COCKROACHES, BED BUGS, AND PUBLIC HEALTH - ZACHARY DEVRIES DEPARTMENT OF ENTOMOLOGY
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5/5/2022
Cockroaches, Bed Bugs,
and Public Health
Zachary DeVries
Department of Entomology
University of Kentucky
zdevries@uky.edu
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Outline
1.Cockroaches
• What are cockroaches?
• Health effects
2.Bed Bugs
• What are bed bugs?
• Health effects
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© Patty Alder
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© Coby Schal
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German Cockroach
(Blattella germanica)
• Small (~5/8”) cockroach
found worldwide
• Reliant on humans and
human built structure
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• Egg to adult in ~3 months
• 160 offspring/female
• Can eat almost anything
• Reach large populations sizes
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We make it very easy for them…
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• Resistant to most spray‐based
formulations (pyrethroids)
• Baits highly effective when
used correctly
• Significant effects on human
health
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Psychological Effects
• Social stigma
• Stress
• Delusional parasitosis
(Ekbom syndrome)
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Cockroaches and Pathogens
• Mechanical transmission
• Lots of nasty things in
garbage and sewage!
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Diseases likely transmitted
by cockroaches
• Bubonic plague • Pneumonia
• Dysentery • Diphtheria
• Diarrhea • Tuberculosis
• UTI • Salmonella
• Food poisoning • Leprosy
• Gastroenteritis
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Do‐it‐Yourself (DIY) Harm
• Often occurs when residents over‐ or
incorrectly use pesticides (ex. TRFs)
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• TRFs are ineffective and should not be used for
cockroach control
• TRFs leave behind high levels of pesticide residues
• Baits are highly effective and are similarly priced
to TRFs
• Unclear why TRFs are still being used
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Cockroach Allergens
• Produce several potent allergens
• Found in feces, muscles, tergal
glands, others
• Significant effects on human health
related to asthma
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Cockroaches, allergens
and allergic disease
• Number of people currently affected with
asthma in the United States
>25 million (>7 million children)
• Estimated cost in the United States
$82 billion annually
• Percentage of US population allergic to
cockroaches
>26% (~37% for inner‐city children with asthma)
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Asthma Disproportionally Effects
Children, Women, Minorities, and
those Living in Poverty
• Children have 2x as many ER visits compared
to adults
• Asthma associated deaths are 2x higher in
women compared to men
• Asthma hospitalization rate is 3x higher among
African Americans compared to Caucasians
• Low‐income environments were found to be
associated with the development of asthma
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Cockroach Allergens
• 1 female = ~156 µg of allergen (Bla g 1) per day!
• Human Sensitization Threshold = 0.2 µg/g dust
• Morbidity Threshold = 0.8 µg/g dust
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Some allergens are
cross‐reactive among
cockroach species
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Through cockroach control alone,
Risks Factors:
• Pollution
Asthma Development
we can reduce or eliminate the
X
• Moisture environmental factor
• Air circulation
• Allergen levels
X
• Diet environment
environment
Asthma Asthma
development exacerbation
human
•
•
•
•
Genetics
Gender
Race
Age X
Medical intervention
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Source Reduction
• e.g., cockroach control
• No roaches = no
allergen production
• Critical for cockroach
allergen mitigation,
but often overlooked
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Can we reduce cockroach
allergens by controlling
cockroaches?
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Cockroach Control,
Education, Cleaning,
and Allergen Mitigation
• Recruited cockroach infested homes
50‐1000 roaches trapped (highly infested)
• Received intensive interventions:
• Baiting
• Education
• Professional Cleaning
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Insecticidal Baits
• Insecticide inside a food matrix
• Cockroaches ingest the food, then
succumb to insecticide
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Education
• Importance of sanitation
• Value of traps and routine
inspections/monitoring
• Health risks associated with cockroaches
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Cleaning
• Scrub floors with • Launder sheets
water and detergent • HEPA air filter
• Deep vacuuming
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Cockroach Control, Education,
Cleaning, and Allergen Mitigation
400 control
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290 treatment
Cockroaches/apt
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0
0 Month 6
Month
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Cockroach Control, Education,
Cleaning, and Allergen Mitigation
700 633
Cockroach control, cleaning, and
U Bla g 1 per grm dust
education togethercontrol
resulted in
treatment
allergen
351 reduction; what is the
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relative contribution of each287element?
Follow up study: cockroach control
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0alone can reduce allergens in homes
0 Month
Month 6
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Cockroach Control, Education,
Cleaning, and Allergen Mitigation
700 633
U Bla g 1 per grm dust
control
treatment
Not 351
everyone has reached the
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same conclusion – not287all
treatments are created equal!
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0
0 Month
Month 6
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Cockroach Control
– What Works?
An integrated approach is key!
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Residual Insecticides
Poor efficacy due to insecticide resistance
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Benefits of Baiting
• Long lasting residual • Point sources:5/5/2022
Importance and Implications
• Cockroach control alone can reduce
allergens and mitigate health risks
• Cockroach control has to be
effective to reduce allergens
• Poor control efforts puts residents
at serious health risk
Are cockroaches the only
indoor pest to worry about?
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Outline
2.Bed Bugs
• What are bed bugs?
• Health effects
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Recent Resurgence!
• Disappeared in the 1950s, but
re‐appeared in the early 2000s
• Found everywhere!
Video courtesy of Rutgers University
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Small, but visible
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Feed on blood
• Require a blood meal for
growth and development
• Feed primarily on humans,
but can feed on other animals
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Aggregations
• Aggregation pheromone
• Typically found in and around the bed
• Leave aggregations to feed or mate
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Known Effects on Human Health
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Immediately after bite
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24 hours after bite
• Severity of reaction changes over time
• First bite often leads to no reaction
• Different people have different responses
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Not known to transmit any
diseases in nature!
• Two papers showing POTENTIAL
to vector pathogens
• ONLY in the lab
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Psychological Effects
• Poorly understood, but has major effects on
humans (Ex. depression, anxiety, sleep
disturbance, PTSD)
• Often more difficult to mitigate than allergens
• Delusional Parasitosis
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Do‐it‐Yourself (DIY) Harm
• Often occurs when residents over‐ or
incorrectly use pesticides (ex. TRFs)
• Most recently, trying to conduct heat
treatments on their own
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Allergens and Other
Contaminants?
Photo courtesy of Brittany Campbell
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Histamine?
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Aggregation Pheromone
1.Dimethyl disulfide
2.Dimethyl trisulfide
3.(E)‐2‐hexenal
4.(E)‐2‐octenal
5.2‐hexanone
6.Histamine
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Aggregation Pheromone
1.Dimethyl disulfide
2.Dimethyl trisulfide
3.(E)‐2‐hexenal
4.(E)‐2‐octenal
5.2‐hexanone
6.Histamine
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Driving Questions:
1. Does histamine accumulate in
household dust?
2. Does histamine persist after bed bug
eradication?
3. What is the relationship between
indoor histamine and human health?
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n = 14 n = 10
DeVries et al., 2018, PLoS One
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What happens after eradication?
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(n = 6) (n = 9)
DeVries et al., 2018, PLoS One
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Histamine Conclusions
• Histamine accumulates in household dust
from bed bug infested homes
• Histamine persists at least three months
after bed bug are eradicated
• IF histamine is a risk to human health, bed
bugs could become a pest of serious
medical concern
The work continues…
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Bed Bug Control –
What Works?
Call a professional!
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Prevention
• Many small things can be done to
prevent bed bugs
• Main idea is to change the way we
think
• Being alert is perhaps the most
beneficial
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Early Detection
• Bed bugs are commonly found directly in
and around the bed when infestations
are small
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Practical Tips
• Be aware of your surroundings
• Watch where you sit/stay!
• Take preventative measures if you
suspect you’ve encountered bed bugs
• Launder or freeze your belongings
• Regularly inspect your own home
• Use repellents
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Thank You!
Zachary DeVries
Dept. of Entomology
University of Kentucky
zdevries@uky.edu
Always looking
for opportunities
to collaborate!
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