Gastrointestinal Infections

Amoebiasis  is  an  infection  caused  by  the  protozoa  organism  Entamoeba  histolytica,  which  can  cause  colitis  and  other  extra-intestinal  manifestations.  The  infection  is  primarily  acquired  through  ingestion of contaminated food and water and occasionally can be acquired through oral-anal sexual  practices. 

Clinical presentation 

• Bloody diarrhea 
• Crampy abdominal pain 
• Fever 
• Weight loss 
• Peritonitis in severe forms 
• Evidence of motile trophozoites or  cysts on saline wet mount from a  stool specimen 

Pharmacological Treatment 

A: metronidazole (PO) 400–800mg 8hourly for 5days 

OR 

B: tinidazole (PO) 2g 24 hourly for 3days   

It is the most frequent extra-intestinal manifestation of Entamoeba histolytica infection which results  from  the  invasion  of  the  portal  venous  system  from  the  colon  leading  to  inflammation  and  subsequently abscess formation particularly involving the right lobe of the liver. 

Clinical presentation 

• High grade fever, 39^°C 
• Right upper quadrant pain
• Tender and enlarged liver 
• Positive imaging evidence of liver abscess   
• Serological evidence of E. histolytica antibodies or antigens

Pharmacological Treatment 

B: metronidazole (IV) 800mg 8hourly for 10days.  

OR  

B: tinidazole (PO) Adults: 2g once daily for 3days  

Note 

• Metronidazole and Tinidazole should not be given in the first trimester of pregnancy due to potential teratogenic effects. 
• Should not be taken with alcohol due to disulfiram like effects 

Surgery: 

Abscess cavity (size >5 cm in diameter) not regressing despite 7days treatment should be aspirated. 

It is the infestation of the upper small intestine caused by the flagellate protozoan Giardia lamblia (or  G. intestinalis), cytopathic effects of which leads to malabsorption and diarrhea. It is more common  in immune compromised individuals and is acquired through ingestion of contaminated water 

Clinical presentation 

• Crampy abdominal pain 
• Chronic diarrhoea  
• Steatorrhea
• Weight loss  

Investigations 

• Evidence of Giardiaintestinalis trophozoites or cysts on serial 3 samples of stool examination
• Serological evidence of G. Intestinalis trophozoites antigen or antibody
• Evidence of G. Intestinalis in duodenal aspirates or biopsy specimen.

Pharmacological Treatment 

A: metronidazole (PO) 400–800mg 8hourly for 5days 

OR 

B: tinidazole (PO) 2g once daily for 3days  

It is a small intestinal infestation caused by Ascaris lumbricoides which leads to malnutrition, iron  deficiency anaemia, impaired growth and cognition in susceptible hosts. It is most common infestation in children, and it is acquired through ingestion of contaminated food and water. 

Clinical presentation 

• Chronic Diarrhea
• Steatorrhea
• Malnutrition
• Chronic Cough (Loffler’s syndrome)
• Intestinal obstruction
• Obstructive jaundice

Investigations 

• Stool examination: evidence of ova or worms on wet mount

Pharmacological Treatment 

A: mebendazole (PO) 500mg stat or 100mg 12hourly for 3days.    

OR 

A: albendazole (PO) 400mg stat

It is a hookworm disease caused by infestation of the small intestine with Ancylostoma duodenale or  Necator americanus leading to anaemia and malnutrition. 

Clinical presentation 

• Abdominal pains
• Chronic diarrhea
• Melena stool
• Weight loss
• Chronic cough (Loffler’s syndrome) PLUS
• Evidence of ova or worms on wet mount stool examination
• Anaemia

Pharmacological Treatment 

A: mebendazole (PO) 500mg stat or 100mg 12hourly for 3days. 

OR 

A: albendazole (PO) 400mg stat 

Note  If persistent, give second course after 4 weeks. Iron replacement and nutritional supplementation (protein and vitamins) should be part of the management strategy. Albendazole is contraindicated in the first trimester of pregnancy 

Small  intestinal  infestation  caused  by  Strongyloides  stercoralis  usually  asymptomatic  in  immune  competent adult but can lead to life-threatening infestation and disseminated strongyloidiasis in an  immune-compromised host associated with high mortality rates 

Clinical presentation  

• Pruritic papulo–vesicular rash at the site of penetration or urticarial rash involving the perennial region extending to the buttocks, thighs and abdomen
• Chronic cough
• Colicky abdominal pains
• Chronic diarrhea and passage of mucus
• Weight loss
• Hyper-infection syndrome

Investigations 

• Evidence of rhabditiform larva in wet mount stool examination with Serological evidence (ELISA) for anti-strongyloides antibody

Pharmacological Treatment 

A: albendazole (PO) 400mg 12hourly for 3days (Repeat after 4 weeks if still positive stool findings) 

OR 

A: ivermectin (PO) 200 µg /kg 24hourly for 2days 

Note: Give treatment for 10 days in case of disseminated/super infestation 

Is a tapeworm disease acquired from eating raw or not-well cooked food. Can be due to Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), Diphyllobothrium latum (fish tapeworm) and Hymenolepsis nana (faecal oral contamination from human and dogs) leading to chronic malnutrition (Taeniasis) or multi-organ dissemination and dysfunction (Cysticercosis)

Clinical presentation

• Taeniasis
• Colicky abdominal pain
• Body Weakness
• Loss of or increased appetite
• Constipation or diarrhea
• Pruritus ani
• Hyperexcitability

Investigations

• Evidence of characteristic ova, proglottids or scolex in the wet mount stool examination

Cysticercosis - The cysticerci are most often located in subcutaneous and intermuscular tissues, followed by the eye and then the brain. The CNS is involved in 60-90% of patients i.e. Neurocystercosis which may manifest as

Convulsions and/or seizures:

• Intracranial hypertension: headache, nausea, vomiting, vertigo, and papilledema.
• Personality and mental status changes (Neuropsychiatric changes)
• Behavioral changes and learning disabilities more marked in children and immunocompromised adults. PLUS
• Head CT scan OR Brain MRI

Note: Refer the patient to high centers for further investigation and expertise.

Pharmacological TreatmentTaeniasis

A: praziquantel (PO) 5–10mg/kg stat

AND

A: magnesium sulphate (PO) 5–10 g in a glass of water after 2hours

Cysticercosis (NCC)

A: praziquantel (PO) 50mg/kg 24hourly for 21days

OR

A: albendazole (PO) 15mg/kg 24hourly for 30days.

AND

B: dexamethasone (IV) 4mg 12hourly can be given up to 7days.

AND

A: carbamazepine (PO) initially 200 mg 12-24hourly, increased slowly to 0.8–1.2 g 24hourly in divided doses

Note: Hydrocephalus should be treated with surgical shutting. Ocular manifestation cysticercosis, should be referred to eye specialist

It is a canine tape worm Echinococcus Granulosus which is transmitted by dogs, sheep and horses.  Human infestation is through contamination of food or water causing visceral cysts (Hydatid Cyst  Disease) particularly in the liver and lungs and is usually asymptomatic in susceptible host.  

Clinical presentation

• Upper abdominal discomfort and pain, poor appetite,
• Upper abdominal mass swelling with enlarged liver.
• Cough with features of acute hypersensitivity reaction (for ruptured cysts)
• Portal hypertension, biliary obstruction or Budd-Chiari syndrome (for complicated cases)

Pharmacological Treatment 

A: albendazole (PO) 400mg 12hourly for 3months  

OR   

A: mebendazole (PO) 500mg 12hourly for 3months  

Referral: For symptomatic/complicated cases refer to higher centres with management and  expertise. 

Parasitic disease caused by blood flukes (trematodes) of the genus Schistosoma. Common species  found in Tanzania are S. haematobium responsible for urogenital schistosomisis and S. mansoni  responsible for intestinal schistosomiasis as a result of immune mediated reaction which leads to  progressive inflammation and fibrosis of the urinary bladder or portal venous system respectively. 

Clinical presentation 

Schistosoma mansoni 

• Swimmer’s itch or katayama fevers in acute infection phase
• Colicky abdominal pains
• Diarrhoea and dysentery
• Anemia
• Hepatomegaly
• Portal hypertension with bleeding esophageal varices
• Decompensated liver disease

Schistosoma hematobium 

• Dysuria and terminal hematuria
• Hematospermia
• Obstructive uropathy (hydronephrosis, hydroureters)
• Glomerulonephritis and amyloidosis
• Bladder carcinoma
• Chronic kidney failure

Investigations 

• Laboratory evidence characteristic eggs in urine (S. Hematobium) or in stool (S. manson, S. japonicum) examined by kato katz thick smear procedure or PCR assays of both urine and stool samples.

Pharmacological Treatment 

A: praziquantel (PO) 40mg/kg stat or in 2 divided doses 

It is an acute systemic disease resulting from infection by Salmonella typhi and S. paratyphi, serovar group A and B respectively. Infection is acquired through ingestion of contaminated food and water. 

Clinical presentation 

• Fever, severe headache, abdominal and muscle pains (myalgia)
• Delirium, obtundation, intestinal hemorrhage, bowel perforation
• Sequela neuropsychiatric complications

Investigations 

• Laboratory evidence of positive cultures from bone marrow aspirates; blood or stool done within 1 week of acute infection OR
• Salmonella stool antigen test
• Indirect fluorescent Vi antibody, ELISA for immunoglobulin M (IgM) and IgG antibodies to S. Typhi polysaccharide.

Pharmacological Treatment  Uncomplicated typhoid fever 

A: ciprofloxacin (PO) 500mg 12 hourly for 10-14days 

OR 

B: azithromycin (PO) Adult 500mg 24hourly for 7days 

OR  

S: cefixime 400mg (PO) 24hourly for 7-14days 

For complicated typhoid fever 

C: ciprofloxacin (IV) 200-400 mg 12hourly daily 7days 

OR 

B: ceftriaxone (IV) 1-2gm 24hourly 4-7days 

Note: Definitive treatment of typhoid (enteric fever) is based on susceptibility. For patients with severe or  complicated  disease  (e.g.  systemic  toxicity,  depressed  consciousness,  prolonged  fever,  organ  system  dysfunction  or  other  features  that  prompt  hospitalization),  initial  therapy  with  a  parenteral  agent is appropriate. 

Shigella organisms are a group of gram-negative, facultative intracellular bacteria pathogens. They  are  grouped  into  4  species:  Shigella  dysenteriae,  Shigella  flexneri,  Shigella  boydii,  and  Shigella  sonnei, also known as groups A, B, C, and D respectively. Shigellosis is spread by means of fecal- oral route, by ingestion of contaminated food or water and leads to bacillary dysentery. 

Clinical presentation 

• Acute abdominal cramping, high-grade fever, emesis and large-volume watery diarrhea
• Tenesmus, urgency, fecal incontinence, mucoid bloody diarrhea
• Severe headache, lethargy, meningismus, delirium, and convulsions
• Hemolytic uremic syndrome (HUS), microangiopathic hemolytic anemia, thrombocytopenia, and renal failure
• Profound dehydration and hypoglycemia

Investigations 

• Laboratory evidence of microscopic isolation of the bacteria from stool or rectal swabs specimens
• Stool culture for suspected cases in early course of infection
• An enzyme immunoassay (ELISA) for shiga toxin detection in stool for S. dysenteriae type I.

Pharmacological Treatment 

A: ciprofloxacin (PO) 500mg 12hourly for 5days 

OR  

A: erythromycin (PO) 500mg 6hourly for 5days. 

For diagnostic criteria, investigations, prevention and treatment refer to under notifiable diseases.