Introduction to Tickborne Diseases Rachel Radcliffe, DVM, MPH CDC Career Epidemiology Field Officer Division of Infectious Disease Epidemiology Good morning.

Overview of Tickborne Diseases Introduction Lyme disease Tickborne rickettsial diseases Babesiosis Prevention of tickborne diseases Case ascertainment exercise In the next two hours, we will present basic clinical and epidemiological information on tickborne diseases. We’ll start out with an introduction to these diseases that includes just general information. Then we will focus more on tickborne diseases most commonly seen in WV with presentations on lyme disease, TBRD, and babesiosis. At the end, we will have discussion on prevention of tickborne diseases. And we will finish with some exercises on case ascertainment.

Tickborne Diseases Diseases spread by bites from infected ticks Can be caused by bacteria, viruses, and parasites Most infections occur in the spring and summer months Geographic distribution of tick species impacts location of human infections Tickborne diseases are spread to humans by bites from infected ticks. There are numerous tickborne diseases that are caused by different pathogens including bacteria, viruses, and parasites. Most tickborne infections occur in the spring and summer months when ticks actively feed on humans. Because various tick species transmit different diseases, the geographic distribution of these tick species impacts the location of human infections.

Tick Life Cycle Hard ticks have four life stages Egg Six-legged larvae Eight-legged nymph Adult Most ticks prefer to feed on different hosts at each life stage Ticks can feed on mammals, birds, reptiles, and amphibians Hard ticks that transmit tickborne diseases have four life stages: egg, six legged larvae, eight legged nymph, and adults. Most tick species prefer to feed on different hosts at each of these life stages. Ticks can feed on a variety of animals including mammals, birds, reptiles, and amphibians.

This diagram shows an example of a tick life cycle This diagram shows an example of a tick life cycle. The eggs hatch in the spring and develop into larvae. The larvae feed on birds and small mammals. If these birds and small mammals have a pathogen in their bloodstream, the tick will ingest this pathogen as they feed on the animal’s blood. Through the fall and winter the larvae develop further and emerges as nymphs in the following spring. As nymphs, the ticks will feed on larger mammals including deer and humans throughout the spring and summer. If the tick was infected with a pathogen at the larval stage while feeding on a bird or small mammal, it will pass this pathogen on to its next host, such as a human, as it feeds in the nymph stage. The nymph develops into an adult which can also feed on larger mammals and eventually lay eggs to start the life cycle over. The birds and wild mammals that ticks feed on actually serve as reservoirs for the pathogens of tickborne diseases and are a necessary part in the transmission of these diseases. In contrast, humans generally act as incidental or dead-end hosts and do not further propagate the transmission of tickborne diseases.

Symptoms of Tickborne Diseases Many diseases produce similar symptoms Asymptomatic or mild to life-threatening illness Most common symptoms Fever/chills Aches and pains Rash Proportion of people with rash varies among diseases Distinctive rash appearance among diseases Many tickborne diseases produce similar symptoms in humans and can manifest clinically as asymptomatic or mild illness to life-threatening illness. The most common symptoms of tickborne diseases include fever and chills, aches and pains, and rash. Not every person with a tickborne disease will develop a rash and the proportion of people that do varies with each disease. A distinctive rash appearance can be seen among some of the diseases and this will be discussed later in the presentation.

Treatment of Tickborne Diseases Supportive therapy Antibiotic therapy for bacterial tickborne diseases Doxycycline commonly used Duration of therapy varies by disease Treatment for tickborne diseases varies but generally includes supportive therapy. Antibiotic therapy is useful for those diseases caused by bacteria and doxycycline is commonly used for several diseases. The duration of therapy varies by disease and will be discussed in further detail as this presentation continues.

Diagnosis of Tickborne Diseases Can be difficult to diagnose Clinical signs and symptoms Patient history Tick bite or tick exposure Laboratory findings Diagnostic tests Serology Polymerase chain reaction (PCR) Immunohistochemistry (IHC) Culture The diagnosis of tickborne diseases can be very difficult, particulalry because the symptoms can be non-specific. However, the clinical signs in conjunction with the patient’s history can offer some clues. A history of a tick bite or tick exposure and where this occurred can be helpful. Certain laboratory tests, such as a CBC or metabolic panel, can also offer some good information. Diagnostic tests include serology, PCR, IHC, and culture. These tests will be discussed in more detail as they pertain to each disease.

Tickborne Diseases in the United States Lyme disease Rocky Mountain Spotted Fever Other Spotted Fevers Ehrlichiosis Anaplasmosis Babesiosis STARI Powassan Tularemia Others Here is a list of some of the tickborne diseases found in the United States. I will briefly give some general information about each of these diseases and several will be covered in more detail later.

Lyme Disease Most common tickborne disease in US Bacterial disease Borrelia burgdorferi Transmitted by blacklegged tick and western blacklegged tick Lyme disease is the most common tickborne disease in the United States. This is a bacterial disease caused by the bacteria Borrelia burgdorferi. Lyme disease is transmitted by the blacklegged tick and the western blacklegged tick.

Geographic Distribution of Blacklegged Tick This map shows the geographic distribution of the blacklegged tick as noted by the orange color. Notice that WV is part of this tick’s range. The other tick that transmits Lyme disease, the western blacklegged tick is only found on the western coast, so I will not present a map of its distribution. I will show several more maps similar to this throughout the rest of the introduction. However, I will only show maps for ticks that are found in WV. For more distribution maps of other tick species not found in WV, please see the CDC’s tickborne disease website.

Rocky Mountain Spotted Fever and Other Spotted Fevers Bacterial diseases Rickettsia rickettsii Rickettsia parkeri Rickettsia phillipi (proposed) Transmitted by American dog tick, Rocky Mountain wood tick, brown dog tick, Pacific coast tick, and Gulf coast tick Rocky Mountain Spotted Fever and other spotted fevers are bacterial diseases caused by the bacteria Rickettsia ricketsii, rickettsia parkeri, and rickettsia phillipi. These diseases can be transmitted by the American dog tick, Rocky Mountain wood tick, brown dog tick, pacific coast dog tick, and gulf coast tick.

Geographic Distribution of American Dog Tick Here is the geographic distribution of the American dog tick and WV is completely within this ticks range.

Geographic Distribution of Brown Dog Tick The brown dog tick is found throughout the US. The other tick vectors of spotted fevers are not found in WV so their distributions are not shown here.

Ehrlichiosis and Anaplasmosis Bacterial diseases Ehrlichia chaffeensis Ehrlichia ewingii Anaplasma phagocytophilum Transmitted by blacklegged tick, lone star tick, and western blacklegged tick Ehrlichiosis and Anaplasmosis are bacterial diseases caused by the bacteria Ehrlichia chaffeensis, Ehrlichia ewingii, and Anaplasma phagocytophilum. These diseases are transmitted by the blacklegged tick, the lone star tick, and the western blacklegged tick. Notice some of these tick species are the same ones that transmit lyme disease.

Geographic Distribution of Lone Star Tick This map shows the geographic distribution of the lone star tick. Notice the northern border of this tick’s range is around WV.

Babesiosis Caused by parasites that infect red blood cells Species found to infect humans include Babesia microti, B. divergens, and B. duncani Transmitted by blacklegged tick Less commonly congenital transmission and blood donor-associated cases have been identified Babesiosis is caused by parasites that infect red blood cells. Species of this parasite that have been found to infect humans include Babesia microti, babesia divergens, and babesia duncani. Like Lyme disease, babesiosis is transmitted by the blacklegged tick. Less commonly congenital transmission and blood donor-associated cases of babesiosis have been identified.

STARI (Southern Tick Associated Rash Illness) Cause is unknown Rash appearance similar to Lyme disease Has not been linked to arthritic, neurologic, or chronic symptoms Transmitted by lone star tick Most cases found in southeastern US STARI or Southern Tick Associated Rash Illness is a newly recognized disease and the cause is unknown. The rash seen in this disease has a similar appearance to the rash seen with Lyme disease, however this disease has not been linked with arthritic, neurologic, or other chronic symptoms like those seen with Lyme disease. STARI is transmitted by the lone star tick and most cases have been found in the southeastern part of the US. The distribution of the lone star tick has already been shown.

Powassan Arbovirus Causes encephalitis Most cases in northern US Transmitted by blacklegged tick and a related tick, Ixodes cookei Powassan is actually an arbovirus that is transmitted by ticks. Similar to other arboviruses, Powassan causes encephilitis and most cases have been identified in the northern US. This virus is transmitted by the blacklegged tick and a related tick called Ixodes cookei.

Tularemia Less common tickborne disease Bacterial disease Francisella tularensis Transmitted by American dog tick, lone star tick, and Rocky Mountain wood tick Other transmission routes include deer fly bites, inhalation, ingestion, skin contact with infected animals Cases found in every state except Hawaii Tularemia is a less commonly identified tickborne disease and it is caused by the bacteria, Francisella tularensis. It is tranmsitted by the American dog tick, the lone star tick, and the rocky mountain wood tick. Based on the tick distribution maps shown earlier, remember that the American dog tick and the lone start tick have ranges in or around WV. Other transmission routes of tularemia include deer fly bites, inhalation, ingestion, and skin contact with infected animals. Cases of tularemia have been found in every state except Hawaii.

Other Tickborne Diseases Tickborne relapsing fever Colorado tick fever Tickborne diseases abroad Tickborne encephalitis Crimean-Congo hemorrhagic fever There are many other tickborne diseases that we don’t have time to cover today. These include Tickborne Relapsing Fever and Colorado tick fever. There are specific tickborne diseases found abroad that travelers should be aware of and take proper precautions to protect themselves while traveling. These include tickborne encephalitis and crimean-congo hemorrhagic fever, both of which are caused by viruses.

Summary Numerous tickborne diseases can infect humans and cause disease Several tick species transmit tickborne diseases Found in various geographic regions Symptoms can be similar among tickborne diseases Diagnosis can be difficult This short introduction was intended to show that numerous tickborne diseases can infect humans and cause disease. Several different tick species are responsible for transmitting these diseases and can be found throughout different geographic regions of the United States. In addition, some tick species can transmit more than one disease. Symptoms can be similar among the tickborne diseases and diagnosis of these diseases can be difficult.

More Information to Come… Lyme disease Tickborne Rickettsial diseases Rocky Mountain Spotted Fever Ehrlichiosis Anaplasmosis Babesiosis Prevention of tickborne diseases Several tickborne diseases are reportable and we will be discussing the surveillance of these diseases as the presentation continues. These include lyme disease, the Tickborne Rickettsial diseases of RMSF, Ehrlichiosis, and Anaplasmosis, and Babesiois. Prevention measures for tickborne diseases will also be discussed.

Case Investigation Procedure Positive lab report received at health department Call healthcare provider Collect clinical data, patient history, supplemental labs Follow up if no response after 3-4 days If needed, attempt to contact patient Collect exposure and other relevant information from case Attempt patient contact for 5-10 days Enter all data into WVEDSS and send case to regional review As we talk more about surveillance, here is an example flow chart for case investigation. This may be a good reference as we talk in more detail about surveillance (and should be available as handout in your packet). This chart will appear again in the case ascertainment exercise. Next up is Jonah Long, the zoonotic disease epidemiologist for our division and he will be speaking about Lyme disease.