Profile of polio-compatible cases in Nigeria, 2006-2016

Background

The tremendous progress made by Nigeria towards polio eradication has recently suffered a setback with the isolation of circulating vaccine-derived poliovirus (cVDPV) type 2 from environmental samples and confirmation of four wild poliovirus (WPV) cases from acute flaccid paralysis (AFP) cases, with dates of onset of paralysis in July and August 2016. All these viruses were confirmed from the security-challenged northeastern state of Borno. Polio-compatible cases exist in Nigeria, and they indicate surveillance failure. Surveillance, therefore, has to be strengthened for the country to achieve certification. The objective of this paper is to highlight the epidemiological profile and magnitude of polio-compatible cases in Nigeria during the reporting period, as well as immunization and surveillance response activities conducted to close immunity and surveillance gaps.

Methods

We conducted a retrospective review of AFP surveillance performance and polio-compatible cases in Nigeria between 2006 and 2016 from the AFP database at the World Health Organization Country Office. We also reviewed and compared key epidemiological features of polio-compatible cases with those of wild poliovirus cases during the reporting period.

Results

The non-polio AFP rate improved from 6.5 in 2006 to 19.5 in 2016. The corresponding figures for stool adequacy rates were 88 and 98%. The total number of polio-compatible cases reported during the reporting period was 888, with the highest number (194) of cases reported in 2006 and the least (24) in 2016. Clusters of polio-compatible cases were reported every year during the reporting period except in 2015. The highest number (65) of polio-compatible cases in clusters was reported in 2006. The key epidemiological features of polio-compatible and wild poliovirus cases were similar.

Conclusion

AFP surveillance performance has improved significantly during the reporting period. Surveillance gaps still existed as shown by the presence of orphan viruses and polio-compatible cases, and these gaps need to be identified and closed to achieve certification.

The global switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV): facts, experiences and lessons learned from the south-south zone; Nigeria, April 2016

Background

The globally synchronized switch from trivalent Oral Polio Vaccine (tOPV) to bivalent Oral Polio Vaccine (bOPV) took place in Nigeria on April 18th 2016. The country is divided into six geopolitical zones. This study reports the experiences and lessons learned from the switch process in the six states that make up Nigeria’s south-south geopolitical zone.

Methods

This was a descriptive retrospective review of Nigeria’s switch plan and structures used for implementing the tOPV-bOPV switch in the south-south zone. Nigeria’s National Polio Emergency Operation Centre (NPEOC) protocols, global guidelines and reports from switch supervisors during the switch were used to provide background information for this study. Quantitative data were derived from reviewing switch monitoring and validation documents as submitted to the NPEOC

Results

The switch process took place in all 3078 Health Facilities (HFs) and 123 Local Government Areas (LGAs) that make up the six states in the zone. A total of $139,430 was used for this process. The ‘healthcare personnel’ component received the highest budgetary allocation (59%) followed by the ‘logistics’ component (18%).

Akwa Ibom state was allocated the highest number of healthcare personnel and hence received the most budgetary allocation compared to the six states (total healthcare personnel = 458, total budgetary allocation = $17,428).

Validation of the switch process revealed that eight HFs in Bayelsa, Cross-River, Edo and Rivers states still possessed tOPV in cold-chain while six HFs in Cross-River and Rivers states had tOPV out of cold-chain but without the ‘do not use’ sticker.

Akwa-Ibom was the only state in the zone to have bOPV and Inactivated Polio Vaccine (IPV) available in all its HFs monitored.

Conclusion

The Nigerian tOPV-bOPV switch was successful. For future Oral Polio Vaccine (OPV) withdrawals, implementation of the switch plan would be more feasible with an earlier dissemination of funds from global donor organizations, which would greatly aid timely planning and preparations. Increased budgetary allocation to the ‘logistics’ component to accommodate unexpected hikes in transportation prices and the general inefficiencies with power supply in the country is also advised.

Estimated Effect of Inactivated Poliovirus Vaccine Campaigns, Nigeria and Pakistan, January 2014-April 2016

In 2014, inactivated poliovirus vaccine (IPV) campaigns were implemented in Nigeria and Pakistan after clinical trials showed that IPV boosts intestinal immunity in children previously given oral poliovirus vaccine (OPV). We estimated the effect of these campaigns by using surveillance data collected during January 2014-April 2016. In Nigeria, campaigns with IPV and trivalent OPV (tOPV) substantially reduced the incidence of poliomyelitis caused by circulating serotype-2 vaccine-derived poliovirus (incidence rate ratio [IRR] 0.17 for 90 days after vs. 90 days before campaigns, 95% CI 0.04-0.78) and the prevalence of virus in environmental samples (prevalence ratio [PR] 0.16, 95% CI 0.02-1.33). Campaigns with tOPV alone resulted in similar reductions (IRR 0.59, 95% CI 0.18-1.97; PR 0.45, 95% CI 0.21-0.95). In Pakistan, the effect of IPV+tOPV campaigns on wild-type poliovirus was not significant. Results suggest that administration of IPV alongside OPV can decrease poliovirus transmission if high vaccine coverage is achieved.

Profiling the immunity status of children with non-polio acute flaccid paralysis who had not received any doses of oral polio vaccine in the South-South region, Nigeria 2011-2014

OBJECTIVES

To demonstrate the immunity status of children with non-polio acute flaccid paralysis (NP AFP) reported through the AFP surveillance system in the South-South region of Nigeria.

STUDY DESIGN

A retrospective study was conducted using AFP surveillance data collected routinely between January 2011 and December 2014 by the Disease Surveillance Department of the regional health service and the World Health Organization (WHO)-accredited regional reference polio laboratory. All cases of AFP reported to the Disease Surveillance Network from all six zones during this period were included in the study.

METHODS

In total, 5111 cases of AFP in children aged ≤15 years were reported between 2011 and 2014. These cases were investigated and verified by WHO surveillance officers using a standard questionnaire, which captured the number of doses of oral polio vaccine (OPV) received by the child. Two stool samples were collected for each case, 24-48 h apart, within 14 days of the onset of paralysis, and transported to the national polio laboratory under reverse cold chain storage. Data retrieved were stored in an AFP database hosted by the WHO server. EPIINFO software was used to query the database and extract the information required for analysis in this study.

RESULTS

The percentage of children who had received at least three doses of OPV (which serves as a threshold to measure immunity status) decreased from 87% in 2011 to 82% in 2014. The percentage of children who had not received any doses of OPV decreased from 2% in 2011 to 1% in 2014. Forty-eight percent of the children who had not received any doses of OPV were aged <1 year.

CONCLUSION

Given the decrease in OPV immunity status, the region risks re-introduction of poliovirus. Swift steps should be taken to improve the immunization coverage, which would boost immunity status in Nigeria.

Population Immunity against Serotype-2 Poliomyelitis Leading up to the Global Withdrawal of the Oral Poliovirus Vaccine: Spatio-temporal Modelling of Surveillance Data

BACKGROUND

Global withdrawal of serotype-2 oral poliovirus vaccine (OPV2) took place in April 2016. This marked a milestone in global polio eradication and was a public health intervention of unprecedented scale, affecting 155 countries. Achieving high levels of serotype-2 population immunity before OPV2 withdrawal was critical to avoid subsequent outbreaks of serotype-2 vaccine-derived polioviruses (VDPV2s).

METHODS AND FINDINGS

In August 2015, we estimated vaccine-induced population immunity against serotype-2 poliomyelitis for 1 January 2004-30 June 2015 and produced forecasts for April 2016 by district in Nigeria and Pakistan. Population immunity was estimated from the vaccination histories of children <36 mo old identified with non-polio acute flaccid paralysis (AFP) reported through polio surveillance, information on immunisation activities with different oral poliovirus vaccine (OPV) formulations, and serotype-specific estimates of the efficacy of these OPVs against poliomyelitis. District immunity estimates were spatio-temporally smoothed using a Bayesian hierarchical framework. Coverage estimates for immunisation activities were also obtained, allowing for heterogeneity within and among districts. Forward projections of immunity, based on these estimates and planned immunisation activities, were produced through to April 2016 using a cohort model. Estimated population immunity was negatively correlated with the probability of VDPV2 poliomyelitis being reported in a district. In Nigeria and Pakistan, declines in immunity during 2008-2009 and 2012-2013, respectively, were associated with outbreaks of VDPV2. Immunity has since improved in both countries as a result of increased use of trivalent OPV, and projections generally indicated sustained or improved immunity in April 2016, such that the majority of districts (99% [95% uncertainty interval 97%-100%] in Nigeria and 84% [95% uncertainty interval 77%-91%] in Pakistan) had >70% population immunity among children <36 mo old. Districts with lower immunity were clustered in northeastern Nigeria and northwestern Pakistan. The accuracy of immunity estimates was limited by the small numbers of non-polio AFP cases in some districts, which was reflected by large uncertainty intervals. Forecasted improvements in immunity for April 2016 were robust to the uncertainty in estimates of baseline immunity (January-June 2015), vaccine coverage, and vaccine efficacy.

CONCLUSIONS

Immunity against serotype-2 poliomyelitis was forecasted to improve in April 2016 compared to the first half of 2015 in Nigeria and Pakistan. These analyses informed the endorsement of OPV2 withdrawal in April 2016 by the WHO Strategic Advisory Group of Experts on Immunization.

Pattern of the meningococcal meningitis outbreak in Northern Nigeria, 2009

OBJECTIVES

Despite the availability of vaccines, children are the people most often affected by epidemic meningococcal meningitis. The pattern of the epidemic meningococcal meningitis outbreak in Northern Nigeria in 2009 and the Neisseria meningitidis strains responsible for this epidemic are described here.

METHODS

A retrospective cross-sectional study was conducted in 16 states, involving 48 local government areas (LGAs), 91 health facilities, and 96 communities. Data collection involved in-depth interviews with key informants from the federal to the community level, a review of records, and a solution-oriented national workshop with participants from all states of the Federation. Cerebrospinal fluid (CSF) samples were collected from some of the suspected cases at the start of the outbreak and were tested using the rapid Pastorex latex agglutination kit.

RESULTS

Kastina (11153, 20.4%), Jigawa (8643, 15.8%), Bauchi (8463, 15.5%), Kano (6811, 12.4%), and Gombe (6110, 11.2%) were the states with the highest prevalence of meningitis. The states of Nasarawa (11.0%), Adamawa (8.0%), and Borno (7.6%) recorded the highest percentage of deaths, while the Shongom (Gombe State 12.5%), Illela (Sokoto State 9.8%), and Ikara (Kaduna State 9.1%) LGAs recorded the most deaths amongst cases seen.

CONCLUSIONS

The testing of CSF samples during meningitis outbreaks is recommended in order to monitor the occurrence of the multiple meningitis serotypes during these outbreaks and to direct serotype-specific vaccination response activities.

Laboratory evaluation of three dual rapid diagnostic tests for HIV and syphilis in China and Nigeria

OBJECTIVE

To determine the laboratory-based performance and operational characteristics of three dual rapid diagnostic tests (RDTs) for testing HIV and syphilis.

METHODS

Three dual RDTs (SD Bioline, Chembio, and MedMira) were evaluated using 1514 serum specimens archived at laboratories or collected from clinics in China and Nigeria to determine sensitivity and specificity, with 95% confidence intervals. Concordance of testing results read by two technicians, stability of testing results read at two time points, and test operation characteristics were also assessed.

RESULTS

All three of the evaluated RDTs gave excellent performance with a combined sensitivity ranging from 99.0%-99.6% for HIV and 98.3%-99.0% for syphilis, and a combined specificity ranging from 97.9%-99.0% for HIV and 97.2%-99.6% for syphilis. Concordance of testing results between two technicians and stability of testing results read within and one hour past the recommended reading period showed excellent agreement, with Kappa greater than or equal to 0.98.

CONCLUSIONS

All the tests were found to be very or fairly easy to use and easy to interpret the results. Further evaluations of these dual RDTs with whole blood in field settings, and more studies on the implication of introduction of these tests in HIV and syphilis control programs are needed.

[Prevalence, risk behavior, and level of information on urinary schistosomiasis in primary school students from the Primeiro de Junho Health District, Maputo, Mozambique]

To assess the prevalence and identify levels of information and risk behavior associated with vesical schistosomiasis, a cross-sectional study was conducted in October-November 1996, involving students from 3 primary schools in the Primeiro de Junho health district in Maputo, Mozambique. Epidemiological interviews and urine samples were taken from 434 male and female students from grades 2 through 5, randomly selected. Estimated prevalence was 11.3% (49/434). Highest prevalence was in the age group ( 15 years old, and the highest intensity of infection among the 10-14-year age group, with 204 eggs/10 ml urine. Approximately 18.9% had heard of schistosomiasis, and of these, only 19.5% (16/82) knew how the disease is manifested. Approximately 50% of the students reported frequent water contacts with potential sources of schistosomiasis. The study shows that vesical schistosomiasis is a public health problem among students in this health district.

Preliminary survey of Leptospirosis and Lyme disease amongst febrile patients attending community hospital ambulatory care in Maputo, Mozambique

OBJECTIVES

To evaluate the importance of the spirochetes Leptospira interrogans s.l. and Borrelia burgdorferi s.l., as causes of human diseases (leptospirosis and Lyme borreliosis), in order to guide the development of laboratory services and patient management and to identify the appropriateness of future epidemiological studies.

DESIGN

Cross sectional serological survey.

SETTING

Maputo, the capital city of Mozambique.

SUBJECTS

160 adult patients (18 to 50 years of age) presenting, sequentially and for the first time, with a febrile illness at the outpatient's department of a community hospital.

METHODS

All sera were examined for L. interrogans s.l. antibodies by the standard microtiter technique (MAT), using as live culture antigens a battery of serovars representing 20 pathogenic serogroups. The IgM and IgG antibody response to B. burgdorferi s.l. was determined in all sera with an indirect IgG ELISA. In order to study potential serological cross-reactivity in malaria positive sera, all samples were further examined for antibodies against Plasmodium falciparum by indirect immunofluorescence. This was complemented with a standardised clinical history and physical examination.

MAIN OUTCOME MEASURES

Presence of antibodies to Leptospira interrogans s.l. and to Borrelia burgdorferi s.l..

RESULTS AND CONCLUSIONS

Although not conclusive, because of the inability to attempt rising serology and positive cultures, the results suggest that 10% of non-specific febrile illnesses could be attributed to leptospirosis. This study may thus form the background for a definitive Leptospira research in the same location. We confirm reports from other African countries that Lyme disease is an unlikely occurrence. We further suggest that some of the seropositivity observed for Lyme disease in Maputo could be attributed to serological cross reactivity with antibodies to P. falciparum malaria, leptospirosis or syphilis.

The effects of peer education on STD and AIDS knowledge among prisoners in Mozambique

The study was designed to evaluate the impact of education on AIDS knowledge among prison inmates in Maputo, Mozambique. A 6-month follow-up study was carried out in 1993 among 300 prisoners. A knowledge, attitudes, and practices questionnaire regarding AIDS and STD was administered to each subject as part of the intake medical examination and after an educational intervention provided by 30 prisoner 'activists'. A large proportion of prisoners had high risk behaviours (65% had 2 or more sexual partners per month and 39% had a history of STD) and low AIDS knowledge at incarceration. Statistically significant increases in knowledge occurred after the intervention. Prisoners with less formal education had a poorer performance on the initial questionnaire (43% vs 69% P < 0.00001) and had a greater improvement after the intervention (41% vs 24%, P < 0.00001). The results demonstrate that educational interventions involving peer health educators contribute positively to the acquisition of knowledge among prisoners.

Syphilis and HIV infection among prisoners in Maputo, Mozambique

A cross-sectional study was carried out among 1284 male and 54 female prisoners to assess the prevalence of and risk factors for sexually transmitted diseases (STD) in 4 correctional institutions of Maputo, Mozambique. Among the men, 32% reported a history of prostitute contact and 41% reported a history of STD. Only 9% reported having ever used condoms. Seventy (5.5%) men reported having had sexual intercourse while in prison, in all but one instance this involved sex with another man. There was no reported intravenous drug use. One hundred and four (7.8%) inmates had positive serological tests for syphilis and 8 (0.6%) had antibodies to HIV. Among men, syphilis was associated with a history of genital ulcer [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.4, 6.4] and uncircumcised status (OR = 1.5, 95% CI = 1.0, 2.5). This study demonstrates that syphilis is common among inmates in Maputo and that risk behaviours for STD transmission exist within Maputo prisons. There is a need for STD screening and treatment programmes within prisons in Mozambique and the introduction of educational interventions, including condom promotion.

Syphilis and HIV infection among displaced pregnant women in rural Mozambique

A cross-sectional study was conducted among displaced pregnant women in Mozambique to determine the prevalence and correlates of HIV infection and syphilis. Between September 1992 and February 1993, 1728 consecutive antenatal attendees of 14 rural clinics in Zambézia were interviewed, examined, and tested for HIV and syphilis antibodies. The seroprevalence of syphilis and HIV were 12.2% and 2.9%, respectively. Reported sexual abuse was frequent (8.4%) but sex for money was uncommon. A positive MHA-TP result was significantly associated with unmarried status, history of past STD, HIV infection, and current genital ulcers, vaginal discharge, or genital warts. Significant correlates of HIV seropositivity included anal intercourse, history of past STD, and syphilis. In summary, displaced pregnant women had a high prevalence of syphilis but a relatively low HIV seroprevalence suggesting recent introduction of HIV infection in this area or slow spread of the epidemic. A syphilis screening and treatment programme is warranted to prevent perinatal transmission and to reduce the incidence of chancres as a cofactor for HIV transmission.