Neglected tropical diseases

Developing surveillance indicators to measure global progress against pork tapeworm

25 January 2019 | Geneva –– The World Health Organization (WHO) is developing a set of indicators on surveillance and control to track global progress in controlling Taenia solium (pork tapeworm). Valid epidemiological data are scarce and knowledge gaps pose a problem to implementing effective control measures. In order to generate evidence towards better surveillance of the disease and make data available more easily, WHO has recently added global data on T. solium to its Global Health Observatory (GHO).

This is an important step towards making available important information on the global situation and trends of T. solium,” said Dr Bernadette Abela-Ridder, Team Leader of WHO’s Neglected Zoonotic Diseases unit. “Increasing access to reliable global data can help the drive for informed control policies, translate into better national policy and community-level action, and tackle the impact of neurocysticercosis and taeniasis on mainly poor communities, worldwide.

Data on the current status of T. solium taeniasis and neurocysticercosis are limited from many countries, so other risk factors are considered. Emphasis is given to evidence indicating active transmission of the disease and not only the presence of imported cases.

In order to classify each country according to their T. solium endemicity status, current GHO data were obtained from publications on the presence of porcine cysticercosis. Other factors were also considered, including pig population in a country; type of pig production (backyard pig rearing practices); notifications to the World Organisation for Animal Health (OIE); inequality adjusted human development index; sanitation data; geography and religion.1

One of the limitations is that data are presented at national level and not at subnational level. This is particularly relevant for some countries as transmission often occurs in specific locations.

The Global Health Observatory

The GHO is WHO’s gateway to health-related statistics for more than 1000 indicators.

Data are organized to monitor progress towards the Sustainable Development Goals (SDGs), providing analyses on global health priorities. Organized by theme pages, each page provides information on a global situation and trends, using core indicators, database views, major publications and links to relevant web pages.

Neglected zoonotic diseases are included under SDG 3.3. The GHO already includes data on rabies, and since December 2018, T. solium has also been included.

The disease

Taenia solium, also called taeniasis/cysticercosis is a neglected tropical disease belonging to the sub-group of neglected zoonoses that are highly endemic in many countries of sub-Saharan Africa, South-East Asia and Latin America.

The socioeconomic impact of cysticercosis is immense as it affects the health and livelihood of subsistence farming communities by causing neurocysticercosis in humans, reducing the market value of pigs and in making pork unsafe to eat.

Human infection with T. solium occurs when people eat raw or undercooked infected pork. Risk factors include poor sanitation, including the lack of latrines, unsafe water, poor pig husbandry practices, inadequate meat inspection and lack of knowledge about the causative parasite.

Neurocysticercosis – a sequelae of T. solium infection – results when parasite larvae lodge in the human brain, forming cysts.

1Donadeu M, Lightowlers MW, Fahrion AS, Kessels J, Abela-Ridder B. Taenia solium: WHO endemicity map update. Wkly Epidemiol Rec. 2016;91:5959.
2By 2030, end the epidemics of AIDS, tuberculosis, malaria and neglected tropical diseases and combat hepatitis, water-borne diseases and other communicable diseases.

Ashok Moloo
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