Schistosoma spp.

Characteristics
Morphology	Species of the genus Schistosoma are trematode blood flukes belonging to the Schistosomatidae family. They are dioecious, have a two host life cycle, and exhibit a high degree of sexual dimorphism. Adult worms are 7-28 mm in length and 0.3-0.6 mm in width. Schistosome eggs, housing the miracidia, are round or oval (150 µm) with one spiny appendage and viable only in fresh water.
Growth Conditions	Schistosoma develops in snails and upon leaving them in their adult form (Cercariae) infect people who are in bodies of fresh water where the snails live

Health Hazards
Host Range	Humans, bovines, other mammals (will vary based on the species)
Modes of Transmission	Transmission occurs in water contaminated with feces or urine. Free swimming cercariae directly penetrate through the skin to infect humans.
Signs and Symptoms	Within days after becoming infected, a rash or itchy skin may develop. Fever, chills, cough, and muscle aches can begin within 1-2 months of infection. Most people have no symptoms at this early phase of infection. When adult worms are present, the eggs that are produced usually travel to the intestine, liver or bladder, causing inflammation or scarring. Children who are repeatedly infected can develop anemia, malnutrition, and learning difficulties. After years of infection, the parasite can also damage the liver, intestine, lungs, and bladder. Rarely, eggs are found in the brain or spinal cord and can cause seizures, paralysis, or spinal cord inflammation.
Infectious Dose	Unknown
Incubation Period	Cercariae reach the portal venous system several days post-infection. 4-6 weeks usually pass before egg production begins. Toxemic schistosomiasis may develop 6-8 weeks post infection. Adult schistosomes may live 20 to 30 years.

Medical Precautions/Treatment
Prophylaxis	Avoid exposure to freshwater when you are in areas in which schistosomiasis occurs. Boiling water for at least 1 minute will kill any harmful parasites, bacteria, or viruses present.
Vaccines	None readily available
Treatment	Praziquantel is the primary drug used against schistosomiasis.
Surveillance	Monitor for symptoms. Confirm by testing stool, urine, or blood using microscopy or antibody detection
GWU Requirements	Report all incidents to the Office of Risk Management as well as the Office of Research Safety (ORS) IMMEDIATELY FOLLOWING THE OCCURRENCE.

Containment
BSL-2/ABSL-2	Risk Group 2 classification is applied the parasite. BSL-2 and ABSL-2 practices, including appropriate PPE and containment equipment/facilities, are recommended for laboratory work with infective stages of the trematode parasites discussed here (i.e., when there may be direct contact with water containing cercariae or vegetation with encysted metacercariae from naturally or experimentally infected snail intermediate hosts).

Containment

BSL-2/ABSL-2

Risk Group 2 classification is applied the parasite. BSL-2 and ABSL-2 practices, including appropriate PPE and containment equipment/facilities, are recommended for laboratory work with infective stages of the trematode parasites discussed here (i.e., when there may be direct contact with water containing cercariae or vegetation with encysted metacercariae from naturally or experimentally infected snail intermediate hosts).

Spill Procedures
Small Spills (<1 liter)	If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup. Schistosoma is not known to be transmitted via aerosols, but caution should be taken during a spill outside of a BSC. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against the parasite (bleach, ethanol, glutaraldehyde), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.
Large Spills	Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911.

Spill Procedures

Small Spills (<1 liter)

If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup.

Schistosoma is not known to be transmitted via aerosols, but caution should be taken during a spill outside of a BSC. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against the parasite (bleach, ethanol, glutaraldehyde), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.

Large Spills

Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911.

Exposure Procedures
Mucus Membrane	Flush eyes, mouth or nose for 15 minutes at eyewash station.
Other Exposure	For an area not protected by skin, wash with soap and water for 15 minutes (open wounds, sores, etc.). Cercariae require 1-2 minutes to penetrate skin.
Reporting	Report ALL injuries to the PI immediately and reported to the Office of Risk Management at [email protected] IMMEDIATELY FOLLOWING THE OCCURRENCE. Exposures that involve a bloodborne-pathogen or recombinant DNA also need to be reported to the Office of Research Safety at [email protected]. If the injury requires immediate medical attention, call GWPD at 202-994-6111 or call 911.
Medical Monitoring	Seek immediate medical evaluation, treatment, and post exposure follow-up at the Employee Health Office at GWU Hospital (900 23rd St., NW, Suite G-1090, Phone: 202-715-4275). Students should go to the Students Health Office at Marvin Center. After hours treatment can be received at the GWU hospital emergency room.

Stability
Disinfection	All infective stages are susceptible to 2% gluteraldehyde, 10% bleach. Surface cercariae are susceptible to 70% ethanol.
Inactivation	Sensitive to low temperatures; S. japonicum does not develop at temperatures lower than 15.4°C
Survival Outside Host	Cercariae may survive in water for about 2 days

Personal Protective Equipment (PPE)
Minimum PPE Requirements	At minimum, personnel are required to don gloves, closed toed shoes, lab coat, and appropriate face and eye protection prior to working with Schistosoma. Additional PPE may be required depending on lab specific SOPs.
Additional Precautions	Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists, gloves, and respiratory protection. Wash hands with soap and water after removing gloves.

References
CDC (https://www.cdc.gov/parasites/schistosomiasis/index.html) BMBL 6th Edition (https://www.cdc.gov/labs/BMBL.html) Canadian PHAC (https://www.canada.ca/en/public-health/services/laboratory-biosafety-bi…)