Title : Emerging faecal-oral-route transmitted diseases
Abstract:
Human gut contains 1013 to 1014 microorganisms, with a huge concentration released in feces (1011-1012 bacteria/gm of stool), largely composed of anaerobic bacteria. Interestingly, these microbes make up 25-54% of the dry weight of faecal solids of bacteria and viruses (living and dead). Faecal water-borne diseases are defined as illnesses caused by pathogenic microorganisms (bacteria, viruses, protozoans, parasites), called germs, transmitted through contaminated drinking water, primarily via the faecal-oral transmission route. These diseases pose major health risks and are life- threatening. Contaminated water causes 1.5 million deaths annually, mostly in children under 5, due to their weak immunity and lacking good gut microbiota. Of these 88% deaths (1 million) are exclusively diarrhea-related and are linked to poor WASH (water, sanitation and hygiene). Cholera (Vibrio cholerae) is one of the most dangerous, bacterial water borne diseases, that causes watery diarrhea and vomiting, leading to severe fatal dehydration and death within 24 hours. Other highly dangerous water borne diseases include: typhoid (Salmonella typhi) causing high fever, accompanied with acute stomach pain, leading to mortality; Dysentery (bacillary- Shigella and amoebic (Entamoeba histolytica)-severe diarrhea associated with blood or mucus, often causing abdominal cramps; Hepatitis A and E-viral infections that cause liver damage, jaundice and severe illness; Cryptosporidiosis (Cryptosporidum)-parasitic persistent diarrheal infection dangerous for children; and Legionnaires's disease (Legionella)-a serious pneumonia through contaminated water aerosols. In a recent report published on April 2026, by Harlie Mitchell and Joanne Naish, stated that the presence of faecal bacteria (E. coli and Campylobacter) were found in 69 rural schools drinking water systems, supplied through the beaches in New Zealand, making children very ill. Most of the beaches tested, numbering 500, contained faecal contaminated water with E. coli (STEC toxin producing strain) that causes bloody diarrhea resulting to haemolytic uraemic syndrome, causing kidney damage. Campylobacter, another bacterial pathogen, causes Guillain-Barre syndrome leading to paralysis. The faecal-oral route (or orofecal route) refers to the pathway of disease transmission whereby germs (pathogens and parasites) from faecal particles of an individual pass to the mouth of another individual often causing diseases like cholera (V. cholerae), typhoid (Salmonella typhi), steatorrhea or giardiasis (Giiardia duodenalis/ G.intestinalis), polio, hepatitis A and many more infections. Every year more than 7 lakh children die from diarrhea, and millions more contact intestinal worms that cause poor health especially in school children. The most common symptoms produced are diarrhea, vomiting, abdominal pain, fever and dehydration. About 18 faecal oral agents are listed as priority pathogens primarily driven by poor sanitation, inadequate hygiene and lack of clean water. These pathogens are transmitted mainly by the following modes: faecal contaminated hands, especially fingers; flies coming in contact with faecal matter: fields, (soils) contaminated with sewage; fluids (drinking water or juices) contaminated with faecal matter; and food handlers with poor hygiene or unwashed/ contaminated-water washed vegetables and fruits. These routes are often described/ summarized by the "5 Fs" which stands for fingers, flies, fields, fluids and food. In 1958, Wagner and Lanox, identified the major means of diseases transmission through faecal-oral route and produced what is known as "F-diagram". This illustrates how pathogens from human feces (the source) reach a new host via 5 main routes leading to oral ingestion. This diagram also provides interventions (barriers) like sanitation, hygiene (hand washing) and water treatment which are inserted at critical points to break down the transmission cycle from the focal point of human feces. The F diagram is extremely useful for engineers and public health workers to intervene in appropriate ways to break the transmission cycle.
Toilet flushing and subsequent inhaled aerosols, fomites (objects and household surfaces) and anal sex are another potential route of oral transmission. The most common mode of transmission is when an infected person does not properly wash or forget to wash hands after using the toilet or changing diapers. As per April 2026 CDC report, drug-resistant incidences of shigellosis, a diarrheal illness, caused by a gram-negative bacterium Shigella (superbug) have "increased substantially" between 2011 and 2023 in the United States of America, especially among males. This bacterial infection spreads easily through an infected person's stool. Infection results on touching contaminated hands to their food or mouth. This can happen when changing the diaper of an infected child or caring for an infected person with Shigella, experiencing prolonged and bloody diarrhea, stomach pains and fever. As per CDC, so far, no antimicrobial agent is available to treat this superbug resistant to antibiotics, namely ampicillin, azithromycin, ceftriaxone and ciprofloxacin. Detection of the live COVID-19 virus (SARS-CoV-2) in stools of infected individuals and sewage has recently been reported. The virus can actively infect and replicate in the gastrointestinal tract because intestinal cells express high levels of the ACE2 receptor, which the virus uses to enter human cells, causing gastrointestinal infection. While respiratory droplets remain the primary transmission mode for COVID-19 virus, researches indicate that it can spread through faecal-oral route, though secondarily through contaminated bathroom surfaces (fomites), faecal aerosols (toilet plume) when flushing a toilet and faulty sewage drainage systems where aerosolized faecal matter moved between apartments through shared pipes. However, WHO considers the risks of faecal-oral transmission to be low compared to respiratory spreading of the virus. Hand hygiene, through proper hand washing with soap and water, after using the toilet and before preparing food, is a highly effective way to interrupt the faecal-oral route. Using instant hand sanitizers when soap and wate rare not available. Worldwide, two international events are celebrated each year: Global Handwashing Day (15th October) by the CDC to raise awareness about the importance of handwashing with soap and water, and World Hand Hygiene Day (May 5) by the WHO with the global campaign: "Save Lives: Clean Your Hands". Other important prevention strategies include: practicing safe and careful food-handling practices; Ensuring access to clean drinking water (chlorination, boiling, filtration, radiation treatment); Avoiding ingestion of water in swimming pools or from other non-potable sources; Proper sanitation systems including checking of water supply systems through multiple tube fermentation test at regular intervals; Using disposable towels; avoiding inhalation of aerosols when a flushing public toilet; Cleaning or disinfecting commonly touched, infected surfaces such as doorknobs, faucet handles, remote controls; and Avoiding irrigation of vegetable crops with contaminated/ sewage water. The WHO in 2018 issued Guidelines on Sanitation and Health on how faecal-oral transmission can be interrupted by water, sanitation and hygiene (WASH) interventions. The need of the hour is in identifying emerging faecal-borne pathogens and inventing drugs to treat them and to prevent diseases spread through faecal-oral route by maintaining rigorous hand hygiene, regular disinfection of bathrooms with standard disinfectants, avoiding public toilets, flushing toilets with the lid down, including public health officials playing their role to intervene in appropriate ways to break the germs transmission routes through 5Fs as outlined in the F-diagram, saving millions of human lives and unnecessary suffering due to diarrheal infections.
