As for the problems caused by ticks, the disease is much more like the limelight. But different bird species transport and transmit a collection of other pathogens, some of which cause serious, even fatalities.
In fact, the number of disease-related disease cases is increasing in the United States. The range in which different species of bird species live in North America can expand due to climate change. Researchers continue to discover new pathogens living in ticks. And new, invasive birds continue to turn up.
In my career as a public health entomologist, I have been amazed at the ticks' ability to bounce back from every way people try to control them, even with pesticides. Ticks stand out to find new ecological niches for survival. So people and ticks often cross roads, expose us to their bites and the diseases they carry.
Here are some of the lesser known, but growing, threats from ticks. Ticks can spread bacterial diseases
Certain very small bacterial species that can cause human diseases, such as rickettsia, ehrlichia and anaplasma, live in ticks. Ticks take these bacteria when they drink the blood of the animals. When the ticks take a subsequent blood meal, they pass the bacteria on to the next animal or person to whom they are fed.
Probably the best known of these bacterial diseases is Rocky Mountain spotted fever, the most commonly reported rickettsial disease in the United States, with about 6,000 cases each year. The number of diagnoses seems to increase throughout the country, especially among the Indians, probably due to exposure to reservations for free roaming dogs that can carry ticks.
When people get sick with Rocky Mountain spotted fever, they usually come to a clinic with three things: fever, skin rash and history of bitch bits. They can also report severe headaches, chills and muscle pain and gastrointestinal symptoms such as abdominal pain and diarrhea. Skin rashes are usually present after a few days, but not always. Mental confusion, coma and death can occur in severe cases. Untreated, mortality is about 20%; and even with treatment, 4% of the infected die.
Not all fasting species are effective transmitters of the rickettsia bacteria. Even within the vector species, only 1% to 5% ticks in an area are often infected. So getting bitten by a pocket that passes rickettsia bacteria on you is like getting stuck with a needle in a haystack. The primary carriers are the American dog land in the eastern US and the Rocky Mountain Wood tick in the west. The brown dog land has also recently been shown to be a vector.
In most attachment-borne diseases, the fastener must be fed for some time before any pathogens it carries are sent to the animal whose blood it eats. Rocky Mountain spotted fever organisms generally take between one and three hours for transmission to occur, so adhesive ticks must be removed quickly. Doctors usually prescribe antibiotic doxycycline to treat Rocky Mountain spotted fever, which works quite well if the disease is known again.
Ehrlichiosis is another bacterial disease that is transmitted from ticks to humans. In the United States, it is usually caused by [E] llichia chaffeensis bacteria, which are borne by single star ticks, which are common in the eastern US Ehrlichia bacteria, infect a type of blood cell called leukocytes. Human monocytic ehrlichiosis occurs mostly in southern and southern central United States; 1 642 cases were reported to CDC 2017.
Ehrlichiosis patients usually have fever, headache, muscle sores and a progressively low number of white blood cells. Unlike Rocky Mountain spotted fever, people only get rashes about 20% to 40% of the time. Doctors usually treat ehrlichiosis with doxycycline.
Another attachment-borne bacterial disease to worry about is human granulocytic anaplasmosis. In human granulocytic anaplasms, Anaplasma phagocytophilum infects a type of white blood cell called granulocytes. It usually occurs in the upper north-west and north-eastern United States, and the incidence increases, with 762 cases of human granulocytic anaplasmosis reported to CDC 2017.
Symptoms include fever, headache, muscle aches and progressively low numbers of white blood cells. It is the deer land Ixodes scapularis – famous also responsible for the Lyme disease – which transmits the Anaplasma bacteria to humans. There is an unfortunate chance that a bit of a deer trace can infect you with both diseases. Again, the recommended therapy is doxycycline.
Ticks can carry viruses as well
People usually think of mosquitoes when they think of insect-transmitted viruses – dengue, Zika or West Nile give many headlines. But ticks can also transmit viruses.
Historically, researchers have grouped attachment-borne viral diseases into two categories. One is diseases similar to dengue fever. The major dengue-like virus disease transmitted by ticks in the United States is Colorado fat fever, which occurs in the mountain regions of the West.
The second group of attachment-borne diseases resembles mosquito-borne encephalitis. Most of these diseases, which are characterized by brain inflammation, do not exist in the United States. Powassan encephalitis is the one found in the northeastern United States and neighboring regions of Canada.
Powassan is a relatively rare but serious human disease characterized by sudden onset of fever with temperature up to 104 degrees Fahrenheit, along with convulsions. Brain inflammation is usually severe, with vomiting, breathing needs and prolonged fever.
Fewer than 100 cases of Powassan have been reported in North America, of which about half are fatal. The occurrence seems to increase. There were 34 cases of Powassan reported in 2017. POW is maintained in a natural cycle when ticks – mainly Ixodes cookei – infect animals with the virus via their bites. Then, these infected animals can serve as scientists calling disease reservoirs, infecting new dice as they feed on their blood.
Over the past decade, researchers have found additional new fast-paced viruses in the United States. About 30 cases of the Heartland virus have so far been identified. It is associated with the lone star tab and has been recognized in Missouri, Oklahoma, Kentucky and Tennessee.
A few cases of a new Thogotovirus called the Bourbon virus have been identified in the Midwest and the Southern United States. The lone star tab can be the vector of the Bourbon virus as well.
A food allergy triggered by a tick bit
Perhaps the most bizarre threat from ticks is the "red meat allergy" that scientists have recently traced back to the fixation bite. People may be allergic to eating meat when a bird's saliva passes on the carbohydrate galactose-α-1,3-galactose that it had previously picked up in an animal's blood meal. If the person is prone to allergies, the person may be sensitized to the alpha-gal molecule found in animal blood and other tissues.
Subsequently or weeks later, he or she may develop hives, swelling skin and lips or even life threatening anaphylactic shock three to six hours after eating red meat. Meat containing alpha-gal contains beef, pork, lamb, squirrel, rabbit, horse, goat, deer, kangaroo, seal and whale. People who become sensitized to alpha-gal can still eat chicken, turkey and fish.
In summary, people should be aware of which attachment-borne diseases are present in their area and use personal protection techniques when outdoors in field-infected areas. Remember that ticks often come in close contact with people via pets or cats. It is a good idea to inspect yourself for ticks after being outdoors in field infected areas. Reducing the number of bitch bites and how much time ticks are left can go a long way to protect you from attachment-borne diseases.
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Jerome Goddard, Extension Professor of Biochemistry, Molecular Biology, Entomology and Plantpatology, Mississippi State University
This article is published from The Conversation under the Creative Commons license. Read the original article.