ASCARIASIS LUMBRICOIDES

Dr. Esther Majaliwa

Photo: CDC/ Dr. Mae Melvin

Importance

• Ascaris lumbricoides is a parasitic worm belonging to the class of Nematodes
• Largest roundworm, with the female being larger than the male
• Most common worm infection of humans worldwide¹

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Female (left) and male A. lumbricoides

Photo: CDC

Importance

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• Most common in tropical and subtropical areas; and the highest burden seen in Sub-Saharan Africa
• Up to 1.2 billion people infected people worldwide^2,3
• Highest rates of infection in 2-10 years old^2,3
• Approximately 60,000 deaths annually^a
• Warm and wet environmental conditions favor the transmission of A. lumbricoides⁵
• Spread of disease is favored by poor sanitation

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Two fertilized eggs with an adult A. lumbricoides specimen in the middle

Photo: CDC/DPDx, Orange County Public Health Laboratory, Santa Ana, CA

^ahttp://www.who.int/water_sanitation_health/diseases/ascariasis/en/

Importance

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• The eggs are extremely resistant to strong chemicals, dryness and low temperatures
• The eggs can remain viable in the soil for months or even years⁶

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Fertilized ascaris egg from human feces (no staining used)

Photo: Graham Beards

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Historical Perspective

• Ascariasis is an ancient disease discussed in Egyptian writings dating from 3000 to 400 BC^7,8
• The worm may have been readily identified due to its size and presence in stool
• Information is not forthcoming on how ancient people managed the disease
• The life cycle was not determined until 1922^8-10
• Japanese researcher Shimesu Koino infected both himself and a volunteer

Life Cycle

Photo: CDC

Life Cycle

• CDC Life Cycle Information²:
• Fecal-oral initiation
• Infection when eggs are ingested in contaminated water, food (e.g. raw fruits or vegetables) and soil
• Eggs hatch, larvae mature, enter the intestinal mucosa and circulate to the lungs
• Worms further mature after 10-14 days in the lungs, then travel up the bronchial tree and are swallowed
• Worms finally reside as adults in the GI tract again and can release eggs after mating occurs
• Females release up to 200,000 eggs per day

Clinical Manifestation

• Significant clinical manifestations:
• Deficiencies related to childhood development
• Allergic Pneumonitis (Loffler’s syndrome)
• Mechanical Obstruction
• Hepatobilliary and pancreatic symptoms

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Ascaris worms being expelled from the anus following antihelmintic drug administration.

Photo: Dr. Lisa Frenkel�

Clinical Manifestation

• Major childhood development issues^11,12:
• Growth retardation
• Cognitive Impairment
• Nutritional Deficiencies

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Clinical Manifestation

• Allergic Pneumonitis (Löffler’s syndrome)
• It is an inflammation of the lung parenchyma.
• Occurs when immature worms migrate to the lungs via the inferior vena cava. Worms actually leave the pulmonary microvasculature and further invade through alveoli
• Symptoms include:
• Coughing
• Wheezing
• Difficulty in breathing

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Clinical Manifestation

• Mechanical Obstruction
• It occurs as a result of worms obstructing the intestinal lumen.
• Leads to emergency surgery
• Common in children in endemic regions⁷
• May cause intussusception and volvulus¹³
• Symptoms include:
• Abdominal pain
• Distension
• Fecal reduction
• Vomiting (vomitus may contain worms)

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Intestine removed from a perished child due to obstruction from a severe A. lumbricoides infection

Photo: Fae

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Clinical Manifestation

• Hepatobilliary and Pancreatic Symptoms
• Adult worm migrates to the hepato-billary tree and may cause obstructive jaundice, cholangitis and biliary perforation^14,15
• Conditions can cause^14,15:
• Biliary colic
• Fever
• Abdominal pains
• Further migration can obstruct the pancreas and appendix causing pancreatitis and appendicitis

A. Lumbricoides obstructing the Ampulla of Vater/biliary tree

Phisalprapa, Pochamana, and Varayu Prachayakul. "Ascariasis as an Unexpected Cause of Acute Pancreatitis with Cholangitis: A Rare Case Report from Urban Area." Journal of the Pancreas 14.1 (2013): 88-91. Web. 9 June 2015.

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Diagnosis

• Microscopy - fecal smear using light microscopy can reveal eggs (400x)¹⁶
• Ultrasound - can demonstrate worms in the hepato-biliary tree and pancreas^17,18
• Blood analysis - during the migration stage of worms eosinophilia occurs¹⁹

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Prevention and Management

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• Drugs are critically necessary^16,20-22:
• Mebendazole (100mg twice daily for 3 days)
• Albendazole (single 400mg dose)
• Contraindicated in early pregnancy
• Levamisole
• Pyrantel Pamoate

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Mebendazole

Photo: NEUROtiker

Levamisole

Photo: Edgar181

Pyrantel pamoate

Photo: Edgar181

Albendazole

Photo: Fuse809

Prevention and Management

• Mass treatments with single doses of Albendazole (400mg)²⁰ to preschool and school children
• Resistance may emerge if drugs are heavily relied upon and sanitation is ignored²¹
• Resistance already documented in veterinary care²¹

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Prevention and Management

• Improvement of sanitation to prevent fecal contamination is key
• Hygienic handling of food and education in general hygiene
• Wash hands thoroughly with soap and water after defecation and before handling food
• Eggs can commonly be found on hands and under nails^23-25

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Photo: CJ Sorg

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Interaction with Healthcare Partners

• Children Without Worms (CWW) has partnered with the World Health Organization, Johnson and Johnson and the Task Force for Global Health to support the control of Soil Transmitted Helminths (STHs)²⁶

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Interaction with Healthcare Partners

• Children Without Worms, GlaxoSmithKline and the WHO have provided and facilitated the treatment of 176 million school children in 14 counties with mebendazole from 2007 to 2012²⁶
• Sabin Vaccine Institute Project Development Partnership, in association with the Bill and Melinda Gates Foundation, are devolving a Pan-anthelmintic vaccine²⁷

Update

• In 2014, USAID conducted an awareness campaign, "One Billion and Counting”, to help accelerate action to eliminate NTDs by 2020²⁸
• Since 2020, USAID, in collaboration with RTI, in Tanzania, Uganda, Nigeria, Mozambique, Ethiopia and DRC NTDs Control Programme, envision and the Act to end NTDs.

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UPDATE

• There has been a rise in number of annual deaths due to Ascaris infection in the last decade even with the increased number of MDAs^b
• FLOTAC technique has been developed as a more sensitive technique for diagnosis, but Kato-Katz technique is still recommended due to its simplicity and cost efficiency.^c
• Ivermectin has been approved as a drug of choice in treatment of Ascaris infection as it is as effective as other current treatments.^d

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^bhttp://www.who.int/water_sanitation_health/diseases/ascariasis/en/

^cFLOTAC: a new sensitive technique for the diagnosis of hookworm infections in Humans, Transactions of the Royal Society of Tropical medicine and Hygiene, Vol 102. 2008

^dWorld Health Organization. The selection and use of essential medicines. WHO Technical Report Series 2017;1006:1‐604

Take Home Messages

• Ascariasis is extremely common and obligates mass drug administration

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• Ascariasis may be difficult to diagnose early and infestations can lead to respiratory complications, bowel obstructions and hepatobiliary complications

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• In order to prevent the spread of infection, avoid open defecation, keep all living spaces clean, handle food hygienically and ensure that clean water and clean toilet facilities are available

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• Ultimately, systematic prevention of infection and re-infection is more important than MDA alone!

References

Zero^TM Best Practices for Prevention of Ascariasis

Zero^TM Best Practices for Prevention of Ascariasis