ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Giardia lamblia

Updated on December 27, 2014


Giardia lamblia, also known as Giardia intestinalis, Giardia duodenalis, Lamblia duodenalis or Lamblia intestinalis, is a flagellated protozoan parasite that specifically infects the small intestines of its host. It has a distinct characteristic of resembling an 'old man with eyeglasses' or a 'monkey face'.

It was first observed by Anton Van Leeuwenhoek in his own stools when he was suffering from diarrhea in 1681.

Appearance of a Giardia lamblia cyst and trophozoite.
Appearance of a Giardia lamblia cyst and trophozoite. | Source


Having the knowledge on what G. lamblia looks like is essential for its diagnosis. There are two stages that can be found in the stool infected by the parasite:

  1. Cyst - can be found in the stool with formed consistency. It is necessary to have precautions when handling stools since this is the infective stage of the parasite.
  2. Trophozoite - can be found in the stool with watery consistency. Its motility can also serve as a diagnosis tool for the parasite.

The cyst is of oval or ellipsoidal in shape and has the size of 8-19 um. In stained smears, a 'halo effect' can be noted around the outer part of the cyst's wall.

Trophozoites, on the other hand, is a pear-shaped parasite measuring 10-20 um. When examined in a wet-mount slide, its 'falling leaf' motility can be demonstrated. It has two sucking disks in its ventral surface, constituting the 'old man with eyeglasses' appearance.

Life Cycle

The infection caused by G. lamblia starts in the ingestion of food contaminated of its cysts by the host. Cysts undergo excystation (exits the cyst stage) becoming trophozoites. The trophozoites will reproduce asexually through binary fission in the intestine. Some of these trophozoites undergo encystation (entering the cyst stage) before reaching the rectum. Both trophozoites and cysts are passed out in the feces but due to its motility, only cyst can survive in the environmental change and can live weeks up to months in cold water.

The life cycle of Giardia lamblia.
The life cycle of Giardia lamblia. | Source

Pathogenesis and Clinical Manifestations

Giardiasis or lambliasis is the disease caused by the parasite G. lamblia.

G. lamblia uses its two sucking disks to facilitate attachment in the intestinal cells which can cause intestinal irritation to the host. The parasite is able to avoid the host's immune system by attaching itself in the villi or within the intestinal mucus. This attachments can cause the alteration of substances absorption in the intestines leading to deficiencies.

In acute infections, symptoms include abdominal pain, cramps, diarrhea, excessive flatulence where the gas expelled resembles the smell of a 'rotten egg'. Other clinical manifestations include bloating, nausea, anorexia and malaise.

Chronic infections may demonstrate steatorrhea (fat malabsorption; presence of fats in feces) where stools float on toilet water. Other patients complain of alternation of diarrhea and constipation.


Examination of the patient's stool specimen is still the most utilized method in the diagnosis of giardiasis. Cysts are often found in formed feces while trophozoites are often demonstrated in watery specimens.

Duodenal aspiration specimens may also be used for diagnosis. The specimen can be obtained through gastroduodenoscopy or through nasogastric insertion. In this specimen, trophozoites are expected to be examined.

String test is usually done if other laboratory methods can't demonstrate the presence of G. lamblia in a suspected host. The test is done by attaching a gelatin capsule at the end of a very long string. The capsule is swallowed by the patient while the other end of the string stays outside the patient's mouth, taped on his or her cheek. After four to six hours, the string is pulled by a health professional and examines the dissolved capsule for the presence of the parasite.

String test is also called Enterotest. Due to its difficult procedure and highly uncomfortable to the patient, the test is now slowly being replaced by endoscopy.

String test or Enterotest for the diagnosis of giardiasis.
String test or Enterotest for the diagnosis of giardiasis. | Source

Treatment and Prevention

There are four drugs often used for human infection: metronidazole, tinidazole, nitazoxanide and albendazole. Metronidazole is the first drug utilized when diagnosed of giardiasis. However, this drug is not advised for pregnant patients since it is mutagenic and carcinogenic in bacteria and mice respectively. These four drugs have different duration of use and side effects when taken.

G. lamblia is most often transmitted through contaminated water. Boiling the water used for drinking for at least five minutes is the best way to prevent infection from the said parasite. Better sanitation in food preparation and organized sewage system can also minimize the giardiasis.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)