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Lecture 14
Insects and Disease
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Ladysmith Black Mombasa
Ungoyani Into Enhle (Destroy not this Beauty)

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Goals

1. Define vector, parasite, myiasis,
   envemonization, plague, and epidemic
2. Know the effects of arthropods on humans and
   other animals

Assignment
Websites
http//www.geocities.com/HotSprings/Spa/6772/michi
gan-index.html
http//www.astdhpphe.org/infect/

http//www.fairharbor.com/fhca_mosq_eee.htm
http//www.medscape.com/SCP/IIM/public/columns/ind
ex-BugVectors.html http//www.ento.vt.edu/Courses/
Undergraduate/IHS/oncampus/html_files/Disease.html
http//www.ento.vt.edu/Courses/Undergraduate/IHS/
oncampus/html_files/Disease2.html/Disease2.html
http//www.isis.vt.edu/fanjun/text/Link_pest9.htm
l http//www.ento.vt.edu/Courses/Undergraduate/IHS
/oncampus/html_files/History.html
http//www.wenet.net/fredarfa/trematod.htm
http//www.biohaven.com/dengue.htm

http//new.health-cente
r.com/db/PageReq?SessionID899TopicID365PageID
1059Actionview http//www.msue.msu.edu/msue/imp/
modc1/06079607.html http//www.cdfound.to.it/html/
atlas.htmatlas
http//www.mednets.com/Lyme.htm

http//www.public-health.uiowa.edu/fuortes/63111/A
RTHROP/index.htm http//www.public-he
alth.uiowa.edu/fuortes/63260/PLAGUELE/index.htm
http//www.public-health.uiowa.edu/fuo
rtes/63111/Trypanosomiasis/index.htm
http//www.public-health.uiowa.edu/fuortes/63260/m
alaria1/index.htm
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Where Have we Come From? Where are we Going?

• What is Science?
• Theory of Life
• Organization
• Organismal
• Theory of Inheritance
• Theory of Evolution
• Germ Theory of Disease

• Arthropods
• Environment Ecology
• Biological Sustainability
• Food Security
• Your Future Biology?

497 Cases of Human West Nile Virus  in Michigan
41 Total Deaths
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I. Introduction
The 12 basic ways in which arthropods affect the
health and well-being of man and animals...
Tsetse fly
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6. Accidental injury to sense organs
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12. Entomophobia--fear of insects or arthropods
or imagined infestation
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B. Biting Arthropods
1. Mosquitoes (Family Culicidae)-- Several
species of mosquitoes bite man and animals in
Michigan. Some species develop in pools while
others develop in ponds and marshes. Occur
during the spring and summer in Michigan.
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Life Cycle of Insects

• Metamorphosis
• Complete
• Egg (1 stage)
• Larva (many stages)
• Pupa (1 stage)
• Adult (1 stage)
• Incomplete
• Egg (1 stage)
• Nymph (many stages)
• Adult (1 stage)

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II. Arthropods as Transmitters of Infectious
Agents of Disease
A. Pathogenic Agent
1. Protozoa
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Invasive Species Tiger Mosquito
Mating

• Introduced into MI
• Transmits Encephalitis
• Came from Asia
• Product of travel
• trade
• Will you be able to
• identify this species?

Female
Male
Human arm feeding the mosquitothe price of
science.
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www.theatlantic.com/trans.atl/issue/97/malaria.htm
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Plasmodium life cycle
Malaria
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2. Helminths - Worms
A. Trematodes and Cestodes (a.k.a. flukes and
tapeworms) -- arthropods may serve as
intermediate hosts for these parasites
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After ingestion cyticercoids released from
beetle, then shed tails and evaginate
Scolex attaches to intestinal wall, develops into
adult cestode
Definitive hosts humans or rodents
Gravid proglottid released and eggs released in
feces
Oncospheres develop into cysticercoid in
lymphatics of villus
Eggs swallowed by definitive host, hatch in
duodenum, and oncospheres penetrate the instinal
villi
Direct reinfection (without intermediate host)
Egg
Life Cycle of Vanpirolepis spp.
Optional intermediate host (larval and adult
beetles)
Tailed cysticercoids develop in hemocoel
Eggs swalloed by beetle hatch in intestine
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2. Helminths - worms
B. Nematodes --
I. Filariasis and Elephantiasis--Filarial worms
transmitted by mosquitoes
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II. Onchocerciasis (river blindness)-- Filarial
worms transmitted by Black Fly
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B. Biting Arthropods
2. Black Flies (Family Simuliidae)-- Immatures
occur in clear streams with high oxygen
concentration, and the adults emerge during
late May and June both Upper and Lower
Peninsulas.
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III. Heart Worm--Filarial Worm Transmitted by
mosquitoes
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3. Viruses
A. Yellow Fever--Transmitted by mosquito
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3. Viruses
B. Dengue Hemorrhagic Fever-- Transmitted by
mosquito
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C. Encephalitides-- (Eastern Encephalitides, St.
Louis , and Western Encephalitides) transmitted
by mosquito
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III. Arthropods and Diseases of Major Importance
to Michigan
A. Diseases
1. Eastern Equine Encephalitis-- enzotic setting
hardwood swamps

• Mosquito vector, Culiseta melanura

• Mosquito passes virus among swamp- dwelling birds

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• pathogenic in both mosquitoes and birds

• virus sometimes leaves swamp setting and is
  transmitted to horses, game birds (penned
  pheasants), and people

• highly pathogenic in these dead-end hosts

• outbreaks occurred in the early 1940s, 1973,
  1980-83, 1989, 1991-8, 2001

• most serious mosquito borne disease in Michigan

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• Virus found in Africa, West Asia, Middle East.
• Imported in USA in the summer of 1999.

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HOSTS

• - Most cases with no symptoms
• or mild flu like symptoms
• Inflammation of brain (encephalitis)
• 3242 cases and 176 deaths by
• October 21, 2002.

• - Survival
• - Without symptoms but infected
• Neurologic disease
• Limb incoordination
• Death

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AVIAN CASES
HORSE CASES
  Counties with testing activity negative to date for West Nile Virus
  Counties with testing activity positive for West Nile Virus
Updated 10/28/2002    342 West Nile Virus Horse
cases to date
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• 30 exhibit any noticeable symptoms
• Less than 1 of these cases become
  life-threatening
• Most people have mild, flu-like symptoms, or no
  symptoms at all.
• Most susceptible are the elderly and those with
  compromised immune systems.
• West Nile Virus is not transmissible from person
  to person.

HUMAN CASES
Updated 11/08/2004 200 PM 497 Cases of Human
West Nile Virus in Michigan 41 Total Deaths in
Michigan
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Michigan WNV Cases
Cases by Age and Sex Cases by Age and Sex Cases by Age and Sex Cases by Age and Sex Cases by Age and Sex
Age Female Male Unknown Total
Unknown 2 1   3
0 to 18 5 8   13
19 to 65 125 151   276
Age 65 83 121 1 205
Total 215 281 1 497
Female or Male 43.26 56.54 0.20
Updated 11/08/2004 200 PM
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How Control?
Eliminate exposure
Insecticides
VECTOR MANAGEMENT
Eliminate Standing water
Vaccine development
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4. Rickettsia
A. Rocky Mountain Spotted Fever and Colorado
Tick Fever Transmitted by Tick
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4. Rickettsia
B. Epidemic Typhus-- Transmitted by the Louse
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5. Bacteria
A. Plague (Yersinia pestis)-- Transmitted by the
flea from rodent to rodent then man to man
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Plague distribution
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B. Tularemia-- Transmitted by ticks, deer flies
to man. Direct inoculation from skinning
Rabbits
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B. Biting Arthropods
3. Stable Flies (Family Muscidae)-- spoiled feed
or hay mixed with wastes from horses and other
livestock on farms or in stables. Upper
Peninsula of Michigan, particularly Porcupine
Mountains and along Lake Superior beaches.
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B. Biting Arthropods
4. Deer and Horse Flies (Family Tabanidae)--
swamps and marshes, along stream banks and
ponds and lakes.
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C. Lyme Disease-- A spirochete bacteria
transferred by the tick
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B. Biting Arthropods
5. Ticks (Family Ixodidae)-- Until the discovery
of Lyme disease and the deer tick, lxodes
scapularis (formerly dammini), in Michigan, the
American dog tick (Dermacentor variabilis) was
the most pestiferous tick in Michigan. Both of
these ticks are more abundant in the Upper
Peninsula.
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• Lyme Disease -- bacteria Borrelia burgdorferi
• Vector deer tick Ixodes dammini in Upper
  Michigan and probably lower Michigan
• The tick feeds on small rodents, deer and man.
• In 1991, Michigan reported 46 cases of Lyme
  Disease, based on the new case definition.
  Michigan has reported 542 Lyme disease casesmany
  cases unreported or misdiagnosed.

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The mortal enemies of man are not his fellows of
another continent or race they are the aspects
of the physical world which limit or challenge
his control, the disease germs that attack him
and his domesticated plants and animals, and the
insects that carry many of these germs as well as
working notable direct injury.
--W. C. Allee (1885 - 1955)
US zoologist,
The Social Life of Insects (1939)