People are spending more time outside since the summer has passed and the weather has become cooler. However, febrile infectious diseases are common at this time of the year. These include hemorrhagic fever with renal syndrome, leptospirosis, and scrub typhus (tsutsugamushi disease). These diseases occur in Korea every year, but can be difficult to diagnose in the early stages because of their atypical symptoms. Failure to treat appropriately can also lead to rare but serious complications, and even death. It is important to understand the clinical patterns and prevention methods of these diseases when visiting areas with high incidence of these diseases, or when spending significant time outdoors.

Haemorrhagic fever with renal syndrome

Hemorrhagic fever with renal syndrome is caused by Hantavirus. It is an acute infectious disease associated with fever, bleeding and renal problems. Of the different types of Hantavirus, Hantan virus and Seoul virus are known to cause hemorrhagic fever with renal syndrome in Korea. These arise in October to November, and between May and June. They commonly infect farmers or soldiers. The cause is inhalation of rat droppings that contain the pathogen, leading to infection. There is no infection between people. The average latency is 2-3 weeks. This disease is divided into five stages: fever, hypotension, oliguria stage (decreased urine output), diuresis (increased urine production), and recovery.

During the fever stage, the patient can develop a fever, headache, myalgia, red swelling of the face and neck, redness to the eyes, redness and swelling of the pharynx, mucosal bleeding of the roof of the mouth or the axilla. There is no specific treatment, but it is important that the patient is admitted to the hospital in the early stages for symptomatic and supportive treatment. Prevention includes avoiding mountains or fields where the disease is prevalent, wearing long sleeves when going outdoors, avoiding lying in the grass, and shaking off dust and washing the body thoroughly when coming home.

Leptospirosis

Leptospirosis is caused by the Leptospira bacteria. Leptospira is a spiral microorganism that can survive for a prolonged time in contaminated water. Infection is caused by exposure of the mucosa or damaged skin to water, soil, or urine from infected animals (usually rats). It is common between September and October in Korea and commonly affects farmers who work in wet soil or water for long hours. Transmission between people is rare and the average latency period is 7-12 days. The clinical symptoms vary widely, including asymptomatic infection, mild infection without jaundice, and although rare, serious infections with jaundice. The clinical pattern includes acute fever, headache, myalgia, nausea and vomiting, redness to the eyes, as well as coughing, respiratory problems, hemoptysis and other respiratory symptoms.

Treatment is symptomatic, together with administration of antibiotics. For prevention, it is important to keep your surrounding environment clean, prevent access by rats, and vaccinate livestock. You should also avoid placing your hands and feet in water in the fields, and wear protective equipment including gumboots and gloves. Try to minimize the amount of time you spend in such environments, and work with rice crops after draining the rice paddies.

Scrub typhus (Tsutsugamushi disease)

Scrub typhus is a febrile illness caused by Rickettsia tsutsugamushi and characterized by fever, headaches, rashes and eschar formation. It is a common disease that occurs in the autumn, accounting for 30 percent of all acute febrile diseases in the season. The vectors of this disease are chiggers and it is transmitted through bites from infected chiggers. It arises between September and November in Korea. There is no transmission between people, and the average latency period is 10-12 days. Symptoms include acute fever, headache, myalgia, and rashes spreading from the body trunk to the limbs. Clues to the diagnosis include ulceration or eschar formation of the bite on the skin. The treatment is relatively simple and includes the administration of antibiotics. Most febrile infectious diseases that occur in autumn mimic the common cold in the early stages, which can lead to delays in diagnosis. Therefore, it is important that people have a general idea of these diseases.

If you experience prolonged flu-like symptoms during this season, or you have visited an area where these diseases are prevalent and have subsequently developed a fever of unknown origin, it is important that you see your doctor first, rather than taking over-the-counter medications. Farmers and soldiers who spend considerable amounts of time outside should make efforts for prevention of such diseases, and understand the causes, infectious routes and clinical patterns of these diseases.

Waterborne diseases

Waterborne diseases are associated with severe symptoms. These include severe diarrhea, fever and chills, vomiting, abdominal pain, fatigue, and a decline in the level of consciousness. If such symptoms occur in many people at once, waterborne diseases can be suspected. A patient complaining of these symptoms should be quickly admitted to the hospital in isolation, and must undergo treatment.

● Typhoid fever

This used to be called febrile disease in the past, and is associated with high temperatures. The patient can develop spots on the body, and may have hepatosplenomegaly on examination. There is insignificant elevation in the heart rate, and reduced white cell count in blood tests early-stage.

● Cholera

This is characterized by severe diarrhea. The diarrhea is sometimes referred to as “rice water stools” and the amount is very large, as if from a running tap. A patient can develop shock from significant dehydration even within a day. It is a serious disease that can cause death in children and the elderly.

● Dysentery

This is characterized by mucous stools. They may contain blood and the patient may also have fever. The patient will need to visit the toilet many times within a day, which can lead to erosion of the anus. However, the amount of diarrhea is not very large.

How to prevent waterborne infectious diseases

1. Boil all water before drinking.

2. Avoid raw foods. If you do eat raw foods, wash several times in clean water. 

3. Store food under 5 degrees, or heat to at least 60 degrees Celsius before storing.

4. Don’t leave food behind.

5. When eating leftovers, boil the food. Boil cutting boards, tea towels and knives every day. Wash hands thoroughly and isolate the patient for treatment.

6. Any plates, beddings or toilet pans used by the patient should be boiled and disinfected. 

By Kang Cheol-in

The author is a doctor in the Division of Infectious Diseases at Samsung Medical Center and a professor of Sungkyunkwan University School of Medicine. ― Ed.