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Q: " ... My son is in Africa and has apparently pick up an intestinal microbe. He has some blood in his stool and has had headache for 3 days or so. He is taking an anti-diarrheal and cotrimoxazole ("Bactrim"). Nothing for the headache. The city (Dar es Salaam) had a water main break, so no running water. He is purifying his water and other than the cramps, etc., he is OK, but depressed because of being sick and far, far away...What would you do? What would you suggest. Is the Bactrim a likely cure for this? Any advice you can offer will help. Thanks"

Dr. Keti:

Your son should seek an immediate professional medical consultation, a physician or an internist, preferably in one of the hospitals' clinics in the city. In the meanwhile we'll discuss what can cause the symptoms that your son is experiencing during his stay in Africa.

Blood in stool or Melena:

As a rule a tarry stool indicates bleeding high in the Gastro Intestinal (G.I.) tract usually above the level of the ileum(part of the intestines). Experimental studies indicate that the blood must enter the small gut or higher and not be passed for at least 8 to 10 hours for the full tarry color to develop.

    However, various ingested substances may color the stool black (i.e., iron, bismuth, charcoal licorice , dark berries, etc.) and strongly simulate a tarry stool. It is well to remember that iron may give a dark stool too.

The blackness of the stool is believed to be caused by certain hemoglobin derivatives (i.e. protoporphyrins and deutoroporphyrins.) At least 4-6 Tablespoons (or 120-200 milliliters) of blood must have been lost in order to cause passage of melena. (1) On the other hand maroon-colored stools or bright red blood usually suggest that the blood is coming from large bowel or rectum. However, sometimes hematochezia(yet another word for blood in stool) can be caused by massive upper GI tract bleeding.(5)

    Anorectal disorders: These are the most common causes of minor rectal bleeding. The rectum is the last portion of the large bowel that ends just before the anus.
    • Hemorrhoids, Rectal fissure, diverticulosis
    • Infection: Bacterial dysentery is commonly the source of infectious, bloody diarrhea
    • Inflammation: Inflammatory bowel disease is a common cause of rectal bleeding in young adults—typically those younger than 50 years.
    • Angiodysplasia: enlarged veins and capillaries in the wall of the right colon. These areas become fragile and can bleed.
    • Tumors and Polyps
    Rectal bleeding with symptoms of weakness, dizziness, or fainting is associated with at least 1 liter of blood lost. This will usually cause one to seek medical care.


Runny stools or Diarrhea:
Infectious colitis is the most common cause of colitis, particularly beyond the first year of life. It can be caused by bacterial, viral, and parasitic agents.

  • Many different types of bacteria can produce the symptoms associated with bacterial gastroenteritis including Salmonella, Shigella, Staphylococcus, Campylobacter jejuni, Clostridium, E. coli, Yersinia and others.
    Some sources of the infection are improperly prepared food, reheated meat dishes, seafood, dairy, and bakery products.
  • Parasitic colitis:
    Entamoeba histolytica is the most common cause of parasitic colitis in the world. Transmission is through ingestion of trophozoites, usually from water contamination, and person-to-person transmission because of poor sanitation.
    Amebic dysentery; Intestinal amebiasis: Typical symptoms of intestinal amebiasis consist of frequent diarrheal bowel movements with cramps or colicky abdominal pain. Pain on defecation (tenesmus) is common. The diarrhea may contain blood or mucus. Uncomplicated attacks may last up to two weeks and recurrences are common unless the diagnosis is made and the individual is treated. Spread of the ameba into the wall of the colon may occur in 8 to 10% of cases and to the liver in approximately 1%. When traveling in tropical countries where poor sanitation exists, one needs to drink purified or boiled water and not eat uncooked vegetables or unpeeled fruit. Public health measures include water purification, water chlorination and sewage treatment programs. (7)
    Balantidium coli is a large ciliated protozoan that manifests very similar to amebiasis.
    Cryptosporidium is a protozoan parasite found in contaminated water. It has been increasingly recognized as the cause of outbreaks of diarrhea when water supplies become contaminated. In normal individuals, it is a self-limited disease.
    Giardia - causes Traveler's diarrhea.
  • Food poisoning can cause nausea and vomiting, abdominal cramps, diarrhea, fever, weakness, headache and dehydration.
    The most common types of food poisoning are named for the bacteria and organisms that cause the condition. The common types of food poisoning are caused by Salmonella, Shigella, E. coli bacteria.(9) Food poisoning is also caused by S. aureus or Campylobacter as well as by certain viruses, parasites and chemical toxins or mild poisons found in seafood, plants, or contaminated foods.
  • Diarrheal disease related to large bowel enteritis: Fever and constitutional symptoms usually accompany the diarrhea caused by invasive pathogens in the large bowel. Dysentery, bloody stools with mucous, and cramps or tenesmus are typical. Campylobacter jejuni: This is a leading cause of bacterial food-borne illness in the United States. Vomiting is uncommon, and the illness is short and self-limiting.
    Salmonella species, nontyphoidal salmonellosis: This is a zoonotic infection acquired from bovine or poultry reservoirs and is very common in the United States. The illness can range from mild nonbloody diarrhea to a severe dysenteric illness.(8)

    Salmonella species, enteric (typhoid) fever: Enteric fever occurs in travelers or recent immigrants and is a systemic toxic illness. Salmonella typhi has an exclusively human reservoir and is acquired either via ingestion of a large inoculum in food or contaminated water or from personal contact with a carrier.
  • Vibrio parahaemolyticus: Although it is a common worldwide pathogen, in the United States, V. parahaemolyticus infection is restricted geographically to the Atlantic and Gulf coasts. The diarrhea is profuse and watery, and blood is not commonly present in the stool. (2)
  • Diarrheal disease, related to small bowel enteritis:
    Enterotoxin-producing strains of E. coli are the most common cause of traveler's diarrhea.
  • References
  • Yellow fever: Epidemic or urban, is spread from one infected human host to the next by Aedes aegypti, a mosquito that inhabits human settlements in Africa, South America, and North America
  • Malaria in travelers typically presents weeks after patients leave the endemic area. In some patients, the disease presents months or years later.
    Malaria can occur despite taking antimalarials. Malaria causes a flu-like illness; symptoms include fever, shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur.
  • Viral hemorrhagic fevers (VHFs). These febrile diseases result from infection by viruses. For example Arenaviridae (Lassa fever) , Bunyaviridae, Flaviviridae(Yellow and and Dengue fever) and Filoviridae (Ebola virus) families all cause increased capillary permeability, leukopenia, and thrombocytopenia. Generally, the viral hemorrhagic fever is manifested by sudden onset, fever, headache, generalized myalgia, backache, petechiae, conjunctivitis, and severe prostration (exhaustion or weakness). Although the viruses are distributed all over the world, they have a higher occurrence in tropical areas: South America, Africa, and the Pacific Islands. Click here for more info on viral hemorrhagic fevers.
    Intensive supportive care is necessary for most cases and antiviral therapy with ribavirin may be useful in several others, especially those caused by Arenaviruses.(4)
  • Hookworm: the classic hookworm disease is a gastrointestinal (GI) infection with chronic blood loss leading to iron deficiency anemia and protein malnutrition. A duodenale is the predominant species in the Mediterranean region, northern regions of India and China, and North Africa. Most helminths, including hookworms, cannot replicate within a human host. Anthelminthic drugs effective against hookworms include pyrantel pamoate and benzimidazoles (e.g. albendazole, mebendazole, thiabendazole).

To find the cause of the symptoms described above, a doctor would ask many more questions with regards to the blood found in stools. When was the blood in the stools noticed? · Do the stools have streaks of blood only on the outside or is there blood throughout the stool? · Is the blood bright red or dark? · How long has there been blood in the stools? · Have the stools been consistently bloody, or does the blood come and go?

Medical Care and Medication
Asymptomatic E. histolytica infections are not treated in endemic areas. Several agents are available for the treatment of various forms of amebiasis. Recommended drugs for treatment of symptomatic intestinal disease and for hepatic abscess are metronidazole and tinidazole. Since these drugs may not eliminate the intraluminal cysts, immediately follow up treatment therapy with iodoquinol, paromomycin, or diloxanide furoate is also indicated.
Bactrim, an antibacterial combination drug, is prescribed for the treatment of certain infections, inflammation of the intestine due to a severe bacterial infection, and travelers' diarrhea in adults. Bactrim is also prescribed for the treatment of Pneumocystis carinii pneumonia and for prevention of this type of pneumonia in people with weakened immune systems. Sulfamethoxazole, an ingredient in Bactrim, is one of a group of drugs called sulfonamides, which prevent the growth of bacteria in the body. It is important that one drinks plenty of fluids while taking this medication in order to prevent sediment in the urine and the formation of stones. Bactrim works best when there is a constant amount in the blood. So one should take Bactrim exactly as prescribed and try not to miss any doses. It is best to take doses at evenly spaced times day and night.
In order for your son to be correctly diagnosed and treated accordingly and in case the symptoms persists for more than a couple of days he should seek a medical assistance and further investigation and evaluation of the condition.
Usually, travellers in the western world are well prepared and supplied with preventive medication before visiting a foreign country. If you'd like to get further information about infections and diseases that frequent travellers may encounter, visit this site:CDC-Traveler's Info(ref.7)


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