Elimination of porcine cysticercosis using an integrated approach in an endemic area of Katete district, Zambia.
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Date
2019
Authors
Chembensonfu, Mwelwa
Journal Title
Journal ISSN
Volume Title
Publisher
University of Zambia
Abstract
Cysticercosis (CC) caused by the pork tapeworm Taenia solium is responsible for widespread
public health problems and economic losses and is a major hindrance to pig production in many
developing countries. Increasing efforts are being made to prevent and control this neglected
parasitic zoonosis but more efforts are needed in order to drastically reduce the disease
occurrence. A number of studies report control of porcine cysticercosis (PCC) by improving
sanitation, pig husbandry, education and meat inspection but these interventions are not effective
when used as single options. A vaccine designated TSOL 18 against porcine cysticercosis is now
available and if combined with oxfendazole is reported to be effective. The aim of this study was
to evaluate the effectiveness of integrated control methods for PCC.
An experimental field trial (parallel group design) was conducted between March, 2015 and
January, 2018 in CC highly endemic areas of Zambia (Katete and Sinda Districts of Eastern
Province). This involved concurrent vaccination with TSOL 18 vaccine, Oxfendazole treatment
in pigs, mass drug administration (MDA) of praziquantel to the community and health education.
Two areas were assigned elimination (E, Nyembe) and negative control (N, Herode) study arms.
Baseline and post intervention data was collected through questionnaire, full carcass pig
dissections, PCR-RFLP and ELISA performed on collected blood and cysticerci.
Treatment/vaccination of pigs and mass treatment of people were conducted only in the
elimination study arm at intervals of four months for two years while community education on T.
solium, control and prevention was carried out in both study arms. All collected data was double
entered in Epidata®, cleaned and analysis performed in R, using logistic regression. The
analyses looked into changes within each study arm before and after the intervention and
between the E-arm and N-arm after the intervention. A significance level of 5% was used.
The primary outcome was PCC as determined by necropsy and Ag-ELISA, and both pre and
post-intervention prevalence were established. The questionnaire was administered to 186
households in both study areas out of which 85% had toilets but 7.7% did not use them. Sixty to
66.4% of the households left the pigs to roam freely during the day thereby, predisposing them to
PCC. At baseline, the prevalence for PCC was 46% and 45.7% after full carcass dissections and
Ag-ELISA respectively in the E study arm while 67.7% after dissection and 45.2% after Ag-
ELISA assay was recorded in the N-arm. Six rounds of interventions were conducted in the E
arm and at mid-intervention (after the third round of intervention) the prevalence of PCC
dropped from 46% to 16.7% on Ag-ELISA analysis. At post intervention dissections, a marked
decrease in prevalence in the E-arm from 46% to 11.5% (non-viable cysts detected only) was
observed. The net effect of integrated interventions was at -1.23. There was, however, no
significant decrease in prevalence (67.7% to 50%) observed in the N-arm at post intervention
dissections. Taeniosis prevalences as detected by coproantigen ELISA, significantly decreased
(P<0.001) in the E-arm from 16% (at baseline) to 7.0% (at mid intervention) and 2.3% (11/480,
95% CI 1.1 – 4.1%) at post-intervention.
The N-arm had significantly more T. solium positive pigs than the E arm (p = 0.003), after the
interventions. The positive reduction in the prevalence of PCC by this combination of control
tools indicates the potential of eliminating cysticercosis using an integrated approach. This calls
for further evaluation studies to determine whether this control/prevention option is cost effective
and sustainable for sub-Sahara Africa.
Key words: Taenia solium – taeniasis – cysticercosis – Neglected Zoonotic Disease – tapeworm
intervention - control – elimination – sub-Saharan Africa – Zambia
Description
Thesis
Keywords
Taenia solium-elimination-sub-Saharan Africa – Zambia , Tapeworm control –sub-Saharan Africa – Zambia , Cholecystitis – Neglected Zoonotic Disease