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      Resurgence of Vaccine-Preventable Diseases in Venezuela as a Regional Public Health Threat in the Americas

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      , , , , , , , , , , , , , , , , , , , , , , , , , , ,
      Emerging Infectious Diseases
      Centers for Disease Control and Prevention
      measles, diphtheria, polio, Venezuela, outbreak, vaccine-preventable diseases, vector-borne infections, viruses, Americas, vaccines, vaccination, immunization

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          Abstract

          Venezuela’s tumbling economy and authoritarian rule have precipitated an unprecedented humanitarian crisis. Hyperinflation rates now exceed 45,000%, and Venezuela’s health system is in free fall. The country is experiencing a massive exodus of biomedical scientists and qualified healthcare professionals. Reemergence of arthropod-borne and vaccine-preventable diseases has sparked serious epidemics that also affect neighboring countries. In this article, we discuss the ongoing epidemics of measles and diphtheria in Venezuela and their disproportionate impact on indigenous populations. We also discuss the potential for reemergence of poliomyelitis and conclude that action to halt the spread of vaccine-preventable diseases within Venezuela is a matter of urgency for the country and the region. We further provide specific recommendations for addressing this crisis.

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          War and Infectious Diseases: Challenges of the Syrian Civil War

          Overview Syria's ongoing three-year civil war has displaced 6.5 million Syrians, left hundreds of thousands wounded or killed by violence, and created a vacuum in basic infrastructures that will reverberate throughout the region for years to come. Beyond such devastation, the civil war has introduced epidemics of infections that have spread through vulnerable populations in Syria and neighboring countries. In this article, we discuss the growing epidemics of poliomyelitis, measles, and cutaneous leishmaniasis in Syria and the region to examine the impact of conditions of war on the spread of infectious diseases in a public health emergency of global concern. Introduction In March 2011, unrest from the Arab Spring found its way to Syria, interrupting over 40 years of political stability and igniting a civil war that continues to ravage the country with no end in sight [1]. Beyond direct casualties, war, particularly civil war, provides ideal conditions for outbreaks of infections, and Syria's ongoing three-year civil war has been no exception to this rule [2]. Measles, hepatitis A, leishmaniasis, poliomyelitis, meningitis, and scabies have spread through vulnerable populations in Syria and refugee camps in neighboring countries, creating a health crisis that will require immense resources to address (Table 1) [3]. Concurrently, the shattered medical infrastructure, the exodus of health care workers, and the deterioration of immunization programs have created a dangerous vacuum in essential health care provision [4]. In the context of Syria's devastated health care infrastructure, we will discuss the spread of infectious diseases, particularly poliomyelitis, measles, and cutaneous leishmaniasis, among Syrian civilians, refugees, and citizens of neighboring countries, to examine what is nothing short of a regional, and arguably global, public health emergency. 10.1371/journal.ppat.1004438.t001 Table 1 Reported cases of communicable diseases per year between 2011 and 2014 in Syria, Lebanon, and Jordan. NUMBER OF COMMUNICABLE DISEASE CASES REPORTED PER YEAR Syrian Arab Republica Lebanese Republicc Syrian Refugees in Lebanonc Hashemite Kingdom of Jordand 2011 2012 2013 2014∧ 2011 2012 2013 2014* 2013 2014* 2011 2012 2013 2014 Poliomyelitis 0 0 35b 1b 0 0 0 0 0 0 0 0 0 n/a Measles n/a 13 n/a n/a 9 9 1760 219 232 92 30 24 205 n/a Cutaneous Leishmaniasis n/a 52,982 n/a n/a 5 2 1033 381 998 364 136 103 146 n/a Hepatitis A n/a 2203 n/a n/a 448 757 1551 738 220 127 418 509 1082 n/a Typhoid Fever n/a 1129 n/a n/a 362 426 407 102 21 7 2 4 4 n/a a Data obtained from the Syrian Ministry of Health website in the Quarterly Report of Communicable Diseases [30]. b Data obtained from the Global Polio Eradication Initiative website [16]. c Data obtained from the Epidemiologic Surveillance Department of the Lebanese Ministry of Public Health [26]. d Data obtained from the Communicable Diseases System on the Jordan Ministry of Health Website [25]. ∧ 2014 Data last reported on 08/13/14 from the Global Polio Eradication Initiative website [16]. * 2014 Data last reported on 08/01/14 from the Epidemiologic Surveillance Department of the Lebanese Ministry of Public Health [26]. The War on Health Care Prior to the conflict, the health care system in Syria consisted of a government-run public system that provided mostly primary care services, with the private sector concentrated in urban areas providing the majority of advanced care services [1]. The past three decades were characterized by an improved capacity of the health system, as well as rapidly improving national health indicators such as a falling infant mortality rate and an increased child immunization rate. Yet the onset of the civil war led to the complete deterioration of the health infrastructure through the wide destruction of facilities, the shortage in health care personnel and medicines, and a lack of secure routes and transportation. Rather than providing a safe place of care and refuge, the Syrian health care system has been integrated into the civil war battlefield. Both the regime's military forces and antigovernment armed groups have attacked and appropriated medical facilities as a tactic of warfare [5]. According to the World Health Organization (WHO), 40% of Syria's ambulances are destroyed and 57% of public hospitals are severely damaged, with 37% remaining out of service [6]. At least 160 doctors have been killed and hundreds jailed, leading to the emigration of an estimated 80,000 doctors [4]. The 90% of pharmaceutical needs that were locally produced prior to the conflict has now been reduced to only 10%, contributing to significant drug shortages in essential medications [1]. Such shortages, power outages, and the lack of security and mobility to seek care all contribute to the growing humanitarian crisis in Syria. This health care crisis has extended beyond Syria's borders with one of the largest refugee crises since World War II [2]. Millions have entered the neighboring countries of Lebanon, Jordan, and Turkey in search of security. In Lebanon, over a million Syrian refugees currently represent a quarter of the country's population, residing among the local population in over 540 sites, as refugee camps are yet to be built [7]. In Jordan, there are 3,500 Syrian refugees crossing the border each day, with 20% residing in the Al Zaatari camp and the remaining 80% living in urban areas in the north of Jordan [8]–[10]. In both countries, Syrian refugees utilize local health care resources. This has significantly strained local health care systems with insurmountable demands ranging from continued chronic care to the management of spreading communicable diseases [11]. The underfunding of UNHCR (United Nations High Commissioner for Human Rights) and other humanitarian organizations has reduced the medical subsidies to refugees, leading many to forgo necessary yet unaffordable treatment [12]. In Syria and its neighboring countries, critical gaps in essential health care delivery continue to aggravate what has been described as the worst humanitarian crisis of the 21st century [6]. War and Infectious Diseases The conditions of war among civilian populations exacerbate risk factors for the spread of infections [13]. Vaccine-preventable diseases: Poliomyelitis, measles, and an international wake-up call The devastated health care infrastructure in Syria has hindered immunization programs, leaving millions of citizens vulnerable to vaccine-preventable diseases [14]. Vaccination coverage in Syria is estimated to have dropped from 91% in 2010 to as low as 45% in some regions by 2013, indicating rapid collapse of immunization systems in conditions of war [3]. Of the 1.8 million Syrian children born since the conflict, over 50% are unvaccinated [15]. Consequently, 36 cases of poliomyelitis have been officially reported in Syria after 15 years of eradication [16]. Although the opposition-held northeastern province of Deir Ez Zur has been the epicenter of the outbreak, cases have been encountered in rural areas of Damascus, Aleppo, and other regions [17]. The poliomyelitis virus lives in sewage, water, and contaminated food. In Syria, raw sewage is pumped directly into the Euphrates River, which provides drinking and washing water to villages and chlorination to decontaminate the water has been discontinued since 2012 [15]. The strain of poliomyelitis in Syria has been linked to the wild-type poliovirus 1 (WPV1) from Pakistan, which is suspected to have been introduced to Syria by Pakistani jihadist fighters [18], [19]. The same strain was detected in the sewage of Cairo in December 2012 and in sewage in Israel and the West Bank shortly thereafter, without any clinical cases thanks to high vaccination rates in these areas [20]. WPV1 can easily and undetectably spread, with only one in two hundred unvaccinated infected individuals developing acute flaccid paralysis [18]. WHO estimates that over 7,600 Syrians are currently infected, since poliomyelitis thrives in unsanitary, crowded conditions and among malnourished children [21]. In response to this outbreak, the biggest immunization campaign in the region's history led to the vaccination of over 2.7 million Syrian children and 23 million in neighboring countries [13]. The campaign employed the bivalent oral polio vaccine, which challenges a child's immune response with the two remaining types of virus and can be used in short intervals for acute outbreak responses [20], [22]. Nevertheless, the constantly migrating population, the lack of precise monitoring mechanisms, and besieged locations that remain out of reach to immunization threaten the success of this campaign. While cases are yet to be reported in Lebanon and Jordan, Iraq has confirmed the first case of poliomyelitis, after a 14-year hiatus, in northern Baghdad [23]. This poliomyelitis outbreak has helped focus international attention on the severity of the ongoing health crisis in Syria, as well as the importance of reinvigorating eradication campaigns in the endemic countries of Afghanistan, Pakistan, and Nigeria to prevent the recurrence of such outbreaks [17]. Polio in Syria has been declared a public health emergency that requires international efforts and solidarity to prevent a global epidemic. The hampering of immunization efforts has also contributed to the spread of other vaccine-preventable diseases such as measles. Overcrowding, unsanitary conditions, and the efficient transmissibility of measles make the Syrian population highly susceptible to acquiring and spreading the infection. Measles has swept through Syria, including Aleppo and the northern regions, with over 7,000 confirmed cases [24]. This epidemic has not spared refugees in neighboring countries, even among highly vaccinated populations [14]. In Jordan, 24 cases of measles were reported in 2012, while over 200 cases were reported in 2013 [25]. In Lebanon, nine reported cases of measles in 2012 increased to 1,760 cases in 2013, only 13.2% of which were among Syrian refugees [26]. The growing rate of infection among Lebanese nationals reveals how conditions of unrest have exploited deficiencies in Lebanon's measles immunization coverage to contribute to a regional crisis. In response, the Lebanese Ministry of Public Health launched a national immunization campaign in April 2014 with over 4,200 trained volunteers administering vaccines for polio, measles, and rubella [27]. While ongoing vaccination campaigns have tried to address this epidemic, challenges continue to prevent adequate coverage. Unlike the poliomyelitis vaccine, which is relatively easy to transport and is administered orally, the measles vaccine must remain chilled and is administered by injection, posing a challenge for aid workers trying to reach vulnerable populations. Although immunization campaigns continue to deliver vaccines for measles and poliomyelitis to millions of adults and children in Syria and the surrounding region, the ongoing civil war restricts access to entire districts, threatens the lives of volunteers in the immunization campaign, and hinders efforts to quell the ongoing humanitarian crisis. Leishmaniasis and a region at risk The risk factors for cutaneous leishmaniasis, including malnutrition, poor housing, population displacement, and poverty, are unfortunately all met in the case of the Syrian crisis, transforming the national epidemic of cutaneous leishmaniasis into a regional threat [28]. Cutaneous leishmaniasis has been endemic in parts of Syria, mainly Aleppo, for decades [29]. However, the Syrian conflict and vast population displacement has significantly increased the incidence of the vector-borne disease within Syria and spread this epidemic into neighboring countries. Reported cases of cutaneous leishmaniasis in Syria continue to rise, with the last official figure reporting 52,982 confirmed cases in 2012 [30]. Lebanon had no cases of cutaneous leishmaniasis before 2008 and sporadic cases in the following years. By 2013, 1,033 cases were confirmed, 96.6% (998) of which were among Syrian refugees [26]. In recently published data on 1,275 patients from 213 displaced Syrian families in Lebanon, the average age among infected individuals was 17 years, with many patients presenting with multiple disfiguring lesions (Figure 1). 77% of the patients manifested the disease after being in Lebanon for more than eight weeks, which is the known incubation period for cutaneous leishmaniasis, suggesting that the sand fly vector was transported to Lebanon with the incoming refugees [31]. Speciation by PCR showed that 85% of cases were caused by Leishmania tropica, with 15% of cases as Leishmania major [31]. 10.1371/journal.ppat.1004438.g001 Figure 1 Syrian child from a Lebanon refugee camp, presenting multiple lesions from cutaneous leishmaniasis, courtesy of Dr. Ibrahim Khalifeh The dense concentration of refugees, the similar environmental conditions, and the limited health care access in rural areas contribute to the higher burden of leishmaniasis in Lebanon. This epidemic has raised concerns that the sand fly vector may find a permanent habitat in Lebanon, particularly in rural areas with a high density of Syrian refugees such as the Bekaa valley, which holds 70% of all reported cases [32]. This outbreak has been the first of its kind in more than a decade and will continue to grow within the upcoming summer months if left unaddressed [32]. The Lebanese Ministry of Public Health (MOPH) and relevant governmental departments are planning a coordinated campaign to contain the spread of the infection, which includes spraying pesticides to kill the vector, providing free treatment and diagnosis for emerging cases and monitoring disease activity [32]. In April 2013, the Lebanese MOPH, in conjunction with WHO, organized workshops to train doctors across Lebanon to recognize the condition. In addition to the growing threat of leishmaniasis, experts have warned against the emergence of other vector-borne diseases such as dengue fever and malaria [33]. A Civil War and a Global Threat Without security, there can be no health. All efforts to quell the humanitarian crisis and to rebuild the broken health infrastructure in Syria will be largely futile as long as the civil war continues to rage on. The immediate end of war is inextricable from efforts to spare innocent lives and control this global threat of infectious diseases. Yet while the political borders of a conflict can be delineated, health care repercussions are uncontained by geopolitical borders. The spillover of refugees and communicable diseases into Lebanon, Jordan, and Iraq demonstrates the rippling consequences of the protracted Syrian conflict. In addition to the aforementioned infections, diseases such as typhoid fever, hepatitis A, meningitis, scabies, and lice continue to affect an increasingly vulnerable population. The international community has fallen short in its response to the crisis of infectious diseases in the Syrian conflict, and the consequences of this failure will continue to grow until there is a coordinated and exhaustive global effort.
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            Vaccine refusal - what we need to know

            Abstract Objective: Opposition to vaccines is not a new event, and appeared soon after the introduction of the smallpox vaccine in the late 18th century. The purpose of this review is to educate healthcare professionals about vaccine hesitancy and refusal, its causes and consequences, and make suggestions to address this challenge. Source of data: A comprehensive and non-systematic search was carried out in the PubMed, LILACS, and ScieLo databases from 1980 to the present day, using the terms "vaccine refusal," "vaccine hesitancy," and "vaccine confidence." The publications considered as the most relevant by the author were critically selected. Synthesis of data: The beliefs and arguments of the anti-vaccine movements have remained unchanged in the past two centuries, but new social media has facilitated the dissemination of information against vaccines. Studies on the subject have intensified after 2010, but the author did not retrieve any published studies to quantify this behavior in Brazil. The nomenclature on the subject (vaccine hesitancy) was standardized by the World Health Organization in 2012. Discussions have been carried out on the possible causes of vaccine hesitancy and refusal, as well as on the behavior of families and health professionals. Proposals for interventions to decrease public doubts, clarify myths, and improve confidence in vaccines have been made. Guides for the health care professional to face the problem are emerging. Conclusions: The healthcare professional is a key element to transmit information, resolve doubts and increase confidence in vaccines. They must be prepared to face this new challenge.
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              Progress Toward Polio Eradication — Worldwide, January 2016–March 2018

              In 1988, when an estimated 350,000 cases of poliomyelitis occurred in 125 countries, the World Health Assembly resolved to eradicate polio globally. Transmission of wild poliovirus (WPV) continues uninterrupted in only three countries (Afghanistan, Nigeria, and Pakistan) ( 1 ), and among the three serotypes, WPV type 1 (WPV1) remains the only confirmed circulating type. This report describes global progress toward polio eradication during January 2016–March 2018, and updates previous reports ( 2 ). In 2017, 22 WPV1 cases were reported, a 41% decrease from the 37 WPV1 cases reported in 2016. As of April 24, 2018, eight WPV1 cases have been reported (seven in Afghanistan and one in Pakistan), compared with five cases during the same period in 2017. In Pakistan, continuing WPV1 transmission has been confirmed in multiple areas in 2018 by isolation from wastewater samples. In Nigeria, ongoing endemic WPV1 transmission was confirmed in 2016 ( 3 ); although WPV was not detected in 2017 or in 2018 to date, limitations in access for vaccination and surveillance in insurgent-held areas in northeastern Nigeria might permit continued undetected poliovirus transmission. Substantial progress toward polio eradication has continued in recent years; however, interruption of WPV transmission will require overcoming remaining challenges to reaching and vaccinating every missed child. Until poliovirus eradication is achieved, all countries must remain vigilant by maintaining high population immunity and sensitive poliovirus surveillance. Routine Poliovirus Vaccination Coverage Among infants aged 1 year, the estimated global coverage with 3 doses of poliovirus vaccines (Pol3, mostly oral poliovirus vaccine [OPV]) through routine immunization services was 85% in 2016 (the most recent year for which data are available). World Health Organization (WHO)/United Nations Children’s Fund estimates for Pol3 coverage in 2016 were 73% in the African Region, 92% in the Region of the Americas, 80% in the Eastern Mediterranean Region, 94% in the European Region, 87% in the South-East Asia Region, and 95% in the Western Pacific Region, with heterogeneity in coverage among countries in all regions.* National Pol3 coverage with the third dose of OPV (OPV3) in the three countries with endemic WPV transmission in 2016 was 60% in Afghanistan, 72% in Pakistan, and 49% in Nigeria. OPV3 coverage is substantially lower in areas of WPV transmission, where children in high-risk mobile populations or areas of conflict are repeatedly missed ( 4 , 5 ). Rarely, in areas with low vaccination coverage, Sabin-like viruses can spread and revert to neurovirulence, resulting in outbreaks of disease caused by circulating vaccine-derived polioviruses (cVDPV). Approximately 90% of cVPDV cases reported since 2006 have been caused by type 2 (cVDPV2). In countries with recent cVDPV detections, Pol3 coverage was 74% in the Democratic Republic of the Congo (DRC), 48% in Syria, 47% in Somalia, and 83% in Laos ( 6 ). In these countries, OPV3 coverage was substantially lower in subnational areas with cVDPV emergence and transmission. Following certification of the eradication of WPV type 2 (WPV2) in 2015, a global, synchronized withdrawal of trivalent OPV (tOPV, containing types 1, 2, and 3 live, attenuated polioviruses), and switch to bivalent OPV (bOPV, containing types 1 and 3 only), was completed by the end of April 2016 ( 7 ). Starting in 2015, injectable trivalent inactivated poliovirus vaccine (IPV) was introduced into routine immunization schedules in OPV-using countries, generally at 14 weeks of age. Some countries had to delay introduction of IPV until 2018 because of global shortages of the vaccine. Supplementary Immunization Activities In 2016, 186 supplementary immunization activities (SIAs) were conducted in five WHO regions, during which approximately two billion total OPV and IPV doses were administered (Table 1), including 1,264,552,301 (63%) doses administered during national immunization days, 710,995,110 (36%) during subnational immunization days, and 17,603,036 (1%) doses during focused SIAs in areas of known or suspected poliovirus circulation (“mop-up” activities). In the event of cVDPV2 outbreaks, on advice of the monovalent OPV type 2 (mOPV2) Global Advisory Group, the WHO Director-General releases mOPV2 for outbreak response immunization. Of the administered doses, more than half (51%) were tOPV and approximately half (47%) were bOPV; an additional 1.4% were mOPV2, 0.05% were IPV plus bOPV, 0.2% were IPV alone, and 0.15% were fractional IPV (0.1 mL administered intradermally). TABLE 1 Number of supplementary immunization activities (SIAs) conducted, and number of oral poliovirus vaccine (OPV) and inactivated poliovirus (IPV) doses administered, by World Health Organization (WHO) region — worldwide, 2016–2017 Year/SIAs/Vaccine doses administered Region Global AFR AMR EMR EUR SEAR WPR 2016 SIAs (no.) 186 97 0 67 2 14 6 Vaccine (no. of doses administered) mOPV2 28,357,599 28,357,599 0 0 0 0 0 bOPV 940,622,006 274,197,570 397,909,506 54,880,271 206,507,773 7,126,886 tOPV 1,017,074,205 407,366,635 0 103,470,392 1,097,605 496,401,815 8,737,758 IPV 3,293,021 1,943,763 134,9258 0 0 0 IPV + bOPV 904,050 0 0 904,050 0 0 0 fIPV 2,899,566 0 0 252,354 0 2,647,212 0 Total doses 1,993,150,447 711,865,567 0 503,885,560 55,977,876 705,556,800 15,864,644 2017 SIAs (no.) 172 82 0 79 2 8 1 Vaccine (no. of doses administered) mOPV2 70,356,186 65,067,196 0 5,288,990 0 0 0 bOPV 1,705,913,274 519,920,180 0 488,368,342 389,314 696,180,796 1,054,642 tOPV 0 0 0 0 0 0 0 IPV 3,522,237 558,897 0 2,963,340 0 0 0 IPV + bOPV 8,920,134 0 8,920,134 0 0 0 fIPV 0 0 0 0 0 0 0 Total doses 1,788,711,831 585,546,273 0 505,540,806 389,314 696,180,796 1,054,642 Abbreviations: AFR = African Region, AMR = Region of the Americas; bOPV2 = bivalent oral poliovirus, types 1 and 3; EMR = Eastern Mediterranean Region; EUR = European Region; fIPV = fractional dose inactivated poliovirus vaccine (one fifth of a 0.5 mL intramuscular dose, given intradermally); IPV = inactivated poliovirus vaccine; mOPV2 = monovalent oral poliovirus, type 2; SEAR = South-East Asia Region; tOPV2 = trivalent oral poliovirus, types 1, 2, 3; WPR = Western Pacific Region. In 2017, 172 SIAs were conducted in five WHO regions, during which approximately 1.79 billion total OPV and IPV doses were administered, including 1,110,923,756 (62%) doses administered during national immunization days, 672,091,158 (38%) during subnational immunization days, and 5,696,917 (0.3%) during mop-up activities. Of the administered doses, 95% were bOPV, 3.9% were mOPV2, 0.5% were IPV plus bOPV, and 0.2% were IPV alone. Poliovirus Surveillance Surveillance for acute flaccid paralysis (AFP) is the means of detecting polio cases caused by WPV or cVDPV, confirmed by stool specimen testing through the Global Polio Laboratory Network. The performance of AFP surveillance is assessed through two main indicators: sensitivity and completeness of case investigation. An annual nonpolio AFP rate of ≥1 case per 100,000 population aged <15 years for countries in the WHO regions certified as poliofree, or ≥2 for all other countries is considered sufficiently sensitive to detect a case of polio, should it occur. Case investigation is considered to be sufficiently complete if at least 80% of reported AFP cases have adequate stool specimens collected (i.e., two stool specimens collected ≥24 hours apart, within 14 days of paralysis onset, with arrival at a WHO-accredited laboratory in good condition). In 2016, among the four countries reporting polio cases, three (Afghanistan, Nigeria, Pakistan) met both performance indicators and one (Laos) did not. Among the five countries reporting polio cases in 2017, four (Afghanistan, DRC, Nigeria, Pakistan) met both performance indicators and one (Syria) did not. Although Nigeria and DRC meet AFP surveillance indicators nationally and subnationally in most provinces, both countries are affected by substantial issues in population accessibility and other impediments to AFP surveillance ( 1 ). AFP surveillance has been supplemented by environmental surveillance through testing of sewage in many countries, including poliofree countries as well as those with endemic transmission ( 1 ). Reported Poliovirus Cases Countries reporting WPV cases. In 2016, 37 WPV cases were detected (Figure): 13 (35%) in Afghanistan, 20 (54%) in Pakistan, and four (11%) in Nigeria. In 2017, 22 WPV cases were identified: 14 (64%) in Afghanistan and eight (36%) in Pakistan. No WPV cases have been identified in countries outside of Afghanistan, Nigeria, and Pakistan since 2014. During January 1–March 30, 2018, as of April 24, the low poliovirus transmission season, eight WPV1 cases were reported (seven in Afghanistan; one in Pakistan) (Figure) (Table 2). FIGURE Number of cases of wild poliovirus, by month of onset — worldwide, January 2015–March 2018* * Data as of April 24, 2018. The figure above is a histogram showing the number of worldwide cases of wild poliovirus, by month of onset, during January 2015–March 2018. TABLE 2 Number of reported polio cases, by country — Worldwide, January 1, 2016–March 30, 2018* Classification/Country 2016 (Jan 1–Dec 31) 2017 (Jan 1–Dec 31) 2017 (Jan 1–Mar 30) 2018 (Jan 1–Mar 30) WPV cVDPV WPV cVDPV WPV cVDPV WPV cVDPV Countries with endemic polio Afghanistan 13 0 14 0 3 0 7 0 Pakistan 20 1 8 0 2 0 1 0 Nigeria 4 1 0 0 0 0 0 0 Total cases in endemic countries 37 2 22 0 5 0 8 0 Other countries with reported cVDPV cases Laos 0 3 0 0 0 0 0 0 Democratic Republic of the Congo 0 0 0 22 0 0 0 3 Syria 0 0 0 74 0 0 0 0 Total cases in other countries 0 3 0 96 0 0 0 3 Total paralytic polio cases 37 5 22 96 5 0 8 3 Abbreviations: cVDPV = circulating vaccine-derived poliovirus; WPV = wild poliovirus. * Data as of April 24, 2018. Afghanistan reported 13 WPV1 cases in four districts in 2016, compared with 14 WPV1 cases in nine districts in 2017 (7.7% increase). In 2016, 54% of WPV1 cases in Afghanistan were reported from Paktika province in the southeastern region. In 2017, 50% of WPV1 cases were reported from Kandahar province in the southern region. During January 1–March 30, 2018, seven WPV1 cases were detected (four in Kandahar province, one in Nangahar province, and two in Kunar province; the latter two provinces are in the eastern region), compared with three WPV1 cases detected during the same period in 2017. Pakistan reported a 60% decrease in the number of WPV1 cases, from 20 cases in four districts in 2016 to eight cases in seven districts in 2017. During January 1–March 30, 2018, one WPV1 case was reported (in Balochistan province), compared with two reported during the same period in 2017. WPV1 continues to be isolated from environmental surveillance sites in five provinces of the country (Balochistan, Islamabad, Khyber Pakhtunkhwa, Punjab, and Sindh). Nigeria reported four WPV1 cases in 2016. No WPV1 cases were reported in 2017 and none to date in 2018. Countries reporting cVDPV cases and isolations. In 2016, five cVDPV cases were reported from three countries ( 8 ). In Laos, an outbreak that began with eight cVDPV type 1 cases in 2015 continued into 2016 with three additional cases reported. One cVDVPV2 case was reported in 2016 in Nigeria and another in Pakistan. In 2017, a total of 96 cVDPV2 cases were reported, including 74 cases from Syria (most recent case in September 2017) and 22 from DRC. The outbreak in DRC has continued into 2018, with four cases to date, as of April 24, 2018 (the most recent case occurring in February) ( 9 ). Isolation of cVDVP2 from environmental samples in Mogadishu, Somalia, in late 2017 and early 2018, and related cVDPV2 from environmental samples in Nairobi, Kenya, in early 2018, has confirmed long-term cVDPV2 transmission, in a broad area, although no associated polio cases have been detected to date. cVDPV type 3 has been isolated in Mogadishu from sewage samples collected in March 2018, again, with no associated polio cases having been detected to date. In Nigeria, cVDPV2 has been recently detected by environmental surveillance in two states in early 2018; no associated polio cases having been detected to date. Response immunization is underway or planned for all these cVDPV cases and isolations. Discussion Although substantial progress was made toward polio eradication during 2016–2017, challenges remain in the countries with endemic transmission. Continued circulation of WPV1 has been confirmed in Afghanistan and Pakistan in the 2018 low WPV season, and it remains uncertain if WPV circulation has been interrupted in Nigeria ( 3 ). The number of WPV cases in Afghanistan declined from 2015 to 2016, but the decrease did not continue in 2017. Although negotiations to obtain local access are constantly being undertaken, the number of children who were inaccessible to vaccination in the south and east because of insecurity increased during 2017 ( 5 ). In Pakistan, a decline in WPV1 cases since 2014 continued during 2016 and 2017. The detection of WPV in environmental surveillance samples in the absence of WPV-positive AFP cases in several provinces might indicate either surveillance gaps or waning in the intensity of transmission. Intensified SIA schedules and efforts to reach previously unvaccinated children, along with expansion of community-based initiatives employing local permanent vaccinators and ensuring worker safety have helped reduce the number of WPV cases. Large-scale movement of high-risk populations across Pakistan’s border with Afghanistan in both directions continues to pose a challenge to interrupting WPV transmission, and crossborder collaborative vaccination efforts made in 2017 are being enhanced in 2018 ( 4 ). In Nigeria, WPV1 circulation went undetected from mid-2014 to mid-2016, and the discovery of both endemic WPV1 and long-standing cVDVP2 transmission in 2016 in Borno State illuminated gaps in surveillance. Continued inaccessibility of insurgent-held areas hinders both immunization and surveillance efforts ( 3 ). Enhancement of initiatives for collaborating with the military to reach currently unvaccinated children will be helpful in ensuring interruption of WPV transmission. In the other countries of the Lake Chad basin bordering Borno State (Cameroon, Chad, and Niger), problems with inaccessibility related to insecurity and a large number of difficult-to-access islands have been addressed through progressive improvements in microplanning and implementation of SIAs, but uncertainties remain regarding SIA quality and success in interrupting undetected WPV transmission. Global WPV2 eradication was certified in 2015 after no detection since 1999 ( 2 ). WPV type 3 has not been detected since 2012 ( 2 ). A minimum of 3 years of sensitive AFP surveillance without detection of WPV is required to certify a WHO region as being poliofree ( 10 ). Four of six WHO regions (the Region of the Americas, European, South-East Asia, and Western Pacific regions) have been certified free of indigenous WPV. Improvements in AFP surveillance performance in critical subnational areas are required to achieve poliofree certification of the African and Eastern Mediterranean regions. Because efforts to increase immunity to poliovirus type 2 before the global tOPV to bOPV switch did not reach all persistently unvaccinated children in hard-to-reach areas, some cVDPV2 emergences have been detected following the switch. Reaching all children for vaccination in areas with cVDPV2 transmission is also an ongoing challenge. Although progress toward global polio eradication has continued, challenges in identifying and vaccinating every missed child remain. Much of the recent progress reaching previously missed children has been associated with recruitment of trusted community volunteers who are invested in their locality for vaccination and surveillance efforts. Intensification of efforts to improve the quality of immunization and surveillance activities and to develop additional innovations in addressing persisting challenges is necessary. Until poliovirus eradication is achieved, all countries must remain vigilant by maintaining high population immunity and sensitive poliovirus surveillance. Summary What is already known about this topic? Transmission of wild poliovirus type 1 (WPV1) has not been interrupted in Afghanistan, Nigeria, and Pakistan. A global, synchronized switch to bivalent oral poliovirus vaccine (bOPV, types 1 and 3 only) was completed in April 2016. What is added by this report? Compared with 2016, the number of WPV1 cases overall decreased in 2017. Some transmission of circulating vaccine-derived poliovirus type 2 (cVDPV2) has been identified more than 1 year following the switch to bOPV in 2016. What are the implications for public health practice? Interruption of transmission of WPV1 and of cVDPV2 will require addressing persistent challenges to vaccinating every missed child. Until poliovirus eradication is achieved, all countries must maintain high population immunity and sensitive poliovirus surveillance.
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                Author and article information

                Journal
                Emerg Infect Dis
                Emerging Infect. Dis
                EID
                Emerging Infectious Diseases
                Centers for Disease Control and Prevention
                1080-6040
                1080-6059
                April 2019
                : 25
                : 4
                : 625-632
                Affiliations
                [1]Clínica IDB Cabudare, Instituto de Investigaciones Biomédicas IDB, Cabudare, Venezuela (A.E. Paniz-Mondolfi, M. Márquez, M.A. Escalona-Rodriguez, G.M. Blohm);
                [2]Venezuelan Science Incubator, Barquisimeto, Venezuela (A.E. Paniz-Mondolfi, M. Márquez, M.A. Escalona-Rodríguez, G.M. Blohm, I. Mejías);
                [3]University of Groningen, University Medical Center Groningen, Groningen, the Netherlands (A. Tami);
                [4]Facultad de Ciencias de la Salud, Universidad de Carabobo, Valencia, Venezuela (A. Tami);
                [5]Universidad Central de Venezuela, Caracas (M.E. Grillet, J. Hernández-Villena, A. Rísquez);
                [6]Universidad Centrooccidental Lisandro Alvarado, Barquisimeto (M. Márquez);
                [7]University of Florida, Gainesville, Florida, USA (G.M. Blohm, J. Lednicky, J.G. Morris Jr.);
                [8]Rotary International, Houston, Texas, USA (I. Mejías);
                [9]Sociedad Venezolana de Puericultura y Pediatría, Caracas (H. Urbina-Medina);
                [10]Sociedad Venezolana de Salud Pública/Red Defendamos la Epidemiología Nacional, Caracas (J. Castro, A. Carvajal, C. Walter, J. Oletta);
                [11]Sociedad Venezolana de Infectología, Caracas (M.G. López);
                [12]University of Glasgow, Glasgow, Scotland, UK (P. Schwabl, L. Hernández-Castro, M. Llewellyn);
                [13]London School of Hygiene and Tropical Medicine, London, UK (M.A. Miles);
                [14]Baylor College of Medicine National School of Tropical Medicine, Houston (P.J. Hotez);
                [15]Instituto Leônidas e Maria Deane/FIOCRUZ, Manaus, Brazil (J. Crainey, S. Luz);
                [16]Universidad del Rosario, Bogotá, Colombia (J.D. Ramírez);
                [17]Mount Sinai Saint Luke’s, New York, New York, USA. (E. Sordillo);
                [18]Hospital de Niños José Manuel de los Ríos, Caracas (M. Canache);
                [19]Universidad de Los Andes, Mérida, Venezuela (M. Araque)
                Author notes
                Address for correspondence: Alberto E. Paniz-Mondolfi, Clínica IDB Cabudare, Instituto de Investigaciones Biomédicas IDB, Department of Tropical Medicine and Infectious Diseases, Av Intercomunal Barquisimeto-Cabudare, Urb Los Rastrojos, Cabudare Estado Lara 3023, Venezuela; email: albertopaniz@ 123456yahoo.com
                Article
                18-1305
                10.3201/eid2504.181305
                6433037
                30698523
                3705ad63-2c51-4c69-bd99-5e33d6700bd8
                History
                Categories
                Perspective
                Perspective
                Resurgence of Vaccine-Preventable Diseases in Venezuela as a Regional Public Health Threat in the Americas

                Infectious disease & Microbiology
                measles,diphtheria,polio,venezuela,outbreak,vaccine-preventable diseases,vector-borne infections,viruses,americas,vaccines,vaccination,immunization

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