Ascaris suum Agent Information Sheet

Boston University
Research Occupational Health Program (ROHP)
617-414-7647

Agent

Ascaris suum also known as “large roundworm of pigs” is a parasitic nematode that causes ascariasis in pigs. It is considered to be a different species from roundworms normally found in humans, but can cross infect. Some consider Ascaris suum to be same species as human roundworms (Ascaris lumbricoides).

Disease/Infection

Initially starts the lifecycle of infection by ingestion of Ascaris eggs by the host. The eggs become larvae in the GI tracts and migrate to the liver where they further mature. They then migrate to the lungs. From the lungs, the larvae are coughed up and swallowed. After reentering the GI tract the larvae mature into adult worms, mate, and lay eggs.

Pathogenicity

• Special Populations at Risk: None

Biosafety Information

Risk Group/BSL
Risk Group 2
BSL-2

Modes of Transmission

Host range/reservoir
Humans and pigs are the primary hosts

Symptoms
Often asymptomatic, but may have bloody sputum, cough, fever, abdominal discomfort, intestinal obstruction, jaundice, or passing worms. Accompanying symptoms include pulmonary infiltration, and eosinophilia.

Incubation period
Days to weeks (14-20 days to initial symptoms in reported case)

Viability
Eggs are resistant to many strong chemicals (acids, bases, oxidants, can survive in formalin), low temperatures, and dehydration

Survival outside of host
Eggs can survive months to years in the open.

Information for Lab Workers

Laboratory PPE

Gloves, lab coat, face, eye and respiratory protection. All procedures that produce aerosols should be performed using a biological safety cabinet.

Laboratorians working with Ascaris spp. should be aware that allergic reactions can develop and can include respiratory, dermatologic, and gastrointestinal symptoms.

Containment

BSL- 2 practices

In Case of Exposure/Disease

• For injuries in the lab which are major medical emergencies (heart attacks, seizures, etc…):
• Medical Campus: call or have a coworker call the Control Center at 4–4144.
• Charles River Campus: call or have a coworker call campus security at 617-353-2121.
  You will be referred to or transported to the appropriate health care location by the emergency response team.
• For lab exposures (needle sticks, bite, cut, scratch, splash, etc…) involving animals or infectious agents, or for unexplained symptoms or illness call the ROHP 24/7 hour number (1-617-414-ROHP (7647); or, 4-ROHP (7647) if calling from an on-campus location) to be connected with the BU Research Occupational Health Program (ROHP) medical officer. ROHP will refer you to the appropriate health care location.
• Under any of these scenarios, always inform the physician of your work in the laboratory and the agent(s) that you work with.
• Provide the wallet-size agent ID card to the physician.

Vaccination

None

Information for First Responders/Medical Personnel

Public Health Issues

After exposure: Immediately wash and decontaminate. If splash to eyes or mouth, irrigate at wash station for 15 minutes. If exposure to open skin, wash and decontaminate with soap and water for 15-20 minutes. Surface decontamination requires isopropyl alcohol or iodine to destroy eggs. Notify ROHP.

PPE: Standard precautions with: (1) hand hygiene and (2) use of gloves when responding to an incident.

In case of suspected illness: The lab worker should contact ROHP. It is important to emphasize good hygiene and universal precautions. The researcher should avoid close contact with household members pending evaluation, if possible. If the lab worker presents to the emergency room or other outside medical facility, caring providers should contact ROHP for further instructions. ROHP will consult infectious disease specialists.

Diagnosis/Surveillance:

Sputum or stool exam for eggs or larvae. Recheck stool for eggs and larvae 3 months after treatment.

First Aid/Post Exposure prophylaxis

Consider post exposure treatment with agents listed below.

Treatment

Post exposure treatment would only be if large oral exposure. Treatment is usually with an Ascaricide which belongs to the group of drugs collectively called anthelmintics which expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. Treatment of choice is either Albendazole, Mebendazole, or Pyrantel Pamoate.

• Mebendazole (Vermox) causes slow immobilization and death of the worms by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. Oral dosage is 100 mg every 12 hours for 3 days.
• Pyrantel pamoate (Antiminth, Pin-Rid, Pin-X), depolarizes ganglionic block of nicotinic neuromuscular transmission, resulting in spastic paralysis of the worm. Spastic (tetanic) paralyzing agents, in particular pyrantel pamoate, may induce complete intestinal obstruction in a heavy worm load. Dosage is 11 mg/kg not to exceed 1 g as a single dose.
• Albendazole, a broad-spectrum antihelminthic agent that decreases ATP production in the worm, causing energy depletion, immobilization, and finally death. Dosage is 400 mg given as single oral dose (contraindicated during pregnancy and children under 2 years).

If a person is immunocompromised, treatment should be determined with consult of an infectious disease specialist.

Recheck stool for eggs and larvae 3 months after treatment if symptomatic.

References

Public Health Agency of Canada, Pathogen Safety Data Sheet, Ascaris Species. http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/msds10e-eng.php

James A. Phills, A. John Harrold, Gabriel V. Whiteman & Lewis Perelmutter (1972). “Pulmonary infiltrates, asthma and eosinophilia due to Ascaris suum infestation in man”http://www.k-state.edu/parasitology/articles/ascariasis.pdf

Biosafety in Microbiological and Biomedical Laboratories (BMBL) 5th Edition. US Government Printing Office, Washington, 2007.

Control of Communicable Diseases Manual. David L. Heymann. Washington DC, USA: American Public Health Association Press, 19th edition 2008

Herwaldt, B.L. Laboratory-Acquired Parasitic Infections from Accidental Exposures. Clinical Microbiology Reviews, October 2001, p. 659-688

Revised: 12/14/2015