Lec.No.1 Prof.Dr.Abdulsalam Al-Mukhtar Medically Important Helminths In contrast to the protozoa one cell parasites (unicellular). Helmthins are worm -like parasites (multicellular) causing diseases to human. They are characterised with:
complex reproductive systems. (2) life cycles involving intermediate hosts or soil for the development of larval stages and a definitive host for the adult worm. (3)Adults may be with separate sexes or hermaphroditic which mean both sexes in one parasite.
3.Trematodes ( Flukes ) Adult flukes are leaf-shaped flatworms. They have oral and ventral suckers. Flukes are hermaphroditic except for blood flukes, which are bisexual. The life-cycle includes a snail intermediate host.
Ascaris lumbricoides(Ascariasis) The infections are usually asymptomatic, especially if the number of worms is small.
Morphology It is the largest nematode (roundworm) parasitizing the human intestine,the male smaller than female . Adult females about 20 to 35 cm.long. Adult male about 15 to 30 cm.long .
Adult worm
Eggs of A.lumbricoidesSymptoms or Clinical Features 1.Ascaris takes most of its nutrients from the partially digested food in the intestine. 2. If the number of worms are few, patients can remain asymptomatic for very long periods of time.
3.Chilidren are more likely than adults to develop gastro-intestinal symptoms because they have smaller intestines and are at greater risk of developing intestinal obstruction.
4.As larval stages travel through the body, they may cause inflammation, and pneumonia and the patient suffer from: Loss of appetid , Fever, wheezing.
5. In haevy infections may cause nutritional deficiency . 6.Complications, sometimes fatal, include obstruction of the intestine by a large number of worms especially in children .and also may cause obstruction with following symptoms:
Vomiting Shortness of breath Swelling of the abdomen Sever abdominal pain.
Epidemiology Ascariasis is the most common intestinal worm infection. World wide distribution. It is found in association with: poor personal hygiene, poor sanitation, and in places where human feces are used as fertilizer.
The source of transmission is from ingestion of infective eggs from contaminated hands with infected human feces or contaminated vegetables and water is the primary source of infection.
3.The diagnosis is easy when the host passes a worm in the stool or larvae in vomit. 4.Larvae may be found in sputum during migration of larvae through the lung. 5.Blood counts may demonstrate peripheral eosinophilia.
Prevention 1.Improved sanitation and hygiene in developing countries will reduce the risk in those areas. 2.preventive (prophylactic) treatment with deworming medications may be advised. The following methods are very important to do :
3.Food and hands should be protected from contamination of infected dirt and soil. 4.Washing of vegitable by running water is very important for cleaning from contaminated infective eggs .
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Treatment Albendazole or mebendazole which are the drugs of choice. If there is a blockage of the intestine caused by a large number of worms, endoscopy or, rarely, surgery may be needed.
Morphology 1.The adult pinworm appears as a white, small and delicate nematode. 2.The adult female has a sharply pointed posterior end, is 8 to 13 millimeters long. 3.The adult male is smaller, measuring 2 to 5 millimeters long , and it has a curved posterior end.
4.The egg are translucent, and may contain a developing embryo or a fully developed larva. The eggs are oval in shape with thick outer shell is flattened on one side, and measure 50 to 60 micrometers by 20 to 30 micrometers. Life cycle
Geographic Distribution: The human pinworm Enterobius vermicularis is being estimated that over 200 million people are infected with this parasite. It is more common in the temperate and tropical regions of Asia, Europe and North America.
However, the scratching of the itch can spread germs from the fingers to other parts of the body. Sleep disturbance may arise from the itching or crawling sensations of the worns. Some case reports proved that severe infestation may be associated with an increased risk for appendicitis.
2.Eggs can also be found, but occasionally, in the stool. 3. Diagnosis is often made clinically by observing the female worm (or many worms) in the stool, or perianal area.
4.Self-diagnosis is also possible with observing worms around the anus. Crawling sensations inside the anus indicate female pinworm migration,this crawling sensations caused by large numbers of pinworms in the lower rectal area, simply by manually removing some of them.
Prevention and control 1. All the patients sould be treated. 2.Personal hygiene should be proved to prevent reinfection and also clothes and bedding sheets, should be washed with hot water and cleaned.
Lec. No.3 Dr.Abdul Salam M.Al-Mukhtar Hookworm: These worms are parasitic nematode worm that lives in the small intestine of human. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus and causing .Ancylostomiasis
Ancylostomiasis, is the disease caused by hookworms. It is caused when hookworms, present in large numbers, produce an abdominal pain and iron deficiency anemia by contineous sucking blood from the host's intestinal walls. There are other species of ancylostoma infect animals like A. braziliense species which infect cats, while A. caninum infects dogs.
Morphology of Adult ,Egg
Pathology and Symptomatology The incubation period can vary between a few weeks to many months and is largely dependent on the number of the parasites, usually the infection is generally considered to be asymptomatic, The hookworm is an extremely dangerous infection because its damage is “silent and insidious. There are general symptoms that appear soon after infection:1. Ground-itch, which is an allergic reaction at the site of parasitic penetration of the skin and entry. 2. Cough and pneumonitis may result as the larvae begin to break into the alveoli and travel up the trachea. 3. Then once the larvae reach the small intestine of the host and begin to mature, the infected individual will suffer from diarrhea and other gastrointestinal discomfort.
4. However, the “silent and insidious” symptoms are mainly related to chronic, heavy-intensity hookworm infections. 5.Major morbidity associated with hookworm is caused by intestinal blood loss, iron deficiency anemia, and protein malnutrition. They result mainly from adult hookworms in the small intestine ingesting blood, rupturing erythrocytes, and degrading hemoglobin in the host.
6.The children who suffer from chronic hookworm infection can suffer from growth retardation. 7. The symptoms can lead to inflammation in the gut stimulated by feeding hookworms, such as nausea, abdominal pain and intermittent diarrhea, and to progressive anemia. 8- Blood examination in early infection often show a rise in numbers of eosinophils. 9-Falling blood hemoglobin levels will be seen in cases of chronic or prolonged infection with anemia.
Epidemiology It is estimated that between 576-740 million individuals are infected with hookworm today. A. duodenale is found in Europe and the Mediterranean. Most infected individuals are concentrated in Africa and East Asia/the Pacific Islands. A majority of these infected individuals live with poor sanitation.
Prevention 1-Hookworm infection results because of non-hygienic practices and fecal contact in the soil,so the low sanitation should be proved. 2- Fecal matter should be chemically treated, and the sewage or untreated 'night soil' should not used as fertilizer in agriculture befor chemically treated.
3-The infective larvae develop and survive in an environment of dirt, sandy or loamy and moist soil, so this type of soil should be desciccated to kill the larvae.. 4-Wearing shoes can prevent penetration of the worms into the skin of the feet. 5-Contaminate water with larvae can also transmit the infection. Therefore, swimming and washing and any other contact with the water should be avoided until it's treated or boiled to kill the larvae.
2-Recent research has focused on the development of DNA-based tools for diagnosis of infection.
2. A. duodenale possess two pairs of teeth, N. americanus possesses a pair of cutting plates in the buccal capsule. Additionally, the hook shape is much more defined in Necator than in Ancylostoma. 3.The eggs of both Ancylostoma and Necator are indistinguishable.
4.A. duodenale can infect both through penetration as well as orally,while N. americanus larvae only infect through penetration of skin. 5.Necator tends to cause a chronic infection, generally 1–5 years. Ancylostoma adults are short lived, surviving on average for only about 6 months. 6.The entire process from skin penetration to adult development takes about 5–9 weeks.
7.The number of eggs released by female of N. Americanus about 9,000-10,000 eggs/day and A. duodenale 25,000-30,000 eggs/day. 8- The ground itch is more common in patients infected with N. americanus. 9-N. Americanus is found in Americas, Africa, and Asia. A. duodenale is found in Europe and the Mediterranean areas.
10.The eggs of both Ancylostoma and Necator are morphologically indistinguishable. 11.The treatment is the same for hookworm are 2-Benzimidazoles (BZAs), specifically albendazole and mebendazole.
Lecture No.5 Dr.Abdul Salam M.Al-Mukhtar Strongyloides stercoralis Aims To provide core knowledge of Strongyloides stercoralis relevant to the morphology, life cycle,diagnosis and management (drug of choice),prevention and control of infectious diseases. Learning Objectives Our goal is to help students become skillful and caring physicians with the knowledge and compassion to prevent, diagnose, and treat infectious diseases.