Overview
Diarrhea caused by viral, bacterial, fungal, protozoal, and other pathogens
Infectious diarrhea is characterized by vomiting, abdominal pain, diarrhea and fever.
Viral diarrhea is usually treated symptomatically, while bacterial diarrhea requires antibacterial treatment.
Viral diarrhea usually resolves on its own
Definition
Infectious diarrhea is diarrhea caused by various pathogens such as viruses, bacteria, fungi, protozoa and other infections [1].
Diarrhea is defined as three or more bowel movements per day, totaling more than 250g; stools may be loose, watery, mucus, pus or blood, and may be accompanied by systemic symptoms such as nausea, vomiting, abdominal pain or fever.
Common diarrhea includes dysentery, cholera, typhoid fever and paratyphoid fever, and infectious diarrhea as stipulated in the Law of the People’s Republic of China on Prevention and Control of Infectious Diseases. The infectious diarrhea described in this article mainly refers to the latter.
The most common types of infectious diarrhea are viral infectious diarrhea and bacterial infectious diarrhea.
Classification
By pathogen
Viral diarrhea
Common pathogens include rotavirus, norovirus, astrovirus, and cupripovirus. The most common are rotavirus and norovirus.
Before rotavirus vaccination rotavirus was an important cause of 30% to 70% of hospitalized cases of acute diarrhea in children [2].
Norovirus is the most common cause of community-acquired diarrhea, diarrhea outbreaks and foodborne illnesses worldwide [3].
The source of viral diarrhea is human and animal, and the transmission route is based on fecal-oral transmission and human-to-human contact, and some can also be transmitted through the respiratory tract.
Fall and winter are the most frequent seasons, and children are more often infected than adults.
Bacterial infectious diarrhea
Common pathogens include Salmonella, Shigella, Vibrio parahaemolyticus, Escherichia coli, Staphylococcus aureus and so on.
Children are at high risk of acute bacterial diarrhea [4].
Bacteria-carrying animals such as livestock, fish and wildlife are the primary source of infection, while patients carry the bacteria for a shorter period of time and are secondary sources of infection.
The route of transmission is through bacterial contaminated food or utensils into the gastrointestinal tract through the mouth.
The population is generally susceptible.
Year-round circulation, summer and fall are more frequent.
Parasitic diarrhea
Parasitic diarrhea can be caused by more than 50 kinds of parasites, mainly amoeba, cryptosporidium, schistosomiasis and so on.
Fungal diarrhea
Fungus usually exists in the human skin mucous membrane, belongs to the condition of pathogenic bacteria.
When the body resistance is lowered or when antibiotics and hormones are used for a long period of time, the fungi multiply and cause fungal infections, so that the normal host microorganisms are dysfunctional in their mutual constraints, resulting in fungal diarrhea.
Classification according to duration
Acute infectious diarrhea: duration of illness <14 days.
Persistent infectious diarrhea: duration of illness 14 to 27 days.
Chronic infectious diarrhea: duration of illness ≥ 4 weeks.
Morbidity
Incidence occurs throughout the year, with peaks in June~August and November~January.
The main pathogen of infectious diarrhea events in China from 2017 to 2021 is norovirus [5].
Etiology
Pathogenic causes
The pathogenic causes of infectious diarrhea are viruses, bacteria, fungi, protozoa and other pathogens.
Bacteria
Mainly include Vibrio cholerae, Escherichia dysenteriae, Escherichia coli, Vibrio parahaemolyticus, Salmonella, Campylobacter, Shigella, Bacillus cereus, Clostridium perfringens, Yersinia pestis and so on.
Viruses
Mainly include norovirus, rotavirus, adenovirus, astrovirus, certain respiratory viruses, etc.
Fungi
Mainly include Candida albicans, Cryptococcus, Aspergillus, Trichoderma, etc.
Parasites
Including Giardia, Amoeba, Cryptosporidium, Cyclospora, etc.
Predisposing factors
Infectious diarrhea is prevalent in adolescents under 20 years of age, the elderly, and immunocompromised people [6].
Dietary impurity.
Recent history of travel or exposure to infected areas.
Immunocompromised or malnourished.
Prolonged heavy use of antibiotics, etc [7].
Pathogenesis
Viral infectious diarrhea
Rotavirus and norovirus can increase the osmotic pressure of the intestinal tract and water enters the intestinal lumen, causing diarrhea and vomiting.
Enteric adenoviruses can cause osmotic diarrhea due to small intestinal absorption dysfunction.
Bacterial infectious diarrhea
Secretory diarrhea: Bacteria release enterotoxins to stimulate the intestinal mucosa, secretion of excessive water and Na+ to the intestinal lumen, when the secretion exceeds the absorption capacity can lead to diarrhea, so it is called secretory diarrhea.
Invasive diarrhea: bacteria cause cellular dysfunction and mucosal necrosis, ulcer formation, and inflammatory exudation, increased intestinal osmolality, impaired absorption of electrolytes, solutes and water, and production of prostaglandins, which in turn stimulate secretion and increase intestinal motility, causing diarrhea.
Fungal Infectious Diarrhea
Fungal infectious diarrhea may be due to dysregulation of the normal intestinal flora and overgrowth of Candida and other bacteria that inhibit lactase activity leading to lactose intolerance and diarrhea [8].
Symptoms
Main Symptoms
Viral infectious diarrhea
Symptoms are relatively mild, with a short incubation period and rapid onset.
The main manifestations are diarrhea, vomiting, abdominal pain, fever and other symptoms of acute gastroenteritis.
Stools are dilute or watery, without mucus, pus or blood, and there is no urgency.
Bacterial infectious diarrhea
The incubation period varies from several hours to several weeks.
Acute onset, symptoms vary in severity, bacterial infection with hidden infection or pathogen carrier or morbidity.
Abnormal stool characteristics, watery stool or mucus, pus and blood stool.
Often accompanied by cold, fever, fatigue, dizziness, general malaise and other manifestations.
Fungal Infectious Diarrhea
Diarrhea, stools are mushy, dilute, watery, or mucus-like, the amount of diarrhea is not large, abdominal pain is not obvious, and some patients show alternating diarrhea and constipation [9].
Complications
Dehydration, acidosis and electrolyte disorders: large amounts of water and electrolytes are lost during diarrhea, which in turn causes dehydration, electrolyte disorders, acidosis, and may lead to death in severe cases.
Bacteremia: commonly caused by Salmonella, Campylobacter fetus and so on.
Hemolytic uremic syndrome: mainly manifested as fever, thrombocytopenia, microangiopathic hemolytic anemia, renal function abnormalities, etc. It often occurs 1~2 weeks after the beginning of diarrhea.
Post-infectious irritable bowel syndrome: 5~15 days after the beginning of diarrhea. It manifests as acute or subacute symmetrical flaccid paralysis of the limbs. There is a high mortality rate.
Consultation
Department of Medicine
Gastroenterology
Vomiting, abdominal pain, diarrhea and other related symptoms after unclean eating are recommended to go to Gastroenterology or Intestinal Clinic in time.
Emergency Department
If the patient has abdominal pain or diarrhea accompanied by symptoms such as dizziness, pallor, sweating, or a drop in blood pressure, it is recommended that he or she go to the Emergency Department immediately.
Pediatrics
Children with the above symptoms may also be seen in the Pediatrics Department.
Preparation
How to get to the doctor: registering, preparing documents, and common problems.
Tips for medical treatment
Before consultation, bed rest is recommended. Drink plenty of fluids.
If you have a bowel movement, remember the nature, color and frequency of the bowel movement, and take a picture of it.
Preparation Checklist
Symptom list
Pay particular attention to the time of onset of symptoms, special manifestations, etc.
Has the diarrhea been preceded by eating unclean food or getting cold?
How long has the diarrhea lasted and how many times a day?
Is there mucus, pus or blood in the stool?
Is it accompanied by nausea, vomiting, fever?
Is there any discomfort such as abdominal pain or bloating?
Medical History Checklist
Has anyone around you experienced the same symptoms?
Have you been exposed to unclean or undercooked food?
Have you traveled or been to an infected area?
Checklist
Test results for the past 6 months, which can be brought to the doctor’s office
Laboratory tests: blood test, stool test, electrolytes, etc.
Imaging tests: abdominal CT, etc.
Medication list
Medication used in the last 3 months, if available, bring along the box or package for medical consultation
Antidiarrheal drugs: Montelukast, Loperamide, etc.
Antispasmodics and analgesics: pivacurium bromide, scopolamine, etc.
Microecological preparations: Saccharomyces boulardii, Bifidobacterium triplex, etc.
Diagnosis
Diagnosis is based on
Epidemiologic history
The patient may have a history of unclean eating prior to the onset of the disease.
Clinical manifestations
The number of stools is ≥3 per day.
Abnormal fecal character, including loose stool, watery stool, mucus stool, pus and blood stool.
It may be accompanied by nausea, vomiting, abdominal pain, fever, loss of appetite and generalized discomfort.
Abdominal pain may be accompanied by abdominal tenderness, and most patients have hyperactive bowel sounds.
Laboratory tests
Routine blood tests: the total number of white blood cells, neutrophils and eosinophils in the peripheral blood can be used to determine the type of infection, whether it is bacterial, viral or parasitic.
Stool routine examination: the appearance of feces in viral infection is mostly yellow watery, without pus cells and red blood cells; feces after bacterial infection can be of different character, such as dilute watery feces, washed feces, pus and blood feces, blood feces, mucus feces and so on.
Pathogenetic examination: commonly used methods include latex agglutination test, enzyme-linked immunosorbent assay (ELISA), passive hemagglutination assay (PHA), immunofluorescence assay (IFA), immunomagnetic sphere assay, enzyme immunofluorescence assay, etc., which are used for the detection of bacterial and viral in the feces, and the detection of specific antigen and antibody in the blood serum.
Nucleic acid test: gene probe technology and polymerase chain reaction technology to detect pathogen-specific gene fragments, the method is simple, rapid and sensitive.
Differential Diagnosis
Irritable bowel syndrome
Similarities: Both can cause abdominal pain, loose, watery or mucus stools, no bloody stools or pus and blood stools.
Differences: There are no abnormalities in the tests for irritable bowel syndrome, and there are no abnormal findings on colonoscopy that can explain the patient’s symptoms. Diarrhea is common during the day and relieved at night, and is associated with stress and mood changes, and may be related to the ingestion of a specific food, and may be triggered or relieved by verbal cues.
Inflammatory Bowel Disease
Similarities: Both can present with diarrhea.
Differences: Inflammatory bowel disease is of unknown etiology and may be immunologic or related to viral infections. It has a chronic course, and episodes may be related to dietary composition or mood. There may be extra-gastrointestinal manifestations, dehydration is not evident; colonoscopy has characteristic superficial ulcers.
Questions you may be concerned about
What are the diagnostic criteria for infectious diarrhea
Diagnostic criteria for infectious diarrhea mainly include medical history, symptoms, and laboratory tests.
1. Medical history: whether there is a history of unclean diet and contact with patients with infectious diseases, such as consuming spoiled food, contacting patients with cholera or rotavirus infection.
2. Symptoms: Infectious diarrhea is often characterized by increased stool frequency, loose or watery stools, accompanied by abdominal pain, vomiting, fever and other symptoms.
3. Laboratory tests: If the neutrophils are elevated, C-reactive protein and calcitoninogen will be increased to consider bacterial infection. If there is leukocytosis, mainly lymphocytosis, but C-reactive protein and calcitonin are not high or slightly increased, it suggests that it may be a viral infection.
Diarrhea caused by parasitic infections can be examined by laboratory tests such as fecal culture or fecal pathogenetic testing, such as amoebic dysentery, in which amoebic trophozoites and cysts can be detected in the feces, and antibodies to lysogenic amoebic trophozoites can be detected in serum neutrophils and tests.
If the above symptoms occur, patients are advised to go to the hospital in time, and under the guidance of the doctor to carry out relevant medical examinations, such as blood routine, stool routine, etc., to clarify the cause of the disease and then actively cooperate with the doctor’s treatment.
Treatment
Aim of treatment: to alleviate the symptoms, control the development of the disease, and prevent and minimize complications.
Treatment principle: some bacterial infections and parasitic infections can be treated with appropriate anti-infective drugs; viral infections are not treated with specific drugs, mainly for diarrhea and dehydration, symptomatic and supportive treatment. Serious cases need to correct acidosis and electrolyte disorders.
General treatment
Rest in bed and reduce strenuous exercise.
Drink plenty of warm water.
Mild dehydration and electrolyte disorders can be treated with oral salted rice soup, sugar saline or oral rehydration salts.
Severe dehydration should receive intravenous rehydration, pay attention to potassium supplementation, and sodium bicarbonate should be used to correct acidosis.
A light and water-rich diet is appropriate.
Infants and young children should continue to be breastfed, and those who are formula-fed may choose to use low-lactose or lactose-free formula.
Those with frequent vomiting and diarrhea can fast for 8~12 hours, and then gradually resume normal diet.
Medications
Antidiarrheal agents
Commonly used medications include montelukast, decongestants, loperamide and so on.
Montelukast has a strong fixing and inhibiting effect on viruses and toxins in the digestive tract, making them lose their pathogenic effect; in addition, it has a strong covering protective ability on the mucous membrane of the digestive tract, repairing and improving the mucous membrane barrier, etc., so it can be used as the first choice.
Elixir of polypeptide is a kind of enkephalinase inhibitor, which can further prolong the physiological activity of endogenous enkephalin in the digestive tract and play the role of antidiarrheal.
Rational use of antimicrobial drugs
Antimicrobial drugs used vary for different pathogens [10].
Viral infections are currently treated with no specific drugs, mainly symptomatic and supportive treatment for diarrhea and dehydration.
Infectious diarrhea caused by bacteria is treated with antimicrobial drugs according to the type of bacteria and severity of infection. Commonly used antimicrobial drugs include ciprofloxacin, levofloxacin and other fluoroquinolones, erythromycin, azithromycin and other macrolides, ceftriaxone, cefaclor and other cephalosporin antimicrobial drugs.
Infectious diarrhea caused by parasites can be treated with parasite-specific medications. For example, metronidazole can be used to treat amoebic dysentery, and metronidazole or azithromycin can be used to treat Giardia infection.
Infectious diarrhea caused by fungal infections is usually treated with antifungal drugs such as fluconazole and voriconazole.
Follow your doctor’s advice on the use of antimicrobial drugs to avoid abuse. If Clostridium difficile enteritis is present, antimicrobials should first be discontinued and vancomycin or metronidazole should be given.
Microecological therapy
Since the cause of bacterial diarrhea lies in the invasion of exogenous bacteria or the translocation and disproportion of normal bacteria, which leads to the destruction of the normal intestinal flora and the imbalance of the intestinal microecology, microecological therapy can be applied to restore the normal intestinal flora, rebuild the intestinal biological barrier, antagonize the colonization and invasion of pathogenic bacteria, which is conducive to the control of diarrhea.
Commonly used preparations are probiotics and prebiotics, probiotics such as bifidobacteria, lactobacilli, fecal cocci, etc.. Prebiotics include lactulose, fructooligosaccharides, inulin, etc.
Oral live bacterial preparations should be taken about 2 hours apart from antimicrobial drugs to avoid being killed and compromising efficacy.
Prognosis
Cure
Viral infectious diarrhea usually resolves spontaneously.
Most bacterial, fungal, and parasitic infectious diarrhea has a good prognosis after treatment.
Prognostic factors
The prognosis for infectious diarrhea varies depending on the type of pathogen, the patient’s age, the patient’s overall health, and the timeliness of treatment.
For many healthy adults, infectious diarrhea usually has a good prognosis, with symptoms resolving spontaneously within a short period of time and without leading to long-term complications.
However, the prognosis for infectious diarrhea may be poorer in the following situations:
Children and the elderly: Infants and the elderly may have a poorer prognosis due to poorer immune function and susceptibility to complications such as dehydration.
Immunocompromised patients: Infectious diarrhea may be more difficult to treat and have a poorer prognosis in patients such as those with AIDS, leukemia, organ transplants, or long-term use of immunosuppressants.
Severe bacterial infections: Certain bacterial infections, such as Salmonella, Shigella, or E. coli, may lead to more serious complications, such as bloodstream infections and hemolytic uremic syndrome (HUS). The prognosis may be poorer in these cases.
Failure to treat promptly: If infectious diarrhea is not treated promptly and appropriately, it may lead to complications such as dehydration, electrolyte disorders, and renal impairment, which may affect the prognosis.
Daily
Daily management
In the absence of vomiting, eat light, easy-to-digest, low-fat, non-slag food such as rice soup or porridge, vegetable soup, etc. Avoid stimulating, allergic food, and prefer small amount of meals.
People with frequent vomiting and diarrhea can fast for 8~12 hours, and then gradually resume normal diet.
Diet should be gradually increased from less to more to minimize the peristalsis of the stomach and intestines and reduce the burden on the intestinal tract.
Drink water appropriately.
Prevention
Prevention of infectious diarrhea is mainly achieved through good personal hygiene practices, safe food handling and clean living environment. The following suggestions can prevent infectious diarrhea:
Wash hands promptly before and after food preparation, after using the toilet, after touching animals, and after caring for the sick and changing diapers of infants.
Store raw and cooked food separately to avoid cross contamination.
Ensure food is well cooked, especially meat and poultry.
Use clean knives and chopping boards.
Avoid eating raw eggs or raw meat.
Keep the temperature in the refrigerator below 4 degrees Celsius (40 degrees Fahrenheit).
Ensure safe drinking water by not drinking raw water and not eating spoiled fruits and vegetables.
Keep your living environment clean by regularly cleaning and disinfecting bathrooms, kitchens and other common areas.
Get vaccinated against certain pathogens, such as rotavirus, as recommended by your doctor and the national immunization schedule [11].