The number of confirmed cases of polio worldwide has declined consistently since 1980 as a result of immunization. This statistic shows the number of cases of polio reported each year from 1980 to 2023 worldwide, by region.

As of August 2020, Africa was declared free of wild poliovirus, a disease that formerly paralyzed thousands of kids every year across the continent. The last cases of wild polio in Africa were registered in 2016, in Nigeria. In the last 24 years, a campaign against the illness has been done in the region, reaching African children, even in remote and insecure areas. Estimates indicate that nine billion vaccine doses were provided, while 1.8 million of wild polio cases were averted in the period. Despite the good results, Africa still has to fight against a circulating vaccine-derived poliovirus, that infects hundreds of people in areas with only partial vaccinations.

Project Tycho data include counts of infectious disease cases or deaths per time interval. A count is equivalent to a data point. Project Tycho level 1 data include data counts that have been standardized for a specific, published, analysis. Standardization of level 1 data included representing various types of data counts into a common format and excluding data counts that are not required for the intended analysis. In addition, external data such as population data may have been integrated with disease data to derive rates or for other applications.

Version 1.0.0 of level 1 data includes counts at the state level for smallpox, polio, measles, mumps, rubella, hepatitis A, and whooping cough and at the city level for diphtheria. The time period of data varies per disease somewhere between 1916 and 2011. This version includes cases as well as incidence rates per 100,000 population based on historical population estimates. These data have been used by investigators at the University of Pittsburgh to estimate the impact of vaccination programs in the United States, published in the New England Journal of Medicine: http://www.nejm.org/doi/full/10.1056/NEJMms1215400. See this paper for additional methods and detail about the origin of level 1 version 1.0.0 data.

Level 1 version 1.0.0 data is represented in a CSV file with 7 columns:

• epi_week: a six digit number that represents the year and epidemiological week for which disease cases or deaths were reported (yyyyww)
• state: the two digit postal code state abbreviation that represents the state for which a count has been reported
• loc: the name of a state or city for which a count has been reported, capitalized
• loc_type: the type of location (STATE or CITY) for which a count has been reported
• disease: the disease for which a count has been reported: HEPATITIS A, MEASLES, MUMPS, PERTUSSIS, POLIO, RUBELLA, SMALLPOX, or DIPHTHERIA
• cases: the number of cases reported for the specified disease, epidemiological week, and location
• incidence_per_100000: the number of cases per 100,000 people, computed using historical population counts for cities and states as reported by the US Census Bureau

These are information forms (copies) recording symptoms and provisional clinical diagnosis of suspected cases of poliomyelitis. There are copies of surveillance forms forwarded by the Director, Poliomyelitis Campaign to the Commonwealth Department of Health, Canberra, and contain, in addition, reports on previous poliomyelitis vaccination of the patient, laboratory specimens and surveillance committees' remarks and diagnosis. Also included is correspondence relating to the submission of surveillance forms. (8/967-68). 2 boxes. Note: This description is extracted from Concise Guide to the State Archives of New South Wales, 3rd Edition 2000.

Due to the advanced stage of polio eradication, the possible role of non-polio enteroviruses (NPEVs) associated to acute flaccid paralysis (AFP) cases has been highlighted. In this study, we described epidemiological aspects of NPEVs infections associated to AFP and explore the viral genetic diversity, information still scarce in Brazil. From 2005 to 2017, 6707 stool samples were collected in the scope of the Brazilian Poliomyelitis Surveillance Program. NPEVs were isolated in 359 samples (5.3%) and 341 (94.9%) were genotyped. About 46 different NPEV types were identified with the following detection pattern EV-B > EV-A > EV-C. The major EV-types were CVA2, CV4, EV-A71, CVB3, CVB5, E6, E7, E11, CVA13 and EV-C99, which corresponds to 51.6% of the total. Uncommon types, such as CVA12, EV-90 and CVA11, were also identified. Different E6 genogroups were observed, prevailing the GenIII, despite periods of co-circulation, and replacement of genogroups along time. CVA2 sequences were classified as genotype C and data suggested its dispersion in South-American countries. CVA13 viruses belonged to cluster B and Venezuelan viruses composed a new putative cluster. This study provides extensive information on enterovirus diversity associated with AFP, reinforcing the need of tailoring current surveillance strategies to timely monitor emergence/re-emergence of NPEVs.