The Possible Effect of Climate Change on
Selected Infectious Diseases in South
Florida
Office of Epidemiology and Disease Control
Miami-Dade County Health Department
Juan A. Suarez
Regional Environmental Epidemiologist
Presentation at the Medical Campus of
Miami Dade College
January 28, 2008
Contributors
 This
presentation was adapted from
a November 2007 version prepared
by:
Fermin Leguen, MD, MPH, Director
Office of Epidemiology and Disease Control
Juan A. Suarez
Regional Environmental Epidemiologist
Menhel Kinno, MPH candidate, Intern OEDC
Some additional data slides from the Bureau of
Community Environmental Health-FDOH
Introduction
Climate change in the form of global
warming and extreme weather are
increasingly mentioned in the media and
journal articles as issues to be dealt with
in the next decades.
 Human health will be affected by changes
in the environment of insects and
microorganisms that in turn are vectors or
agents for disease in man.

Assumptions
The following discussion assumes rise in
sea levels, global increase in temperature,
and intrusion of the ocean water on fresh
bodies of water and drinking water wells.
 The science behind these assumptions is
based on observations but also on
predictions.
 Causes of these effects remain
controversial. Anthropogenic vs. natural
variations.
 The physical results are based on the
Intergovernmental Panel on Climate
Change’s report.

Selected Infectious Diseases
 Vector
borne diseases
 Water borne diseases
 Rodent borne diseases
 Rabies
Vector-borne diseases:
Mosquito transmitted diseases:
 Dengue & Dengue Hemorrhagic Fever
 Yellow Fever
 West Nile Fever
 Malaria
 Other insects transmitted diseases:
 Lyme disease
 Tularemia
 Chagas disease

Dengue Fever & Dengue
Hemorrhagic Fever
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genus Flavivirus
There are four serotypes of the virus that cause the
disease.
Transmitted by Aedes aegypti (a domestic, daybiting mosquito, has a world wide distribution in
tropical area)
Clinical features:
High Fever, headache,
Backache, joint pain, eye pain,
Rash
Nausea and vomiting
Hemorrhagic manifestation (DHF) which is
potentially lethal.
No specific treatment is available.
No vaccination is available.
Mosquito control.
Source: CDC, 2007
Dengue Fever & Dengue
Hemorrhagic Fever
In 2005, 2.5
billion people at
risk of Degue
fever.
 The Aedes
mosquito has a
worldwide
distribution in
the tropical and
sub-tropical
areas.

Source: CDC, 2005
Yellow Fever
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Genus Flavivirus
It is also transmitted by Aedes mosquito.
This virus is restricted to only 2 regions: Africa and South
America.
Clinical Features (incubation period of 3-6 days):
Asymptomatic.
Acute phase: Fever (sometimes Paradoxical fever with low pulse
rate), aches, Nausea and vomiting,
15% Toxic phase: jaundice, abdominal pain with vomiting.
Bleeding can occur from the mouth, nose, eyes and/or stomach.
½ die within 10-14 days.
Three types of transmission cycle:
Sylvatic (jungle): sporadic cases in forest.
Intermediate yellow fever: in Africa only.
Urban yellow fever: epidemics.
No specific treatment is available.
Prevention: Vaccination and mosquito control
WHO, Fact Sheet, 2001
West Nile Fever:
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Genus Flavivirus
Transmitted by female Culex pipiens mosquitoes
Clinical Features:
Incubation period: 2-15 days
fever, headache, tiredness, and body aches,
occasionally with a skin rash and swollen lymph
glands
1 in 150 ( Neuro-invasive disease, West Nile
encephalitis or meningitis or West Nile
poliomyelitis)
Treatment: no specific treatment (antiviral
“Ribravirin”)
Prevention: mosquito control, vaccination only
available for horses.
CDC, 2007
2007 West Nile Virus Activity in the United
States
(Reported to CDC as of November 6, 2007)
Source: CDC, 2007
Malaria
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Parasitic infection by Plasmodium
Human malaria is caused by four species:
Plasmodium vivax & ovale
P. malariae
P. falciparum
41% of the global population lives in area at risk of
malaria.
Malaria is transmitted by female anopheles mosquito.
Clinical Feature (incubation period of 10-14 days):
Fever
Rigor
Sweating
Treatment: anti-malarial medication and supportive
therapy
Prevention: prophylactic
treatment
and mosquito
WHO, 2007;
CDC, 2007
control.
Lyme disease
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Bacterial infection by Borrelia burgdorferi.
It usually lives in small animals (mice, squirrels,
Transmitted by: Ixodes scapularis, Ixodes pacificus
(blacklegged ticks)
Clinical Feature (incubation period 3-30 days):
fever, headache, fatigue
Erythema migrans (characteristic rash in 70-80%).
In untreated patient it can cause a wide ray of symptoms
(Nervous system, heart, and joint).
Treatment: oral antibiotics, intravenous AB in severe cases
Prevention: vaccine is no longer available, tick control
This disease may be more of an issue in the Northeast/Central
states, unclear if South Florida would be affected.
Reported Cases of Lyme Disease by
Year, United States, 1991-2005
Source: CDC, 2005
Chagas disease
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It is a parasitic infection by Trypanosoma cruzi
Transmitted by kissing bud (triatomine vector).
Clinical Feature:
Acute: occurs after infection and it is
characterized by fever or swelling around the site
of inoculation
Chronic Intermediate: asymptomatic stage.
Chronic (30%): life-threatening chronic
complications (dilated cardiomyopathy, dilated
esophagus, toxic megacolon)
Treatment:
Prevention: insect control.
CDC, 2007
Why there will be an increase in
Vector Transmitted disease?
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Warm temperature and surface water are essential for
insect breeding (especially mosquito)
Stagnant water with humid condition are both necessary for
breeding.
Warmer temperature leads to:
Enhance vector breeding,
Increase vector survival,
Increase vector biting rate,
Reaching higher altitude,
and reduce the pathogen’s maturation period with the
vector.
Very hot temperature with dry condition can reduce the
survival of insects.
WHO, 2007
Water & Food borne diseases:
 Giardiasis
 Cholera
and other Vibrios
 Salmonella
Giardiasis
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Parasitic infection by Giardia lamblia
Transmitted mainly through contaminated
water.
Clinical Feature (incubation period 1-2 weeks):
Asymptomatic.
Diarrhea, Nausea and Vomiting, gas and
flatulence, abdominal cramps
Chronic diarrhea and malabsorption and weight
loss.
Treatment: oral antibiotics
Prevention: good hygiene, avoidance of
contaminated water and food.
CDC, 2007
Cholera
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Causative agent: Vibrio cholera
It is mainly a water-borne disease
Clinical symptoms:
Acute, watery (rice water like) diarrhea.
Vomiting
Leg cramps
Rapid loss of body fluids and dehydration that
might lead to death within hours without
treatment.
Treatment: antibiotics and IV fluids
Prevention: oral vaccine, avoid contaminated
water and food.
WHO, 2007
Salmonella
Bacterial infection by Salmonella
 Water & food borne disease
 Clinical features:
 Fever
 Diarrhea, and abdominal cramps
 Reiter's syndrome
 Chronic carriers
 Treatment: oral antibiotics
 Prevention: avoidance of raw or
undercooked eggs, poultry, or meat.
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WHO, 2007
Vibrio vulnificus
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Causative agent: marine bacterium Vibrio vulnificus
Water-borne (wounds) and consumption of raw oysters and
shellfish
Incubation: 12-72 hours
Clinical picture:
Septicemia in immunosuppressed, or chronic liver disease,
or hemochromatosis, or cirrhosis
Case fatality from 50-90%
Cellulitis, myositis, shock, hypotension, bullous skin lesions,
intravascular coagulation, thrombocytopenia
Treatment: antibiotics
Prevention: avoid contact of wounds with seawater and
avoid eating raw or undercooked oysters and shellfish
Vibrio vulnificus in Florida, 1990-2006
Exposure
Wound
Oysters
Unknown
Crab
Clams
Shrimp
Total
# Cases
211
156
55
7
3
1
433
Deaths from Vibrio vulnificus in Florida,
1990-2006
Exposure
Oysters
Wound
Unknown
Crab
Shrimp
Clams
Total
# Deaths
66
24
20
2
1
1
114
% Total
Cases
15.2
5.5
5.2
0.5
0.3
0.3
26.4
Vibrio vulnificus Cases and Deaths from Various
Exposures, Florida 1990-2006
Exposure # Cases #
Deaths
Deaths % Total
Cases
Wound
211
24
5.5%
Oysters
156
66
15.3%
55
20
4.6%
Crab
7
2
0.5%
Clams
3
1
0.2%
Shrimp
1
1
0.2%
433
114
26.4%
Unknown
Total
Rodent-Borne Disease:
 Plague
Plague
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Bacterial infection Yersinia pestis
Transmitted by:
Flea bite
Contact with infected rodent
Inhalation or ingestion of infected material.
It is still widely distributed in the tropics and subtropics and in
warmer areas of temperate countries.
Clinical Feature:
Bubonic form (most common type in which the disease is
transmitted by flea and it mainly affects the lymph nodes
(bubo) which became painful and may suppurate)
Septicaemic form
Pneumonic form (least common but most virulent)
Treatment: antibiotics and supportive therapy
Prevention: rodent control, flea control, vaccination only for
high risk group.
WHO, Fact Sheet, 2005
Rabies
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Viral infection by
Animal bite (domestic and wild animals).
Clinical Feature:
Initially, non-specific symptoms
Acute stage, signs of hyperactivity (furious rabies) or
paralysis (dumb rabies) predominate.
paralysis eventually progresses to complete paralysis
followed by coma and death in all cases, usually due
to respiratory failure.
Without intensive care, death occurs during the first
seven days of illness.
Treatment: immediate cleaning of the wound, and
post-exposure vaccination
Prevention: vaccination of domestic animals,
vaccination of individuals at high risk, avoidance and
control of wild animals.
WHO, Fact Sheet, 2006
Control Measures
 Control
measures for these diseases
and their vectors are well known and
established. However, new
challenges will be encountered in the
control of insects and
microorganisms under the new
environmental conditions and new
methods must be researched and
implemented.
Summary
The true effects that climate change will
have on infectious diseases will be hard to
predict but we can, with the present
knowledge, estimate which of these will be
more of a problem.
 We must also not forget that today’s
challenges with other issues in infectious
diseases, not related to climate change,
may also continue. Examples include
antibiotic resistance, limited resources,
and new emerging pathogens.

UN Millennium Development Goals
Goal # 7
Ensure environmental sustainability:


Integrate the principles of sustainable
development into country policies and
programmes; reverse loss of environmental
resources

Reduce by half the proportion of people without
sustainable access to safe drinking water

Achieve significant improvement in lives of at
least 100 million slum dwellers, by 2020
Dr. Julie Gerberding,
CDC Oct 2007

Many of the activities needed to protect
Americans from the health effects of
climate change are mutually beneficial for
overall public health….it is also important
that potential health effects of
environmental solutions be fully
considered.
I am persuaded that global climate change is one of
the most important issues that we will face this
century. With almost 1,200 miles of coastline and the
majority of our citizens living near that coastline,
Florida is more vulnerable to rising ocean levels and
violent weather patterns than any other state…Florida
will provide not only the policy and technological
advances, but the moral leadership, to allow us to
overcome this monumental challenge."
References
IPCC, 2007: Summary for Policymakers. In:
Climate Change 2007: The Physical
Science Basis. Contribution of Working
Group I to the Fourth Assessment Report
of the Intergovernmental Panel on Climate
Change [Solomon, S., D. Qin, M. Manning,
Z. Chen, M. Marquis, K.B. Averyt,
M.Tignor and H.L. Miller (eds.)].
Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA.
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
References
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Control of Communicable Diseases Manual, 18th
Ed. David L. Heymann, MD, Editor, APHA, WHO.
Centers for Disease Control and Prevention
http://www.cdc.gov/
Environmental Protection Agency
http://www.epa.gov/climatechange/effects/health.html
World Health Organization
http://www.who.int/en/
United Nations. UN Millennium Development
Goals. http://www.un.org/millenniumgoals/