Tick-borne Illnesses Lecture Flashcards
Borrelia burdorferi ss
Lyme disease
Babesia microti
Human babesiosis
Anaplasma phagocytophila
Human granulocytic anaplasmosis
- Multisystem inflammatory disease
- Causes by spirochetes: Borrelia burgdorferi – identified in 1981
- Spread by Ixodes ticks
Lyme disease
Transmission: Bite of an infected nymph in the spring
Preferred host: White-tailed deer
Lyme disease
Egg
Six-legged larvae
Eight-legged nymph
Adult
Life cycle of hard ticks
Adults peak in spring and fall – preferred host is white-tailed deer. Mating occurs.
Nymphs peak May-July – aggressive - frequently bite humans
Larvae peak August-September (from eggs on the ground)
Life cycle of Ixodes scapularis
To transmit lyme dz bacterium, ticks must feed for at least…..
24 hours
_____ secrete an anesthesia and anticoagulant when biting
Ticks
Blacklegged (or deer) ticks (Ixodes scapularis can transmit several tick-borne diseases including:
anaplasmosis
babesiosis
Lyme disease
Which type of ticks most commonly bite humans, adult or nymphal?
Nymphal
Agent – Anaplasma phagocytophilum
Originally confused with Ehrlichiosis
Tick – Ixodes scapularis
Animal reservoir (deer and white footed mouse)
Human Anaplasmosis (aka Human Granulocytic Anaplasmosis)
- Bacterial infection: Caused by the rickettsial agent Anaplasma phagocytophilum
- Infects white blood cells: Granulocytes
- Unknown transmission time from tick: Suspected to be between 24 and 48 hours
Human Anaplasmosis
Bacterial diseases
Ehrlichia chaffeensis
Ehrlichia ewingii
Anaplasma phagocytophilum
Ehrlichiosis
Cause is unknown Rash appearance similar to Lyme disease Has not been linked to arthritic, neurologic, or chronic symptoms Transmitted by lone star tick Most cases found in southeastern US
Southern Tick Associated Rash Illness (STARI)
Incubation period – 1 to 2 weeks
Fever, chills, severe headache – common
Malaise, Myalgia, Arthralgia – also common
Cough, GI upset, stiff neck – less common
“summer-flu”
Anaplasmosis
Mild anemia
Thrombocytopenia
Leukopenia with a left shift
Mild elevation of LFT’s
Anaplasmosis
Anaplasmosis diagnosis is made via…
PCR assay for DNA
Four-fold rise in IgG antibody by IFA
Immunochemistry staining of organism
Isolation in cell culture
Diagnosis of Anaplasmosis
Anaplasmosis tx for adults…
Doxycycline
if Doxy resistant, consider Rifampin
Anaplasmosis tx for kids..
start with Doxy, may follow up with Beta-lactam
Parasitic infection:
Caused by protozoa of the Babesia genus (Babesia microti and others)
Babesiosis
Infects RBCs
Unknown transmission time from tick
Babesiosis
Tick-borne illness Protozoa of family Babesiidae Animals: rodents and small mammals **enters RBCs and causes hemolysis Vector= Ixodid tick
Babesiosis
Incubation period.. 1-3 weeks following tick bite. 6-9 weeks following blood transfusion
Babesiosis
Fever, chills, sweats
Myalgias, arthralgia, fever
N/V
Exam shows: splenomegaly, hepatomegaly, jaundice
Babesiosis
High-level parasitemia (> 10 percent)
Significant hemolysis ( plus DIC)
Renal, hepatic, pulmonary compromise
Risk factors:
Age over 50 years
Asplenia,Malignancy,HIV,Immunosuppressives
Severe Babesiosis
Asymptomatic Disease—Common
1 May not need treatment
2 Can be monitored – clear 4-6 weeks
3 If no underlying disease- watch
Babesiosis
Laboratory: Anemia-thrombocytopenia-increased conjugated bilirubin
Confirmation: Blood smear- Intra-erythrocytic parasites
PCR **
Serology: Indirect immunofluorescent antibody test
Dx of Babesiosis
Clindamycin/Quinine or Atovaquone/Azithromycin
First line tx for Babesiosis
For severe Babesiosis, tx includes antibiotics plus…
exchange transfusion (until parasitemia is under 5%)
Erythema migrans (Bull’s eye) rash Muscle and joint pain Fatigue Chills, fever, and headache Swollen lymph nodes
Early Lyme dz symptoms
Symptoms: Arthralgias (oligoarticular and migratory)
Headache (often occipital)
Paresthesias (face/arm/leg)
No GI or respiratory symptoms
Lyme dz
Early localized: Erythema migrants rash (80-90%) and associated symptoms
Lyme disease
Early disseminated: Multiple EM rashes, associated symptoms (weeks to months)
-Lyme carditis (fluctuating AV Block)
- Neurologic SX: Cranial neuritis (7th nerve palsy—can be bilateral)
Lymphocytic meningitis
Radiculoneuritis
Lyme disease
Lyme dz dissemination is greater than _____
6 months
- Arthritis (migratory polyarthritis or monoarthritis)
- Neurologic (peripheral axonal neuropathy, mild encephalopathy, encephalomyelitis)
Lyme disease dissemination (greater than 6 mo)
What is used to confirm the diagnosis of lyme disease?
Serologic tests
Two-test step – Elisa followed by Western Blot:
If ELISA positive-test Western blot
If ELISA negative-no Western blot
Same sample tested by each test
Used in dx of lyme disease
Antibiotics in early disease may prevent seroconversion
Lyme dz
If less than 4 weeks illness - IgM and IgG tested
If more than 4 weeks illness - IgG tested
(can also test synovial fluid or CSF)
Lyme disease
Treat lyme dz with..
Doxycycline
Caused by the bacteria Rickettsia ricketsiae
Carried by Dermacenter (hard or dog) ticks
Untreated, the mortality is very high
Rocky mountain spotted fever
Rickettsia ricketsiae
Rocky mountain spotted fever
The disease is usually characterized by a fine skin rash, high fever, headaches and muscle pain
Doxycycline and chloramphenicol are very effective in treating the disease
Is less common on Nantucket than previously, probably because the dog ticks are less common
Rocky mountain spotted fever
Over 90% of cases occur during April-September
Peridomestic acquisition may account for majority of cases
Age-specific incidence highest in children, disease more frequent in males
Case clusters occur in hyperendemic foci
Rocky mountain spotted fever
Early: high fever, severe headache, myalgia, and gastrointestinal symptoms
Late: rash, photophobia, confusion, ataxia, seizures, cough, dyspnea, arrhythmias, jaundice, severe abdominal pain
Thrombocytopenia, hyponatremia
Long term sequelae: CNS deficits, amputations
Rocky mountain spotted fever
Rash not apparent until 2-5 days after onset of fever
Begins as 1 to 5 mm macules, typically on ankles, wrists, and forearms, spreads centripetally to trunk
Petechial rash occurs on or after day 6
Rash may be asymmetric, localized, or absent
rocky mountain spotted fever
85% of patients lack diagnostic titers in the first week of illness
As many as 50% of patients lack a diagnostic titer 7-9 days after onset of illness
Need to test acute and convalescent samples (2-4 weeks apart)
Indirect immunofluorescence assay (IFA)- four fold rise in titers confirmatory
RMSF
Rocky mountain spotted fever DOC
Tetracyclines
Less common tickborne dz
Bacterial: Francisella tularensis
Transmitted by American dog tick, lone star tick, and Rocky Mountain wood tick
Other transmission routes include deer fly bites, inhalation, ingestion, skin contact with infected animals
Cases found in every state except Hawaii
Tularemia
Francisella tularensis
Gram negative non-motile non-sporulating cocco-bacillus
Tularemia
-Infects small mammals:
ground squirrels, rabbits, hares, voles, muskrats, water rats and other rodents
-Arthropod vectors: ticks, biting flies, mosquitoes
Uncommon zoonosis
125 cases/year in USA
farmers, hunters, walkers, forest workers
**kills less than 50 people a year worldwide
Tularemia
**Highly infectious: inhalation of 10 bacteria can cause disease
-Avenues:
ingestion (water and food)
inhalation
direct contact
arthropod intermediates
animal bites
No person to person spread
Tularemia
Ulceroglandular (
Tularemia
Dx made thru…
-Culture (high risk to lab!)
- Non culture (ELISA, micro agglutination, Western blot, flow cytometry, indirect immunofluorescence)
- also PCR!
Tularemia
Streptomycin
Gentamicin
Recommended for….
Tularemia
A group of acute infections caused by arthropod born spirochetes of the genus Borrelia.
*Characterized by recurrent cycles of febrile episodes, separated by asymptomatic intervals of apparent recovery.
Relapsing fevers
Louse-Borne Relapsing Fever (Borrelia recurrentis)
Trench Fever (Bartonella quintana)
Epidemic typhus (Rickettsia prowazekii)
Body lice diseases
Which types of lice spread dz (head, body, pubic)?
only body! (can spread bacterial disease)
A single organism, Borrelia recurrentis, is the cause of louse borne….
relapsing fever
In ____ Borreli duttoni, and Borrelia croicuidare are the predominant species.
Africa
______ are slender actively motile spirochetes.
and measure10-20µ long and 0.2-0.5µ wide, with 4-10 loose coils.
Borrelia
Portal of entry, infected lice crushed into abraded skin.
Incubation period, 5-10 days.
High level spirochetemia.
Patients’ producing neutralizing antibodies, clearing of the circulating strain Borrelia in 3-5 days
Relapsing fever
Aims of Management:
Clinical cure
Prevention of relapse
Prevention/treatment of complications
Antibiotic treatment: Penicillin Tetracycline Chloramphenicol Erythromycin
Borrelia relapsing fever
