Transboundary nomadic population movement: a potential for import-export of poliovirus.

BACKGROUND: Nomadic populations have a considerably higher risk of contracting a number of diseases but, despite the magnitude of the public health risks involved, they are mostly underserved with few health policies or plans to target them. Nomadic population movements are shown to be a niche for the transmission of diseases, including poliomyelitis. The nomadic routes traverse the northern states of Nigeria to other countries in the Lake Chad subregion. As part of the February 2016 polio supplemental immunization activity (SIA) plans in Bauchi state, a review of nomadic routes and populations identified a nomadic population who originated from outside the international borders of Nigeria. This study describes the engagement process for a transboundary nomadic population and the interventions provided to improve population immunity among them while traversing through Nigeria. METHODS: This was an intervention study which involved a cross-sectional mixed-method (quantitative and qualitative) survey. Information was collected on the nomadic pastoralists entry and exit points, resting points, and health-seeking behavior using key informant interviews and semistructured questionnaire. Transit vaccination teams targeted the groups with oral polio vaccines (OPVs) and other routine antigens along identified routes during the months of February to April 2016. Mobile health teams provided immunization and other child and maternal health survival interventions. RESULTS: A total of 2015 children aged under 5 years were vaccinated with OPV, of which 264 (13.1%) were zero-dose during the February 2016 SIAs while, in the March immunization plus days (IPDs), 1864 were immunized of which 211 (11.0%) were zero-dose. A total of 296 children aged under 1 year old were given the first dose of pentavalent vaccine (penta 1), while 119 received the third dose (penta 3), giving a dropout rate of 59.8%. CONCLUSIONS: Nomadic pastoralists move across international borders and there is a need for transboundary policies among the countries in the Lake Chad region to improve population immunity and disease surveillance through a holistic approach using the One-health concept.

Brote de poliomielitis en Haiti y la Republica Dominicana debido a un virus derivado de la vacuna antipoliomielitica oral / Poliomyelitis outbreak caused by vaccine-derived virus in Haiti and the Dominican Republic

In October 2000, the Ministries of Helth of the Dominican Republic and Haiti notified two cases of acute flaccid paralyis (AFP) in rural areas, one of them in a 9-month-old female, and the other in a 2-year-old female, respectively. Stool samples that were obtained from these cases, which occured in July and August 2000, after a 9-year interruption of wild poliovirus circulation in the Western Hemisphere, revealed the presence of type 1 poliovirus. Genetic sequencing, which was later performed at the CEnters for Disease Control and Prevention, in Atlanta, Georgia, United States of America, revealed an atypical descendant of the virus used in the manufacture of the oral polio vaccine (OPV), but with 3 percent genetic divergence with respect to the parent strain. Normally, viral isolates that derive from vaccine components show 99.5 percent genetic agreement with the parent strain; in wild polioviruses, on the other hand, this agreement is usually less than 82.0 percent. Thus, the 3 percent genetic divergence detected in this study suggests that, in areas with low vaccine coverage, the virus used in the vaccine remained in circulation for at least two years, during which it recovered the neurovirulence and communicability of wild poliovirus type 1. This report describes the characteristics and results of the active search for cases of AFP that was sparked by the detection of the two index cases. It also looks at the public health implications of this outbreak for the entire Region of the Americas (AU)

The future of polio eradication.

As the global polio eradication initiative comes ever closer to its goal of terminating of all wild poliovirus transmission, significant challenges remain. Wild poliovirus transmission must be terminated in countries where low-level transmission persists, in large reservoir countries with high population density, and in conflict countries. Eradication can be achieved in these countries with determined and persistent effort, assuming that sufficient resources are mobilised. High quality surveillance needs to be implemented in the remaining polio endemic countries, especially in Africa. Surveillance is necessary in all countries until eradication is certified. A strategy for stopping immunisation after eradication is yet to be defined. A definition of this strategy would address the emergence of feral polioviruses, chronic vaccine virus infection in immunodeficient persons, and containment of laboratory strains. Until immunisation is stopped, high-population immunity should be maintained through uniformly high immunisation coverage with potent vaccines.

Control of influenza and poliomyelitis with killed virus vaccines.

The requirements for inducing immunity against an infectious disease are outlined, and the application of these requirements to the development of effective vaccines (vaccinology) is discussed. Influenza and poliomyelitis are examined from this viewpoint, and data are presented that demonstrate the effectiveness of killed virus vaccines against these diseases. A comparison between live and killed poliovirus vaccines suggests the desirability of returning to the use of a killed virus vaccine for the eradication of polio. The natural history of influenza and experience with vaccination suggest that influenza might be brought under effective control by routine immunization in childhood with a polyvalent killed virus vaccine potentiated by an immunologic adjuvant.