Haitian Child

Haitian Child

Friday, November 22, 2013

Parasites in Nicaragua

Parasites in Nicaragua

Intestinal parasites in Nicaragua are endemic and contaminated water is the most common source. The common parasites include Entamoeba histolytica, Giardia lamblia, and Cryptosporium species. 

In one recent study, 53% of tested wells in Nicaragua contained amoeboflagellates. A study of 480 apparently healthy individuals in Leon, Nicaragua reported that Entamoeba histolytica or Entamoeba dispar was present in 12% of stool specimens. Another study found that Entamoeba histolytica or Entamoeba dispar was present in 19% of individuals and that Giardia lamblia was present in 16%. These percentages are high enough, that all rural children who drink well water should be presumed to have parasites in their intestine.

Infection by Giardia lamblia occurs by ingestion of mature cysts from fecally contaminated food, water, or hands. Swallowing as few as 10 cysts is enough to cause illness. The cysts are hardy and can survive several months in cold water. The symptoms of giardiasis normally begin 1 to 3 weeks after a person has been infected.
Giardia lamblia trophozoites L & R images, cyst in center. Images courtesy of CDC.

Infection by Entamoeba histolytica occurs by ingestion of mature cysts in fecally contaminated food, water, or hands. Although Entamoeba histolytica is commonly found in the stool, the majority of individuals are not symptomatic, but are potential carriers (able to transmit parasite but not symptomatic). About 10% of individuals develop amoebic dysentery. Amoebic dysentery has a gradual onset with watery or bloody diarrhea, crampy abdominal pain, and poor appetite and weight loss. Liver abscess is a possible complication. The infection is more common and more severe in malnourished children. 
Entamoeba histolytica trophozoites with ingested red blood cells. Images courtesy CDC.

Amoebic dysentery and giardiasis are treated with metronidazole. Unless the source of the infection is eliminated, many individuals will be re-infected after treatment. 

Prevention is therefore important. To prevent infection, the contaminated water source needs to be eliminated or the water needs to be treated. Drinking only bottled water is a good idea but might be too expensive for the average Nicaraguan family. Water can treated in a variety of ways shown in the table below. Careful hand washing and cleaning uncooked vegetables and fruits with clean or treated water is important.



Boiling
Filter
1 micron
Chemical

Solar
Irradiation
Entamoeba histolytica
Yes
Yes
Yes
?
Giardia lamblia
Yes
Yes
No
?
Cryptosporidium species
Yes
Yes/No
No
?


For chemical disinfection, two drops of bleach per liter of water is sufficient. Let the treated water stand for at least thirty minutes. Chemical disinfection is not sufficient for Giardia lamblia or Cryptosporidium

Not all filtration systems work for Cryptosporidium. A filtration system is adequate for Cryptosporidium only if the description includes one of the following three statements - reverse osmosis, absolute pore size 1 micron or less, or tested and certified by National Safety Foundation (NSF) Standard 53 or 58 for cyst removal.

Solar Irradiation is a promising method but the Centre for Disease Control (CDC) does not comment on effectiveness for parasites. There are emerging studies that do report effectiveness. 

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