Post on 25-Sep-2020
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
1The screen versions of these slides have full details of copyright and acknowledgements
Epidemic Typhus and Other Louse- and Mite-Borne Infections
1
Kevin R. Macaluso Ph.D.School of Veterinary Medicine
Louisiana State UniversityBaton Rouge, La
Outline
• Louse-borne infections
Epidemic typhus
Trench fever
Relapsing fever
• General characteristics
Life cycle
Classification
Medical importance
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• Mite-borne infections
Rickettsialpox
Scrub typhus
• History of disease
• Etiological agent
• Vector(s)
• Transmission cycle
Lice: general characteristics
• Small, wingless insects
• 4-10 mm long
• Adult lice are dorsal-ventrally flattened
Head
Thorax
3
ventrally flattened
• Elongate with 3 distinct body segments
• Mouthparts adapted for chewing or sucking
• Host-specific Image courtesy of Michael Groves
Thorax
Abdomen
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
2The screen versions of these slides have full details of copyright and acknowledgements
Lice: life cycle
• Hemimetabolous life cycle with 3 immature stages superficially
4
resembling the adult
• Female lice lay <10 eggs/day
• Louse eggs are called “nits”
Image modified from cdc.gov
Louse-borne: life cycle
5Image PHIL#5289 (WHO) from cdc.gov
Lice: classification
Class:
Order:
Suborders:
Insecta
Phthiraptera
Anoplura, Amblycera, Ischnocera (Mallophaga), Rynchophthirina
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• 3,200 species of lice described
• 12 families of chewing lice
• 15 families of sucking lice
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
3The screen versions of these slides have full details of copyright and acknowledgements
Lice: species of medical importance
• The species of greatest medical importance is Pediculus humanus
• Lice infestation is still
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persist in less developed countries
Image PHIL#9218 from cdc.gov
Lice: disease-causing agents
• Rickettsia
• Bartonella
• Borrelia
8Image (modified) from cdc.gov
Alpha-proteobacteria
Organization of louse-borne pathogens
Order: Rickettsiales
Family: Rickettsiaceae
Genus: Rickettsia
Spotted fever
Typhus
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Orientia
Anaplasmataceae
Rhizobiales
Bartonellaceae
BartonellaSpirochetesOrder: Spirochaetales
Family: Spirochaetaceae
Genus: Borrelia
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
4The screen versions of these slides have full details of copyright and acknowledgements
Biological characteristics of Rickettsia• Obligate intracellular parasite
• Gram negative bacteria(0.3 x 1 to 2 µm)
• Coccobacillus with complex outer coats with capsule
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por slime layer
• LPS (weak endotoxin activity)
• Human pathogens
• Virulence factors: unknown
• Transmitted by fleas, lice, mites (ticks) Image by K. Macaluso
Biological characteristics of Bartonella
• Facultative intracellular
• Gram negative rod (0.3 x 0.5 µm wide and 1-1.7 µm long)
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• Can be grown on axenic media or cocultivated in cell culture
• Transmitted or associated with fleas, lice, and mites (ticks) Image from Foucault et al., 2006 (cdc.gov)
Biological characteristics of Borrelia
• Gram negative, long helically coiled (spiral-shaped)
• 0.1 x 0.6 µm wide and 5-250 µm long
• Chemoheterotropic
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• Chemoheterotropic
• Flagella that run between the cell wall and outer membrane
• Human pathogens
• Transmitted by lice and ticksImage modified from Cutler et al.,
1997 Int. J. Syst. Bacteriol.
F= flagella of Borrelia recurrentis
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
5The screen versions of these slides have full details of copyright and acknowledgements
Louse-borne: epidemic typhus
History:• 1083 – described in Spain
• 1536 – distinguished from plague
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• 1700’s and 1800’s –distinguished from typhoid fever
• 1900’s – louse transmission
• 1930 – ZinsserImage from Roland Huet
Louse-borne: epidemic typhus (2)Etiological agent: Rickettsia prowazekii
14www.ciesin.org/docs/001-613/001-613.html
Infected lice common source
Years or decades
Infected ticks?Aerosols from infected ectoparasites (lice and
fleas) rare source
Infected flying squirrels (USA)
Patient with epidemic typhus
Apparently cured
patientStress
Relapses,
Louse-borne: epidemic typhus (3)
Transmission cycle• Transmission occurs
via contamination
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p ,bacteraemia (Brill-Zinsser
disease)Louse feeding Current
feeding
yields infecte
dlice
Typhus outbreak
Louse infestation (e.g., war, jail,
homeless)
a co a a oof bite sites with feces
• Infection through aerosols has also been reported
• Lice also suffer from R. prowazekii
• Vertebrate host is necessary for R. prowazekii lifecycle
Bechah et al., Lancet Infect Dis. 2008
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
6The screen versions of these slides have full details of copyright and acknowledgements
Louse-borne: trench feverHistory:
• Affected >1 million people during World War I
• The name ‘trench fever’ was first mentioned in 1915
• In 1919, transmission by lice demonstrated
Aff t d th G i R i i W ld W II
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• Affected the German army in Russia in World War II
• In 1949, laboratory accident lead to outbreak and precise characterization of the disease
• Sporadic epidemics since World War II
• Reemergence of B. quintana among the homeless in Europe and the United States and in refugee camps
Louse-borne: trench fever (2)
Etiological agent: Bartonella quintana
• Clinical symptoms include:
Headache, dizziness, pain in shins, and elevated temperature
3 7 days post infection temperature drops;
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3-7 days post-infection temperature drops; followed by a relapse to fever
• Variable clinical manifestations:
Classic with shin pain
Typhoid-like with prolonged fever and rash
Abortive form, brief, less intense
Louse-borne: trench fever (3)
Transmission cycle
• Between humans and lice:
Lice ingest take blood meal from bacteremic host
Lice are transmitted bet een indi id als
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Lice are transmitted between individuals via clothing or bedding
B. quintana multiplies in the louse’s intestine
Subsequent biting of new host results in scratching; thus facilitating fecal transmission of B. quintanato uninfected hosts
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
7The screen versions of these slides have full details of copyright and acknowledgements
Louse-borne: relapsing fever
History:• Discovered by Otto Obermeier
• Large epidemics in the first
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half of last century
• 1970’s - cultivated and animal models developed
• 1980’s discovery of antigenic variation
Image modified from Cutler, Clinical Microbiology and Infection, 2009
Louse-borne: relapsing fever (2)Etiological agent: Borrelia recurrentis
20www.ciesin.org/docs/001-613/001-613.html
Louse-borne: relapsing fever (3)
Transmission cycle• Between humans and lice:
Lice ingest take blood meal from bacteremic host
B. recurrentis mostly destroyed
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Image modified from Cutler, Clinical Microbiology and Infection, 2009
B. recurrentis mostly destroyed in the louse’s gut, but few persist and move to the hemoceol
Lice are transmitted between individuals via clothing or bedding
Subsequent biting of new host results in scratching; thus facilitating fecal transmission of B. recurrentis
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
8The screen versions of these slides have full details of copyright and acknowledgements
Summary
• Louse-borne infections
Epidemic typhus
Trench fever
Relapsing fever
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• Lice transmitted between people via clothes/bedding
• Agents are transmitted to vertebrates during feeding via fecal transmission
• While less prevalent, important for stressed populations
Outline• Louse-borne infections
Epidemic typhus
Trench fever
Relapsing fever
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• Mite-borne infections
Rickettsialpox
Scrub typhus • General characteristics of mites
• Species of medical importance
• Disease-causing agents
Mites: general characteristics• Typically less than 1 mm long
• Abdomen joined to cephalothorax, no segmentation
• Chelicerae for tearing or piercing in parasitic species
• Feeding chiggers inject a salivary fluid which dissolves the host's cells, then suck up the liquefied tissue; Within a few h ll ddi h i l i hi l
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hours, small, reddish, intensely itching welts appear
• These bites may continue to itch for several days up to two weeks after the chigger is dislodged
• Inhabit areas of tall grass, associated with wet spots, ponds and stream banks, and forest underbrush
• Larvae attach to passing animals; On humans, typically move to a part of body that is constricted, e.g., waistband
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
9The screen versions of these slides have full details of copyright and acknowledgements
Mite: life cycle
25Image by Rebecca L. Nims, from Medical and Veterinary Entomology Eds. Mullen and Durden
Mites: classification
Subclass: Acari
Order: Prostigmata
Class: Arachnida
26Source: http://tolweb.org/tree/phylogeny.html
• Free-living, predaceous and parasitic – ectoparasites
• Indirect and direct effects on humans and animals:
Dermatitis or other tissue damage
Mites: species of medical importance
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Dermatitis or other tissue damage
Cause of strong allergic reactions
Loss of blood
Transfer of pathogenic agents
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
10The screen versions of these slides have full details of copyright and acknowledgements
Mites: disease-causing agents
• Rickettsia
• Orientia
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Mite-borne: rickettsialpox
History:
• First described in 1946 – Queens epidemic
• Characterization – from isolation of the agent t bli h d d i ti ti t
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to published description as causative agent of disease was 5 months
• 2001-2003 – an increase in cases due to increased laboratory conformation
Mite-borne: rickettsialpox (2)Etiological agent: Rickettsia akari
30Image courtesy of Christopher Paddock
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
11The screen versions of these slides have full details of copyright and acknowledgements
Mite-borne: rickettsialpox (3)
Vector:Liponyssoides mite vector
31Image courtesy of Christopher Paddock
Mite-borne: rickettsialpox (4)
Transmission cycle House mite(vector)
32Image modified from Azad and Beard, EID, 1996
House mouse(maintenance host)
Mite-borne: scrub typhusHistory:
33Image taken from medscape.com
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
12The screen versions of these slides have full details of copyright and acknowledgements
Mite-borne: scrub typhus (2)Etiological agent: Orientia tsutsugamushi
34Image courtesy of Michael Groves
Infection: Orientia tsutsugamushi
35Image PHIL#9218 from cdc.gov
Scrub typhus: eschar
36Image courtesy of Michael Groves
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
13The screen versions of these slides have full details of copyright and acknowledgements
Scrub typhus: eschar and rash
37Images courtesy of Michael Groves
Mite-borne: scrub typhus
Vector: Trombiculid mites
38Images courtesy of Michael Groves Image by Rebecca L. Nims, from Medical
and Veterinary Entomology Eds. Mullen and Durden
Scrub typhus: transmission cycle
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Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
14The screen versions of these slides have full details of copyright and acknowledgements
Scrub typhus: transmission cycle (2)
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Image courtesy of Michael Groves
Scrub typhus: mites on rodents
41Images courtesy of Michael Groves
Scrub typhus: mite habitat
42Images courtesy of Michael Groves
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
15The screen versions of these slides have full details of copyright and acknowledgements
Scrub typhus: mite habitat (2)
43Image courtesy of Michael Groves
Scrub typhus
44Images courtesy of Michael Groves
Scrubtyphus (2)
45Images courtesy of Michael Groves
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
16The screen versions of these slides have full details of copyright and acknowledgements
Scrub typhus (3)
46Images courtesy of Michael Groves
Summary
• Mite-borne infections
Rickettsialpox
Scrub typhus
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• Only larval ‘chigger’ stages are parasitic
• Agents are transmitted to vertebrates during feeding via salivary secretions
Acknowledgements
Abdu F. Azad
Michael Groves
Walairat Pornwiroon
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Piyanate Sunyakumthorn
Epidemic Typhus and Other Louse- and Mite Borne Infections
Kevin R. Macaluso Ph.D
17The screen versions of these slides have full details of copyright and acknowledgements
Literature referencesLouse-borne diseases
• Durden LA, 2005, ‘Lice, the Phthiraptera’ in Biology of Disease Vectors, Second Edition ed. W.C. Marquardt, pp.67-75, Elsevier Acad. Press, Oxford, UK
• Bechah Y et al., 2008; Epidemic typhus; Lancet Infect Dis. 8:417-26
Mite-borne diseases
W lt DE d Sh M 2005 ‘Mit d Di ’ i Bi l f Di V t
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• Walter DE and Shaw M, 2005, ‘Mites and Disease’ in Biology of Disease Vectors, Second Edition ed. W.C. Marquardt, pp.25-44; Elsevier Acad. Press, Oxford, UK
• Paddock et al., 2006, Isolation of Rickettsia akari from eschars of patients with Rickettsialpox, Am. J. Trop. Med. Hyg., 75: 732-738
• Yeon Joo Jeong et al., 2007, Scrub Typhus: clinical, pathologic, and imaging findings, RadioGraphics 27: 161-172
• Kelly DJ et al., 2009, Scrub typhus: the geographic distribution of phenotypic and genotypic variants of Orientia tsutsugamushi, Clinical Infect Dis. 48(3): S203-30
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