Travel warning for American tourists as outbreak of dangerous tropical virus accelerates

Two Asian countries are experiencing outbreaks of the chikungunya virus, a mosquito-borne disease that had prompted Covid-era precautions in China and official US government warnings.  

The CDC has issued Level 2 travel advisories for Bangladesh and Sri Lanka, urging Americans to ‘practice enhanced precautions’ when visiting these countries.

The virus is vaccine-preventable, and all international travelers to these destinations should get the shots before they leave the US, according to the health agency.

Public health officials in Bangladesh have confirmed roughly 4,000 chikungunya cases nationwide. This includes over 785 cases detected this year in the capital, Dhaka, the highest number recorded since a major 2017 outbreak. In the port city of Chittagong, 30 new cases were reported in a single day, bringing the city's total to more than 3,000 infections. 

In Sri Lanka, at least 170 confirmed chikungunya cases have been documented at various sites in Colombo, Gampaha and Kandy this year. Cases in Sri Lanka continued to rise and peaked in June, marking the country’s first outbreak since 2016.

Chikungunya tears through communities with large populations of infected mosquitoes, causing rapid, large outbreaks. In China, the outbreak began in Foshan on July 8, 2025, with over 3,000 confirmed cases in the first two weeks and more than 10,000 by late August.

Guangdong Province implemented aggressive, technology-driven vector control modeled on Covid measures, including eliminating stagnant water, releasing larvae-eating fish, door-to-door inspections, mandatory patient isolation and strict surveillance to curb the spread.

The chikungunya virus is transmitted to humans by Aedes aegypti and Aedes albopictus mosquitoes infected with it. Chikungunya primarily causes sudden high fever and severe, often debilitating, joint pain. Other common symptoms include rash, muscle pain, headache and fatigue.

A sanitation worker is pictured spraying insecticide to prevent the spread of chikungunya in Dongguan, Guangdong Province of China. The country implemented covid-style surveillance and infection response efforts, including the widespread spraying of insecticides

Chikungunya has already made it to the US. In September, New York health officials reported that a 60-year-old Hempstead, Long Island woman was diagnosed with a suspected case the previous month. 

Having not traveled off the island, lab tests have since confirmed she contracted the virus locally, marking the first locally acquired case ever recorded in New York City. 

Three additional people in New York have tested positive for chikungunya in 2025 after returning from countries where the virus is known to circulate, according to the the city's Department of Health. 

Since the beginning of the year, new cases have been confirmed in 16 countries.  

According to the CDC's advisories from Bangladesh and Sri Lanka: ‘You can protect yourself by preventing mosquito bites, which includes using insect repellent; wearing long-sleeved shirts and pants; and staying in places with air conditioning or that have screens on the windows and doors.’

Pregnant women should reconsider their travel plans, especially if they are close to delivering. 

Mothers who become infected around the time of delivery can pass the virus to their baby before or during birth.

The CDC said: ‘Newborns infected in this way or by a mosquito bite are at risk for severe illness, including poor long-term outcomes,’ including cognitive deficits and developmental delays.

Sri Lanka (pictured) has recorded at least 170 chikungunya cases this year, marking its first outbreak since 2016. Cases peaked in June, with infections reported in Colombo, Gampaha and Kandy

Symptoms of the virus generally appear three to seven days after being bitten. 

The infection first appears as a severe flu with a high fever and excruciating joint pain, typically in the hands, feet and knees. A rash, headache, and severe muscle aches quickly follow.

While most people start to feel better after a week or two, the joint pain can be persistent. 

For many, it lingers, causing ongoing stiffness, swelling and arthritis-like pain that can last for months or even years.

There is no specific treatment for chikungunya, but the death rate is generally low, around one in 1,000 symptomatic cases. 

But the risk of death is far higher, up to 15 percent, among people with pre-existing conditions such as diabetes, kidney and heart disease.

Chikungunya deaths are often more directly caused by complications from kidney and brain failure rather than the virus itself.

Several other countries have reported chikungunya cases this year, including Cuba, Singapore, Pakistan and Brazil. 

Cuba is seeing its own chikungunya outbreak. The image shows fumigation smoke spreading throughout eastern Havana last month in an effort to kill off disease-carrying mosquitoes

The chikungunya virus is transmitted to humans through bites from Aedes aegypti and Aedes albopictus mosquitoes infected with it

This year, there have been at least 459,000 cases and 146 associated deaths due to the chikungunya virus reported worldwide. 

The final tally for 2025 is showing signs of surpassing the number of infections detected this time last year, about 480,000.

Cases reported in October this year increased by 108 percent compared to September, when 21,266 were reported, according to the European Centre for Disease Prevention and Control.

Vector-borne diseases, most of which are preventable, account for more than 17 percent of all infectious diseases and result in roughly 700,000 annual worldwide deaths.

Climate change is exacerbating the rising threat posed by mosquito-borne viruses by fostering an environmental evolution that makes more areas hospitable to the disease-carrying insects, putting more Americans at risk than in the past.

Longer, warmer summers and milder winters extend the breeding and biting seasons, allowing more time for diseases to spread. 

Even a slight temperature increase, as small as 1 degree Celsius, can significantly boost transmission rates.

Viral adaptation also plays a key role in the emergence of the chikungunya virus. As an RNA virus, it can mutate easily, allowing it to evolve under selective pressure, such as adapting to a new host species for better survival and transmission.

The vaccine is about 98 percent effective, with nearly everyone maintaining immunity for about three years after getting the shot.

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