Taenia solium Human Cysticercosis: A Systematic Review of Sero-epidemiological Data from Endemic Zones around the World

Abstract

Background Taenia solium cysticercosis is a zoonotic neglected disease responsible for severe health disorders such as seizures and death. Understanding the epidemiology of human cysticercosis (HCC) in endemic regions will help to expose critical information about the transmission of the disease, which could be used to design efficient control programs. This review gathered serological data on apparent prevalence of T. solium circulating antigens and/or seroprevalence of T. solium antibodies, apparent prevalence of human taeniasis and risk factors for HCC from endemic communities in order to understand the differences in exposure to the parasite and active infections with T. solium metacestodes in endemic areas around the world.MethodsThree databases were used to search sero-epidemiological data from community-based studies conducted between 1989 and 2014 in cysticercosis endemic communities worldwide. The search focused on data obtained from T. solium circulating antigen detection by monoclonal antibody-based sandwich ELISA and/or T. solium antibody seroprevalence determined by Enzyme-linked Immunoelectrotransfer Blot (EITB). A meta-analysis was performed per continent.Principal FindingsA total of 39,271 participants from 19 countries, described in 37 articles were studied. The estimates for the prevalence of circulating T. solium antigens for Africa, Latin America and Asia were: 7.30% (95% CI [4.23–12.31]), 4.08% (95% CI [2.77–5.95]) and 3.98% (95% CI [2.81–5.61]), respectively. Seroprevalence estimates of T. solium antibodies were 17.37% (95% CI [3.33–56.20]), 13.03% (95% CI [9.95–16.88]) and 15.68% (95% CI [10.25–23.24]) respectively. Taeniasis reported prevalences ranged from 0 (95% CI [0.00–1.62]) to 17.25% (95% CI [14.55–20.23]).SignificanceA significant variation in the sero-epidemiological data was observed within each continent, with African countries reporting the highest apparent prevalences of active infections. Intrinsic factors in the human host such as age and immunity were main determinants for the occurrence of infections, while exposure was mostly related to environmental factors which varied from community to community.

Taenia solium Taeniasis and Cysticercosis in Southeast Asia

“…47 WHO recommends the use of lentil lectin-purified glycoproteins in enzyme-linked immunoelectrotransfer blot (EITB) format for antibody testing, 48 while detection of circulating antigens is achieved via enzyme-linked immunosorbent assay (Ag-ELISA) detecting T. solium metacestode antigens (B158/ B60 or HP10). 11,49,50 The presence of antibodies indicates past or present infection, therefore usually overestimates the true prevalence, whereas the presence of circulating antigens indicates viable cysticerci in the human host and is usually reflective of active disease burden. Newer QuickELISA™ (Immunetics Inc., Boston, MA) assays also look promising due to the ease of use, but their performance has not been widely validated in various field conditions including SEA.…”

“…Such epidemiologic data are important in analyzing critical information about the transmission of disease and other relevant risk factors, and therefore can be used to design effective control programs. 11 However, caution should be exercised in interpreting these data because of several limitations, namely, small sample sizes, lack of strong study methodology, lack of national or regional representativeness, paucity of clinical data particularly in association with seizures, varied laboratory diagnostic methods, heavy reliance on serologic data, and intrinsic limitations of diagnostic tests. 14 …”

“…Recent publication by Coral-Almeida and others 11 analyzed epidemiologic studies that used only the WHO-recommended EITB or Ag-ELISA methods and found that the seroprevalence of T. solium antibodies in Asia was estimated at 15.7% (95% confidence interval [CI] = 10.3-23.2). However, only one study from Bali, Indonesia, represented the SEA region with estimated prevalence of 12.6% (95% CI = 10.3-15.2).…”

“…56 On the other hand, analysis of studies using Ag-ELISA method estimated an overall prevalence of 3.9% (95% CI = 2.8-5.6) of T. solium cysticercosis in Asia. 11 Only four studies from two countries within SEA region were represented in this analysis (Vietnam and Lao PDR).…”

“…8 In southeast Asia (SEA), taeniasis/cysticercosis is moderately endemic and has been identified as one of the major NTDs afflicting the region. [9][10][11] SEA is a politically, socioeconomically, ethnoreligiously, and culturally diverse region consisting of 10 Association of Southeast Asian Nations (ASEAN) member states bound by the 2008 Charter in efforts to regional cooperation on many top level issues including that of population health. 12 In the last three decades, while many ASEAN member nations have undergone rapid economic growth with significant improvements in health-care and living standards, certain countries such as Cambodia, Laos People's Democratic Republic (Lao PDR), and Myanmar remain on the United Nation's list of least developed countries.…”