More on Diarrhea at the Summer-Autumn Transition
In ancient Chinese medicine, the transition between summer and autumn is called late summer (changxia), a season when diarrhea easily occurs. The Suwen's "Jin Gui Zhen Yan Lun, Chapter 4" states: "Thus in spring one is prone to nasal bleeding; in midsummer to chest and rib illness; in late summer to draining diarrhea and interior cold; in autumn to wind-malaria; in winter to bi and jue." This shows people have observed since antiquity that diarrhea is common at the summer-autumn transition.Why is diarrhea so common in late summer? Mainly because the microbes affecting the intestines are highly active then; cholera, bacterial enteritis, and viral enteritis all tend to occur in late summer. According to incomplete WHO figures, infectious diarrhea reaches 3–5 billion cases worldwide each year; among children under five there are about 1.8 billion cases yearly, over 3 million fatal. Diarrhea is the leading illness and cause of death in under-fives, most common in summer and autumn.So-called autumn diarrhea in children is mostly viral enteritis from rotavirus; if not treated promptly it often kills the child. Rotaviruses are grouped A–G; groups A, B, and C infect humans and animals, the rest only animals. Rotavirus diarrhea mainly occurs in autumn and winter. Regardless of hygiene, nearly all children over five have been infected with group A human rotavirus. Besides diarrhea, rotavirus causes fever and vomiting.Besides rotavirus, norovirus is another common cause of diarrhea and often triggers clustered outbreaks. Norovirus has neither vaccine nor specific drug; people are universally susceptible, and outbreaks can occur year-round, though they peak in summer and autumn.Cholera, bacterial diarrhea, and dysentery also peak in summer and autumn. Cholera is caused by Vibrio cholerae; as a Class A notifiable disease, it is highly lethal. Escherichia coli, Shigella, and other pathogens also rage in summer and autumn.Diarrhea from these pathogens peaks in this season partly due to lifestyle and diet, since they spread mainly by the fecal-oral route. In summer and autumn natural waters are more often contaminated, vectors like flies breed in numbers, and people favor raw and cold foods—greatly increasing transmission.Apart from cholera, most viral and bacterial diarrhea spread in summer and autumn is self-limiting. Cholera, however, is a Class A disease under strict global surveillance, and with current medicine large cholera outbreaks are no longer easy. So robust people rarely get diarrhea at this season, or if they do it is not severe.But the immunocompromised—children and those with chronic disease—should guard against fecal-oral pathogens. Avoid raw and cold foods, disinfect tableware and cookware with heat, exterminate flies and cockroaches at home, cook food thoroughly, and wash vegetables in separate vessels from tableware.Door handles in public restrooms and aerosols can also transmit diarrhea-causing viruses and bacteria; protect yourself when using public restrooms. Because many pathogens are zoonotic, common pets and poultry/livestock are also important sources. Practice good hygiene when touching animals or their feces.Long influenced by TCM concepts, most Chinese, on developing loose stools, think not of pathogens but of words like "spleen deficiency." They thus easily misuse medicine and consult doctors along a spleen-strengthening line, while neglecting the infectious source and repeatedly reinfecting themselves. Some harmful bacteria, such as Clostridium perfringens and Pseudomonas aeruginosa, once in the intestine, can colonize long-term and multiply, causing recurrent bloating, pain, and diarrhea. So many people are chronically plagued by bloating and diarrhea.Since antibiotics appeared, humanity has widely used them, but overuse also kills beneficial gut bacteria, causing antibiotic-associated diarrhea. When investigating a patient's diarrhea, one must consider antibiotic overuse.Because the causes of diarrhea at the summer-autumn transition are complex, Western medicine should first identify the cause and the pathogen before treating. Chinese medicine mostly treats symptomatically, with the doctor selecting herbs according to the patient's signs.But prevention is better than cure. Patients themselves must guard their mouths, wash hands often, and avoid misusing drugs. A healthy lifestyle and good hygiene greatly lower the chance of summer-autumn diarrhea.