From mild illness to meningitis: how tick infections manifest

A tick bite does not always mean that you will get tick-borne encephalitis or borreliosis, but the risk is still high, especially in endemic areas. We understand what common diseases are carried by ticks and what to do

What diseases are called tick-borne infections

The tick is a small blood-sucking arachnid, a relative of spiders and scorpions, that lives on almost all continents, in different settings, including the city. In the parks of our country, Europe and the USA, for example, you can find a carrier of Lyme disease. The main danger of ticks is the infectious diseases they carry. These infections are called transmissible, as they are transmitted to humans through a bite. There are many types of ticks, but infections are carried mainly by ixodid, gamas and argas. The most numerous – ixodid – ticks “wake up” usually twice a year – from April to May and from August to September. These times may vary by region. In this case, the tick can attack at “non-standard” times. They usually bite a person in the armpits, back, neck, legs, groin, or behind the ears.

According to the risk of infection with tick-borne infections, the regions are divided into endemic and non-endemic. The list of endemic regions is published on its website by Rospotrebnadzor.

By the way, ticks can not only carry infections, but also independently cause diseases – acariases. The most famous acariasis is scabies, which develops due to a microscopic intradermal parasitic mite.

Tick-borne encephalitis

Tick-borne encephalitis is probably the first disease that comes to mind when mentioning tick-borne infections. However, it is not even the most common among them – the most common is borreliosis, or Lyme disease. Read about it below.

Tick-borne encephalitis is a viral disease caused by the tick-borne encephalitis virus of the same name from the flavivirus family. (Flaviviridae). The pathogen is transmitted to humans through the bite of an infected ixodid tick, very rarely through the raw milk of infected cows, goats and sheep. When the disease affects the central nervous system (CNS) – inflammation of the meninges develops – meningitis – and the brain itself – in fact, encephalitis. Two-thirds of infected people are asymptomatic. The incubation period of the disease ranges from 4 to 28 days, with an average of 7-14 days. Typically, tick-borne encephalitis occurs in two phases – general symptoms and CNS damage.

The first phase of the disease lasts 2-7 days. Symptoms are non-specific:

• temperature rise,
• weakness and fatigue
• nausea,
• pain in the muscles,
• headache.

After this, an asymptomatic period begins, which lasts about a week (but maybe a whole month). In the second phase, the brain and its membranes are involved – disorders characteristic of meningitis and encephalitis develop:

• heat,
• tension – rigidity – of the occipital muscles (stiffness is a bright marker of meningitis for doctors),
• Strong headache,
• psychosis and other disorders of consciousness,
• speech problems,
• limb muscle weakness
• sleep disorders,
• movement disorders, in severe cases – paralysis.

The most dangerous subtype of the virus is the Far East. The mortality rate due to it still reaches 35%, patients often develop neurological disorders, and the disease proceeds in one phase – the central nervous system is immediately involved. The consequences of contracting viral tick-borne encephalitis can be severe, ranging from paralysis, sensory disturbances, to irreversible cognitive impairment and death.

There is no specific highly effective treatment for viral tick-borne encephalitis. Patients are hospitalized and symptomatic therapy is carried out depending on the manifestations of the disease. The best way to deal with a disease is prevention.

There is also an emergency prevention of the disease – immunoglobulin against tick-borne encephalitis. It is administered no later than 96 hours after the bite.

Tick-borne encephalitis is detected by analyzing the cerebrospinal fluid or blood serum for specific IgM, which appear in the body a maximum of six days after the onset of the first symptoms. However, the risk of disease can be determined more quickly – the extracted tick is examined in the laboratory for infection.

Lyme Disease

As already mentioned, Lyme disease is the most common tick-borne infection worldwide. The causative agent is bacteria Borrelia burgdorferi, afzelii и garini- enters the body through the bite of an ixodid tick. The infection spreads through the lymphatic pathways from the site of suction to other organs, affects the nervous system, joints, heart and proceeds in three stages: early localized, disseminated and late.

Late symptoms appear if borreliosis is not detected and cured after a tick bite. Unlike viral tick-borne encephalitis, there is a specific treatment for Lyme disease – antibiotics. You should not prescribe them yourself – consult a doctor. There is no vaccine, therefore, in order to avoid infection, you must follow the rules of general prevention.

Ehrlichiosis and anaplasmosis

Two more rare diseases that ixodid ticks carry are ehrlichiosis and anaplasmosis. Human monocytic ehrlichiosis is a bacterial infection caused by Ehrlichia bacteria (Ehrlichia). Human granulocytic anaplasmosis is also a bacterial disease caused by anaplasmas (Anaplasma phagocytophilum). Both diseases attack the cells of the immune system, causing non-specific cold-like symptoms. The incubation period usually lasts about two weeks.

Manifestations of anaplasmosis and ehrlichiosis:

• fever,
• pain in muscles and joints,
• headache,
• nausea,
• vomiting,
• loss of appetite,
• malaise.

Ehrlichiosis is also characterized by impaired consciousness, a feeling of disorientation, and a rash.

If the disease is not treated, the inflammatory process can affect the brain and its membranes, lead to organ failure, including the respiratory system, severe bleeding, seizures, and in rare cases, death.

Ehrlichiosis and anaplasmosis are diagnosed by PCR. Like other bacterial infections, they are treated with antibiotics. There is no vaccine to protect against these diseases, so general precautions must be followed.

tick-borne relapsing fever

Another type of borreliosis is an infection caused by bacteria. Borrelia/Lyme disease, which is carried by ixodid ticks – relapsing fever. An infected person suddenly develops chills, fever, muscle and joint pain, and vomiting. Sometimes a rash appears. A black scab forms at the site of the tick bite. This type of typhus is called relapsing because of the unusual course: all symptoms last only a few days, then the patient gets better, but soon the disease returns. On average, symptoms worsen once a week, and relapsing fever can continue for months. In severe cases, the liver enlarges, jaundice, heart failure, and meningitis occur. For diagnosis, a microscopic examination of blood or, very rarely, PCR is performed. With relapsing fever, antibiotics are prescribed that are active against borrelia. There is no vaccine.

Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever is a viral infection that provokes outbreaks with a high mortality rate in Africa, Asia, the Middle East and the Balkans. It is transmitted through the bites of ixodid ticks or through contact with the blood and tissues of infected animals and people. The incubation period of the disease after a tick bite is 1–9 days, with an average of 1–3 days. Early symptoms appear suddenly:

• temperature rise,
• muscle pain,
• headache,
• backache,
• fear of light – photophobia,
• abdominal pain,
• nausea,
• vomiting,
• diarrhea,
• sore throat,
• mood swings
• confusion,
• increased irritability and excitability,
• tachycardia,
• swollen lymph nodes,
• petechial rash – small hemorrhages on the skin and mucous membranes.

After two to four days, the infected person develops drowsiness, weakness, depressive symptoms, and the liver may enlarge. The outcome depends on the severity of the symptoms – some die in the second week of illness due to kidney and liver failure, others begin to recover on the ninth day. Although there is a specific treatment for viral hemorrhagic fever, the drug ribavirin, the main strategy is supportive therapy that reduces clinical manifestations. There is no vaccine against Crimean-Congo fever.

How not to get tick-borne infections: general prevention rules

• Check if your region is in an endemic zone. Sometimes infected ticks are distributed only in certain areas of the region or region.
• If you are going to travel, look at the map of endemic regions and countries.
• In endemic areas, when going outdoors, wear closed clothing and tuck your trousers into your socks.
• Use tick repellent.
• If there is a vaccine for the infection, get vaccinated before traveling to an endemic area. If you live in such a region, vaccination is recommended by the Ministry of Health.

What to do if the tick has already bitten