[Sportschosun Reporter Jang Jong-ho] In the hot and humid summer months, people tend to be more alert to food poisoning, gastroenteritis, skin diseases, and heat-related illnesses. Awareness of pyelonephritis, however, remains relatively low.
According to statistics from the Health Insurance Review & Assessment Service (HIRA), the number of pyelonephritis patients showed seasonal fluctuations. In February 2025, the number fell to a yearly low of 24,506. But in July, when the peak summer heat began, it rose to 29,091, up 11.4% from the previous month’s 26,103. The figure remained high in the following months, with 28,524 in August and 29,332 in September.
Pyelonephritis, a type of urinary tract infection, is a disease in which bacteria infect the kidneys. Infections in the urethra are classified as urethritis, while infections in the bladder are classified as cystitis. Urethritis and cystitis are lower urinary tract infections, while pyelonephritis is an upper urinary tract infection in which the infection spreads to the kidneys.
In most cases, pyelonephritis develops when bacteria enter through the urethra and travel upward from the bladder to the kidneys. Escherichia coli accounts for about 85% of the causative bacteria. Women face a relatively higher risk because their urethra is anatomically shorter.
During summer, when high temperatures increase sweating, the body can become dehydrated more easily.
When the body lacks fluids, urine output decreases. As a result, bacteria in the urinary tract are not flushed out sufficiently and can multiply more easily. High temperatures and humidity in summer can also create conditions that favor bacterial growth, increasing the risk of urinary tract infections. As lower urinary tract infections such as cystitis spread to the kidneys, the risk of pyelonephritis also rises.
Unlike simple cystitis, pyelonephritis is typically marked by a high fever of 38 C or above, chills, and flank pain. In particular, pain when lightly tapping or pressing the costovertebral angle, where the lowest rib meets the spine, may indicate pyelonephritis. Nausea, vomiting, and general weakness may also occur, along with lower urinary tract symptoms such as painful urination, frequent urination, and a feeling of incomplete bladder emptying.
Pyelonephritis is diagnosed through blood tests, urine tests, and urine culture tests. Depending on the results, appropriate antibiotic treatment is given, and hospitalization may be necessary if symptoms are severe. If a urinary tract abnormality is suspected, imaging tests such as kidney ultrasound or CT scans may be added to assess the cause.
Lee Ga-hee, head of the artificial kidney center at Daedong Hospital and a nephrology specialist, said, "Pyelonephritis can occur regardless of the season, but environmental factors make it relatively more common in summer." She added, "In many cases, early symptoms such as high fever or body aches are mistaken for a cold, causing treatment to be delayed. If symptoms such as flank pain or painful urination are present, it may be a urinary tract infection rather than a simple cold, so it is important to visit a medical institution early for an accurate diagnosis and proper treatment."
To prevent pyelonephritis, people without conditions that require fluid restriction should drink enough water, about 1.5 to 2 liters a day, and avoid holding in urine for long periods. On days when you sweat heavily, it is especially important to drink water more frequently than usual to prevent dehydration. It also helps to avoid wearing a wet swimsuit for long periods after swimming and to pay attention to personal hygiene.
Jang Jong-ho, bellho@sportschosun.com
