Epidemic Typhus and Other Louse- and Mite Borne Infections ...Order: Suborders: Insecta Phthiraptera Anoplura, Amblycera, Ischnocera (Mallophaga), Rynchophthirina 6 • 3,200 species

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

2

• 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




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

6

• 3,200 species of lice described

• 12 families of chewing lice

• 15 families of sucking lice




Lice: species of medical importance

• The species of greatest medical importance is Pediculus humanus

• Lice infestation is still

7

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




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




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




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




Louse-borne: relapsing fever

History:• Discovered by Otto Obermeier

• Large epidemics in the first

19

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

21

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




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

23


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




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




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

29

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




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




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





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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Scrub typhus: transmission cycle (2)

40

Image courtesy of Michael Groves

Scrub typhus: mites on rodents


Scrub typhus: mite habitat





Scrub typhus: mite habitat (2)


Scrub typhus


Scrubtyphus (2)





Scrub typhus (3)


Summary


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




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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Documents

Epidemic Typhus and Other Louse- and Mite Borne Infections ...Order: Suborders: Insecta Phthiraptera Anoplura, Amblycera, Ischnocera (Mallophaga), Rynchophthirina 6 • 3,200 species