Stomach Infections Symptoms (Bacterial, Viral, Fungal, Parasite)

There are a number of pathogenic microorganisms that can affect the stomach and the infection usually extends to neighboring structures, namely the esophagus proximally and duodenum distally. Stomach infections can broadly cause two common conditions – gastritis and gastroenteritis. At times, toxins from infectious agents, mainly bacteria, can cause inflammation without the pathogen infecting the stomach itself.

Other infections involving the esophagus and duodenum of the small intestine may also affect the stomach, like is seen in infectious colitis.


Gastritis is the inflammation of the stomach lining due to a host of possible causes, with Helicobacter pylori infection being among the leading causes. It tends to be longer lasting than gastroenteritis, with chronic infectious gastritis lasting for months or even years. The infective agent typically invades the gastric mucosa.


H.pylori gastritis is often chronic and can lead to stomach ulcers. Treatment for H.pylori gastritis involves eradication with a triple therapy approach. Other pathogenic microorganisms may also be involved although these are rare.

  • Virus
    • Cytomegalovirus (CMV)
    • Herpes simplex virus (HSV)
  • Fungi
    • Candida spp (candiasis)
    • Histoplasmosis capsulatum (histoplasmosis)
    • Mucorales spp (mucormycosis)
    • Paracoccidioides brasiliensis (South American blastomycosis)

Most viral and fungal cases of gastritis tend occur in patients who are immunocompromised (low immune functioning) as is seen in HIV infection and uncontrolled diabetes mellitus (sugar diabetes).

  • Parasites
    • Strongyloides spp
    • Schistosomiasis (Schistosoma mansoni, Schistosoma japonicum, Schistosoma mekongi, and Schistosoma intercalatum are more likely to affect the stomach)
    • Diphyllobothrium latum

Signs and Symptoms

Infectious gastritis may cause the following signs and symptoms :

  • Stomach ache frequently described as a dull, gnawing pain
  • Bloating – sensation of fullness
  • Belching
  • Nausea, sometimes vomiting

Many of these symptoms are broadly described as indigestion by many suffering with gastritis.


Gastroenteritis is the inflammation of the stomach, small and large intestines. The severity of the infection seen in the extent of mucosal irritation, invasion or even ulceration, causes very acute symptoms like severe and sudden vomiting and diarrhea.

It is an acute infection frequently caused by viruses, hence the common name, stomach flu or stomach virus. Bacteria, fungi and various protozoa may also be responsible.


Viruses are a common cause of gastroenteritis (stomach flu) outbreaks due to person-to-person transmission (airborne). Protozoa are typically associated with water-borne outbreaks. With food infection and food poisoning, bacteria or its toxins are the more common causative organs.

These list of causative organisms, incubation periods and the duration of infection is discussed in detail under Stomach Bug.

Signs and Symptoms

The symptoms do not emanate solely from the stomach and is more frequently linked to irritation of the small intestine.

  • Nausea
  • Vomiting
  • Diarrhea
  • Abdominal pain
  • Stomach cramps
  • Fever

Stomach Infection Related Articles

  1. Stomach Virus
  2. Gastritis
  3. Gastroenteritis
  4. Tummy Bug


  1. Chronic Gastritis. Emedicine

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