Lecture 14
Insects and Disease
Now playing:
Ladysmith Black Mombasa
“Ungoyani Into Enhle (Destroy not this Beauty)”
50
55
60
65
70
75
80
85
Quantiles
100.0% maximum
99.5%
97.5%
90.0%
75.0%
quartile
50.0%
median
25.0%
quartile
10.0%
2.5%
0.5%
0.0%
minimum
Moments
84.000
84.000
81.775
79.000
74.000
68.000
62.000
56.900
50.000
46.000
46.000
Mean
Std Dev
Std Err Mean
upper 95% Mean
low er 95% Mean
N
67.71875
8.3721863
0.7400037
69.183084
66.254416
128
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/michigan-index.html
http://www.astdhpphe.org/infect/
http://www.fairharbor.com/fhca_mosq_eee.htm
http://www.medscape.com/SCP/IIM/public/columns/index-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.html
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-center.com/db/PageReq?SessionID=899&TopicID=365&PageID=1059&Action=view
http://www.msue.msu.edu/msue/imp/modc1/06079607.html
http://www.cdfound.to.it/html/atlas.htm#atlas
http://www.mednets.com/Lyme.htm
http://www.public-health.uiowa.edu/fuortes/63111/ARTHROP/index.htm
http://www.public-health.uiowa.edu/fuortes/63260/PLAGUELE/index.htm
http://www.public-health.uiowa.edu/fuortes/63111/Trypanosomiasis/index.htm
http://www.public-health.uiowa.edu/fuortes/63260/malaria1/index.htm
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…
I. Introduction
The 12 basic ways in which
arthropods affect the health
and well-being of man and
animals...
Tsetse fly
1. Annoyance - Buzzing flies or feeding mosquitoes.
2. Envenomization - toxemia - Stinging of Wasps or
Biting of Spiders
Brown recluse
wound two
years after the
bite
3. Mechanical pain from
bites.
4. Blood loss or Weight Loss, Reduction in egg, milk
production
5. Myiasis and mechanical pain associated with
larval invasion of, and establishment in tissues
6. Accidental injury to sense organs
7. Dermatosis -- dermatitis
8. Allergy and related conditions
9. Vectoring or parasites causing such diseases as
plague, malaria, yellow fever, and encephalitis
10. Causing paralysis of
animals & humans--as in
tick paralysis
11. Gadding, running , or milling of
animals caused by insect-induced
fright or extreme annoyance
12. Entomophobia--fear of insects or
arthropods or imagined infestation
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.
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)
II. Arthropods as Transmitters of
Infectious Agents of Disease
A. Pathogenic Agent
1. Protozoa
A. Leishmania spp. (sand fly vector)
B. Trypanosoma spp. (human sleeping sickness):
Tsetse Fly and Assassin Bug vector
C. Plasmodium spp (malaria)– mosquitoes vector
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 mosquito…the price of science.
www.theatlantic.com/trans.atl/issue/97/malaria.htm
Plasmodium life cycle
Malaria
2. Helminths - Worms
A. Trematodes and Cestodes
(a.k.a. flukes and
tapeworms) -arthropods may serve as
intermediate hosts for
these parasites
Fluke
60 ft from
head to tail
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
Eggs swallowed by
definitive host, hatch in
duodenum, and
oncospheres penetrate
the instinal villi
Direct reinfection
(without intermediate
host)
Oncospheres develop
into cysticercoid in
lymphatics of villus
Egg
Life Cycle of
Vanpirolepis spp.
Tailed
cysticercoids
develop in
hemocoel
Optional
intermediate host
(larval and adult
beetles)
Eggs swalloed
by beetle hatch
in intestine
2. Helminths - worms
B. Nematodes -Elephantiasis
I. Filariasis and Elephantiasis-Filarial worms transmitted by
mosquitoes
Filarisis world distribution
II. Onchocerciasis (river blindness)-Filarial worms transmitted by Black Fly
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.
Bite mark
III. Heart Worm--Filarial Worm Transmitted
by mosquitoes
3. Viruses
A. Yellow Fever--Transmitted by mosquito
3. Viruses
B. Dengue Hemorrhagic Fever-Transmitted by mosquito
C. Encephalitides-- (Eastern
Encephalitides, St. Louis , and Western
Encephalitides) transmitted by mosquito
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 swampdwelling birds
• 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 1940’s,
1973, 1980-83,
1989, 1991-8, 2001
• most serious mosquito
borne disease in
Michigan
-Virus found in Africa, West Asia, Middle East.
-Imported in USA in the summer of 1999.
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
HORSE CASES
AVIAN
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
•30% exhibit any noticeable
symptoms
•Less than 1% of these cases
become life-threatening
HUMAN
CASES
•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.
Updated 11/08/2004 2:00 PM
497 Cases of Human West Nile Virus in Michigan
41 Total Deaths in Michigan
Michigan WNV Cases
Cases by Age and Sex
Age
Female
Male
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 2:00 PM
Unknown
Total
Eliminate
exposure
How Control?
Insecticides VECTOR MANAGEMENT
Eliminate
Standing
water
Vaccine development
4. Rickettsia
A. Rocky Mountain Spotted Fever and Colorado
Tick Fever Transmitted by Tick
4. Rickettsia
B. Epidemic Typhus-Transmitted by the
Louse
5. Bacteria
A. Plague (Yersinia pestis)-- Transmitted by the
flea from rodent to rodent then man to man…
Western Reservoir
Eastern Reservoir
Plague distribution
B. Tularemia-- Transmitted by ticks, deer
flies to man. Direct inoculation from skinning
Rabbits…
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.
B. Biting Arthropods
4. Deer and Horse Flies (Family Tabanidae)-swamps and marshes, along stream banks and
ponds and lakes.
C. Lyme Disease-- A spirochete bacteria
transferred by the tick
Borrelia burgdorferi
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.
Life stages of deer tick
Life stages of dog tick
2. 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 cases…many cases unreported or
misdiagnosed.
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)