Shoo Fly, Don’t
Infect Me!
Mechanical Vectors of Bacterial GI
Diseases
Liz Melton
March 9th, 2012
HUMANITARIAN CRISIS – Mechanical Transmission
Coincides with Vector
Habitat/Behavior:
-latrines (human and animal feces)
-unsanitary overcrowding
-refugee/prisoner of war camps
-areas with inadequate screening
techniques
-on dead corpses
-unfiltered garbage composts
www.un.org/millenniumgoals/pdf/mdg2007.pdf
What is Mechanical Transmission?
“a form of indirect
transmission in which the
infectious agent does not
undergo physiologic changes
inside the vector” (CDC
definition)
Examples:
*fly-borne
cockroach-borne
coprophagic beetle-borne
Hinshaw, J. (Photographer). (2000). [Photograph]. Retrieved February 13, 2012, from:
http://www.worldwidewounds.com/2000/oct/Janet-Hinshaw/Larval-Therapy-Human-andVeterinary.html.
Common Mechanical Vectors
•
•
•
•
Orangeacid. (Photographer). [Photograph]. Retrieved
February 13, 2012, from:
http://www.flickr.com/photos/orangeacid/189512184/siz
es/z/in/photostream/.
House Flies
Filth Flies
Blowfly
Cockroaches
Lerlind. (Photographer).
[Photograph] Retrieved February 13,
2012, from:
http://www.flickr.com/photos/lerlind/3
520284423/sizes/z/in/photostream/.
Keiding J. The housefly—biology and control. Training and information guide (advanced
level). Geneva, World Health Organization, 1986 (unpublished document WHO/VBC/
86.937; available on request from Division of Control of Tropical Diseases, World Health
Organization, 1211 Geneva 27, Switzerland).
• Common Cockroach
Characteristics:
-5-73 mm in length
-2 pair of wings
-flattened appearance
-yellow/brown color
-agile
-exhibits endophagic behavior
-active at night, in latrines
*RESPONSIBLE FOR:
•Diarrheal diseases
•Typhoid fever
•Dysentery
Hinshaw, J. (Photographer). (2000). [Photograph]. Retrieved February 13, 2012, from: http://www.worldwidewounds.com/2000/oct/JanetHinshaw/Larval-Therapy-Human-and-Veterinary.html.
Egypt Scenario
“The role of cockroaches and flies in mechanical transmission of medically important parasites”
Journal of Entomology and Nematology, Gehad T. El-Sherbini and Eman T. El-Sherbini, 2011
METHODS:
1) Surveyed residential areas in
Khaldyia Village, Egypt 2009 – 2010
• 45 cockroaches collected in
control, 178 total collected
• Flies from human feces also
observed
1) Parasites isolated/identified from
defecation areas in and around
houses
(Photograph). [Photograph]. Retrieved February 13, 2012, from: http://www.cockroachesextermination.info/?f.
Egypt Scenario
RESULTS:
-Cockroaches trapped in the
toilets of:
• houses with pit
latrines: 98 parasites/ml
• houses with water
system: 31 parasites/ml
-Pathogens isolated from
external and internal surface
of 98% of test cockroaches
Ric_k. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/ric_k/3196975264/sizes/z/in/photostream/.
Thailand Scenario
“THE MAJORITY OF COCKROACHES FROM THE SAMUTPRAKARN PROVINCE OF
THAILAND ARE CARRIERS OF PARASITIC ORGANISMS”
Pennapa Chamavit, Panupong Sahaisook, Nunthawadee Niamnuy, EXCLI Journal 2011
METHODS:
1) 920 cockroaches obtained in
Samutprakarn province of Thailand
• 18 open-air shopping markets
in 5 districts, 1 subdistrict
• captured during feeding,
natural habitat
1) Conducted wet smear/modified acidfast bacilli staining identified
pathogens
Corbie. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/crow/401136434/sizes/l/in/photostream/.
Thailand Scenario
RESULTS:
-498/920 (54.1%) of the
cockroaches harbored parasitic
organisms
**Cockroaches isolated from these
markets are carriers of several
organisms:
• cause commonly found
symptoms of illness such as
diarrhea or bowel disorder
Gusthed. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/bokage/5570904814/.
Flies as Mechanical Vectors
**350 fly species in 29 families are associated with food-borne diseases**
• > 50 species of synanthropic flies
correlated with unsanitary conditions
• 21 species of filth flies transmit human
gastrointestinal diseases
• ALL disseminate human pathogens in the
environment
• breed in:
• animal manure
• human excrement
• garbage
• animal bedding
• decaying organic matter
UNICEF Bangladesh. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/unicefbangladesh/6791300900/sizes/z/in/photostream/.
• Musca domestica
Characteristics:
-6-7 mm long, grey color
-marked by 4 dark longitudinal stripes
-breed in animal/human excrement or domestic
organic waste
-land, breed, and feed on feces and human
food
*RESPONSIBLE FOR:
• Infantile diarrhea
• Shigellosis diarrhea
• Dysentery
• Typhoid
Indian Housefly Scenario
“Vector potential of houseflies (Musca domestica) in the transmission of Vibrio cholerae in India”
R. Fotedar, Acta Tropica, 2001
METHODS:
1) Small village 15 km away from
Delhi city outbreak of diarrhea
1) 150 houseflies captured with
sterilized nets from animal pens,
yards or houses
1) Collect stool samples from 50
patients within 24 hrs of illness,
before anti-microbial
Praline 3001. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/praline3001/6672614287/sizes/l/in/photostream/ .
Indian Housefly Scenario
RESULTS:
-60% fly pools were positive
for V. cholerae
-during outbreak: V. cholerae
Ogawa T2 El Tor isolated from
stools of patients suffering from
diarrhoea
Medicinssansfrontieres. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/medecinssansfrontieres/3085562538/sizes/z/in/photostream/.
**Houseflies act as mechanical
vectors of V. cholerae biotype
El Tor, and aid in dissemination
Hospital Housefly Scenario
The housefly (Musca domestica) as a carrier of pathogenic microorganisms in a hospital environment
R. Fotedar, U. Banerjee,, S. Singh, Shriniwas and A. K. Verma, Journal of Hospital Infection, 1992
METHODS:
1) Collect Musca domestica from:
• surgical ward (All India Institute of
Medical Sciences Hospital)
• remote residential area 5 km away
as a control
1) A total of 113 flies were collected:
• 65 from a surgical ward (test)
• 48 from a residential area
(comparison)
Gusthed. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/bokage/5521594305/sizes/l/in/photostream/.
Hospital Housefly Scenario
RESULTS:
-10 genera of bacteria isolated from
the test group, 9 from control group
-the load of bacteria carried by the
test group of flies was significantly
more
**House flies therefore may act as
vectors of potentially pathogenic
bacteria in a hospital environment.
Cardiff Biossi Imaging. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/biosiimaging/5517090693/sizes/l/in/photostream/.
• Musca sorbens
Characteristics:
-resides in tropical areas
-breed in human feces
-feed on the secretion produced by
eyes of people, especially children.
-6 mm long, grey
-2 dark stripes on the thorax.
*RESPONSIBLE FOR:
•diarrheal diseases
•transmission of the eye
disease trachoma
• Chrysomya spp.
Characteristics:
-worldwide distribution
-breeds in open latrines, garbage, animal
excrement
-compact body, measuring 10 mm
-shiny blue or green
*RESPONSIBLE FOR:
• Diarrheal diseases
• Dysentery
• Intestinal worm eggs
Fly Life Cycle
MANTRA: “food, feces, flies, feces”
Sir Richard Feachem, KBE, FREng, DSc(Med), PhD, Director, The Global Health Group, Professor of
Global Health UCSF
Four Stages:
1) Egg
2) Maggot
Photograph by: Jim Kalisch, University of Nebraska – Lincoln
3) Pupa
4) Adult
Photograph by: Jim Kalisch, University of Nebraska - Lincoln
Photograph by: Jerry F. Butler, University of Florida
Mechanical Transmission Process
“feces enhances transmission of infectious agents much greater than
that of any other substrate or medium”
1) Dislodgement onto Food
• electrostatic charge
2) Fecal Deposits
• without changing infectivity
• increased viscosity of feces
Iwork2travel1. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
fhttp://www.flickr.com/photos/72457981@N00/353447863/sizes/l/in/photostream/.
3) Airborne Particles
• electrocution traps
• further spread of infectious
particles
“Super” Transmitters
Carry Pathogens on:
• spongy mouthparts
• body and leg hairs
(setae)
• sticky substance
• adherence during
fly resting periods
PKMousie. (Photographer). [Photograph]. Retrieved February
13, 2012, from:
http://www.flickr.com/photos/pkmousie/2618446877/sizes/l/in/ph
otostream/.
• sticky pads of the feet
(tarsi)
Jatin.muddu. (Photograher). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/jatinmuddu/2374306028/sizes/l/in/photostream/.
“Filthy Flies” – U of F insect pathologist, Dr. Jim Maruniak
http://www.youtube.com/watch?v=hMcf9C-iqJc
Results of Transmission
Major spread of bacterial enteric disease agents:
1) Inflammation of the gut
2) Diarrhea
And parasitic disease agents:
RachSilvester. (Photographer). [Photograph]. Retrieved fFebruary 13, 2012, from:
http://www.flickr.com/photos/rachsilvester/6155801573/sizes/m/in/photostream/.
Rubber Slippers in Italy. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/rubber_slippers_in_italy/5997107603/sizes/z/in/photostream/.
-Sarcocystis spp
-Toxoplasma gondii
-Isospora spp.
-Giardia spp.
-Entamoeba coli
-Entamoeba histolytica/Entamoeba dispar
-Endolimax nana
-Pentatrichomonas hominis
-Hammondia spp.
-Cryptosporidium parvum
Mechanically Transmitted GI Diseases
• Salmonella
• Typhoid
• Bacillary Dysentery (Shigellosis)
Gusthead. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/bokage/5570316311/sizes/l/in/photostream/.
• Salmonella
Signs and Symptoms
Who is affected:
-elderly
-children
12 – 72 Hr Presentation (lasts 4 – 7 days):
-diarrhea
•May require hospitalization
•Can be fatal
-fever
-abdominal cramps
Can Develop:
-Reiter’s Syndrome
Treatment:
-antibiotics
NIAID_Flickr. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/niaid/5613656967/.
• Typhoid - Salmonella Typhi
Signs and Symptoms
-un-industrialized nations
• Asia
• Africa
• Latin America
Presentation:
-sustained fever (103° to 104° F)
-stomach pains
-headache
Result of :
-International travel
-Food/water contamination
Sanofi Pasteur. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/sanofi-pasteur/5279772517/.
Treatment:
-antibiotics
• Bacillary Dysentery - Shigellosis
Signs and Symptoms
Location:
-distributed worldwide
Presentation (lasts 5 - 7 days):
-diarrhea (bloody)
-fever
-stomach cramps
Can Develop:
-chronic arthritis
Treatment:
-antibiotics (Bactrim, Septra,
Rocephin)
-anti-diarrheals (Imodium)
Nathan Reading. (Photographer). [Photograph]. Retrieved February 13, 2012, from: http://www.flickr.com/photos/nathanreading/6808291881/.
Historical Significance
Wartime Effects
-WWI: strong correlation
between fly density and the
incidence of dysentery
-WWII battle of El Alamein: Axis
losses due to dysentery
-1992-93, relief forces in Somalia
faced huge fly problems
-Operation Enduring Freedom and
Operation Iraqi Freedom: camps
placed in midst of unsecure
population centers
-Monumental nuisance during
the Vietnam War
-Similar problems were
encountered in the Persian Gulf
War of 1991/subsequent
humanitarian relief operations
http://www.defense.gov/multimedia/web_graphics/dod/DODc.jpg, http://www.defense.gov/multimedia/web_graphics/army/USARVc1.jpg,
http://www.defense.gov/multimedia/web_graphics/navy/USNc.jpg: Courtesy of U.S. Dept of Defense
Sample Wartime Precautions
Armed Forces Pest Management Board:
Disease Vector Ecology Profiles
(DVEPs) and TECHNICAL GUIDE
NO. 30 - Filth Flies
Significance, Surveillance and Control
in Contingency Operations:
Fly - Associated Diseases in Somalia:
ENTERIC DISEASES
AGENTS: a variety of organisms, primarily
bacteria and protozoa.
VECTOR TRANSMISSION: Fecal-oral
Example
EMPHASIS:
-essential epidemiology
-vector bionomics/behavior
-pesticide resistance
-house flies and other filth flies are
implicated in amplifying outbreaks
• house fly, Musca domestica
• filth flies, M. sorbens and M. biseta
-Cockroaches may also serve as
mechanical vectors
Primary Reduction Example
“Reduction of transmission of shigellosis by control of houseflies (Musca domestica)”
Dani Cohen, et. al, The Lancet, 1991
Prospective Crossover Intervention
Study
METHODS:
1) 2 military field bases several km
apart in early summer, 1988
2) Implement and track progress of
intensive fly control measures at
one base, keep another as
control
US Army Africa. (Photographer). [Phorograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/usarmyafrica/4325510666/sizes/l/in/photostream/.
Primary Reduction Example
RESULTS:
-after 11 weeks, fly counts were 64%
lower on the bases exposed to
fly control
**Clinic visits for diarrheal diseases
dropped by 42%:
• 85% for shigellosis (76% for
antibodies to Shigella)
• 57% for antibodies to
enterotoxigenic Escherichia coli
IFRC. (Photographer). [Photograph]. Retrieved February 13, 2012, from:
http://www.flickr.com/photos/ifrc/6152296211/sizes/l/in/photostream/.
Preventative Measures
4 Main Goals:
1) reduction or elimination of fly breeding
sites
2) reduction of sources that attract flies
from other areas
3) prevention of contact between flies and
disease-causing germs
4) protection of food, eating utensils and
people from contact with flies.
Keiding J. The housefly—biology and control. Training and information guide (advanced level). Geneva, World Health Organization, 1986
(unpublished document WHO/VBC/ 86.937; available on request from Division of Control of Tropical Diseases, World Health Organization,
1211 Geneva 27, Switzerland).
• "zero fly" tarps
• insecticide
• new technology (WHO) shelter
PATH & WaterAid America
“Defeating a Global Killer: The
Need for Action on Diarrheal
Disease, a discussion of a
growing global health crisis
that receives little attention
and what we can do about it”
(May, 2009). Defeating a Global Killer: The Need for Action on Diarrheal Disease. www.who.int/entity/pmnch/events/2009/InvitationDDevent.pdf. [Flyer].
February 13, 2012.
**Diarrheal disease is the 2nd killer of children
2 leading NGOs explore steps toward stopping deaths owing to diarrheal
diseases internationally:
•
•
•
•
adequate resources
effective implementation of available health
clean water
sanitation solutions