PARASITIC INFECTION

Nelson and Masters Williams, 2014

PARASITIC INFECTION

Co-evolved with human hosts Adapted to evade immunity Evolve in a manner that can enable migration to new

hosts

Transmission Direct—person to person, via fecal waste Indirect—involves additional hosts or vectors

Nelson and Masters Williams, 2014

Nelson and Masters Williams, 2014

SCHISTOSOMIASIS- CLINICAL PRESENTATION Symptoms can vary

Type of worm involved Location of parasite in the body

Considerable morbidity in intestines, liver and urinary tract

Some cases can lead to death

Harrison’s Principles of Internal Medicine, Chapter 210, Malaria

SCHISTOSOMIASIS- CLINICAL PRESENTATION Three phases of disease manifestation:

Invasion at site (rash/ dermatitis) Acute schistosomiasis- fever, chills, muscle aches,

lymph node enlargement, liver or spleen enlargement Chronic schistosomiasis- for intestinal species may

involve abdominal pain, bloody diarrhea, anemia Children—anemia, malnutrition and learning

disabilities

Harrison’s Principles of Internal Medicine, Chapter 219

SCHISTOSOMIASIS- CLINICAL PRESENTATION

www.radiobridge.net; www.scielo.br

SCHISTOSOMIASIS- CLINICAL PRESENTATION

Urinary species (S. haematobium) Frequent, painful, or bloody urine Inflammation/ scarring of bladder Bladder cancer may develop

Harrison’s Principles of Internal Medicine, Chapter 219

https://commons.wikimedia.org/wiki/File:Schistosoma_mansoni_Life_Cycle.tif#/media/File:Schistosoma_mansoni_Life_Cycle.tif

GLOBAL BURDEN OF SCHISTOSOMIASIS

240 million infected worldwide 700 million reside in endemic areas Vast majority of burden in Africa 280,000 deaths annually Approximately 2 million suffer severe outcomes including

disfiguring disabilities, kidney disease, liver disease, and bladder cancer

www.who.int/schistosomiasis/en; www.globalnetwork.org/schistosomiasis

GLOBAL DISTRIBUTION OF SCHISTOSOMIASIS

Harrison’s Textbook of Medicine, 2015

SCHISTOSOMIASIS IN SAUDI ARABIA

S.mansoni is mainly found in the highland of the western region, and S.haematobium is mainly reported from Tabouk in the Northwest and from Baha and Mahael in the Low Land of the coastal plain in the Southwest region

Recent studies done in 2004 indicate that Saudis accounted for 61.2% of total infected cases and infection peaked at 15-39 years

Ministry of Health statistical data in 2008 confirmed that Saudis are more infected than non-Saudis; the percentage of infection was 55.5 % and 45.5 % for Saudis and non-Saudis, respectively

http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0001475

CONTROL STRATEGIES Education campaigns about risks of getting infected by

bathing in fresh water lakes and ponds Praziquantel is the primary form of treatment A single dose of Praziquantel has been shown to reduce

the severity of symptoms in cases of subsequent re-infection

A schistosomiasis vaccine is currently in the early stages of development by Sabin’s vaccine development team

http://www.globalnetwork.org/schistosomiasis

CONTROL STRATEGIES

Preventive chemotherapy: “Rather than identifying every infected individual, large-scale preventive chemotherapy interventions assess entire communities for endemicity or ongoing transmission of the target helminthic diseases. The recommended drug or drug combination is then administered to all eligible members of the endemic communities.”

Praziquantel is the drug of choice. Usually co-administered with other anti-helminthic drugs such as Albendazole

Detailed procedures for mass screening and implementing preventive chemotherapy can be found at: http://whqlibdoc.who.int/publications/2006/9241547103_eng.pdf?ua=1

World Malaria Report, 2014, WHO

CONTROL STRATEGIES

Schistosomiasis outbreaks can be identified by mapping the rates of blood in the urine of school-age children. If the rates are high, Praziquantel is distributed to the entire community at risk

Annual dosing of Praziquantel is sometimes recommended for areas at high risk for reinfection with the disease

http://www.globalnetwork.org/schistosomiasis

CONTROL STRATEGIES IN SAUDI ARABIA

A national program for elimination of schistosomiasis was initiated in12 known endemic foci in Saudi Arabia in 2005. The strategies employed by this program are:

Active case detection and treatment by examination of 80-100% of the infected population once a year and 80-100% of school children in the same areas

Safe potable water supply and good sanitation are made available to infected communities.

Snail control using chemical molluscicides and mechanical methods Health education

http://www.researchgate.net/publication/233748271_Human_Schistosomiasis_in_the_Kingdom_of_Saudi_Arabia_A_Review)