IMMUNIZE AND PROTECT YOUR FAMILY IN THIS ISSUE: PANAMERICANHEALTHORGANIZATION 1 AFP Surveillance in Canada 1 EPI Evaluation in Uruguay, 2006 6 Human Hookworm Vaccine Initiative 7 Update on Pro-Vac Initiative 8 Pan American Games & Rubella Alert Volume XXIX, Number 2 April 2007 Summary of EPI AFP Surveillance in Canada Evaluation in Uruguay, Elimination of indigenous wild poliovirus transmission was certified in Canada and the rest of the Region November 2006 of the Americas in September 1994. However, until global eradication of poliomyelitis is achieved, Canada recognizes there is an ongoing risk for importation of wild polioviruses.[1] Therefore, Canada maintains an The Pan American Health Organiza- acute flaccid paralysis (AFP) surveillance system with the overall goal to ensure prompt investigation of AFP tion (PAHO) offers its Member States cases to rule out poliovirus infections, in keeping with recommendations from the World Health Organiza- the opportunity to evaluate their tion (WHO).[2] This article describes the results of AFP surveillance for 2006 in Canada and highlights chal- national immunization programs lenges. through an international multidisci- plinary evaluation of the Expanded Methods Program on Immunization (EPI). The EPI evaluation serves as a tool for Canada’s AFP case definition includes any patient aged <15 years with onset of focal weakness or paralysis monitoring program advances and characterized as flaccid (reduced tone) without other obvious cause (e.g., trauma). Key surveillance indica- assessing the degree of development tors are based on WHO quality assurance criteria. They are as follows: and technical capacity available to 1) Sensitivity of surveillance: The ability to detect at least one case of non-polio AFP (including Guillain-Barré face new challenges. The third evalu- Syndrome/GBS) per year for every 100,000 children aged <15 years; ation of the National Immunization 2) Stool specimen collection from AFP cases: The collection of adequate stool specimens for poliovirus exami- Program (NIP) of the Republic of nation from at least 80% of AFP cases within 14 days of paralysis onset; and Uruguay took place from 6-17 No- 3) Case follow-up: Follow-up exam conducted at least 60 days after paralysis onset to verify the presence of vember 2006. residual paralysis in at least 80% of AFP cases. Canada’s AFP surveillance systems consists of two complimentary pediatric surveillance networks actively Background monitoring for AFP cases in children aged <15 years. One is hospital-based and the other is pediatrician practice-based. The IMPACT (Immunization Monitoring Program, ACTive) hospital-based sentinel network Uruguay has been a pioneer country consists of twelve pediatric tertiary care centers where AFP surveillance began in 1991. The Canadian Paedi- with regards to vaccine introduction. atric Surveillance Program (CPSP) consists of a over 2,300 pediatricians who began supplementing national It was the first country in Latin Amer- case detection and documentation in 1996. ica to introduce MMR (1982, with a second dose in 1992), Hib (1994), Virological investigation of cases includes collection and testing of stool specimens, cerebrospinal fluid (CSF), and varicella vaccines (1999). It is throat swabs and/or polio-specific serology. Additionally, bacterial culture for Campylobacter in stool was also one of the first countries to rec- ommend seasonal influenza vaccine. Figure 1. Non-Polio AFP Detection Rate, Canada, 1996-2006 Currently, Uruguay’s routine immu- nization schedule includes BCG at 1.20 1.03 1.04 WHO Target birth, pentavalent vaccine (DTP-Hib- . 0.97 s r 1.00 0.92 Hep B) and OPV at 2-4-6-12 months, y 5 MMR and varicella vaccines at 12 1 0.80 0.74 0.74 0.73 < 0.66 months, DTP and MMR vaccines at 5 0 0 0.59 0 0.60 , 0.50 0.48 years, and Td vaccines at 12 years, 0 0 with booster doses of the latter every 1 / 0.40 e t 10 years. Additionally, influenza vac- a R 0.20 cine is administered annually in cam- 0.00 paigns targeting seniors and children 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 aged 6-23 months. The 23-valent Year Source: Immunization & Respiratory Infections Division, Public Health Agency of Canada. See URUGUAY page 4 2 IMMUNIZATION NEWSLETTER Volume XXIX, Number 2 April 2007 PAN AMERICAN HEALTH ORGANIZATION Figure 2. Percentage of AFP Cases with Adequate Polio-Specific Stool Investigation, (96%) of the 2006 AFP cases were hospitalized. Canada, 1996-2006 The average length of stay was 14 days with a range of 1 to 39 days. Outcome at the time of 100 the initial report was missing for two cases. Of 90 WHO Target the remaining 25 cases for whom outcome was 80 reported, 5 (20%) had fully recovered, 17 (68%) s 70 e had partially recovered with residual weakness s 60 54.1 a 50.0 C 46.5 or paralysis, and 3 (12%) had not recovered but 50 f 41.0 42.6 39.5 41.8 o 37.1 40 33.3 their condition was progressing. % 29.5 30 Only one-third of cases (9/27) had the 60-day 20 14.8 follow up exam reported. Five of nine had fully 10 recovered, one had residual paralysis, one still 0 has exam pending, and one died. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year Discussion Source: Immunization & Respiratory Infections Division, Public Health Agency of Canada. The AFP rate in Canada is below the expected rate (Table 2). Since 1996, the WHO target was added to Canada’s AFP surveillance in 2001 to pears to be decreasing, with only seven (15%) of met only twice (in 1999 and 2000). However, the explore possible links between Campylobacter cases investigated in 2006 (Figure 2). Of these number of cases captured multiple times by IM- infection and GBS. Finally, to assist with case di- seven cases, only four were tested for poliovi- PACT and CPSC was high. In 2006, there was an agnosis, neurological investigation of AFP cases rus or non-polio enterovirus isolation within two average of two reports (initial notification report consists of CSF examination, nerve conduction weeks of paralysis onset. Two of the cases with or full case investigation report) for each con- studies, electromyography, MRI, or CT scan. stool collected were missing stool specimen col- firmed case, suggesting a sensitive surveillance lection dates and one had stool collected after based on multiple case detections (capture and Results two weeks of paralysis onset, when the sensitivi- re-capture). Late reports may still increase the ty of virus isolation is decreased. There were two Non-Polio AFP Detection Rate: During 2006, a 2006 detection rate. Nine confirmed AFP cases, instances where stool collection was requested with onset in 2005, had case investigation report total of 77 reports were received through the two but was not conducted. While there was no posi- pediatric surveillance networks, including 27 AFP forms submitted in 2006, the largest ever num- tive identification of polioviruses from any of the ber of late reports. These late reports elevated cases, 8 excluded reports, and 38 duplicate re- virological investigations, another viral etiology ports (single events captured two or more times the 2005 AFP rate to its highest level within five was identified in three cases (mononucleosis, through either network). Six of the eight reports years (0.97/100,000). Canada’s lower than ex- mycoplasma infection, and influenza B). (10%) were excluded based on age >15 years at pected AFP rates may be a result of under-detec- paralysis onset, and two (3%) based on another Campylobacter Investigation: Testing for Cam- tion of cases or, alternatively, they may be a true obvious cause. The final 27 confirmed cases for pylobacter steadily increased to 24% of AFP reflection of lower baseline levels for non-polio 2006 represent a non-polio AFP detection rate cases in 2005. In 2006, investigations increased AFP in Canada and other developed countries. of 0.48/100,000 children aged <15 years of age to 33% of APF cases and none were positive for Over the past 10 years, the proportion of cas- (Figure 1). Campylobacter. Given the short period for this es with adequate stool investigation has been type of investigation and the relatively low num- Age, Sex, and Immunization Status: In 2006, consistently below the WHO surveillance target ber of cases investigated each year, it is not pos- AFP cases ranged in age from 11 months to 14 of 80% of cases (Table 2). Surveillance qual- sible to draw any conclusions regarding Campy- years (median 7.4 years). As in previous years, ity could be improved through increased stool cases reported in 2006 were evenly distributed lobacter infection and the development of GBS sampling and virological testing for polioviruses across age groups. The male-to-female ratio was at this time. and non-polio enteroviruses. Given that most 1.2:1.0. Neurological Investigations: The majority of AFP cases in Canada are diagnosed as either GBS or transverse myelitis, clinical signs and Of the 27 AFP cases reported in 2006, 48% had cases (100% in 2006) continue to undergo one or more neurological investigations. Cases are symptoms consistent with these conditions may detailed documentation of routine childhood favor neurological investigation over virological immunization. Eleven of these had received age- diagnosed based on the clinical and neurologi- cal evaluation. Table 1 shows the distribution testing. However, the clinicians participating in appropriate polio immunization with inactivated AFP surveillance and investigation in Canada are poliovirus vaccine (IPV). An additional six cases of diagnosis for AFP reported since 1996. The majority are diagnosed as GBS. In 2006, there reminded that the importance of polio-specific had polio vaccination information reported as stool investigations and other virological inves- “up-to-date”, but with no accompanying details.