Political instability as threat to global health gains

1. Political instability as threat to global health gains • Yemen • Cholera, famine, and the collapse of medical infrastructure • Venezuela • The collapse of medical infrastructure • Afghanistan and Pakistan • Eradicating polio

3. By mid-to late 1970’s last cases were being documented, including Bangladeshi Rahima Banu, a 2-year old in 1975 • Last global occurrence in 1977 in Somalia • Formally declared eradicated in 1980 although • Immunization of humans led to its disappearance as active agent of disease • Samples of smallpox virus remain in a few labs (and has been recovered in bodies uncovered in Arctic)

5. Polio (poliomyelitis) • Highly contagious viral infection that can lead to life-long paralysis, breathing problems, or even death. • Spread largely through fecal-oral route but can also be spread through aerosols, less commonly water and food • Mainly effects children under 5 • 95% of people who are infected are asymptomatic • 1 in 200 infections leads to irreversible paralysis. Among those paralyzed, 5% to 10% die when their breathing muscles become immobilized. • Three wild-type viruses, all classified as enteroviruses • Spreads through contact with the stool of an infected person or droplets from a sneeze or cough. • Reservoirs in the environment are soil and sewage, but only for a few months

6. History of polio • For most of history, poliomyelitis was relatively unremarkable – it caused paralysis and occasionally death, but only in a few of those infected. • Essentially unknown in infants and adults, and usually only caused mild symptoms in children. • This changed in the early 1900s, when the disease became an epidemic, killing and paralyzing many, even among the supposedly ‘protected’ populations of adults and infants

7. The first major polio epidemic in the United States hit Vermont in 1894 with 132 cases. • A larger outbreak struck New York City in 1916, with more than 27,000 cases and 6,000 deaths. • By the 1950s, polio had become one of the most serious communicable diseases among children in the United States and Europe. • Common to close public facilities and schools during outbreaks

11. The role of sewer systems • Late 1800’s many cities recognized that large open cesspools were not viable. Storm water would flood and push sewage out and sometimes into surface drinking water causing outbreaks of cholera • Early 1900s: sewer lines installed in homes, along with pipes to take it to more modern waste treatment centers • Water supplies were also increasingly piped into homes

12. The adoption of modern plumbing, sewer systems and water treatment facilities in the late 1800s and early 1900s set the stage for polio • Improved sanitation prevented some diseases (less cholera, for example) • However, with improvements in hygiene, encounters with the virus decline. • Without exposure , we became more susceptible and a scarce disease became an epidemic. • At the height of the polio epidemic in 1952, nearly 60,000 cases with more than 3,000 deaths were reported in the United States alone

13. 1953: announcement made that a polio vaccine had been successful • Inactivated polio vaccine (IPV) credited to Jonas Salk • In 1955, the U.S. began widespread vaccinations using IPV. • In 1962, Albert Sabin’s improved oral polio vaccine (OPV) goes into use • By 1979, the virus had been completely eliminated in the US • However, it remained in the world at large.

14. IPV: inactive polio virus vaccine (Salk, 1953) • Has to be injected to stimulate antibody production • No live virus, so no chance of acquiring polio through vaccination. • Requires booster shot after first inoculation. • More expensive and harder to make than OPV • U.S. used this vaccine until the 1970’s, then switched to the oral polio vaccine (OPV), and has switched back to IPV

15. OPV: oral polio virus vaccine (Sabin, 1962) • Easy to administer and inexpensive – two drops of a sugary solution given orally and repeated up to four times • Vaccine uses attenuated polio virus type that replicates in intestines and facilitates production of protective antibodies but does not infect central nervous system • Vaccine associated paralytic poliomyelitis (VAPP) can cause polio in a small number of people who receive OPV • Provides passive immunity: for 6-8 weeks after vaccination, the weakened live can spread from person to person, boosting immunity even in those who didn’t receive the polio drops. • Excreted in the feces as well: in areas where sanitation is poor, other people can acquire "passive" immunization

17. The Global Polio Eradication Initiative • In 1988, the World Health Organization set a new goal of eliminating polio. • Aim was to reach every child under age 5 • Public-private initiative: Bill and Melinda Gates Foundation have contributed along with other major health organizations. • Since 1988, billions of doses of OPV have been delivered in door-to-door campaigns, to remarkable effect: • Global polio cases have dropped more than 99%. • Two of three wild virus types eliminated, one remains

20. WPV vs cVDPV • Wild poliovirus vs circulating vaccine-derived polioviruses • OPV passive immunity was initially benefit, but now a challenge • How cVDPV originates • If a population remains under-immunized, there are enough susceptible children for the excreted vaccine-derived polioviruses to begin circulating in the community. • If vaccine-virus circulates for a prolonged period of time, it can mutate and, over 12-18 months, reacquire virulence and cause polio as CVDPV • The lower the population immunity, the longer these viruses survive. The longer they survive, the more they replicate, change, and exchange genetic material with other enteroviruses as they spread through a community.

22. Strategies for the remaining polio

23. For wild-type viruses (WPV) • Afghanistan and Pakistan • Caused by WPV type 1 • Wild poliovirus type 2 was declared globally eradicated in 2015 • WPV type 3 not detected since 2012 • Strategy for elimination: • OPV vaccines target only Type 1 and 3 polioviruses to increase herd immunity • Switch to IPV to lower risk of re-emergence of mutated circulating poliovirus • For circulating vaccine-derived polio virus (cVDPV) • Chiefly central African countries but also recently Philippines • Caused mostly by cVDPV type 2 • Strategy for elimination • Type 2 OPV (mOPV2) administered to increase herd immunity • Switch to IPV to lower risk of re-emergence of mutated circulating poliovirus

24. More than science needed to eradicate polio • Afghanistan and Pakistan • Regional wars with outside powers (USSR) and civil wars between pro-Western and Islamic factions • Political instability • Poverty and weak public infrastructure, including wastewater treatment

25. Barriers to eradication • Mistrust of outsiders based on history • Religious interpretations that may forbid immunizations • Fears about sterilization and impotence on the behalf of the enemies of Islam • Male health care workers not allowed to enter home where only women are present • Parents of immunized children fearful of retaliation by the Taliban • Immunization workers are fearful for their lives

29. Nigeria • Barriers to eradication • Boko Haram and Islamic fundamentalism, particularly in northern part of the country, see vaccine as Western plot • Fear that vaccine will cause sterility of contains HIV • Traditional medicine also attributes polio symptoms to other causes

30. Democratic Republic of Congo • Barriers to eradication • Ongoing civil war and regional conflict • Peace is uncertain with multiple armed groups vying for power throughout eastern DRC, terrorizing civilians • Poverty promotes conditions that facilitate polio transmission sewage • Immunization programs have collapsed, and have also been focused on Ebola