An emerging disease is any disease that appears in a population for the first time. Infectious diseases that have existed in the past but suddenly start to rapidly increase in incidence or geographic locations are called re-emerging diseases.
Why would infectious diseases suddenly appear or reappear? One example involves changes in human behaviors, such as inhabiting new areas and modifications to land use. These changes alter disease transmission mechanisms; people come into greater contact with pathogens through greater contact with the carriers of disease. Other examples are discussed in “Factors in the Increase of Emerging Infectious Disease”.
New infectious diseases continue to evolve and emerge through natural genetic variation and adaptation. Human immune systems have not been exposed to the new strains and therefore have no built-in immunity against the diseases.
Reasons for increases in disease occurrence are complex. Read “Emerging and Re-emerging Infectious Diseases” for more information on the issues surrounding this serious public health threat.
The table below lists information on today’s emerging or reemerging infectious diseases as well as images of the pathogens which cause the disease. As you read the descriptions, note the varying types of pathogens that cause the emerging or reemerging disease as well as the varying methods of transmission. Also note the variability within type of pathogen; for example, a bacterial disease may be caused by a bacillus, coccobacillus, coccus, or spirochete and a viral disease may be caused by a DNA or RNA virus.
Disease Pathogen
Transmission Regions of Increased Incidence Comments
Lyme Disease Spirochete, motile, two-membraned, spiral-shaped bacterium- Borrelia burgdorferi
Transmitted through bite of black-legged deer tick Occurs In 43 states in the U.S.
Numbers of infections are increasing in NE and N central U.S., Asia, and parts of EuropeB. burgdorfi was the 3 rd microbe genome (an organism’s complete set of DNA) that was sequenced.
West Nile virus (WNV) Single-stranded RNA virus
Spread by mosquito vectors; also spread through blood transfusions, organ transplants, and mother-to-baby. Increasing globally.
More virulent strains have been associated with outbreaks in Europe, Middle East, and North America.The most serious complication of West Nile Virus (WNV) infection is fatal encephalitis (inflammation of the brain).
Hepatitis C
Single-stranded RNA virus
Transmitted through contact with blood of infected persons, through sharing needles or syringes, sexual contact with infected persons, staring personal care items, and tattooing. Increasing in both developed and developing countries worldwide. Intravenous drug use is the primary route of transmission in developed countries.
Tattooing increases the risk of acquiring hepatitis C.
Dengue hemorrhagic fever RNA virus of the Flavivirus genus.
Transmitted by bite of infected mosquito, usually of the Aedes genus. Cases have increased dramatically in recent decades. WHO estimates about 390 million infections occur each year.
Occurs in tropical regions of the world, including Mexico, Central and South America, Africa, India, Southeast Asia and Australia.
Dengue cases occurred in Florida in 2013.Hemorrhaging (massive bleeding) in the severe form of dengue is caused because blood vessel walls become leaky.
Hantavirus pulmonary syndrome (HPS) Single-stranded RNA virus of the Bunyaviridae family.
Airborne transmission through contact with infected rodents, their urine, feces, or saliva.
Also by rodent bite or eating contaminated food.Found in North, Central and South Americas.
Hantavirus infections occur throughout the U.S. There are two main types of hantavirus infection. Hanta with renal (kidney) complications occurs in Europe and Asia. Hantavirus Pulmonary (lung) Syndrome occurs in the Western Hemisphere.
E.coli 0157.H7 Gram-negative, rod-shaped bacterium
Transmitted through a fecal-oral route--through eating food or water that comes into contact with fecal material infected with E. coli. Occurs worldwide E. coli is a type of bacteria that lives in the intestines and usually does not cause disease.
Some strains, however, (such as O157:H7) can cause severe cases of food poisoning.
Cyclosporiasis Protozoan parasite- Cyclospora cayetanensis
Transmission is through consuming food or water contaminated with the parasite. Occurs most commonly in tropical and subtropical regions.
In the U.S., outbreaks of cyclosporiasis have been linked to imported fresh produce, including raspberries, basil, peas, and lettuce. The infective form of the parasite is the cyst stage.
An infected person sheds the cysts in feces and other people become infected when they come into contact with the contaminated feces in food or water.
Vancomycin-resistant Staphylococcus aureus Gram-positive, round-shaped bacterium
Transmitted by contaminated equipment, contact with contaminated surfaces, or person-to-person.
Can produce serious infections in healthcare settings.Occurs worldwide. VRSA can live in human intestines without causing disease. It causes serious disease if it enters the bloodstream or wounds.
People in healthcare facilities are particularly susceptible because they come into contact with the bacteria more often and they may be immune compromised due to their illness.
Multi-drug resistant tuberculosis Rod-shaped bacterium Mycobacterium tuberculosis
Transmitted person-to-person through the air when an infected person coughs, sneezes, or speaks. Primarily in Russia, Asia, Africa, South America, and Central America M. tuberculosis usually attacks the lungs, but can attack any part of the body, such as the kidney, spine, and brain.
The bacterium has a waxy coating on its cell membrane and is resistant to Gram staining. An acid-fast stain is used to show structure.
H1N1 influenza Influenza A (H1N1) virus
Spreads from person-to-person when an infected person coughs or sneezes or by contact with a contaminated surface. H1N1 caused a worldwide pandemic in 2009-2010.
(This influenza pandemic resulted in approximately 60.8 million cases, 274,304 hospitalizations, and 12,469 deaths in the U.S.) (NIH)
The best way to prevent the swine flu is to get a seasonal flu vaccine.This influenza is called “swine flu” because lab testing showed that many of the virus genes are similar to the viruses that normally occur in pigs in North America.
Typhoid fever Gram-negative, rod-shaped, motile bacteria Salmonella typhii 
Spread by poor hygiene habits and poor sanitation conditions which put people into contact with infected feces.
Also spread by flying insects feeding on infected feces and by food or drink contaminated by infected feces.Not common in developed countries with proper sanitation, but travelers can be carriers and pass the disease along to other people. About 5,700 cases of typhoid fever are treated each year in the U.S., most acquired while traveling internationally.
If properly treated, typhoid fever is usually not fatal; if not treated, persons may continue to have fever for months and about 30% may die of complications.
Treated people recover but may become carriers.
Ebola hemorrhagic fever RNA virus of the Filoviridae family 
Host is not known, but bats and chimpanzees are suspected
Virus is transmitted through:
● direct contact with blood or body fluids of an infected person
●contact with contaminated objects
●contact with infected animals
Occurs in West and Central Africa but has spread to other countries by returning health workers from Africa.
Ebola was brought into the U.S. by infected healthcare workers and by an infected traveler entering Texas. The Ebola outbreak in 2014 has been the largest outbreak in history.
Exit screening from African countries involved in the outbreak and entrance screening into the U.S. from outbreak countries depends on the country involved.
Cholera Gram-negative, comma-shaped bacteria- Vibrio cholera
Transmitted through infected drinking water or food contaminated with cholera bacteria.
Also transmitted through eating raw or undercooked shellfish contaminated with the bacteria.Also transmitted through eating raw or undercooked shellfish contaminated with the bacteria.
Found mostly in Africa, Southeast Asia, and Haiti. Large outbreaks are associated with drinking water contaminated with feces containing large amounts of cholera bacteria from the profuse diarrhea from cholera patients.
Drug resistant malaria Parasitic protozoan Plasmodium falciparum, P. vivax, P. ovale, and P. malariae
Transmitted through bite of female Anopheles sp. mosquito Malaria occurs mostly in tropical and subtropical areas of the world, including Africa, South America, India, and Papua New Guinea.
Malaria is the leading cause of death in many endemic countries; most vulnerable are children.
According to the CDC, approximately 627,000 people died from malaria in 2012, mostly young children. Drug resistance is confirmed in P. falciparum and P. vivax.
Chloroquine-resistance has spread to almost all areas of the world where P. falciparum malaria occurs.
P. falciparum has developed drug resistance to nearly all antimalarial drugs.
Drug resistance is a threat to malaria control and results in increased disease and death.
Plague Gram-negative, rod-shaped bacteria Yersina pestis
Zootonic: Transmitted by bite of an infected flea (when infected rodents die, the fleas seek another blood supply and jump to nearby humans and small animals).
Also transmitted by contact with contaminated fluid or tissue.Plague epidemics have occurred in Africa, Asia, and South America.
Plague endemic countries include Madagascar, the Democratic Republic of Congo, and Peru.
In the U.S., most plague cased occur in the Western states.There are three forms of plague: bubonic (lymph node involvement), septicemic (blood infection), and pneumonic (lung infection).
Bubonic plague is most common.
Marburg hemorrhagic fever RNA virus of the Filovirus family
Transmitted by animals (zoonotic), but exact method of transmission to humans is unknown.
Unprotected contact with infected bat feces or aerosols are likely methods of transmission.
Reservoir is the African fruit bat.
Outbreaks spread through person-to-person contact with body fluids of an infected person or contact with infected materials.
Outbreaks have occurred in Germany, Serbia, Democratic Republic of the Congo, Angola, South Africa, Uganda, Zimbabwe, and Kenya. The World Health Organization rates Marburg Fever as a Risk Group 4 Pathogen.
Marburg virus is one of the most deadly pathogen known to infect humans.
HIV (Human Immunodeficiency Virus) Single-stranded RNA retrovirus
Spread from person-to-person through sexual contact, through blood (predominantly by needle-sharing), from mother-to-child (during pregnancy or through breast milk). Occurs worldwide with epidemics being more severe in the Sub-Saharan areas in Africa.
WHO estimated 35 million people were living with HIV/AIDS in 2013 and the number has increased in the following years. HIV can be found in body tissues and fluids, including blood, semen, breast milk, saliva, tears, and spinal fluid.
Diphtheria Gram-positive bacterium Corynebacterium diphtheriae
Spread by direct contact, through the air, or by contact with contaminated objects. Occurs worldwide, especially in tropical countries.
Although vaccine is available, toxigenic C. diphtheriae still circulates in the U.S. in areas in which the disease was previously endemic. Symptoms of disease are due to toxin produced by the bacteria.
Toxin is produced by bacteria only when the bacillus is infected with a virus (bacteriophage) that carries the genetic information for toxin production and inserts it into the bacteria.
The toxin travels through the blood stream and results in tissue destruction.
Lassa Fever
Single-stranded RNA virus of the Arenavirus family
Zoonotic: Spread through rat bite, through rodent urine and feces, and through direct contact with objects or food contaminated with rodent urine or droppings.
Also spread by infection through a cut or wound, or by eating a rodent infected with the virus.100,000-300,000 infections per year; 5,000 deaths
Occurs mostly in west African countries, including Nigeria, Benlin, Togo, Shana, Cote d’Ivoire, Liberia, Sierra Leone, Guinea, Mali, and Burkina Faso.
There have been six cases of Lassa fever in the U.S. and all have been in people who have traveled to countries known to have the virus. Although Lassa Fever has symptoms similar to Ebola disease, it is far less deadly. Lassa Fever mortality rate is approximately 1% while Ebola mortality is about 70%.
Human Monkeypox DNA virus of the Orthopoxvirus genus
Zoonotic-animal-borne
Index cases-through direct contact with blood, body fluids, or rashes of infected animals.
Secondary cases-from close contact with infected respiratory tract excretions, skin lesions of infected persons, or with infected objects.Found in Central and West Africa (Cameroon, Democratic Republic of the Congo, Gabon, Liberia, Nigeria, Sierra Leone, Sudan, Republic of Congo and the United States. The 2003 outbreak in the Unites States is the only outbreak reported outside of Africa.
Niaph disease RNA virus of the Paramyxoviridae family
Spread by infected pigs, horses, dogs, cats and humans.
Natural reservoir—fruit batOccurs in Southeast Asia and Australia.
Outbreaks in different locations were caused by different transmission methods; in Malaysia and Singapore, NiV (Nipah virus) was associated with infected pigs; in Bangladesh and India, it was associated with contact with infected bats.The most recent outbreaks of Nipah virus disease has resulted in a mortality rate of 100%.
Although Bangladesh is the only country that annually reports cases of Nipah virus, the disease has been reported in numerous SE Asia countries for decades.
Chikungunya Disease RNA virus of the Togaviridae family
Zoonotic: Spread via mosquitos.
Mosquitos become infected when they feed on a person infected with Chikungunya virus and then pass along the virus to the next person they bite.
Occurs in Africa, Asia, Europe, India, Pacific islands, South America, Mexico, the U.S., including Alaska. First local transmission in the Americas (mosquitos in the area have the virus and are spreading it to people) occurred in 2013.
Chagas Disease (American sleeping sickness) Protozoan parasite - Trypanosoma cruzi
Transmitted primarily by insect vector.
Also transmitted mother-to-baby, contaminated blood products, infected organ transplant, or contaminated food or drink.Insect-borne Chagas disease has been found only in the Americas.
In the U.S. Chagas disease is classed as a Neglected Parasitic Infection (NPI) which has been targeted by the CDC for public health action.
It is estimated that about 300,000 people with T.cruzi infections live in the U.S.
Most of these people acquired their infections in endemic countries.
Cryptococcosis Fungi -Cryptococcus neoformas, C. gatti
By inhalation of the fungus Occurs mostly in Africa, but is a common opportunistic infection of AIDS.
Found worldwide in the soil.
C. neoformans infections are rare in people with healthy immune systems even though they have been exposed to the fungus.
In addition to affecting HIV/AIDS patients, C. neoformans also infects organ transplant recipients and patients having cancer treatments.
Cystericercosis Parasite - Taenia solium
(cysts infect brain, muscle, and other tissues)
Transmitted by ingestion of tapeworm eggs found in food contaminated with infected feces.
Feces of a person infected with the adult tapeworm contain eggs. Human cysticercosis is found worldwide, mostly in rural areas with poor sanitation.
A Neglected Parasitic Infection (NPI) in the U.S. cystericercosis is 1 of 5 parasitic infections targeted for public health action.People who live with someone with a tapeworm infection have a higher risk of becoming infected.
Histoplasmosis Fungus-Histoplasma capsulatum
Airborne transmission by breathing in microscopic fungal spores from the air.
Found in bird and bat droppings. Mainly in Ohio and Mississippi River Valleys of U. S. and is considered to be endemic in these areas.
Also found in Central and South America, Africa, Asia, and Australia.Histoplasmosis is not contagious and is not spread from person-to-person.
Professions with a higher degree of exposure to fungal spores of H. capsulatum (and therefore an increased likelihood of disease) include farmers, poultry farmers, roofers, gardeners, pest control workers, and cave explorers.
Norovirus Single stranded RNA virus of the Norovirus genus
Spread person-to-person, by contaminated food or water, and by contact with contaminated surfaces. Most common cause of acute gastroenteritis in U. S.; 19-21 million cases per year, 56,000-71,000 hospitalizations, and 5790-8000 deaths. Norovirus is known as the winter vomiting bug in the U.K.
Outbreaks occur in communities such as long-term care facilities, camps, hospitals, schools, prisons, and cruise ships where infection is transmitted and spreads quickly from person-to-person.
Rift Valley Fever (RVF) Virus of the genus Phlebovirus in the Bunyaviridae family.
Spread by infected animals; spread to humans from direct or indirect contact with blood or organs of infected animals and through inhalation of aerosols containing the virus while handling animal tissue during slaughtering, assisting with animal births, vet procedures, disposal of carcasses, from unpasteurized milk of infected animals, and bits of infected mosquitos. Major outbreaks have occurred in Africa; has spread to Saudi Arabia and Yemen Outbreaks of RVF can have major economic and societal impacts.
RVF is most often observed in animals; an RVF epizootic (outbreaks in animal populations) in Kenya resulted in the death of 100,000 animals.
Epizootics can lead to epidemics in humans.
Leptosporosis Spirochete bacteria Leptospira sp.
From contact with Leptospira sp bacteria in fresh water and soil contaminated with animal urine or direct contact with the animal urine.
Often found in floodwaters. Bacteria enter the body through skin or mucus membranes.
Animals that carry the disease include cattle, pigs, horses, dogs, rodents, and wild animals.
Leptosporosis is found worldwide, more often in warm climates.
Often found after flooding due to hurricanes. Without treatment Leptospirosis can lead to kidney damage, liver failure, respiratory distress, inflammation of the membranes of the brain and spinal cord, and death.
Tularemia
(Rabbit Fever)Gram-negative, rod-shaped coccobacillus, aerobic Francisella tularensis
Transmitted by bite from an infected tick, horsefly, or mosquito, by breathing in infected dirt of plant material, or by direct contact through a break in the skin.
Transmitted to humans through the skin when handling infected animal tissue, such as when skinning infected rabbits, muskrats, prairie dogs, or other animals.Domestic cats have been known to transmit the disease to humans and hamsters purchased at pet stores have been known to have the disease.
Domestic cats have been known to transmit the disease to humans and hamsters purchased at pet stores have been known to have the disease.Tularemia is widespread in animals in the U.S.
About 200 cases of tularemia are reported in the U.S. each year.
Most cases occur in the south-central and western states, but cases in the northeast have also occurred. Almost all are in rural areas. Classified by the U.S. government as a potential agent for bioterrorism due to its low infections dose and ease of spread by aerosol.
The pneumonic form of tularemia is often fatal without treatment.
Yellow Fever RNA virus of the Flavivirus genus.
Transmitted by mosquitos and delivered into the victim through the mosquito bite.
The Aedes sp. or Haemagogus sp. mosquito is the primary vector for yellow fever. Found in tropical and subtropical areas of South America and Africa.
Yellow fever is endemic in many areas. The case fatality ratio for yellow fever is greater than 20% and infants and children are at greatest risk for infection.
The yellow fever vaccine has been used effectively for decades and is recommended for travelers to countries with yellow fever.
The vaccine may be required for entry into certain countries.
Legionnaires' Disease Gram negative, aerobic rod-shaped (bacillus) bacteria of the Legionella genus
Scanning electron micrograph (SEM) of L. pneumophila, magnified 6500x. 32Transmitted by aerosolized water
L. pneumophila is found only in aquatic systems.
Also found in symbiosis with aquatic-borne amoeba
Bacteria invade macrophages and lung epithelial cells and replicate intracellularly.
Sources of infection: humidifiers, whirlpools, hot water systems, showers, windshield washers, hot tubs, air conditioners, freshwater ponds, creeks, and fountains.Legionnaires’ Disease occurs worldwide. According to the CDC about 8,000-18,000 people are hospitalized in the U.S. each year due to Legionnaires’ Disease.
OSHA estimates 10,00-50,000 cases each year.
People who smoke and heavy drinkers are more at risk of infection with Legionella sp. after exposure.
Measles Single-stranded RNA virus, a paramyxovirus, of the Morbillivirus genus
Transmitted from person-to-person through coughing and sneezing.
Measles virus can live for up to two hours on a surface or in an airspace.Measles occurs worldwide and is one of the leading causes of death in young children.
In 2014, there were 114,900 deaths from measles worldwide even though there is a safe vaccine available.
Measles vaccination programs prevented an estimated 17.1 million deaths from 2000-2014. (WHO) Measles is highly contagious. If someone has measles, 90% of the people close to that person will become infected.
Humans are the only natural hosts for measles virus.
Pertussis
(Whooping cough)Gram-negative, aerobic, coccobacillus Bordetella pertussis
Highly contagious, B. pertussis is transmitted from person-to-person by coughing or sneezing, and even by sharing airspace for an extended period of time.
Young children can become infected from older family members who may not know they harbor the bacteria. Pertussis occurs worldwide. Pertussis bacteria attach to cilia in the upper respiratory tract and release toxins which cause airways to swell.
Serious complications such as pneumonia, convulsions, apnea (slowed or stopped breathing), diseases of the brain, and death can occur.
Humans are the only known host for B. pertussis.
1 Lyme Disease—Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Photo credit: National Institute of Allergy and Infectious Diseases (NIAID)
http://phil.cdc.gov/Phil/home.asp
2 West Nile Virus—Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Photo credit: Cynthia Goldsmith
http://phil.cdc.gov/Phil/home.asp
3 Hepatitis C—Courtesy of the Center for the Study of Hepatitis C, The Rockefeller University; Maria Teresa Catanese, Marina Kopp, K. Uryo, and Charles Rice. http://en.wikipedia.org/wiki/Hepatitis_C#/media/File:HCV_EM_picture_2.png
4 Dengue—CDC per U. of South Carolina Biomedical Sciences http://commons.wikimedia.org/wiki/File:Dengue.jpg
5 Hantavirus— Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/Brian W.J. Mahy, Ph.D; Luanne H. Elliott, M.S.
http://phil.cdc.gov/Phil/home.asp
6 E. coli—Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: Janice Haney Carr
http://phil.cdc.gov/Phil/home.asp
7 Cyclosporiasis—Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/DPDx- Melanie Moser
http://phil.cdc.gov/Phil/home.asp
8 VRSA— Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: Janice Haney Carr
http://phil.cdc.gov/Phil/home.asp
9 Multi-drug resistant tuberculosis—— Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: National Institute of Allergy and Infectious diseases (NIAID)
http://phil.cdc.gov/Phil/home.asp
10 H1N1— Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: National Institute of Allergy and Infectious Diseases (NIAID)
http://phil.cdc.gov/Phil/home.asp
11 Typhoid Fever— Centers for Disease Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC
http://phil.cdc.gov/Phil/home.asp
12 Ebola—— Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: Cynthia Goldsmith
http://phil.cdc.gov/Phil/home.asp
13 Vibrio cholera— Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: Janice Carr
http://phil.cdc.gov/Phil/home.asp
14 Drug resistant malaria— Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider—Dr. Mae Melvin
http://phil.cdc.gov/Phil/home.asp
15 Plague—National Institute of Allergy and Infectious Diseases (NIAID)—Public Health Image Library (PHIL)
Photo Credit: NIAID
http://phil.cdc.gov/Phil/home.asp
16 Marburg hemorrhagic disease—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: Dr. Erskine Palmer
http://phil.cdc.gov/Phil/home.asp
17 HIV—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/C. Goldsmith, P. Peorino, E.L. Palmer, W.R. McManus
http://phil.cdc.gov/phil/details.asp
18 Diphtheria—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: Dr. Theo Hawkins
http://phil.cdc.gov/phil/details.asp
19 Lassa Fever—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: C.S. Goldsmith
http://phil.cdc.gov/phil/details.asp
20 Monkeypox—Image source: https://commons.wikimedia.org/wiki/File:Monkeypox.gif
21 Nipah Disease—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Photo Credit: Cynthia Goldsmith
http://phil.cdc.gov/phil/details.asp#modalIdString_CDCImage_0
22 Chikungunya Disease—Centers for Disease and Control and Prevention
Photo Credit: Cynthia Goldsmith
http://phil.cdc.gov/PHIL_Images/17369/17369.tif
23 Chagas Disease—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC
http://phil.cdc.gov/phil/details.asp
24 Cryptococcosis—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/Dr. Edwin P. Ewing
http://phil.cdc.gov/phil/details.asp
25 Cysticercosis—Image: https://en.wikipedia.org/wiki/Taenia_solium
26 Histoplasmosis—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/Dr. Libero Ajello
http://phil.cdc.gov/phil/details.asp
27 Norovirus—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider” CDC/Charles D. Humphrey, Ph.D.
http://phil.cdc.gov/phil/details.asp
28 Rift Valley Fever—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/F.A Murphy; J. Dalrymple
http://phil.cdc.gov/phil/details.asp#modalIdString_CDCImage_0
29 Leptosporosis—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/NCID/Rob Weyant
Photo Credit: Janice Haney Carr
http://phil.cdc.gov/phil/details.asp
30 Tularemia—National Institutes of Allergy and Infectious Disease
Image source: https://en.wikipedia.org/wiki/Francisella_tularensis
31 Yellow Fever—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/Erskine Palmer, Ph.D.
http://phil.cdc.gov/phil/details.asp
32 Legionnaires’ Disease—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/Margaret Williams, Ph.D; Claressa Lucas, Ph.D.; Tatiana Travis, BS
Photo Credit: Janice Haney Carr
http://phil.cdc.gov/phil/details.asp
33 Measles—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC/Cynthia S. Goldsmith/William Bellini, Ph.D.
http://phil.cdc.gov/phil/details.asp
34 Pertussis—Centers for Disease and Control and Prevention—Public Health Image Library (PHIL)
Content Provider: CDC
http://phil.cdc.gov/phil/details.asp
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