Submitted By :-

Dr.Laximan Sawant

(L-2011-V-91-M)

INTESTINAL HELMINTHS & INTESTINAL PROTOZOA

Intestinal helminths

Ascaris

• Ascaris is a genus of parasitic nematode worms known as the "giant intestinal roundworms". 

• One species, A. suum, typically infects pigs, 

• while another, A. lumbricoides, affects human populations, typically in sub-tropical and tropical areas with poor sanitation.

•  A. lumbricoides is the largest intestinal roundworm and is the most common helminth infection of humans worldwide, an infection known as ascariasis.

Morphology

Fertile egg• mammillated • thick external layer 

Morphology Cont.Infertile egg• elongated and larger than 

fertile egg • thin shelled 

Morphology Cont.

Infertile Fertile

Adult worm: tapered ends; length

15 to 35 cm Female are larger in

size and have a genital girdle

Adult worm of A. lumbricoides

The 3 prominent “lips”

TRANSMISSION

Ascariasis is not spread directly from one person to another.

By the FAECAL-ORAL route, i.e., by ingestion of infective eggs with food or drink.

Foods that are eaten raw such as salads and vegetables readily convey the infection, and so is polluted water.

• There is increasing evidence that dust may play an important role in the dissemination of ascaris in arid areas.

Pre-patency: 2 months

Pneumonitis: 4 – 16 days after infection, short duration (~3 wks)

Symptoms

1. Symptoms associated with larvae migration

• eosinophilic pneumonia, cough (Loeffler's Syndrome)

• Breathing difficulties and fever

• Complications - asthmatic attacks, pulmonary infiltration 

Löeffler Syndrome (Pneumonitis)

Transverse sections of Ascaris larvae in pulmonary alveoli

Symptoms Cont.2. Symptoms associated with adult parasite in the intestine

• Usually asymptomatic

• Abdominal discomfort, nausea in mild cases

• Malnutrition

• Sometimes fatality may occur when mass of worm blocks the intestine

Adult Ascaris worms migrating in liver

Ascaris causing intestinal obstruction.

Ascaris (roundworm):

The only nematode ever coughed or vomited up

Diagnosis

• Stool microscopy :

• Eosinophilia:  eosinophilia can be found, particularly during larval migration through the lungs

• Ultrasound:  ultrasound exams can help to diagnose hepatobiliary or pancreatic ascariasis.  

• Endoscopic Retrograde Cholangiopancreatography (ERCP) :A duodenoscope with a snare to extract the worm out of the patient

Treatment

• Mebendazole• Albendazole

• Proper washing of the vegetables.

• Health education.

• Washing hands before meals.

• Mass treatment for the patients.

• Sanitary disposal for the feces.

• Avoid uses of feces as manures.

Prevention

The Human Hookworms

Necator americanus Ancylostoma duodenale

   Morphology

1. Adults: They look like an odd piece thread and are about 1cm.

2. They are white or light pinkish when living. ♀is slightly larger than♂.

2. Eggs: oval in shape, shell is thin and colorless. Content is 2-8cells.

Acylostoma duodenale & Necator americanus -- human hookworms

• Small nematodes (1-1.5 cm)

• Head is slightly bend (hook) and the ‘mouth’ carries characteristic teeth (Ancylostoma) or plates (Necator,

• note the presence of four "teeth," two on each side. 

• Note the presence of two cutting "teeth“.

Necator americanus

Pathogenesis and Clinical Manifestations

• Skin penetration and associated secondary bacterial infection can result in “ground itch”

• Pulmonary phase is usually asymptomatic

• Intestinal phase: worms attach to the mucosa and feed on blood. Worms continuously move to new places exacerbating bleeding

Hookworms

• The main concern with hook worm disease is blood loss

•  0.03 ml to 0.26 ml (A.d) per worm, up to 200 ml per day in heavy infections

• Chronic heavy infection results in anemia and iron deficiency

Adults in intestinal mucosa

Diagnosis

Criterion: 1. Hemoglobin is lower than 120g/L in man, 110g/L in

woman. 2. find hookworm egg Method: 1. saturated brine flotation technique2. direct fecal smear3. culture of larvae

     

TREATMENT

1. Albendazole 2. Mebedazole

Prevention

1. sanitary disposal of night soil2. individual protection3. health education4. cultivate hygienic habits5. treat the patients and carriers.

Entamoeba histolytica(amoebiasis)

Transmission

• Amoebiasis is usually transmitted by the fecal-oral route,

•  but it can also be transmitted indirectly through contact with dirty hands or objects as well as by anal-oral contact.

Pathology and Clinical Manifestation

• Pinpoint lesion on mucous membrane• Flask-shaped ulcers

A. Intestinal amoebiasis

•   aa. dysentery:. dysentery: dysenteric stools (pus and blood without feces). fever, dehydration, and

      electrolyte abnormalities. 

•   b. non-dysenteric colitisb. non-dysenteric colitis

•   c. appendicitisc. appendicitis

•   d. d. amoeboma: may become the leading point of an intussusception or may cause intestinal obstruction.

Histopathology of a typical flask-shaped ulcer of intestinal amebiasis

B. Extra-intestinal amoebiasis

•   a. Hepatic •     (1) acute non-suppurative•     (2) liver abscess:•   b. Pulmonary

Amoebic Liver Abscess

Gross pathology of liver containing amebic

abscess 

Gross pathology of amebic abscess of liver. Tube of "chocolate" pus from abscess.

Note the reddish brown colour of the pus . This colour is due to the breakdown of liver cells.

Diagnosis

1. Stool examination

2. Serologic studies: indirect hemagglutination, skin tests, ELISA and latex agglutination.

3. Tissue examination: biopsy, aspiration

Treatment and Prevention

• Treatment:• Diodoquin-carriers• Metronidazole-dysentery, liver abscess

Preventing Amoebiasis

• Drink only bottled or boiled (for 1 minute) water.

•  Fountain drinks and any drinks with ice cubes are not safe. Water can be made safe by filtering it through an "absolute 1 micron or less" filter and dissolving iodine tablets in the filtered water. 

• Avoid milk, cheese, or dairy products that may not have been pasteurized. 

Food safety• Thoroughly cook all raw foods. 

• * Thoroughly wash raw vegetables and fruits before eating. 

• * Reheat food until the internal temperature of the food reaches at least 167º Fahrenheit.

• Wash your hands before preparing food, before eating, after going to the toilet or changing diapers, 

 

Trophozoites Cysts

EpidemiologyEpidemiology

DistributionDistribution

Worldwide distribution, endemic and epidemic.

Traveler diarrhea

Patients with variable immunodeficiency are increasingly susceptible to infection with Giardia.

EpidemiologyEpidemiology

Transmission sourceTransmission source

Persons whose feces containing cysts

Transmission Transmission

Infected by drinking contaminated water

eating contaminated food

Monkeys Monkeys and pigspigs can also be infected, the infectedpig may be a source of human infection.

DiagnosisDiagnosis

Pathogenic examination

(1) Fecal examination

(2) Duodenal fluid or bile examination

(3) Intestinal examination by gelatin capsule

DiagnosisDiagnosis

Immunological diagnosis

ELISA: enzyme-linked immunosoebent assay

IFA: indirect fluorescent antibody

Cysts have strong resistance

Cysts can keep alive 10 or more days in feces

Cysts are often waterborne, either by takinginadequately treated municipal water supplies of contaminated river or stream Giardiasis is more common in travelers,

Immunodeficiency persons

Prevention and controlPrevention and control

Treat the patients and cyst carriersTreat the patients and cyst carriers

MetronidazoleTinidazole

Treatment of the drinking waterTreatment of the drinking water

Suspect water should be boiled or adequatelyfiltered to remove the infective cysts beforedrinking.

CRYPTOSPORIDIUMCRYPTOSPORIDIUM

fecal-oral Animal to human Contamination of

water supplies (result of waste runoff)

*WATER-BORNE *WATER-BORNE MOST COMMONMOST COMMON*

SYMPTOMS

• ImmunocompetentImmunocompetent– Mild self-limiting 

enterocolitis (watery bloodless diarrhea, abdominal pain, nausea, vomiting, and fever)

• Immunocompromised Immunocompromised – 50 or more stools per 

day– Dehydration (fatigue, 

abdominal cramping, and nausea)

– Common in AIDS patients

LAB DIAGNOSIS

Microscopic examMicroscopic examAcid fast stain of

stool sampleEndoscopic biopsy

of small intestine

Cryptosporidium oocysts with acid-fast stain

LAB DIAGNOSIS

ImmunodiagnosisImmunodiagnosis Immunofluorescence

assay (IFA) Enzyme linked

immunoabsorbant assay (ELISA)

Polymerase Chain Reaction (PCR) Test of choice

• Infectious agents are the OOCYSTSOOCYSTS• In immunocompromised patients ID50 is about 10

to 30 oocysts      

TREATMENT• Immunocompetent

– Self-limiting– Usually symptoms

subside within 10 days

• Immunocompromised– Cocktail therapy -

used to treat symptoms but NOT THE DISEASE

– Drugs include: letrazuril, azithromycin, paramycin, and hyperimmune bovine colostral immunoglobulin

*The only immunity is previous exposure and extent

of this immunity is not known.*

PREVENTION• Wash hands• Wash fruits and

vegetables • Avoid untreated

water• Treat contaminated

water• MAINTAIN PROPER

HYGIENE!!

WATER PREVENTION

• Ozone• UV light• boiling

• ““Chlorine not Chlorine not effective against effective against crypto!!”crypto!!”

CONTROL OF PROTOZOA IN DRINKING WATER

Multiple barrier approach: Filtration Chemical inactivation- ozone, combination of

disinfectants Medium-pressure ultraviolet light (UV)

Monitoring: Presence of protozoa in raw water