I. Tick Overview
Ticks, also known as wood ticks or seed ticks, exhibit reddish-brown or grayish-brown elongated oval bodies. They are classified into hard ticks (Ixodidae) and soft ticks (Argasidae) based on the presence of a chitinous scutum on their dorsal side. Globally, over 900 tick species (subspecies) have been identified. China has documented more than 100 species (subspecies) of hard ticks and over 10 species of soft ticks. Unfed ticks appear flat, resembling mung beans in size. After blood feeding, their volume can expand 3 to 400 times, reaching the dimensions of soybeans.
Hard ticks lay eggs only once in their lifespan, producing between 1,000 to over 10,000 eggs. Soft ticks undergo multiple oviposition cycles, each yielding several to dozens of eggs. Their indiscriminate feeding habits enable ticks to parasitize diverse hosts including mammals (e.g., cats, dogs), birds, reptiles, amphibians, and humans – collectively serving as their blood meal sources.
In China, ticks are widely distributed, primarily found in provinces such as Henan, Hubei, Shandong, Anhui, Jiangsu, and Liaoning. Ticks primarily inhabit wild environments like grasslands, forests, and mixed woodlands. In recent years, they have also been detected in urban green belts along roadsides, parks, and tourist attractions. Ticks are most active during warm seasons, with regional variations typically spanning from April to October.
II. Hazards of Ticks
Ticks possess an acute sense of smell, being highly sensitive to animal scents, human perspiration, and exhaled carbon dioxide. They can detect hosts from up to 15 meters away. They congregate in groups on grass tips and leaves, lying in wait. Upon contact with potential hosts, they swiftly initiate their blood-feeding behavior.
As seasoned blood-sucking parasites, ticks embed their mouthparts deep into a host's skin upon attachment. Similar to mosquitoes, they secrete anesthetic compounds during feeding, often making the bite painless. However, this can lead to localized skin reactions including erythema, edema, and acute inflammatory responses.
Ticks are notorious "mobile disease vectors". While their bites primarily cause dermatological issues, they serve as significant transmitters of zoonotic pathogens. When ticks previously fed on pathogen-infected hosts subsequently bite humans, they efficiently transmit these pathogens to new victims.
III. Common Tick-Borne Diseases
(I) Lyme Disease
This infectious tick-borne illness primarily spreads through tick bites. Early clinical manifestations feature migratory erythema with characteristic target or "bull's-eye" appearance. Progressive stages involve neurological and cardiovascular complications, with late-stage disease typically presenting with arthritic symptoms.
(II) Severe Fever with Thrombocytopenia Syndrome (SFTS)
An acute infectious disease caused by the novel Bunyavirus infection, classified as a type of tick-borne disease. It was first identified in China in 2009 as an emerging infectious disease.
The primary symptoms include fever (typically above 38°C), with severe cases presenting persistent high fever exceeding 40°C, accompanied by fatigue, nausea, and vomiting. Some patients may also experience headaches, muscle pain, or diarrhea.
(III) Tick-borne encephalitis
An acute zoonotic infectious disease affecting the central nervous system, caused by the tick-borne encephalitis virus.
Main clinical manifestations include high fever (39.5°C-41°C), systemic toxicity, consciousness impairment, neurological damage, muscle paralysis, and multi-organ dysfunction.
(IV) Other bacterial diseases
As a significant vector and reservoir host, ticks play a crucial role in transmitting various bacterial diseases including plague, brucellosis, and tularemia through their bites.
IV. Infectious Disease Prevention and Vector Surveillance at Border Ports
Pursuant to the Frontier Health and Quarantine Law of the People's Republic of China, customs authorities are tasked with frontier health and quarantine responsibilities. Tick surveillance constitutes a vital component of vector monitoring at border ports. As guardians of national borders, customs authorities bear the responsibility of preventing cross-border transmission of major infectious disease outbreaks. In accordance with Article 12 of the Implementation Measures for Infectious Disease Surveillance at Frontier Ports jointly issued by the General Administration of Customs (GACC), National Health Commission, and National Disease Control and Prevention Administration: Customs shall conduct identification of captured vectors and submit them to laboratories for pathogen testing, thereby rigorously preventing the cross-border spread of vector-borne diseases.
Customs advisory: Travelers who experience tick bites with subsequent symptoms abroad should proactively complete health declarations upon entry and cooperate with customs authorities for epidemiological investigations and medical examinations.
V. Essential Tick Prevention Guidelines
For outdoor activities, it is advisable to wear light-colored, smooth long-sleeved shirts and pants with tight cuffs, avoiding sandals or slippers. Refrain from prolonged sitting or lying in grassy or wooded areas. When walking dogs, steer clear of densely vegetated areas and promptly clean and inspect your pet's body. If bitten by a tick, remove it carefully without using excessive force and seek medical attention promptly if discomfort occurs.
(Author Affiliation: Nanjing Customs)
Disclaimer：The above content is translated from Chinese version of China Inspection and Quarantine Times. The China Inspection and Quarantine Times version shall prevail.
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