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• Schistosomiasis


  One of the Neglected Tropical Diseases (NTDs)
• More than 200 million people are infected with schistosomiasis worldwide
• Schistosomiasis is second only to malaria as the most destructive parasitic disease
• Schistosomiasis is an important cause of disease in many parts of the world, most commonly in places with poor sanitation
• School-age children

  • They tend to spend time swimming or bathing in water containing infectious cercariae, so they are often most at risk
• Most human infections are caused by

  • Schistosoma mansoni
  • S. haematobium
  • S. japonicum
• Epidemiology


  The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems
• Schistosomiasis affects almost 210 million people worldwide, and an estimated 12,000 to 200,000 people die from it a year
• The disease is most commonly found in Africa, as well as Asia and South America
• Around 700 million people, in more than 70 countries, live in areas where the disease is common
• Schistosomiasis is second only to malaria, as a parasitic disease with the greatest economic impact
• Schistosoma species that cause human infection


  • S. mansoni
  • S. haematobium
  • S. japonicum
  • S. Mekongi
  • S. Intercalatum
• Incubation period


  May be weeks- months (3-5 weeks)
• Symptoms of acute schistosomiasis


  • Rash or itchy skin (cerciral dermitits)
  • Katayma fever (cough, fever, lymphadenopathy and hepatosplenomegaly)
• Manifestations of continuing schistosomiasis infection


  • Colonic polyposis with bloody diarrhea (S. mansoni)
  • Portal hypertension with hematemesis and splenomegaly (S. mansoni, S. japonicum)
  • Cystitis and ureteritis (S. haematobium) with hematuria, which can progress to bladder cancer
  • Pulmonary hypertension (S. mansoni, S. japonicum, more rarely S. haematobium)
  • Glomerulonephritis
• Laboratory diagnosis methods


  • Microscopic identification of eggs in stool or urine
  • Immunological tests: FAT, ELISA, Antibody detection
  • Pelvic x-ray for bladder wall calcification (S. haematobium)
  • Tissue biopsy (rectal biopsy for all species and biopsy of the bladder for S. haematobium)
• Factors contributing to schistosomiasis endemicity


  • Environmental sanitation: water supply, water channels, contamination
  • Irrigation system
  • Migration from rural to urban area
  • Seasonal: summer more than winter
  • Socioeconomic: low standard living
  • Host factors: increase with 10-19 yr. old, male >female, occupational
  • Ecology: snails affected by salinity, also pure water unfavorable for breeding, temperature more than 30c are not good for breeding
• Schistosomiasis treatment


  • Metriphonate (Bilarcil) 10mg/kg once every 2weeks for 3 doses
  • Praziquantel (Biltricide) single oral dose 30-40 mg/ kg or 3times a day
  • Oxamniquine (for S. mansoni exclusively)
  • Mirazid (new Egyptian drug, under investigation)
• Schistosomiasis prevention and control measures


  • Health Education, know the life cycle and M.O.T, wearing protective clothes, avoid exposure with contaminated water, right and hygienic defection and urination habits
  • Drink safe water, also water used for bathing boil for 1 minute to kill any cercariae
  • Eliminating the snail
  • Avoid swimming or wading in rivers where the infection is endemic
  • Treating and finding all cases and mass drug praziquantel treatment of entire population and targeted treatment of school-age children
  • No vaccine is found
• Human Schistosome species


  • Schistosoma guineensis (Bulinus forskalii, West Africa)
  • Schistosoma intercalatum (Bulinus spp, Africa (local))
  • Schistosoma haematobium (Bulinus spp, Africa, Middle East)
  • Schistosoma japonicum (Oncomelania spp, China, East Asia, Philippines)
  • Schistosoma mansoni (Biomphalaria spp, Africa, South America, Caribbean, Middle East)
  • Schistosoma malayensis (Robertsiella spp, Southeast Asia)
  • Schistosoma mekongi (Neotricula aperta/ definitive-dog, Southeast Asia (local))

  
• Oncomelania hupensis is the first intermediate host for Schistosoma japonicum
• Neotricula aperta is the first intermediate host for Schistosoma mekongi
• Biomphalaria glabrata is the first intermediate host for Schistosoma mansoni
• Toxoplasma gondii


  A protozoan parasite

  
• Domestic cats


  • The only known definitive hosts in which the parasite can undergo sexual reproduction
• Up to 95% of some populations have been infected with Toxoplasma in various places throughout the world

  
• Infection is often highest in areas of the world that have hot, humid climates and lower altitudes
• In a study in Iraq in Al-Khathmia Teaching Hospital 94% of pregnant women under study were sero positive IgM, IgG related to the parasite
• In UK 22% of pregnant women carries the parasite, and in India almost 60-65 % of pregnant women are seropositive
• Incubation period


  1. 23 days
• Causal agent


  T. gondii
• Modes of transmission


  • Foodborne; eating undercooked, contaminated meat
  • Ingesting water, soil, vegetables, or anything contaminated with oocysts shed in the feces of infected Cat
  • Drinking unpasteurized milk
  • Animal-to-human (zoonotic)
  • Mother-to-child, particularly when T. gondii is contracted during pregnancy (congenital)
• Cats


  • Play an important role in the spread of toxoplasmosis. They become infected by eating infected rodents, birds, or other small animals

  
• Clinical features


  Usually mild with "flu-like" symptoms (e.g., non-tender lymph nodes, myalgia, anorexia, sore throat, night sweet) that last for weeks to months and resolve. However, the parasite remains in their body in an inactive state. It can become reactivated if the person becomes immunosuppressed
• Only 10-20% of toxoplasmosis cases in adults and children are symptomatic

  
• Toxoplasmosis is a serious and often life-threatening disease in immunodeficient patients

  
• Complications of toxoplasmosis


  • CNS toxoplasmosis occurs in 50% of patients - Seizure, focal neurologic deficit, headache, encephalitis
  • Myocarditis and pneumonitis are reported
• Chronic toxoplasmosis


  The parasite localizes within tissue cysts, mainly in the central nervous system. It is primarily regarded as benign and asymptomatic, but might be responsible for a vast array of neuropsychiatric symptoms

  
• Congenital toxoplasmosis


  Most severe when maternal infection occurs early in pregnancy. Approximately 67% of patients have no signs or symptoms of infection. T gondii –specific IgM antibodies at birth or early infancy. Retinochoroiditis occurs in about 15% of patients. Infected newborns have anemia, thrombocytopenia, and jaundice at birth. Affected survivors may have mental retardation, seizures, visual defects, spasticity, hearing loss or other severe neurologic sequelae

  
• The prevalence of hearing loss is as high as 28% in children who do not receive treatment