Health officials upgraded a recent travel warning amid a concerning surge of a mosquito-borne illness that causes pain potentially lasting for years. The Centers for Disease Control and Prevention has issued a Level 2 travel warning for Guangdong Province in China, advising visitors to “practice enhanced precautions” due to an outbreak of chikungunya. The outbreak has shaken the province, with Foshan city at the epicenter, sparking an aggressive response from authorities that some are comparing to early COVID-era measures. Thousands of people in China have been infected with the painful virus. It’s an illness that is spread when a mosquito...