Schistosomiasis: Still a Cause of Significant Morbidity and Mortality

Abstract

Tropical diseases remain severe threats to global health with acute or chronic debility. Public health issues are regularly monitored and reported by the WHO. Conditions with high prevalence and virulence such as Schistosomiasis or Malaria still need active treatment. Advances over the decades in the treatment and management of Schistosomiasis have reduced morbidity and mortality in patients. However, poverty, adverse environments, lack of education and awareness, with parasites and vectors that can thrive if uncontrolled, remain issues for the successful global eradication of Schistosomiasis. From the disease's discovery in 1850, the author relates historical details to its current status. Several countries previously affected, including Japan and Tunisia, have eliminated the disease while others seek the same goal. Africa remains the most severely affected continent with vulnerable women and children, although the infection persists in South America and the Far East of Asia as well. Realistic improvements for continuing health conditions are vogue and emphasized for those at risk or afflicted by the infection, illustrating success models of concerted efforts of extirpation. Constant proximity to infected water, with a parasite host, are hurdles in reducing exposure. Effective medication for acute treatment is available, and prophylaxis by vaccination is promising. Where endemic Schistosomiasis is prevalent, significant morbidity and mortality have far-reaching complications in multiple human organ systems, including irreversible pulmonary hypertension, renal, genitourinary, central nervous system conditions, and neoplasia. Two hundred and thirty million people are estimated to have contracted Schistosomiasis globally, with up to 700 million still at risk of infection, and 200,000 deaths occur annually. The disease may be more prevalent than thought after newer tests have shown increased sensitivity to pathological antigens. The author discusses infectivity risks, investigations, prognosis, treatment, and management, as well as morbidity and mortality.

Keywords: cercariae; cestode; egg load; granulomas; miracidia; morbidity; mortality; schistosomulae; trematode.

Figure 1

(A and B) Eggs of S. haematobium in a urinary bladder biopsy specimen, H & E stain. Notes: Reproduced from Michael E, De Bakey VA. Medical Center, Houston, Texas, United States. Available from: https://www.cdc.gov/dpdx/index.html.

Figure 2

Egg of S. mansoni embedded in a liver. Notes: Reproduced from Lambertucci JR. Acute schistosomiasis mansoni: revisited and considered. Mem Inst Oswaldo Cruz. 2010;105(4):422–435. Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0074-02762010000400012.

Figure 3

Biomphalaria glabrata, an example of a snail host, is illustrated. Notes: Reproduced from Blouin laboratory, Oregon State University. Available from: https://www.flickr.com/photos/oregonstateuniversity/16730248430/in/photolist-ruoTZ9.

Figure 4

Eggs of Schistosoma, S. hematobium, S. intercalatum, and S. mansoni with their typical spines and comparative sizes. Notes: Reproduced from CDC. Atlanta, United States. Figure 6. Available from: https://www.cdc.gov/dpdx/diagnosticprocedures/stool/morphcomp.html.

Figure 5

The life cycle of the schistosoma parasite. Notes: Reproduced from CDC. Atlanta, United States. Image courtesy of DPDx, Centers for Disease Control and Prevention. Available from: https://www.cdc.gov/parasites/schistosomiasis/biology.html.