Arun Thapa | WHO - Academia.edu (original) (raw)

Papers by Arun Thapa

Journal of Infectious Diseases, 2008

Between June and October 2005, 45 laboratory-confirmed type 1 vaccine-derived poliovirus (VDPV) c... more Between June and October 2005, 45 laboratory-confirmed type 1 vaccine-derived poliovirus (VDPV) cases were identified on Madura Island in Indonesia. Genetic sequencing data on VDPV isolates were consistent with replication and circulation for up to approximately 2 years. Concurrent circulation with type 1 wild poliovirus (WPV) enabled comparisons of VDPV and WPV cases and found that clinical and epidemiological features of both were similar. Attack rates for VDPV were as high as those for WPV. Of 41 VDPV case patients with known vaccination status, 25 (61%) had received zero oral polio vaccine (OPV) doses. Low population immunity due to low routine OPV coverage in rural areas and the absence of WPV circulation for more than a decade were major predisposing factors for the emergence of VDPV. Suboptimal surveillance and a limited initial immunization response may have contributed to widespread circulation. Sensitive surveillance and prompt high-quality immunization responses are recommended to prevent the spread of VDPVs.

MMWR. Morbidity and mortality weekly report, Jan 24, 2014

In 1988, the World Health Assembly resolved to interrupt wild poliovirus (WPV) transmission world... more In 1988, the World Health Assembly resolved to interrupt wild poliovirus (WPV) transmission worldwide. By 2006, the annual number of WPV cases had decreased by more than 99%, and only four remaining countries had never interrupted WPV transmission: Afghanistan, India, Nigeria, and Pakistan. The last confirmed WPV case in India occurred in January 2011, leading the World Health Organization (WHO) South-East Asia Regional Commission for the Certification of Polio Eradication (SEA-RCC) in March 2014 to declare the 11-country South-East Asia Region (SEAR), which includes India, to be free from circulating indigenous WPV. SEAR became the fourth region among WHO's six regions to be certified as having interrupted all indigenous WPV circulation; the Region of the Americas was declared polio-free in 1994, the Western Pacific Region in 2000, and the European Region in 2002. Approximately 80% of the…

Despite recommendations from WHO to conduct measles outbreak response vaccination campaigns based... more Despite recommendations from WHO to conduct measles outbreak response vaccination campaigns based on the age distribution of cases at the beginning of an outbreak, few data exist to specifically examine whether the age distribution of cases remains constant over time in a measles outbreak. This analysis explores this question with use of measles outbreak surveillance data from Bangladesh from the period 2004-2006. Pearson v 2 tests were conducted of age distributions over 2 periods during 41 large laboratory-confirmed measles outbreaks. Statistically significant changes in age distribution over time were observed in 24% of the outbreaks. No single pattern was detected in the shifts in age distribution; however, an increase in the proportion of cases occurring among infants ,9 months of age was evident in 6 outbreaks. These findings suggest a need to consider the possibility of a shift in the age distribution over time when planning an outbreak response vaccination campaign.

Journal of Infectious …, 2008

Between June and October 2005, 45 laboratory-confirmed type 1 vaccine—derived poliovirus (VDPV) c... more Between June and October 2005, 45 laboratory-confirmed type 1 vaccine—derived poliovirus (VDPV) cases were identified on Madura Island in Indonesia. Genetic sequencing data on VDPV isolates were consistent with replication and circulation for up to ∼2 years. Concurrent ...

Journal of Infectious Diseases, 2014

Journal of Infectious Diseases, 2008

Between June and October 2005, 45 laboratory-confirmed type 1 vaccine-derived poliovirus (VDPV) c... more Between June and October 2005, 45 laboratory-confirmed type 1 vaccine-derived poliovirus (VDPV) cases were identified on Madura Island in Indonesia. Genetic sequencing data on VDPV isolates were consistent with replication and circulation for up to approximately 2 years. Concurrent circulation with type 1 wild poliovirus (WPV) enabled comparisons of VDPV and WPV cases and found that clinical and epidemiological features of both were similar. Attack rates for VDPV were as high as those for WPV. Of 41 VDPV case patients with known vaccination status, 25 (61%) had received zero oral polio vaccine (OPV) doses. Low population immunity due to low routine OPV coverage in rural areas and the absence of WPV circulation for more than a decade were major predisposing factors for the emergence of VDPV. Suboptimal surveillance and a limited initial immunization response may have contributed to widespread circulation. Sensitive surveillance and prompt high-quality immunization responses are recommended to prevent the spread of VDPVs.

MMWR. Morbidity and mortality weekly report, Jan 24, 2014

In 1988, the World Health Assembly resolved to interrupt wild poliovirus (WPV) transmission world... more In 1988, the World Health Assembly resolved to interrupt wild poliovirus (WPV) transmission worldwide. By 2006, the annual number of WPV cases had decreased by more than 99%, and only four remaining countries had never interrupted WPV transmission: Afghanistan, India, Nigeria, and Pakistan. The last confirmed WPV case in India occurred in January 2011, leading the World Health Organization (WHO) South-East Asia Regional Commission for the Certification of Polio Eradication (SEA-RCC) in March 2014 to declare the 11-country South-East Asia Region (SEAR), which includes India, to be free from circulating indigenous WPV. SEAR became the fourth region among WHO's six regions to be certified as having interrupted all indigenous WPV circulation; the Region of the Americas was declared polio-free in 1994, the Western Pacific Region in 2000, and the European Region in 2002. Approximately 80% of the…

Despite recommendations from WHO to conduct measles outbreak response vaccination campaigns based... more Despite recommendations from WHO to conduct measles outbreak response vaccination campaigns based on the age distribution of cases at the beginning of an outbreak, few data exist to specifically examine whether the age distribution of cases remains constant over time in a measles outbreak. This analysis explores this question with use of measles outbreak surveillance data from Bangladesh from the period 2004-2006. Pearson v 2 tests were conducted of age distributions over 2 periods during 41 large laboratory-confirmed measles outbreaks. Statistically significant changes in age distribution over time were observed in 24% of the outbreaks. No single pattern was detected in the shifts in age distribution; however, an increase in the proportion of cases occurring among infants ,9 months of age was evident in 6 outbreaks. These findings suggest a need to consider the possibility of a shift in the age distribution over time when planning an outbreak response vaccination campaign.

Journal of Infectious …, 2008

Between June and October 2005, 45 laboratory-confirmed type 1 vaccine—derived poliovirus (VDPV) c... more Between June and October 2005, 45 laboratory-confirmed type 1 vaccine—derived poliovirus (VDPV) cases were identified on Madura Island in Indonesia. Genetic sequencing data on VDPV isolates were consistent with replication and circulation for up to ∼2 years. Concurrent ...

Journal of Infectious Diseases, 2014