With increasing global travel and trade activities, the risk of cross-border transmission of mosquito-borne diseases has significantly escalated. This article provides an overview of common mosquito-borne diseases, their vector species, and corresponding prevention measures.
I. Definition of Mosquito-borne Diseases
Mosquito-borne diseases refer to natural focal diseases transmitted from infected individuals to healthy persons by the bites of mosquito vectors. They mostly pose a serious threat to human health, being highly infectious and prone to cause epidemics or even outbreaks. As such, they represent a substantial portion of port health quarantine measures and are most prevalent during the summer and autumn seasons.
II. Common Mosquito-borne Diseases and Their Public Health Impact
Globally distributed mosquito-borne diseases pose significant health threats, with some exhibiting high mortality rates or causing severe sequelae. Several are listed as quarantinable infectious disease or notifiable diseases under the revised Frontier Health and Quarantine Law of the People's Republic of China.
(I) Quarantinable Infectious Diseases
Yellow Fever: Caused by the yellow fever virus and transmitted primarily by Aedes aegypti and African Haemagogus mosquitoes, this disease is predominantly endemic in South America and Africa. Mild cases present influenza-like symptoms, while severe cases may lead to high fever, jaundice, hemorrhage, and multiple organ failure, with a case fatality rate as high as 50%. Customs authorities strictly enforce the inspection of the International Certificate of Vaccination or Prophylaxis (ICVP), also known as the Yellow Card, requiring all inbound travelers to present valid proof of vaccination.
(II) Notifiable Diseases
1. Dengue Fever: Caused by the dengue virus and mainly transmitted by Aedes aegypti and Aedes albopictus, this disease is prevalent in tropical and subtropical regions including Southeast Asia, South America, and Africa throughout the year, and has maintained a high level of incidence in recent years. Symptoms include sudden high fever, severe headache, joint pain, and rash. In severe cases, it may progress to dengue hemorrhagic fever or dengue shock syndrome, with a fatality rate of up to 20%.
2. Malaria: Caused by Plasmodium parasites and primarily transmitted through the bite of infected female Anopheles mosquitoes. There are five species of Plasmodium parasites that infect humans, with Plasmodium falciparum and Plasmodium vivax being the most common. The incubation period typically ranges from 7 to 35 days, with characteristic symptoms such as cyclical high fever, chills, headache, and muscle pain, and severe cases of anemia, cerebral malaria, organ failure, and even death. Children and pregnant women are particularly vulnerable. Although China obtained World Health Organization (WHO) malaria-free certification in June 2021, the disease remains endemic in regions including Africa, Southeast Asia, and South America. Sub-Saharan Africa is the hardest hit, accounting for over 90% of global malaria-related deaths.
3. Zika Virus Disease: Caused by the Zika virus and mainly transmitted by Aedes aegypti and Aedes albopictus, this disease is often prevalent in areas such as South America and Southeast Asia, with a significant outbreak occurring in the Americas in 2015 to 2016 that drew global attention. Most infected individuals are asymptomatic or experience only mild fever and rash. However, infection during pregnancy can lead to microcephaly (congenital Zika syndrome) and other neurodevelopmental disorders in the fetus.
4. Chikungunya Fever: Caused by the chikungunya virus and primarily spread by Aedes aegypti and Aedes albopictus. In recent years, outbreaks have been reported in various parts of Africa, Asia, and the Americas. Infected individuals typically develop high fever, severe joint pain which may persist for months or even years, rash, and muscle pain, significantly affecting their quality of life.
III. Common Vector Mosquito Species
Mosquitoes rank among the most significant vector organisms worldwide. There are currently over 3,500 known species of mosquitoes globally, approximately 100 of which are capable of transmitting diseases to humans.
(I) Aedes Genus: Aedes aegypti, originally from Africa, has now spread throughout tropical and subtropical regions worldwide. It serves as the primary vector for dengue fever, yellow fever, Zika virus disease, and chikungunya fever. This species prefers breeding in small water containers such as tires and flower pots, making it highly adaptable to urban environments. Aedes africanus, found mainly in sub-Saharan Africa, is an important vector of yellow fever.
(II) Anopheles Genus: Anopheles gambiae, the primary malaria vector in Africa, is often regarded as one of the “most dangerous animals.” Anopheles sinensis, a major malaria vector in China and East Asia, favors large water bodies like rice paddies for breeding.
(III) Culex Genus: Culex quinquefasciatus, distributed globally, can transmit diseases such as West Nile fever and lymphatic filariasis.
IV. A Guide to Preventing Mosquito-borne Diseases
(I) Daily Protective Measures: Remove standing water around homes in a timely manner to reduce mosquito breeding sites; install screen doors and windows to effectively keep mosquitoes out; use repellents containing ingredients such as Diethyltoluamide (DEET) or Ethyl butylacetylaminopropionate when outdoors, as well as mosquito coils, electric vaporizing mats, or liquid electric vaporizers containing pyrethroids.
(II) Vaccination: Vaccines for Japanese encephalitis and yellow fever are currently available in China. Individuals traveling to regions where yellow fever is endemic should consult Customs for vaccination advice. There are currently no approved vaccines in China for other viruses such as dengue or Zika.
(III) Strengthening Immunity: Maintain healthy lifestyle habits, including regular sleep patterns, a balanced diet, and moderate exercise, to improve the body’s resistance to viruses. Seek prompt medical attention if infectious disease symptoms occur, such as fever, headache, muscle or joint pain, rash, or altered mental status.
V. Customs Reminder
Under the Frontier Health and Quarantine Law of the People's Republic of China, all individuals entering or exiting the country are required to comply with health quarantine inspections carried out by Customs. Customs implements appropriate prevention and control measures based on the public health risk of infectious diseases. Travelers, especially those arriving from regions where mosquito-borne diseases are endemic, must accurately complete health declarations and cooperate with Customs officials during temperature checks, epidemiological surveys, medical screenings, specimen collection, and laboratory testing. These measures facilitate early detection and proper management of cases, strengthening our port quarantine defense system.
Disclaimer：The above content is translated from Chinese version of Official Platform for China Customs. The Official Platform for China Customs version shall prevail.
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