1. 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

2. 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

3. 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.

4. 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.

5. Selected Infectious Diseases
Vector borne diseases
Water borne diseases
Rodent borne diseases
Rabies

6. 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

7. Dengue Fever & Dengue Hemorrhagic Fever
genus Flavivirus
There are four serotypes of the virus that cause the disease.
Transmitted by Aedes aegypti (a domestic, day-biting 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.
Two competent mosquito vectors, Ae. aegypti and Aedes albopictus, are present and, under certain circumstances, each could transmit dengue viruses.
The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, South-east Asia and the Western Pacific. South-east Asia and the Western Pacific are most seriously affected. Before 1970 only nine countries had experienced DHF epidemics, a number that had increased more than four-fold by 1995.
Source: CDC, 2007

8. 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.
In 2005, dengue is the most important mosquito-borne viral disease affecting humans; its global distribution is comparable to that of malaria, and an estimated 2.5 billion people live in areas at risk for epidemic transmission
Source: CDC, 2005

9. Yellow Fever 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 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
Thirty-three countries, with a combined population of 508 million, are at risk in Africa. These lie within a band from 15°N to 10°S of the equator. In the Americas, yellow fever is endemic in nine South American countries and in several Caribbean islands. Bolivia, Brazil, Colombia, Ecuador and Peru are considered at greatest risk.
WHO, Fact Sheet, 2001

10. West Nile Fever: 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

11. 2007 West Nile Virus Activity in the United States (Reported to CDC as of November 6, 2007)
Source: CDC, 2007

12. Malaria 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 days):
Fever
Rigor
Sweating
Treatment: anti-malarial medication and supportive therapy
Prevention: prophylactic treatment and mosquito control.
WHO, 2007; CDC, 2007

13. Lyme disease 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.

14. Reported Cases of Lyme Disease by Year, United States, 1991-2005
Source: CDC, 2005

15. Chagas disease 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.
Chagas disease is endemic throughout much of Mexico, Central America, and South America where an estimated 8 to 11 million people are infected.
CDC, 2007

16. Why there will be an increase in Vector Transmitted disease?
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

17. Water & Food borne diseases:
Giardiasis
Cholera and other Vibrios
Salmonella

18. Giardiasis 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

19. Cholera 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.
Rainfall and the IOI affect the aquatic environment in which Vibrio cholera develop, where the cholera bacillus lives in contact with elements of the zooplankton. These tiny aquatic crustaceans, known as copepods, comprise the main reservoir of the bacterium and feed upon microscopic algae called phytoplankton. Therefore, they collect in areas where the density of phytoplankton is highest. Understanding this relationship provides a way of monitoring areas rich in phytoplankton using remote sensing, allowing scientists to identify potential reservoirs for Vibrio cholera from space.
WHO, 2007

20. 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.
WHO, 2007

21. Vibrio vulnificus Causative agent: marine bacterium Vibrio vulnificus
Water-borne (wounds) and consumption of raw oysters and shellfish
Incubation: 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

22. Vibrio vulnificus in Florida, 1990-2006
Exposure
# Cases
Wound
211
Oysters
156
Unknown 55
Crab 7
Clams 3
Shrimp 1
Total
433

23. Deaths from Vibrio vulnificus in Florida, 1990-2006
Exposure
# Deaths
% Total Cases
Oysters 66
15.2
Wound 24
5.5
Unknown 20
5.2
Crab 2
0.5
Shrimp 1
0.3
Clams
Total
114
26.4

24. Vibrio vulnificus Cases and Deaths from Various Exposures, Florida 1990-2006
Deaths % Total Cases
Wound
211 24
5.5%
Oysters
156 66
15.3%
Unknown 55 20
4.6%
Crab 7 2
0.5%
Clams 3 1
0.2%
Shrimp
Total
433
114
26.4%

25. Rodent-Borne Disease:
Plague

26. Plague 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

27. Rabies 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

28. 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.

29. 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.

30. UN Millennium Development Goals
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

31. 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.

32. 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."

33. 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.

34. References
Control of Communicable Diseases Manual, 18th Ed. David L. Heymann, MD, Editor, APHA, WHO.
Centers for Disease Control and Prevention
Environmental Protection Agency
World Health Organization
United Nations. UN Millennium Development Goals.