The rainy season or monsoon season is relatively cool and highly humid, allowing many types of pathogens to thrive better than usual. Knowing the diseases that come with the rainy season, including their modes of transmission, causes, symptoms, and self-care methods, is important both for prevention and for being aware of the diseases. The diseases that commonly outbreak during the rainy season can be categorized as follows:
1. Respiratory Tract Infections
Common respiratory tract infections are usually caused by viruses and bacteria. Most pathogens spread through secretions such as mucus, saliva, and sputum, transmitted by contact, coughing, or sneezing. Common diseases include:
- Common cold is caused by rhinoviruses. Symptoms are not as severe as influenza. Most patients recover on their own by taking symptomatic medication. Antibiotics are not necessary, but adequate rest, plenty of fluids, and monitoring for high fever are recommended.
- Influenza is caused by the influenza virus. Patients experience high fever, muscle aches, and respiratory symptoms such as cough, runny nose, and sore throat. Symptoms are more severe than the common cold. Some cases may develop complications such as pneumonia, ear infection, bronchitis, sinusitis, or if bacterial infection occurs, severe complications like encephalitis, pericarditis, or bloodstream infections that can be life-threatening.
- Pneumonia results from infections in the upper respiratory tract caused by viruses or bacteria. It is commonly found in people with poor health, chronic diseases, and the elderly.
2. Mosquito-borne Diseases
- Dengue fever occurs year-round but outbreaks increase during the rainy season due to stagnant water sources suitable for Aedes mosquito breeding. Early symptoms include high fever up to 38-40 degrees Celsius lasting 2-7 days, along with flushed face, loss of appetite, lethargy, and some may develop red spots on the body, arms, and legs. Without treatment, it may progress to a critical stage with liver enlargement and vomiting blood. Severe cases can be fatal.
- Zika fever is transmitted by Aedes mosquitoes. Patients experience fever, muscle pain, headache, red eyes, and rash on the body. Zika fever in pregnant women may affect the brain development of the fetus.
- Chikungunya is transmitted by Aedes mosquitoes. Key symptoms include fever, muscle pain, joint pain such as in wrists and ankles, sometimes accompanied by red eyes and rash. Currently, there is no vaccine available. Treatment is symptomatic.
- Japanese encephalitis is transmitted by Culex mosquitoes commonly found in agricultural areas and pig farms. Symptoms include brain infection, fever, headache, lethargy, seizures, unconsciousness, and can be fatal. Survivors often have lasting brain disabilities. There is no specific treatment, but it can be prevented with the Japanese encephalitis vaccine, which is a live attenuated vaccine commonly used today.
3. Skin and Wound Infections
- Melioidosis is caused by bacteria found in soil. During dry weather, the bacteria remain embedded in the soil, but when it rains, they surface. Farmers who come into contact with soil are at risk. The bacteria enter the body through inhalation or wounds, especially in people with poor health, chronic diseases such as diabetes, kidney disease, or regular alcohol consumption. Symptoms can affect multiple systems such as pneumonia, bloodstream infection, and skin infection. At-risk individuals who develop fever, shortness of breath, or chills should inform their doctor about their occupation or underlying diseases to aid diagnosis.
- Leptospirosis is transmitted by rodents and various mammals. The bacteria reside in the urinary tract of animals. When animals urinate in water, people wading through water or working in rice fields can be infected through the skin. Symptoms include fever, muscle pain, and headache. Severe cases may develop acute kidney failure or inflammation of the liver and bile ducts, causing jaundice.
4. Other Common Diseases During the Rainy Season
Often caused by viruses, such as acute diarrhea, conjunctivitis, and hand, foot, and mouth disease, these are also diseases to be cautious of.
Many infectious diseases can be prevented or their severity reduced by vaccination, such as influenza vaccine, dengue vaccine, pneumonia vaccine, and Japanese encephalitis vaccine. Vaccination not only benefits health but also reduces economic losses and improves the mental well-being of oneself and family members.
Additionally, maintaining good hygiene, eating a varied diet, getting enough rest, and exercising regularly help strengthen the immune system, which is part of preventing illness or reducing disease severity if one falls ill.
Dr. Phatthaya Riangchan
Infectious Disease Specialist
Internal Medicine Center, Phyathai Nawamin Hospital
