Viral hemorrhagic fevers (VHFs) constitute a category of acute infectious diseases, primarily vector-borne, characterized by the sudden onset of high fever and hemorrhagic symptoms. Prominent examples include Crimean-Congo hemorrhagic fever (CCHF), Ebola hemorrhagic fever (EHF), Marburg hemorrhagic fever (MHF), Lassa fever (LF), Rift Valley fever (RVF), dengue hemorrhagic fever (DHF), and yellow fever. These conditions are notably severe, often progressing to shock and carrying a substantial risk of death.
I. Defining the Threat: Common Traits of VHF Viruses
Viral hemorrhagic fevers encompass a large and diverse family of pathogens, yet they share a set of critical and hazardous characteristics.
1. Fever and Hemorrhagic Symptoms
Fever serves as the universal and initial warning sign across all VHFs. The defining hallmark, however, is a pronounced bleeding tendency. This can range from minor skin manifestations such as petechiae and ecchymoses on the skin and mucous membranes, to catastrophic internal hemorrhaging that threatens vital organs and is often life-threatening.
2. High Risk of Shock
A primary danger stems from the viruses' ability to damage blood vessels. This injury increases vascular permeability, leading to significant leakage of plasma from the bloodstream. This loss of fluid volume can rapidly precipitate a dangerous drop in blood pressure and progress to shock.
3. Zoonotic Origins (Natural Foci)
These viruses circulate naturally among animal hosts such as rodents, bats, and livestock. Humans become accidental hosts when they enter this cycle, most often through the bite of an infected mosquito or tick, or by direct contact with a sick animal or its secretions.
4. Primary Transmission Routes
(1) Animal-to-Human (Zoonotic) Transmission: This occurs through direct contact with an infected animal or its contaminated waste, as seen in epidemic hemorrhagic fever and Lassa fever, both of which are spread by rodents.
(2) Tick-Borne Transmission: This route involves the bite of an infected tick, as exemplified by Xinjiang hemorrhagic fever (XHF).
(3) Mosquito-Borne Transmission: Transmission occurs via the bite of an infected mosquito, with key examples including dengue hemorrhagic fever, yellow fever, and Rift Valley fever.
II. Spotlight on Key Diseases
1. Yellow Fever
Yellow fever is a mosquito-borne illness caused by the yellow fever virus. The initial phase of infection involves viremia caused by virus in the bloodstream, presenting with sudden fever, headache, and fatigue. As time passes by, the virus attacks major organs, particularly the liver and kidneys, leading to jaundice, proteinuria, and severe coagulation dysfunction. This breakdown in the body's clotting mechanism can trigger life-threatening hemorrhagic symptoms, such as bleeding from the gums and nose, as well as gastrointestinal hemorrhage manifesting as vomiting blood and melena. The first documented global pandemic originated in Mexico in 1648, later spreading across the Americas, Africa, and Europe. A major outbreak in the United States in 1878 resulted in approximately 100,000 infections and 20,000 deaths. Today, yellow fever remains endemic in tropical regions of Africa and South America. According to the World Health Organization (WHO),it is estimated that the disease causes about 130,000 cases and 44,000 deaths annually. Countries of particular concern include Nigeria and Uganda in Africa, and Brazil, Peru, and Venezuela in South America.
2. Ebola hemorrhagic fever
Ebola hemorrhagic fever (EHF), caused by the Ebola virus, is one of the most lethal known infectious diseases, with historical case fatality rates reaching 90 percent. It was first identified in 1976 in two simultaneous outbreaks: one near the Ebola River in what is now the Democratic Republic of the Congo (DRC, then Zaire), and another in present-day Sudan. Transmission occurs almost exclusively through direct contact with the blood, secretions, or other bodily fluids of infected individuals (living or deceased) or animals such as gorillas or monkeys. In some affected regions within Africa, high-risk funeral practices including the kissing of the deceased, have significantly fueled outbreaks.EHF remains endemic in regions of Central, Western, and Southeastern Africa. Countries that have experienced major outbreaks include the Democratic Republic of the Congo, Republic of the Congo, Uganda, and Sudan.
3. Marburg hemorrhagic fever
Marburg hemorrhagic fever (MHF) is a severe and often fatal acute illness caused by the Marburg virus, primarily occurring in specific regions of Africa. The virus is transmitted initially from bats to humans, and then spreads through direct, close contact between people. It was first identified in 1967 after workers at a vaccine lab in Marburg, Germany, contracted the disease from infected African green monkeys imported from Uganda – the incident that gave the virus its name. The WHO classifies Marburg virus as one of the world's most deadly pathogens, with an average case fatality rate of approximately 50 percent. The disease is mainly prevalent in parts of Africa and its geographic distribution closely overlaps with the range of its natural host, the Rousettus aegyptiacus. Countries that have reported significant outbreaks include Angola, the Democratic Republic of the Congo, and Uganda.
4. Lassa fever
Lassa fever (LF) is an acute zoonotic disease caused by the Lassa virus and transmitted primarily by rodents. It is named after the town of Lassa in northeastern Nigeria, where the first case was identified in 1969. The disease subsequently spread within West Africa tocountries including Liberia and Sierra Leone. The primary animal reservoir is the Mastomysnatalensis, which serves as an asymptomatic carrier, shedding the virus in its urine and feces. Lassa fever is now endemic to West Africa, with key affected countries being Nigeria, Liberia, Sierra Leone, and Guinea. It is estimated to cause 300,000 to 500,000 human infections annually, resulting in approximately 5,000 deaths.
5. Epidemic hemorrhagic fever
Hemorrhagic fever with renal syndrome (HFRS), commonly known as epidemic hemorrhagic fever, is an acute and often severe zoonotic disease caused by Hantavirus. It is transmitted to humans primarily through contact with infected rodents and other small mammals. The prototype virus was first isolated in 1976 from striped field mice along the Hantan River in South Korea and was named Hantaan virus; it was later classified under the genus Hantavirus. These viruses now have a widespread global distribution, with human cases reported in more than 70 countries across six continents.
6. Rift Valley Fever
Rift Valley fever (RVF) is an acute viral zoonos is caused by the Rift Valley fever virus (RVFV). The disease is transmitted to humans through the bite of infected mosquitoes or through direct contact with infected animals. The disease was first recognized in Kenya in 1912, and the virus itself was first isolated and given its name in the Rift Valley region of Kenya in 1931. Historically, RVF was largely confined to sub-Saharan Africa. According to a WHO report, a total of 404 confirmed cases and 42 deaths were reported in Mauritania and Senegal between September 20 and October 30, 2025.
7. Crimean-Congo hemorrhagic fever
Crimean-Congo hemorrhagic fever (CCHF) is an acute viral hemorrhagic fever caused by the CCHF virus. It is transmitted to humans mainly through the bite of infected ticks, but also through direct contact with the blood or tissues of infected animals. The disease was first clinically described in Crimea (then part of the Soviet Union) in 1945, and the virus was first isolated in the Congo (now the Democratic Republic of the Congo) in 1956, leading to its dual name. In China, it was first identified in Bachu, Xinjiang, and is therefore also known as Xinjiang hemorrhagic fever. In 2025, human cases were reported across a wide geographical range, including Iraq, Afghanistan, Pakistan, Uganda, Turkey, Spain, and Greece. Among these, Afghanistan reported a cumulative total of 1,049 suspected cases, with 79 deaths.
8. Dengue hemorrhagic fever
Dengue fever is a mosquito-borne infectious disease caused by the dengue virus and transmitted by Aedes mosquitoes, primarily Aedes aegypti and Aedes albopictus in China. The virus, first isolated in 1952 by Japanese and American scientists, comprises four distinct serotypes. Its hallmark symptom –severe muscle and joint pain - has led to its colloquial name, "break bone fever". Dengue hemorrhagic fever (DHF) is a severe and potentially fatal complication. Patients may develop scattered petechiae on the limbs, axillae, mucous membranes and face, which may coalesce into larger bruises. In severe cases, hemorrhage can occur from multiple sites, including the conjunctiva, nasal cavity, gums, and the gastrointestinal, urinary, and female genital tracts. Massive bleeding is a life-threatening emergency.
III. Prevention and Treatment
Currently, there are no highly effective specific antiviral drugs for the vast majority of viral hemorrhagic fevers. Therefore, clinical management is primarily based on comprehensive supportive care and symptomatic treatment, with the core objective of helping patients survive the critical acute phase.
1. Breaking the Chain of Infection
For rodent-borne hemorrhagic fevers, breaking the chain of infection is the cornerstone of prevention. Key measures involve maintaining environmental hygiene, securing food and disposing of waste properly, as well as sealing rodent entry points, and implementing scientific rodent control programs. When in high-risk outdoor settingslike fields, forests, or pastures, wearing long-sleeved clothing and trousers and applying insect repellent are essential to prevent bites from vectors such as ticks and mosquitoes.
2. The “Detect, Rest, Treat Locally” Rule
For diseases like epidemic hemorrhagic fever, the key is to adhere to the principle of “Detect, Rest, Treat Locally”. This means early detection, early rest, early treatment, and seeking care locally at a medical facility with appropriate treatment capability, to avoid long, arduous journeys that could worsen the patient’s condition.
3. Supportive Care
Treatment primarily consists of supportive care tailored to the patient's condition, including fluid replacement to maintain electrolyte and water balance, administration of antipyretics and analgesics for fever and pain control, hemostatic measures, anti-shock therapy when indicated, and dialysis in case of kidney failure.
4. Patient Isolation
For viral hemorrhagic fevers, especially highly transmissible ones like Ebola, immediate isolation of the patient is paramount to prevent further viral spread.
IV. Customs Advisory
1. Stay Informed on Health Alerts
Before international travel, proactively research the prevailing infectious disease risks at your destination, checking the Health and Quarantine section on the General Administration of Customs website for global outbreak updates and prevention advisories. It is also recommended to consult local Customs-administered International Travel Health Care Centerfor personalized pre-travel health guidance.
2. Personal Protection
Enhance your awareness of infection risks and take protective measures against rodents, mosquitoes, and ticks.
3. Promptly Declare Health Concerns
Travelers presenting with any of the following symptoms upon entry, including but not limited to fever, chills, headache, fatigue, rash, vomiting, diarrhea, or joint pain, are required to make a proactive declaration to the Customs officers, provide details of their recent travel history as well as any potential exposures, and cooperate with procedures such as temperature monitoring, epidemiological investigation, and medical examination to facilitate timely diagnosis and treatment.
Disclaimer：The above content is translated from Chinese version of Fuzhou Customs Service Hotline 12360. The Fuzhou Customs Service Hotline 12360 version shall prevail.
