples drawn at least 2 weeks apart. A single acute titer greater than 1:50 can also be used as a preliminary diagnostic cutoff in travelers returning from endemic areas.
70
What are the common complications associated with Human granulocytic Anaplasmosis (HGA)?
Complications of HGA can include: Adult respiratory distress syndrome, Myocarditis, Pericarditis, Disseminated intravascular coagulation.
71
What is the definition of pericarditis?
Pericarditis is the inflammation of the pericardium, the fibrous sac surrounding the heart.
72
What is disseminated intravascular coagulation?
Disseminated intravascular coagulation (DIC) is a serious condition in which the proteins that control blood clotting become overactive.
73
What is hemophagocytic syndrome?
Hemophagocytic syndrome is a severe systemic inflammatory response characterized by the activation of macrophages and hemophagocytosis.
74
What is retinal vein occlusion?
Retinal vein occlusion is the blockage of a vein in the retina, which can lead to vision loss.
75
What is renal failure?
Renal failure is a medical condition in which the kidneys fail to adequately filter waste products from the blood.
76
What is hepatitis?
Hepatitis is an inflammation of the liver, often caused by viral infections.
77
What is the typical duration of fever in untreated patients with Human monocytic ehrlichiosis (HME)?
In untreated patients, fever lasts for approximately **2 weeks**.
78
What are the preventive measures against Rickettsial diseases?
Preventive measures include:
- Avoidance of tick exposure
- Use of chemical repellents such as **DEET**
- Wearing light-colored clothing to visualize ticks
- Careful removal of attached ticks.
79
What laboratory findings are commonly associated with Human monocytic ehrlichiosis (HME)?
Common laboratory findings in HME include:
- **Leukopenia** (often with a left shift)
- **Thrombocytopenia**
- Elevated transaminases.
80
What is the recommended treatment for Human granulocytic Anaplasmosis (HGA)?
The recommended treatment for HGA is **doxycycline** for 5 to 14 days. If co-infection with **B. burgdorferi** is suspected, treatment may continue for 14 to 21 days.
81
What is the likely diagnosis for a patient with fever, chills, and a centrifugal macular rash that started on the trunk?
The likely diagnosis is Scrub Typhus. The recommended treatment is doxycycline for 14 days.
82
What is the likely diagnosis for a patient with fever, chills, and a centrifugal rash, with a history of exposure to scrub vegetation?
The likely diagnosis is Scrub Typhus. The causative agent is Orientia tsutsugamushi.
83
What laboratory findings are shown in a patient with fever, chills, and a rash?
Laboratory findings show leukopenia.
84
What are the symptoms presented by a patient with Human Monocytic Ehrlichiosis (HME)?
Fever, chills, and a rash. The rash is centrifugal and started on the trunk.
85
What is the likely diagnosis for a patient with fever, chills, and a rash?
Human Monocytic Ehrlichiosis (HME).
86
What is the first-line treatment for Human Monocytic Ehrlichiosis (HME)?
Doxycycline.
87
What is the likely diagnosis for a patient with fever, chills, and a rash that is centrifugal and started on the trunk?
Scrub Typhus.
88
What is the recommended treatment for Scrub Typhus?
Doxycycline for 14 days.
89
What is the causative agent of Scrub Typhus?
Orientia tsutsugamushi.
90
What are the common complications associated with Human Granulocytic Anaplasmosis (HGA)?
Complications can include:
- Adult respiratory distress syndrome
- Myocarditis
- Pericarditis
- Disseminated intravascular coagulation
- Hemophagocytic syndrome
- Retinal vein occlusion
- Renal failure
- Hepatitis.
91
How does the rash presentation differ between Human Monocytic Ehrlichiosis (HME) and Human Granulocytic Anaplasmosis (HGA)?
**HME**: Rash can present as erythematous macules and papules, petechiae, or diffuse erythema; rash is common in children (66%) and rare in adults.
**HGA**: Rash is rare; absence of rash in a patient with systemic findings suggestive of RMSF should prompt consideration of anaplasmosis.
92
What laboratory findings are typically observed in patients with Human Monocytic Ehrlichiosis (HME)?
Laboratory findings in HME often include:
- Leukopenia.
93
What are common laboratory findings in HME?
Common findings include leukopenia (often with a left shift), thrombocytopenia, and elevated transaminases.
94
What is the significance of PCR in diagnosing Rickettsial infections such as HME and HGA?
PCR is significant because it provides high sensitivity and specificity for diagnosing Rickettsial infections. It is more useful than tissue biopsy as these pathogens are trophic for circulating leukocytes and can help in early detection of infection, especially within the first 48 hours of disease.
95
What are the recommended preventive measures against Rickettsial diseases?
Preventive measures include avoidance of tick exposure, use of chemical repellents such as DEET, wearing light-colored clothing to visualize ticks, and careful removal of attached ticks.
96
What is the typical duration of disease for Human granulocytic Anaplasmosis (HGA) with treatment?
The median duration of disease for HGA with treatment is approximately **1 to 2 weeks**.
97
What is the treatment protocol for Human granulocytic Anaplasmosis (HGA)?
The treatment protocol typically involves doxycycline for **5 to 14 days**. If co-infection with B. burgdorferi is suspected, treatment may continue for **14 to 21 days**. Rifampin can be used successfully in pregnant women and young children.
98
What are the clinical implications of a negative smear in diagnosing Rickettsial infections?
A negative smear should not delay treatment because smear sensitivities are low, clinical illness often precedes laboratory diagnosis, and false positives can occur due to toxic granulation or superimposed platelets.
99
What is the relationship between high O. tsutsugamushi DNA loads and disease severity?
High O. tsutsugamushi DNA loads, as determined by PCR, are associated with increased disease severity, indicating a potential correlation between the amount of pathogen present and the clinical outcome.
100
What are the common symptoms that may indicate a severe progression of Human monocytic ehrlichiosis (HME)?
Common symptoms indicating severe progression of HME may include:
- Fever
- Rash (though rare)
- Systemic findings suggestive of RMSF
- Severe leukopenia and thrombocytopenia
- Elevated transaminases
101
Is a rash common in rickettsia, occasionally in ehrlichia, and rare in anaplasmosis?
True
102
Are prophylactic antibiotics after tick exposure recommended?
True
103
Does the rash of RMSF start on the face and neck and spread centrifugally with relative sparing of the palms and soles?
True
104
Is Rickettsialpox lethal without treatment?
False
105
Do all rickettsiae pathogens target vascular endothelial cells, resulting in septic vasculitis?
True
106
Do overall, non-RMSF spotted fevers run a less aggressive course than RMSF?
True
107
Has the Epidemic Typhus been reported in all continents except Antarctica?
False
108
Is chemoprophylaxis with weekly doxycycline efficacious for scrub typhus when traveling to endemic areas?
True
109
What is the clinical triad of Rocky Spotted Mountain Fever?
Fever, rash, and history of tick exposure
110
What is the drug of choice for RMSF?
Doxycycline
111
What is the cutaneous hallmark of MSF?
Eschar formation
112
What studies suggest about the limited use of this antibiotic for treatment of RMSF in children?
It has a negligible effect on the color of permanent ink.
113
What effect does it have on the color of permanent incisors?
It has a negligible effect on the color of permanent incisors.
114
How can ATBF be distinguished from MSF?
By the presence of eschar and the type of rash.
115
What disease involves house mice and rodent mites that produce painless bites?
Rickettsialpox.
116
On histopathology of Rickettsialpox, what do the pathogens appear to?
Vascular endothelial cells.
117
What does prior infection with this pathogen provide?
Lifelong immunity to subsequent infection.
118
What type of typhus is common in camps and among the homeless and imprisoned?
Epidemic typhus.
119
Is a rash common in rickettsia, occasional in ehrlichia, and rare in anaplasmosis?
True.
120
Are prophylactic antibiotics after tick exposure recommended?
True.
121
Does the rash of RMSF start on the face and neck, spreading centrifugally with relative sparing of the palms and soles?
True.
122
Is Rickettsialpox lethal without treatment?
True.
123
Do all rickettsiae pathogens target vascular endothelial cells, resulting in septic vasculitis?
True.
124
Overall, do non-RMSF spotted fevers run a less aggressive course than RMSF?
True.
125
Has the Epidemic Typhus been reported in all continents except Antarctica?
False.
126
Is chemoprophylaxis with weekly doxycycline efficacious for scrub typhus when traveling to endemic areas?
True.
127
What is the clinical triad of Rocky Spotted Mountain Fever?
Fever, rash, and history of tick exposure.
128
What is the drug of choice for RMSF?
Doxycycline is the drug of choice for RMSF.
129
What is the cutaneous hallmark of MSF?
The cutaneous hallmark of MSF is a rash that starts at the wrists and ankles and spreads centrifugally.
130
What studies suggest about the limited use of antibiotics for treatment of RMSF in children?
Studies suggest limited use of antibiotics for treatment of RMSF in children.
131
What is the use of antibiotics for treatment of RMSF in children?
Studies suggest that limited use of doxycycline for treatment of RMSF in children during the first 6 to 7 years of life has a negligible effect on the color of permanent incisors.
132
How can ATBF be distinguished from MSF?
ATBF can be distinguished from MSF by the presence of a different rash pattern and clinical history.
133
What disease involves house mice and rodent mites that produce painless bites?
The disease is known as Murine Typhus.
134
On histopathology of Rickettsialpox, what do the pathogens appear to target?
On histopathology, the pathogens appear to target endothelial cells.
135
What does prior infection with Rickettsialpox provide?
Prior infection with Rickettsialpox provides lifelong immunity to subsequent infection.
136
What type of typhus is common in camps and among the homeless and imprisoned?
The type of typhus common in these settings is known as Epidemic Typhus.
137
What are the primary vectors for Epidemic typhus and what is its incubation period?
The primary vectors for Epidemic typhus are **Pediculus humanus var. corporis** (human body louse) and **Neohaematopinus scurfieldi** lice. The incubation period is approximately **1 to 2 weeks** (average: 8 days).
138
What is the prognosis for Human monocytic ehrlichiosis and what factors influence it?
The prognosis for Human monocytic ehrlichiosis is **poor** for individuals with **immunosuppression** (e.g., HIV, transplantation). Factors influencing prognosis include age (males, adults older than 70 years) and the presence of other health conditions.
139
What is the recommended first-line treatment for Human granulocytic anaplasmosis?
The recommended first-line treatment for Human granulocytic anaplasmosis is doxycycline.
140
What is the recommended first-line treatment for Human granulocytic anaplasmosis?
**Doxycycline**
141
What is the dosage of Doxycycline for adults with Human granulocytic anaplasmosis?
100 mg by mouth every 12 hours for 10 to 14 days.
142
What is the dosage of Doxycycline for children with Human granulocytic anaplasmosis?
2.2 mg/kg by mouth every 12 hours for 10 to 14 days.
143
What is the recommendation for Doxycycline use during pregnancy?
Doxycycline is generally avoided.
144
What are the risk factors associated with Epidemic typhus?
**Wartime conditions**, **poor hygiene**, **natural disasters**, and **cold weather**.
145
What is the incubation period for Human granulocytic anaplasmosis?
**5 to 21 days**.
146
What are the primary vectors for Human granulocytic anaplasmosis?
**Ixodes scapularis** (Eastern United States) and **Ixodes pacificus** (Western United States).
147
What are the primary vectors for Epidemic typhus?
**Pediculus humanus var. corporis** (human body louse) and **Neohaematopinus scurfieldi** (lice).
148
What is the incubation period for Epidemic typhus?
Approximately **1 to 2 weeks**.
149
What is the prognosis for Human monocytic ehrlichiosis and what factors influence it?
The prognosis for Human monocytic ehrlichiosis is **poor** for individuals with **immunosuppression** (e.g., HIV, transplantation). Risk factors include being **male** and **older than 70 years**.
150
What is the recommended first-line treatment for Human granulocytic anaplasmosis?
The recommended first-line treatment for Human granulocytic anaplasmosis is **doxycycline**: 100 mg by mouth every 12 hours for 5 to 14 days. For children, the dosage is 2.2 mg/kg by mouth every 12 hours for 5 to 10 days.
151
What are the risk factors associated with Epidemic typhus?
Risk factors for Epidemic typhus include **wartime conditions**, **poor hygiene**, **natural disasters**, and **cold weather**.
152
What is the incubation period for Human granulocytic anaplasmosis and what are its primary vectors?
The incubation period for Human granulocytic anaplasmosis is **5 to 21 days**. The primary vectors are **Ixodes scapularis** (Eastern United States) and **Ixodes pacificus** (Western United States).
153
What is the prognosis for patients with Human monocytic ehrlichiosis who are older than 70 years?
Patients with Human monocytic ehrlichiosis who are older than 70 years have a **poor prognosis** due to factors like **immunosuppression** and other comorbidities.
154
What are the second-line treatment options for Human granulocytic anaplasmosis?
Second-line treatment options for Human granulocytic anaplasmosis include **rifampin**: 10 mg/kg by mouth every 12 hours for 7 to 10 days, and **tetracycline**: 500 mg by mouth every 6 hours.
155
What is the dosage of tetracycline for treatment?
500 mg by mouth every 6 hours for 10 days.
156
What is the epidemiology of Human monocytic ehrlichiosis in the United States?
Human monocytic ehrlichiosis is found in the **South and Mid-Atlantic**, **North/South-Central United States**, and isolated areas of **New England**, primarily in **spring and summer** (peaking in May to July).
157
What are the first-line treatments for Epidemic typhus?
**Doxycycline**: 100 mg by mouth every 12 hours for 7 to 14 days, and for children, **doxycycline**: 2.2 mg/kg by mouth every 12 hours for 5 to 10 days.
158
What factors influence the prognosis of Epidemic typhus?
The prognosis of Epidemic typhus is influenced by factors such as **hygiene**, **natural disasters**, and **cold weather**. Patients may recover in 2 to 3 months with treatment.
159
What are the common initial signs and symptoms of Rocky Mountain Spotted Fever?
- Fever to 38.9°C (102°F)
- Chills
- Malaise
- Myalgia
- Nausea
- Vomiting
- Anorexia
- Headache
- Periorbital edema
- Abdominal pain mimicking appendicitis (in adults)
- Conjunctival injection
- Palatal petechiae
- Edema of dorsal hands
- Calf pain
160
What laboratory abnormalities are commonly associated with Human Monocytic Ehrlichiosis?
- Leukopenia
- Lymphopenia
- Thrombocytopenia
- Anemia
161
What systemic sequelae can occur in patients with Rocky Mountain Spotted Fever?
- **Cardiovascular**: Hypotension, hypovolemia, peripheral edema, inappropriate tachycardia, myocarditis, arrhythmias
- **Neurologic**: Confusion, delirium, stupor, meningismus, coma, motor deficits, cranial nerve palsy, deafness, photophobia, hallucinations
162
What are the differential diagnoses to consider for Rickettsial and Ehrlichial diseases?
Most Likely:
- Enteroviral infection (e.g., coxsackievirus, echovirus)
- Roseola infantum (human herpesvirus 6)
- Drug eruption
- Group A streptococcal pharyngitis
- Vasculitis
- Kawasaki disease
- Measles (coryza, Koplik spots, cough)
- Epstein-Barr virus/infectious mononucleosis
163
What are some other considerations for Rickettsial and Ehrlichial diseases?
- Viral meningoencephalitis
- Mycoplasma pneumoniae infection
- Parvovirus B19
- Tularemia
- Leptospirosis
- Immune complex-mediated illness
- Atypical erythema multiforme
- Typhoid fever
- Dengue
- Viral hemorrhagic fevers (Ebola, Marburg, Lassa)
164
What are the common initial signs and symptoms of Rocky Mountain Spotted Fever?
- Fever to 38.9°C (102°F)
- Chills
- Malaise
- Myalgia
- Nausea
- Vomiting
- Anorexia
- Headache
- Periorbital edema
- Abdominal pain mimicking appendicitis (in adults)
- Conjunctival injection
- Palatal petechiae
- Edema of dorsal hands
- Calf pain
165
What laboratory abnormalities are commonly associated with Human Monocytic Ehrlichiosis?
- Leukopenia
- Lymphopenia
- Thrombocytopenia
- Anemia
166
What systemic sequelae can occur in patients with Rocky Mountain Spotted Fever?
- Cardiovascular: hypotension, hypovolemia, peripheral edema, inappropriate tachycardia, myocarditis, arrhythmias
- Neurologic: confusion, delirium, stupor, meningoencephalitis, coma, motor deficits, cranial nerve palsy, deafness, photophobia, hallucinations, seizures, Guillain-Barré syndrome
167
What are the symptoms associated with Human Monocytic Ehrlichiosis?
A fever, chills, headache, myalgia, and nausea.
168
What is a common rash associated with Human Monocytic Ehrlichiosis?
Erythematous macules and/or papules, petechiae, or diffuse erythema approximately 5 days after onset of systemic symptoms.
169
What are the most likely differential diagnoses for Rickettsial and Ehrlichial diseases?
Enteroviral infection (e.g., coxsackievirus, echovirus), Roseola infantum (human herpesvirus 6), drug eruption, Group A streptococcal pharyngitis, vasculitis, Kawasaki disease, measles (coryza, Koplik spots, cough), Epstein-Barr virus/infectious mononucleosis.
170
What common laboratory abnormalities are seen in Human Granulocytic Anaplasmosis?
Thrombocytopenia, transaminitis, leukopenia, anemia, elevated creatinine, and neutropenia is more common than lymphopenia.
171
What are the systemic sequelae associated with Human Granulocytic Anaplasmosis?
General: septic or toxic shock syndrome; Coagulopathy, disseminated intravascular coagulation; Respiratory: adult respiratory distress syndrome; Neurologic: brachial plexopathy, demyelinating polyneuropathy, cranial nerve paralysis.
172
What is the typical rash associated with Rocky Mountain Spotted Fever?
Erythematous blanching macules and/or papules that appear 2 to 4 days after fever onset, starting at wrists/ankles and spreading centrifugally; may involve palms and soles; rash evolves over a few days to petechial and purpuric lesions.
173
What are the common initial signs and symptoms of Human Granulocytic Anaplasmosis?
Fever, chills, headache, myalgia, and nausea.
174
What are the symptoms of Rickettsial diseases?
Fever, chills, headache, myalgia, nausea, vomiting, abdominal pain mimicking appendicitis (in adults), conjunctival injection, palatal petechiae, edema of dorsal hands and calf pain.
175
What are the key considerations when diagnosing Rickettsial diseases?
Always rule out conditions such as:
- Meningococcemia
- Lyme disease
- Tick-borne viral fevers (e.g., Colorado tick fever)
- Toxic shock syndrome
- Stevens-Johnson syndrome
- Secondary syphilis.
176
What are the common laboratory findings in Rocky Mountain Spotted Fever?
Common: thrombocytopenia, anemia, mild hyponatremia.
Variably elevated: liver transaminases, lactate dehydrogenase, creatine kinase, bilirubin, alkaline phosphatase, blood urea nitrogen, creatinine.
Cerebrospinal fluid: leukocytosis, moderately elevated protein, and a normal glucose level.
177
What are the clinical features of Rocky Mountain spotted fever?
Fever, malaise, headache, GI symptoms.
Rash starts on ankles/wrists, spreads centripetally.
May involve palms/soles.
Progresses from erythematous macules to petechiae.
178
What is the typical season and onset for Human monocytic ehrlichiosis?
**Season**: Spring to summer.
**Onset**: Fever, malaise, headache, rash in ~30% of patients.
179
How does the rash presentation differ between Meningococcal disease and Fifth disease (erythema infectiosum)?
| Disease | Rash Presentation |
|---|---|
| Meningococcal disease | Erythematous macules and/or papules, petechiae usually begin |
180
What are the common clinical features of Endemic (murine) typhus?
Fever, malaise, headache
- Rash after 4 to 5 days
- Erythematous macules and/or papules involving trunk > extremities
181
What is the typical season for Enteroviral infection and its associated symptoms?
Season: Summer to early fall most commonly, but occurs year-round
- Symptoms: Nonspecific febrile illness, with or without rash
182
What are the clinical features of Rocky Mountain spotted fever?
Fever, malaise, headache, GI symptoms
- Rash starts on ankles/wrists, spreads centripetally
- May involve palms/soles
- Progresses from erythematous macules to petechiae
183
What is the typical season and onset for Human monocytic ehrlichiosis?
Season: Spring to summer
- Onset: Fever malaise, headache, rash in ~30% of patients
184
How does the rash presentation differ between Meningococcal disease and Group A streptococcal pharyngitis?
Meningococcal disease: Erythematous macules and/or papules, petechiae usually beginning on lower extremities and spreading centripetally; toxic appearing
Group A streptococcal pharyngitis: Abrupt onset of fever and sore throat, malaise; rash follows acute illness, may cause petechial rash in children who appear well
185
What are the clinical features of Fifth disease caused by Human parvovirus?
Erythematous macules and/or papules, typically beginning on the cheeks with a 'slapped cheek' appearance; may have a lacy erythematous rash on the trunk
186
What are the clinical features of Fifth disease caused by Human parvovirus B19?
Low fever and mild constitutional signs before rash onset.
## Footnote
'Slapped cheek' appearance with erythematous rash on face.
187
What are the clinical features of Fifth disease caused by Human parvovirus B19?
Lacy erythematous rash on trunk.
188
What are the clinical features of Fifth disease caused by Human parvovirus B19?
Papular-purpuric gloves-and-socks syndrome in young adults.
189
What is the typical season for Enteroviral infections and their clinical presentation?
Season: Summer to early fall most commonly, but occurs year-round.
190
What is the clinical presentation of Enteroviral infections?
Nonspecific febrile illness, with or without rash.
191
What is the onset and clinical feature of Roseola infantum?
Onset: Fever for 3 to 5 days, then rash.
192
What is the clinical feature of Roseola infantum?
Commonly in children <2 years of age; morbilliform rash begins on trunk, spreads and fades rapidly.
193
What distinguishes the rash of endemic (murine) typhus from that of Rocky Mountain spotted fever?
Endemic (murine) typhus: Erythematous macules and/or papules involving trunk > extremities.
## Footnote
Rocky Mountain spotted fever: Rash starts on ankles/wrists, spreads centripetally.
194
What is the typical clinical progression of symptoms in Meningococcal disease?
Fever and rash within 24 hours.
195
What is the typical clinical progression of symptoms in Meningococcal disease?
Rapid progression to severe systemic illness.
196
What is the typical clinical progression of symptoms in Meningococcal disease?
Erythematous macules and/or papules, petechiae usually beginning on lower extremities.
197
What are the common symptoms associated with Human monocytic ehrlichiosis?
Fever.
198
What are the common symptoms associated with Human monocytic ehrlichiosis?
Malaise.
199
What are the common symptoms associated with Human monocytic ehrlichiosis?
Headache.
200
What are the common symptoms associated with Human monocytic ehrlichiosis?
Rash in ~30% of patients.
201
What is the seasonal pattern of Group A streptococcal pharyngitis?
Season: Fall to winter.
202
What are the clinical features of Group A streptococcal pharyngitis?
Abrupt onset of fever and sore throat, malaise; rash follows acute illness.
203
What follows acute illness in relation to rash?
Rash follows acute illness.
204
How does the rash of Human parvovirus B19 present in young adults?
It presents as popular-purpuric gloves-and-socks syndrome.
205
What is another presentation of the rash in young adults infected with Human parvovirus B19?
Erythematous rash on face and trunk.
