Monday, February 6, 2017

Opportunistic protist and helminths infections

There are thousands of opportunistic infections for now though lets just look at five 

  1. Entamobiasis  
  2. Blastocystic hominis
  3. Giardia Intestinalis
  4. Dientamoeba Fragilis
  5. Trichomonas vaginalis
first lets define opportunistic infections ,An opportunistic infection ia one where in the parasite /protozoan takes advantage of the host weakened or compromised immune system. In other words the  parasite may have been in the host/individual and does not seem to affect the host harmfully until the host is most vulnerable.

Entamoeba histolytica is the first such protist that we will look at.
Histo= tissue  lytica=dissolves
the life cycle,mode of transmission ,prevalence or distribution,treatment,identification,problems it causes .

the life cycle is a rather simple one. the cyst is ingested accidentally it further develops into a more prefound mature cyst  this process is called excystation then its becomes a trophozoite, followed by multiplication increased in number of trophozoites and cysts.

how is this infection usually acquired is probably the question  , the answer is easy bad plumbing ,drinking contaminated water with eggs or  trophozoites ,filth flies are also carriers they may pitch on your food and contaminate it with eggs or trophozoite .close living environment may also advance the process of transmission. reservoir hosts such as pigs and dogs should be monitored carefully to decrease the process of transmission.

prevalence and distriobution  entamoeba histolytica is spread worldwide it  however affects mostly developing countries  .it is the 3rd most cause of parasitic death only malaria and visceral leishmaniasis comes before it .Its responsible for 70,000-100,000 deaths per year.It is not common in the caribbean  but its affects central american countries , it affects mostly travellers ,homesexual men

identification of the problem , entamoeba hystolitica  can distroy the liver , lungs ,(brain and skin rare cases ) the protist feels on the enteric mucosa  lining the large intestine in the process protelytic enzyme is released which break down or dissolves the tissue  note Histo=tissue lytica=dissolving in the process abscess can take place on the liver  .abscess this is when tissue is swollen and is infected with pus.note this often causes ulceration of the liver and lung tissue .the infected lung and liver tissues have pus contaminated with trophozoites which will only make the condition worst.

dysenery will take place as well the patient will have bloody diarrhea , persons infected have gross fatigue they will pass 15/20 stool per day.there are three different stage of infection
1 benign  3  invasive  3 chronic stage

in benign stage the persons shows little to no symptoms and are considered to be in good standing

in invasive stage the trophozoites are within the large intestine or colon and start to cause ulceration and abscess of body tissues

chronic stage is when the liver , lungs  neurologic and in rare case the skin can be affected .

 iodinoquinol in  early stages

metabendazole in chronic stages .

laboratory test for infection

stool analysis to find egg of entamoeba histolytica  or trophozoites of entamoeba histolytica  note the size should be an average of 10-15 um .

Blastocystic hominis

there has been many debate as to whether blastocystic hominis is actually infectious or whether it has caused any serious problems .
blastocystic hominis is believed to cause nausea , watery diarrhea , vomiting ,abdominal pain and excess flatulence have been reported.

Image result for blastocystis hominis

Giardiasis Intestinalis
Image result for giardiasis intestinalis cycle

Giardiasis intestinalis  , laboratory analysis  alternate method of analysing the protozoan .

giardiasis is considered to be common  , the method of transmission is mainly due to drinking contaminated water infected with the cyst or trophozoites of the giardiasis intestinalis.
the trophozoites are between 10-18 um  they contain up to four pair of flagellates 

the cyst are usually between 10-12 um in size they contain from 2 to 4 pairs of flagella ,

giardiasis is known worldwide its distribution is without a doubt recognised as well in 2013 there was  250m cases reported to be symptomatic giardiasis  its not known to cause any serious fatalities but it gives gross discomfort 

persons will experience bloating,nausea ,vomiting,abdominal pain,diarrhea  .in jamaica there is < 5% prevalence  its also known as travellers disease  beavers are the reservoir host in usa .

there are two stages of giardiasis acute and chronic stage 

Acute stage 1
        persons experience ;vomiting,nausea ,diarrhea 

chronic stage  3
 persons experience malabsorption of fats and vitamin b12   the perosn will experience drained energy and vitality

 metronidazole is the drug of choice

 Laboratory analysis

stool smear containing cysts or trophozoites

 dudonial fluid may contain trophozoites

alternate immunoassay enzyme used to test for antigen of giardiasis

Trichomonas vaginalis 

mode of transmission ,treatment,prevention ,laboratory testing, distribution/prevalence,method of reproduction ,describe the protozoan.

trichomonas vaginalis is a parasite that have of it shapes like a pear the other half  is flat it  has four pair of flagella anteriorly and one posterior flagellum .It also contains a single nucleus .the trophozoites are between 15-18um

Trypanosomas is less than <5% on the normal female population and it is also as high as 70% among prostitutes and inmates
trypanosomas is highly contagious and is spread through direct contact its dosent have a cyst stage

trypanosomas vaginalis reproduce through the process of binary fission rather longitudinal binary fission. thgis is also favoured by low acidity . hence the protozoan changes the ph of the female genital environment .

extreme conditions would be yellowish conspicious foul smelling discharge from female genitals which in some cases are frothy.

dependent damage to the epithelium of infected organ
 Severe case 
infertility in women and cervical erosion

associated with the increased risk of acquiring HIV-1 which is related to the inflammation of gental tract.

smear of vaginal discharge  if trophozoites are found within the vaginal fluid then that person has trichomonas vaginalis



works for both male and female.

use condoms
vinegar douche can prevent infection of disease.
Opportunistic helminth infection


There are more than one helminths but one of the most undestimated and dangerous type is the  Schistosomiasis

the cycle ,little detail of how the schistosome funstions  where they are found ,the types and what they cause to happen to persons infected , treatment ,prevention and contol .

Schistosomes have a cycle the eggs are found when the egg matures it releases miracidia which finds a host which is mostly aquatic or amphibious snails ,the miracidia penetrates the snails skin . The snail releases  sporozoites that  develop into the cercaria the cercaria loses its tail  then further develops inside a host which is usually human the  cercaria gets caught up in the blood flow and is brought to portal blood in liver and develops into adult. the adult then releases the eggs in either urine or stool

the schistoma functions in different ways the cercarial schistosomes (free living swimming form) has an acidophillic head and a basophillic  tail . the acidophillic(-ve) head Post acetabular gland  secretes a sticky mucus when it comes into contact with a host skin ,it then dissolves into the skin of that individual.the basophillic tail Pre acetabular gland secretes collagenase  and the tail drops off from the cercarial schistosomes ,now its called a schistosomule.
unencysted metacercaria.

there are three types of schistosomes these are S. mansoni, S.haematobium and S.japonicum.

S.Mansoni has eggs that are have hooks , there are two forms of infection Acute and intermediate-chronic stage .In the acute stage  there is a onset of nausea , vomiting diarrhoea  as well as fever.This fever is called katayama ,katayama is caused because of the onset of female laying eggs five weeks after infection and granuloma formation around eggs trapped in the liver and intestinal walls.granulaoma formation is induced by cell -mediated immunity
high eosinophilia ,less than 1/3 of the eggs excape into the intestine when symptoms occurs they manifest themselves in nausea , headache ,irritating coughing (migrating larvae or escaped eggs)in extreme cases diarrhea accompanied with blood.

intermediate to chronic cases
there are thousands of eggs trapped in the tissues

intestinal schistosomiasis 

the pathogenic reaction is a cellular , granulomatous inflammation around eggs trapped in the intestinal tissues,with subsequent fibrosis.The large intestine shows the most severe legions.

Hepatosplenic Schistosomiasis 

the pathology is similar to that seen in the intesine with granulomatous inflammation around eggs trapped in the hepatic portal vein  and liver , leading to fibrosis and hepatosplenic disease .

portal hypertension  may result in ascites (accumulation of fluids in the abdomenal cavaties and rupture of the oesaphageal varices.

Schistosomiasis   S.Mansoni eggs are 150um long  eggs have terminal spines.


The adult form of these parasites are normally found in the bladder or in the uterus . when the female lays 1000s of eggs they are calcified and are trapped in the tissues . eggs are often passed in the urine
thousands of eggs are passed in urine and causes problems such as;

  • bladder ulceration
  • difficulty urinating 
  • frequent  urination
  • haematuria (blood in urine)- urinary schistomiasis
on rare occassions eggs are passed in the liver and causes granuloma formation as well ,however it is much less severe.


its practically the same as S.mansoni except for the case where it has a higher fecundity than s.mansoni  .Hence it is more severe in almost all aspects

the eggs are small 80um times 65um these species of the parasites has the smalles eggs ,the eggs also lacks terminal spines  these species can also cause stunt growth in host that they infects .this occurs when eggs get trapped in the hypothalamus of the infected organism .

there are a few species of schistomiasis that have there definitive host but get caught up in the wrong host and therefore meet a dead end because they have or rather cannot develop to maturation within another organism .One such case is the species of schistosomiasis that normally infects birds ,when these organisms affect individual which are not direct host such as human a condition occurs that is known as swimmers itch.

this gives discomfort to the victim ,rash appears soon as the skin is penetrated larvae are dying some already dead this causes hypersensitivity  and painful rash.

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andre thompson

Author & Editor

Yard Life is a blog developed by a group of students from the U.W.I it covers a wide range of topics from science and technology to programming.

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