Outbreak of paralytic poliomyelitis in Namibia

Reaching the unreached with polio vaccine and other child survival interventions through partnership with military in Angola

BACKGROUND

Growing conflict and insecurity played a major role in precipitating polio outbreaks in the Horn of Africa and the Middle East. In Angola, the early post-conflict situation was characterized by the presence of many inaccessible zones and districts due to insecurity and poor infrastructure. Partnership with the Angolan Army health service (AAHS) was one of the innovative strategies that the Polio Eradication Initiative (PEI) introduced into the country to support the polio vaccination campaigns in insecure and hard to reach zones.

METHODS

Before embarking on creating a partnership with Angolan military it was essential to make high-level advocacy with top military decision makers to engage the leadership in the process for better and sustainable support to the strategy. The principal supports provided by the AAHS were the administration of oral polio vaccine, vitamin A, deworming agents, social mobilization, monitoring campaign quality, and surveillance. Distribution of logistics using military vehicles and helicopters to hard to reach and insecure zones was also part of the support.

RESULTS

Using this partnership it was possible to reach a significant number of children in insecure and hard to reach areas with polio vaccine and other child survival interventions. The military partnership also contributed in increasing the demand and addressing rejection for the polio vaccine.

CONCLUSION

Military is a potentially productive force that can be used for any development activities in any country. The Angolan experience has demonstrated that it is possible to form a partnership with the military for basic health intervention activities with little training and investment.

Using short-message-service notification as a method to improve acute flaccid paralysis surveillance in Papua New Guinea

Background

High quality acute flaccid paralysis (AFP) surveillance is required to maintain polio-free status of a country. Papua New Guinea (PNG) is considered as one of the highest risk countries for polio re-importation and circulation in the Western Pacific Region (WPRO) of the World Health Organization due to poor healthcare infrastructure and inadequate performance in AFP surveillance. The Government of PNG, in collaboration with WHO, piloted the introduction of short-message-service (SMS) to sensitize pediatricians and provincial disease control officers on AFP and to receive notification of possible AFP cases to improve surveillance quality in PNG.

Methods

Ninety six health care professionals were registered to receive SMS reminders to report any case of acute flaccid paralysis. Fourteen SMS messages were sent to each participant from September 2012 to November 2013. The number of reported AFP cases were compared before and after the introduction of SMS.

Results

Two hundred fifty three unique responses were received with an overall response rate of 21 %. More than 80 % of responses were reported within 3 days of sending the SMS. The number of reported AFP cases increased from 10 cases per year in 2009–2012 to 25 cases per year during the study period and correlated with provincial participation of the health care professionals.

Conclusions

Combined with improved sensitization of health care professionals on AFP reporting criteria and sample collection, SMS messaging provides an effective means to increase timely reporting and improve the availability of epidemiologic information on polio surveillance in PNG.

Polio eradication in the African Region on course despite public health emergencies

The World Health Organization, African Region is heading toward eradication of the three types of wild polio virus, from the Region. Cases of wild poliovirus (WPV) types 2 and 3 (WPV2 and WPV3) were last reported in 1998 and 2012, respectively, and WPV1 reported in Nigeria since July 2014 has been the last in the entire Region. This scenario in Nigeria, the only endemic country, marks a remarkable progress. This significant progress is as a result of commitment of key partners in providing the much needed resources, better implementation of strategies, accountability, and innovative approaches. This is taking place in the face of public emergencies and challenges, which overburden health systems of countries and threaten sustainability of health programmes. Outbreak of Ebola and other diseases, insecurity, civil strife and political instability led to displacement of populations and severely affected health service delivery. The goal of eradication is now within reach more than ever before and countries of the region should not relent in their efforts on polio eradication. WHO and partners will redouble their efforts and introduce better approaches to sustain the current momentum and to complete the job. The carefully planned withdrawal of oral polio vaccine type II (OPV2) with an earlier introduction of one dose of inactivated poliovirus vaccine (IPV), in routine immunization, will boost immunity of populations and stop cVDPVs. Environmental surveillance for polio viruses will supplement surveillance for AFP and improve sensitivity of detection of polio viruses.

Outbreak of type 1 wild poliovirus infection in adults, Namibia, 2006

A paralytic poliomyelitis outbreak occurred in Namibia in 2006, almost exclusively among adults. Nineteen cases were virologically confirmed as due to wild poliovirus type 1 (WPV1), and 26 were classified as polio compatible. Eleven deaths occurred among confirmed and compatible cases (24%). Of the confirmed cases, 97% were aged 15-45 years, 89% were male, and 71% lived in settlement areas in Windhoek. The virus was genetically related to a virus detected in 2005 in Angola, which had been imported earlier from India. The outbreak is likely due to immunity gaps among adults who were inadequately vaccinated during childhood. This outbreak underscores the ongoing risks posed by poliovirus importations, the importance of maintaining strong acute flaccid paralysis surveillance even in adults, and the need to maintain high population immunity to avoid polio outbreaks in the preeradication period and outbreaks due to vaccine-derived polioviruses in the posteradication era.

Mass vaccination campaigns to eradicate poliomyelitis in Madagascar: oral poliovirus vaccine increased immunity of children who missed routine programme

To assess the impact of mass vaccination campaigns using oral poliovirus vaccine (OPV) in Madagascar, serum neutralizing antibodies and geometrical mean titres (GMTs) to poliovirus were measured among 472 children aged up to 59 months, before and after the mass campaign, regardless of their previous history of routine vaccination. In this study, overall coverage with three routine and two mass campaign OPV doses was 69.9 and 93.4%, respectively. Seroprevalences to all poliovirus types were significantly higher after the mass campaign among the children who were not vaccinated through routine programme: 67.5% vs. 90.2% (P < 0.001) for type 1; 66.7% vs. 95.1% (P < 0.001) for type 2; and 55.3% vs. 82.9% (P < 0.001) for type 3. Geometrical mean titres to all poliovirus types also significantly increased after the mass campaign among the same study group: 34.5 vs. 238.9 (P < 0.001) for type 1; 35.1 vs. 402.6 (P < 0.001) for type 2; and 13.3 vs. 92.6 (P < 0.001) for type 3. Post-mass campaign seroprevalences and GMTs for poliovirus, especially types 1 and 3, among children who received up to two routine and two mass campaign OPV doses were significantly higher than pre-mass campaign seroprevalences among children who received three routine OPV doses. Reasons for lack of adherence to the vaccination programme and the mass campaign are discussed. The findings strongly support the WHO strategy of conducting mass campaign in all endemic countries. However, as the mass campaign strategy now has been discontinued, it is crucial to increase the routine coverage and to improve acute flaccid paralysis surveillance in order to fulfil the goal of poliomyelitis eradication.

Decline in immunity to polio among young adults

A serologic survey was conducted on a population-based representative sample of 521 18-year-old soldiers recruited to the Israel Defence Forces in 1997. The prevalence of neutralizing antibodies and geometric mean titers (GMTs) against the three types of poliovirus (Mahoney, MEF and Saukett strains) were found to be 98.7% (GMT--169.95), 99.6% (GMT--297.14) and 96.4% (GMT - 59.48), respectively. These GMTs are markedly lower than those recorded 4 years after booster vaccination carried out during a 1988 polio outbreak, and suggest a decline in immunity against polio among young adults. These findings support the policy of routine revaccination of children and adolescents in countries at risk of imported polioviruses and of revaccination of adults traveling to areas to which polio is endemic.

Wild poliovirus circulation among healthy children immunized with oral polio vaccine in Antananarivo, Madagascar

From July 1995 to December 1996, 3185 stool specimens from healthy children aged 6-59 months attending 6 dispensaries in the Antananarivo area were examined for poliovirus. The children had been routinely immunized according to the Expanded Programme on Immunization (EPI) schedule and received the last dose of oral polio vaccine (OPV) more than 1 month before stool collection. 99.4% of the children were immunized with at least 3 doses of OPV. HEp-2 cell culture revealed virus infections in 192 stools (6.0%), including 9 poliovirus (0.3%) and 183 nonpolio enterovirus isolates (5.7%). Infections occurred throughout the year, but incidence was higher during the hot and rainy season (P=0.01). Using a neutralization test with monoclonal antibodies and PCR-RFLP in two genomic regions coding for the VP1 capsid and RNA polymerase, 4 wild polioviruses (3 type 1 and 1 type 3) and 5 vaccine-related polioviruses (2 Sabin 1-like variants, 1 Sabin 2-like and 2 Sabin 3-like) strains were identified. The wild polioviruses were isolated at the beginning and the end of the dry season. Similar RFLP patterns were observed for the 3 wild type 1 polioviruses. Comparison of partial genomic sequences in the VP1/2 A region of 1 of the wild type 1 isolates with 2 wild type strains isolated in Antananarivo in 1992 and 1993 showed a divergence of at least 10% between the strains, suggesting at least two different pathways of transmission during this period. Our findings demonstrate that immunization with 3 doses of OPV did not prevent intestinal carriage of wild poliovirus strains, and that there is a risk of wild poliovirus transmission to susceptible children in the area. Multiple strategies are required to improve immunization coverage in Madagascar.

Rare adverse events associated with oral poliovirus vaccine in Brazil

Oral poliovirus vaccine (OPV) developed by A. Sabin has been effectively used to control poliomyelitis in Brazil, and the last case with the isolation of a wild poliovirus strain occurred in March 1989. Although the vaccine controlled the circulation of wild strains and poliomyelitis cases associated with these strains were not detected during the last eight years, rare cases classified as vaccine-associated paralytic poliomyelitis (VAPP) have been detected. Molecular characterization studies of poliovirus strains isolated from VAPP cases and from healthy contacts have confirmed that the isolates are derived from the Sabin vaccine strains and also detected genomic modifications known or suspected to increase neurovirulence such as mutations and recombination. The molecular characterization of polioviruses isolated during the last eight years from paralysis cases classified as Guillain-Barré (GBS) syndrome and transverse myelitis (TM), and from facial paralysis (FP) cases also confirmed the vaccine origin of the strains and demonstrated mutations known to increase neurovirulence. Analysis of the epidemiologic data of these GBS, TM and FP cases demonstrated that in most of them the last OPV dose was given months or years before the onset of the disease and the isolation of the polioviruses. The temporal association between the isolation of these strains and the GBS, TM and FP suggested that the Sabin vaccine-derived poliovirus strains could also rarely trigger the diseases.

Molecular characterisation of type 1 polioviruses associated with epidemics in South Africa

The molecular epidemiology of wild-type 1 polioviruses isolated in South Africa during 2 major poliomyelitis epidemics in the 1980s and during the pre- and inter-epidemic periods was investigated by partial sequence analysis across the VP1/2A junction. Poliovirus-specific primers were used to amplify and subsequently sequence the region of interest. Viruses belonging to different genotypes were found to have been responsible for the 2 outbreaks. The Gazankulu outbreak in 1982 was caused by a poliovirus genotype which was unique to South Africa and which circulated endemically throughout much of the country between 1980 and 1985. Two additional genotypes, imported from the Middle East and West Africa, cocirculated endemically with the South African genotype between 1982 and 1985. The 1988 epidemic in Kwazulu-Natal was attributed to an imported genotype apparently introduced into South Africa in 1985 from countries north of the border. This genotype displaced the 3 genotypes previously in circulation and continued to be transmitted within the country until 1989, when the last confirmed cases of poliomyelitis associated with wild-type viruses were documented. All circulating wild-type poliovirus strains appear to have been eliminated from South Africa.

Differentiation between vaccine-related and wild-type polioviruses using a heteroduplex mobility assay

A heteroduplex mobility assay (HMA) was developed for intratypic differentiation between poliovirus isolates. The assay is based on polymerase chain reaction (PCR) amplification of a 480 base pair fragment which encodes a variable segment of VP1, followed by denaturation and reannealing of the resulting single strands with those from reference Sabin targets. Mismatches between wild-type and Sabin vaccine templates result in the formation of detectable heteroduplexes of reduced electrophoretic mobility. Poliovirus strains confirmed previously as wild-type or vaccine-like by PCR and sequencing were all correctly identified using the HMA. Mixtures of both wild-type and vaccine-like strains in a single isolate could also be detected using this technique. The results of this study demonstrate that heteroduplex analysis is a simple, rapid, and sensitive means for differentiating between vaccine-like and wild-type poliovirus isolates.