Flashcards in Lecture 4: Leptospirosis Deck (59)
Greek meaning for
Lepto + Spira
Has how many species? Serovars? How many are pathogens?
13 named species with over 250 serovars, 9 are pathogenic
Which is the most implicated serovar of Leptospira?
L. interrogans (is more commonly implicated)
Describe look of leptospira? How are they visualized?
Thin, tightly coiled spirochetes, with a characteristic hook
Due to their small diameter, they are visualized by darkfield microscopy
Leptospira was first described the organisms in renal tubules of a patient who died of __________-
Leptospira was first isolated where? And was also known as?
Rice harvest jaundice
Leptospira is endemic throughout the world
(Peak cases occur during the rainy season in tropical regions and later summer-early fall in temperate regions)
Which state has the highest incidence of leptospira in the US
What are animal vectors of leptospira?
rodents, cattle, swine, dogs, horses, sheep, and goats
Mortality in dogs is about 10%
- Rodents(mice) are hte most important
What is the most important vector for leptospira
How do rodents pass leptospira?
1. Passed in urine and infects water
2. Organisms remain viable for weeks to months in neutral pH water
3. Rats can shed the organisms in their urine for an extended period of time
4. Rats tend to carry the most virulent strain
Different species of Leptospira have evolved to be passed by a particular host
Humans are the ________ host for leptospira
(Acquire the bacteria from contaminated environmental sources)
Portals fo entry for leptospira are
cuts or abraded skin, mucous membranes, or conjunctivae
(Controversial if Leptospira species can penetrate intact skin)
What are the risk factors for leptospira?
1. In the tropics and in poverty (low educaiton, poor housing, contaminated water)
2. Occupational exposures (animal exposures, ranches, farmers, sewer workers"
3. Recreational Activity (freshwater swimming, kayakying)
4. Hosuehold exposure (pet dog, domesticated livestock, rodent infestions)
What are the transmission patterns of leptospira?
Epidemic - monsoons/floodding
Describe disease transmission of leptospira
What are the transmission patterns of leptospira?
Epidemic - monsoons/flooding
Endemic - Crowded urban areas
Sporadic - Travelers, jobs exposure
Leptospira concentrates in which bodily fluid?
Urine (primary source of infectivity)
(Animals get it from water)
The spirochete (of leptospira) can live for at least several weeks without a host at room temperature in moist environment or water
(Survives well w/o host
Water, warm --> tropical climate increased risk)
Direct or indirect contact with urine can pass leptospira
Direct exposure most common
Indirect exposure most common
Regarding leptospira clinical awareness on the part of physicians is necessary to care for travelers returning from vacation to endemic areas
Leptospirosis is a biphasic illness
The initial leptospiremic phase lasts _________ days and is characterized by fever.
Abx therapy is only effective during this phase
What phase is abx therapy effective for leptospira
leptospiremic phase lasts 3–10 days
Immune phase of leptospira
return of fever, headache, and other systemic symptoms in association with the clearance of leptospires from the blood
What phase does leptospira clear the blood
What is the most common clinical disease for leptospira?
Biphasic pattern is associated with __________ fever
Severe form of leptospira is associated with what disease?
Describe the initial phase of illness for leptospira?
- Average 1-2 weeks after infection
- Occurs during bacteremia
- Usually fever with ‘non-specific’ other complaints… muscle aches, abdominal pain, chills, malaise, vomiting
Describe the second phase symptoms for leptospira?
1. Eyes (conjunctivitis)
2. Kidneys (Renal failure ....Confusion -> death)
3. Heart (Chest pain, leg swelling, dilated heart)
4. Liver (Jaundice, hepatomegaly)
Severity of leptospira is affected by following factors (3)
1. Number of infecting organisms
2. Host’s immune status
3. Virulence of infecting strain
Where does leptospira generally stay in the human body
Generally stays outside of human cells, causes intense inflammation in areas it infects:
1. Acute kidney injury with acute tubular necrosis
2. Disrupts hepatocellular adhesion leading to bile stasis
3. Hemorrhage into the lung alveoli
4. Dysregulates coagulation in the blood
5. Causes necrosis of myocytes in the hear
Up to 55% of cases of leptospira demonstrate conjunctival suffusion
This symptom plus fevers is highly suggestive of leptospirosis
Severe Clinical Disease of leptospira occurs in what percent of cases? And is also known as what?
Roughly 1% of cases
Known as the Weil Syndrome
What is the Weil Syndrome triad?
2. Acute kidney injury
3. +/- pulmonary hemorrhage
(Renal injury can be so severe as to warrant dialysis)
Older dogs affected more than younger dogs by leptospira
Younger dogs affected more than older dogs
)Dogs infected the same way; contact with contaminated water or rat urine)
Diagnosis of Leptospira
- High clinical suspicion
- No gold standard testing
- Serology most frequent test (MAT) (ELISA)
- PCR not widely available
- Cultures can grow within 10 days if antibiotic was not given (still low success rate)
Microscopic agglutination test (MAT) is most frequently used but is imperfect for leptospira
Serology is most frequently used test
Treatment for leptospira
- Doxycycline for very mild disease
- Penicillin or ceftriaxone for moderate – severe disease (Weil’s disease)
In practice, if a patient presents with symptoms of leptospirosis, broad spectrum antibiotics will be started.
A ______________ may occur following antimicrobial therapy for leptospirosis; this is an acute inflammatory response to clearance of spirochetes from the circulation and is characterized clinically by fever, rigors, and hypotension
Prevention of Leptospira
- Avoid swimming in freshwater
- Wear protective equipment when coming into contact with animals or wet soil (i.e. gloves)
- Boil any catchment or freshwater before drinking
- Control rodents and wildlife around home
- Vaccinate pets and farm animals
- Drain standing water
Whats the most common cause of leptospira in hawaii?
Recreational, occupational, habitational
Leptospirosis in Hawaii is associated with an increase in -_______ farming
What is the most common form of leptospira in Hawaii
L. australis most common in Hawaii
( Kauai, the island with the highest annual rainfall and second most rural island, had and continues to have the highest incidence rate, followed by Hawaii, the most rural island)
Angiostrongylus cantonensis is found where?
Angiostrongylus cantonensis incidental host are?
Angiostrongylus cantonensis vertebrate reservoir?
Angiostrongylus cantonensis is exposed to humans by ________
(Infective larvae are found in a number of mollusks, including slugs, land snails, and a land planarian; they are also found in a number of unrelated animals, including freshwater prawns, land and coconut crabs, and frogs)
Angiostrongylus cantonensis lifecycle
1. The females lay eggs that hatch, yielding first-stage larvae, in the terminal branches of the pulmonary arteries of the rat
2. The first-stage larvae migrate to the pharynx, are swallowed, and passed in the feces
3. They penetrate, or are ingested by, an intermediate host (snail or slug)
4. After two molts, third-stage larvae are produced, which are infective to mammalian hosts.
5. When the mollusk is ingested by the definitive host, the third-stage larvae migrate to the brain where they develop into young adults.
6. The young adults return to the venous system and then the pulmonary arteries where they become sexually mature.
Angiostrongylus cantonensis clinical disease
- Some asymptomatic
- Most common cause of human eosinophilic meningitis
- Ocular invasion occurs.
- Eosinophilia is present in most of cases.
- Symptoms include headache, stiff neck, fever, rash, pruritus, abdominal pain, constitutional complaints, nausea, and vomiting.
- Neurologic involvement varies
- In general, the patients do not appear to be as ill as those who have bacterial meningitis.
Angiostrongylus cantonensis diagnosis
- Clinical Suspicion is key
- The cerebrospinal fluid (CSF) is abnormal (elevated pressure, proteins, and leukocytes; eosinophilia)
- CDC offers a real-time PCR assay for the specific detection of A. cantonensis in human CSF specimens
- No good serum serologies
There is a good serum serology to diagnoses Angiostrongylus cantonensis
Angiostrongylus cantonensis Treatment
- Most cases do not require treatment
- Supportive care
- Conflicting data on anti-helminthic drugs like albendazole
-Use of corticosteroids to decrease brain swelling
- From 2001-2005, there was an outbreak of Angiostrongyliasis in Hawaii on the big island
- 18 patients were evaluate
- Case-patients were more likely to consume raw homegrown produce in a typical week and to see snails/slugs on produce.
- Three patients specifically remember finding a slug in their food/drink.