Oesophagostomum bifurcum

Biology department

Practical Parasitology2013

Prepared by: Dashty Latif

Classification

An Overview

Morphology

Life cycle

Contents:O. bifurcum’s Hosts

History of reporting

Geographical distribution

Disease, Habitat &Fector

Transmission

Symptoms

Laboratory diagnosis

References

Kingdom: Animalia

Phylum: Nematoda

Order: Strongylida

Family: Strongylidae

Species: O. bifurcum

Genus: Oesophagostomum

Classification

The nodule worm Oesophagostomum bifurcum is a parasite that is commonly found in humans in northern Togo and Ghana. Currently, it is estimated that 250 000 people are infected with this nematode and at least one million people are at risk of infection. Infection can cause significant disease as a consequence of encysted larvae in the wall of the large intestine. In spite of the health problems caused by O. bifurcum, there are serious gaps in the knowledge of the biology and transmission of the parasite. For instance, it has been proposed that non-human primates can act as a reservoir for human infection with O. bifurcum, but it has been unclear to what extent non-human primates in Ghana are infected with O. bifurcum and whether the parasite infecting humans represents the same species as is found in non-human primates.It is dioecious (i.e., there are separate males and females). Each female produces around 5000 eggs per day. Eggs are shed in the feces of the definitive host.

Overview

Eggs of Oesophagostomum bifurcum, the most-common species infecting humans, cannot be differentiated morphologically from the eggs of Necator or Ancylostoma(eggs of other animal oesophagostome species tend to be larger than typical hookworm eggs, however). The eggs of O. bifurcum measure 60-75 µm long by 35-40 µm wide.  Eggs are often in a later stage of cleavage than hookworm species when shed in feces.

Eggs Morphology

Adult worms of all Oesophagostomum spp. exhibit a cephalic groove by its proximal gut as well as a visible secretory pore, or stomum, at the same level of the oesophagus. Like other nematodes, Oesophagostomum spp. contain a developed, multi-nucleate digestive tract as well as a reproductive system.

Their developed buccal capsule and club-shaped oesophagus are useful for distinguishing Oesophagostomum spp. from hookworms.

Both sexes of adults have a cephalic inflation and an oral opening lined with both internal and external leaf crowns.

Female adults, which have a length range of 6.5-24 mm, are generally larger than their male counterparts, with a length range of 6-16.6 mm.

Males can be distinguished by their bell-like copulatory bursa, located in the tail, and their paired rodlike spicules.

Adults reside in the large intestine of the definitive host.

Adult Morphology:

C: Adult of Oesophagostomum sp./D: Higher magnification of the anterior end of the specimen in Figure C. Note the presence of the cephalic vesicle (CV), cephalic groove (CG) and esophagus (ES).

G, H: Posterior end of a male Oesophagostomum sp., shown in two different focal planes. Note the spicule (SP) and bursa (BU).

O.BifurcumHookworm_filariform

O.Bifurcum similar to Hookworms

1. Eggs are shed in the feces of the definitive host , and may be indistinguishable from the eggs of Necator and Ancylostoma. Eggs hatch into rhabditiform (L1) larvae in the environment , given appropriate temperature and level of humidity. develop in 1 or 2 days at 30"C, in the soil into third-stage infective larvae in 5–7 days.

2. the larvae will undergo two molts and become infective filariform (L3) larvae. It can penetrate the intestinal wall and produce asolitary, tumorlike inflammatory mass or abscess (helminthoma), measuring one to 2 cm.

3. Worms can go from eggs to L3 larvae in a matter of a few days, given appropriate environmental conditions. Definitive hosts become infected after ingesting infective L3 larvae.

4. After ingestion, L3 larvae burrow into the submucosa of the large or small intestine and induce cysts. Within these cysts, the larvae molt and become L4 larvae. These L4 larvae migrate back to the lumen of the large intestine, where they molt into adults. When the worms mature, they break out of the nodule in about 6–7 days and sometimes become attached to the caecal wall.

5. Eggs appear in the feces of the definitive host about a month after ingestion of infective L3 larvae.

O.bifurcum Life cycle

Life cycle

Oesophagostomum bifurcum is a common parasite of Monkeys.

Common livestock such as sheep, goats, and swine, wild pigs, as well as non-human primates, are the usual defi niti ve hosts for Oesophagostomum spp., but other animals, including humans and catt le, may also serve as defi niti ve hosts.

Humans are largely presumed to be an accidental host, as they are not suitable for completi on of the Oesophagostomum spp. development.

Different Hosts

In 1991, following the discovery that the human population in northern Togo excreted eggs of Oesophagostomum bifurcum, it was concluded that O. bifurcum is a locally common parasite of humans not requiring any animal reservoir to complete its lifecycle (Polderman et al. 1991).

A 2005 study done by van Lieshout and de Grujiter found that O. bifurcum in humans from northern Ghana is distinct from the O. bifurcum found in olive baboons and mona monkeys outside the endemic area.

History

Oesophagostomum  bifurcum are widely distributed wherever livestock(animal) is raised, but more common in the tropics and subtropics.  The highest incidence in humans  infections found in Africa from Togo and Ghana.

 Sporadic cases in humans have also been recorded in Brazil, Malaysia, Indonesia, French Guiana, and Asia.

In a report in (2010 APR 26), 'Nodular worm infection in wild chimpanzees in Western Uganda: a risk for human health,' is newly published data in PLoS Neglected Tropical Diseases. According to recent research from Paris, France, "This study focused on Oeosophagostomum sp., and more especially on O. bifurcum, as a  parasite  that can be lethal to humans and is widespread among humans and monkeys in endemic regions, but has not yet been documented in apes.

Geographical distribution

Disease: Oesophagostomiasis or esophagostomiasis nodular worm, cause nodule formation.

Habitat: Adults in nodules in the wall of the colon and caecum junction between small and large intestine.

Vector: Like the other intestinal nematodes, this parasite has no vector. Instead, it has a free-living stage in the soil where eggs hatch and L1 develop into infective L3 parasites.

Oesophagostomum bifurcum

dozens of nodules, each 2–3 cm in diameter. The wall of the colon becomes grossly thickened, although the mucosa and serosa remain intact. There is no definite cyst wall but there is a layer of macrophages, epithelial cells and fibroblasts, and often many plasma cells and eosinophils. Nodules contain thick pus or caseous material. In the majority of cases the infection is selflimiting and eventually resolves without treatment.

Nodular lesion caused by O. bifurcum presenting as a para-umbilical mass in an 8-year-old girl in Nigeria. At laparotomy the mass was found adhering to muscles and fascia of the anterior abdominal wall of the ascending colon.

Transmission of Oesophagostomum is believed to be oral-fecal for both humans and animals.

Infection through the skin is also possible.the transmission of infection appears to be

limited to the rainy season.percutaneous infection with O. bifurcum has

never been reported. It is unclear whether or not parasite transmission is specifically waterborne, foodborne, or both.

Much about the biological mechanism of transmission is still unknown, and current knowledge of oral-fecal transmission mechanisms does not explain why Oesophagostomum are mostly localized to Northern Togo and Ghana.

Transmission

Acute abdomen is the most-common manifestation in humans, mimicking an appendicitis.

Intestinal obstruction may also occur, mimicking a hernia.

most-common symptoms; vomiting, anorexia, anemia, intussusception, and diarrhea are less-common.

Patients may also present with large, painless cutaneous masses in the lower abdominal region.

Symptoms

Diagnosis is difficult during routine ova and parasite (O&P) examinations of stool, due to the similarity of Oesophagostomum eggs to the eggs of Necator and Ancylostoma.

a biopsy specimen can provide a definitive diagnosis.

PCR :In recent years, however, there have been advances in the diagnosis of Oesophagostomum infection with PCR assays.

 ultrasound and recent interventions involving mass treatment with albendazole shows promise for controlling and possibly eliminating Oesophagostomum infection in northern Togo and Ghana.

Laboratory Diagnosis:

M. Ralph, DSc, PhD, FIBiol. (2002.) Worms and Human Disease. 2nd ed. CABI Publishing. London, UK. PP 150-151-152.

Cox FEG, Wakelin D, Gillespie SH, & Despommier DD. TOPLEY & WILSON'S MICROBIOLOGY& MICROBIAL NFECTIONS: PARASITOLOY. (2005). 10th ed. Flodder Arnold. PP 811-812.

Schmidt GD, & Roberts LS. (2009). Foundations of Parasitology. 8th ed. McGraw Hill. Boston.PP 446.

ZIEM. J. B., OLSEN. A., MAGNUSSEN. P., HORTON. J., AGONGO. E., GESKUS. R. B. and POLDERMAN.A.M.(2006).Distributionand clusteringof Oesophagostomum bifurcum and hookworm infections in NorthernGhana. Parasitology. Volume 132 (Issue 04). Cambridge University Press.UK. pp 525 – 534.

http://www.dpd.cdc.gov/dpdx/html/Oesophagostomiasis.htm http://eolspecies.lifedesks.org/node/3804 http://www.stanford.edu/group/parasites/ParaSites2009/

AndrewPlan_Oesophagostomum/AndrewPlan_Oesophagostomum.htm http://www.ncbi.nlm.nih.gov/pubmed/17125544 http://www.vet-zone.com/Livestock/Oesophagostomum.html http://www.ajtmh.org/content/71/2/227.abstract http://www.newsrx.com/health-articles/1898587.html

References:

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