Predicting the long-term impact of rotavirus vaccination in 112 countries from 2006 to 2034: A transmission modeling analysis.

Rotavirus vaccination has been shown to reduce rotavirus burden in many countries, but the long-term magnitude of vaccine impacts is unclear, particularly in low-income countries. We use a transmission model to estimate the long-term impact of rotavirus vaccination on deaths and disability adjusted life years (DALYs) from 2006 to 2034 for 112 low- and middle-income countries. We also explore the predicted effectiveness of a one- vs two- dose series and the relative contribution of direct vs indirect effects to overall impacts. To validate the model, we compare predicted percent reductions in severe rotavirus cases with the percent reduction in rotavirus positivity among gastroenteritis hospital admissions for 10 countries with pre- and post-vaccine introduction data. We estimate that vaccination would reduce deaths from rotavirus by 49.1 % (95 % UI: 46.6-54.3 %) by 2034 under realistic coverage scenarios, compared to a scenario without vaccination. Most of this benefit is due to direct benefit to vaccinated individuals (explaining 69-97 % of the overall impact), but indirect protection also appears to enhance impacts. We find that a one-dose schedule would only be about 57 % as effective as a two-dose schedule 12 years after vaccine introduction. Our model closely reproduced observed reductions in rotavirus positivity in the first few years after vaccine introduction in select countries. Rotavirus vaccination is likely to have a substantial impact on rotavirus gastroenteritis and its mortality burden. To sustain this benefit, the complete series of doses is needed.

Foot and mouth disease in selected districts of western Ethiopia: seroprevalence and associated risk factors.

A study was conducted in western Ethiopia--in two districts of Oromia state and four districts of Beneshangul Gumuz state--to determine the seroprevalence of foot and mouth disease and the associated risk factors, using multistage random sampling. A 3ABC blocking enzyme-linked immunosorbent assay was used to measure antibody against the non-structural protein of foot and mouth disease virusto differentiate between vaccinated and infected animals.Atotal of 1,144 sera from 181 herds were collected and examined. The overall seroprevalence at animal level and herd level was 9% (95% Cl 7.2-10.6) and 38.1% (95% CI 29.1-47.1), respectively. Statistically significant differences (p < 0.05) were recorded among different species, with 13%, 5% and 3% seropositivity in cattle, sheep and goats, respectively. Statistically significant differences (p < 0.05) in herd seroprevalence were observed among districts, with 52%, 50%, 50%, 44%, 21% and 11% in Gidami, Begi, Tongo, Bambasi, Mange and Asosa districts, respectively. In univariable and multivariable logistic regression, the variables that had a positive relationship with seroprevalence at herd level (p < 0.05) were herd size, contact of livestock with ungulate wildlife, and contact of animals with animals/herds of a different peasant association. Univariable and multivariable logistic regression analysis indicated that, at the animal level, age and species had a statistically significant association (p < 0.05) with seropositivity. In conclusion, herd size, contact of livestock with ungulate wildlife, contact between herds from different peasant associations, and the age and species of the animals were the main risk factors for virus circulation in the study area.

Risk factors for foot and mouth disease seroprevalence in indigenous cattle in Southern Ethiopia: the effect of production system.

A serological survey to investigate risk factors for Foot and Mouth Disease (FMD) occurrence was conducted between October 2007 and March 2008 in Southern Ethiopia. Antibodies against non-structural protein of FMD virus (using 3abc ELISA) were measured as indicator of exposure to the virus. The seroprevalence of FMD was 9.5% (95%CI = 7.7 - 11.3, n = 1020) and 48.1% (95% CI = 36.8 - 59.4%, n = 79), respectively at animal and herd levels. Within herd seropositivity was ranged from 6.7 to 46.7% with 18.6% (95%CI = 14.6 - 22.5%) risk of being seropositive for an animal in positive herds. The most important herd level risk factors identified were pastoral system (OR = 16.3, 95% CI = 2.0 -133.7) compared to sedentary, low altitude (OR = 7.5, 95% CI 1.4 -40.7) compared to high altitude, keeping cattle with small ruminants (OR = 5.1, 95% CI 1.0 -25.2) when compared to one species or alone. Seroprevalence was significantly higher (P <0.05) in South Omo than Sidama and Gamo Gofa areas. The odds of seropositivity were 2.8 and 2.3 times higher in the adult (>4 years) and maturing animals (3-4 years) compared to young age category (<3 years). Both multivariable logistic and negative binomial regressions depicted that production system was the major risk factor for FMD seropositivity. Consequently, higher prevalence of FMD in pastoral system where animals are an integral part of life has substantial livelihood and economic implications, which signifies the need for devising control measures.

Polio outbreak response in Ethiopia.

BACKGROUND: Ethiopia had been polio-free for almost four years until December 2004. However, between December 2004 and February 2006, 24 children were paralysed as a result of infection with wild poliovirus imported from the neighbouring country of Sudan. In response, the country has attempted to document the impact of various response measures on the containment of wild poliovirus transmission. OBJECTIVES: This study aims at systematic and epidemiological assessment of the extent of the outbreak, its determinants, and the lessons learned as well as the implications for future control strategies to interrupt wild poliovirus transmission. DESIGN: A cross-sectional study design with qualitative and quantitative data collection approaches was used to conduct the epidemiologic assessment. SUBJECTS: All confirmed wild poliovirus cases, and reported acute flaccid paralysis cases in close proximity to the confirmed polio cases were the study subjects. Child caretakers and health service providers were interviewed as part of the investigation. RESULTS: Between December 2004 and February 2006, eight children from Tigray Regional State, nine children from Amhara Regional State and seven children from Oromia Regional State were paralysed as a result of infection with wild poliovirus type 1. Genetic sequencing demonstrated two separate importations to Ethiopia. Risk factors that may have facilitated spread of the outbreak within the country included gaps in vaccination coverage and interruption of the cold chain system, gaps in acute flaccid paralysis surveillance performance, high population mobility, poor environmental sanitation, crowded living conditions and unsafe drinking water. In response to the outbreak, Ethiopia conducted detailed outbreak investigations within two days of confirmation of the index cases. Large-scale, house-to-house vaccination campaigns were also implemented. As a result, the three regions interrupted the wild poliovirus transmission within the regions within one year of confirmation of the index case. CONCLUSION: Outbreak response activities were successful in interrupting the imported wild poliovirus transmission in Tigray, Amhara and Oromia Regional States of Ethiopia within a one-year period of time. In Ethiopia, programme strategies should be intensified to contain further spread and prevent future importation of wild poliovirus. Large-scale immunisation campaigns should reach every child, including those isolated by geography, poverty and security.

Inexpensive vaccines and rapid diagnostic kits tailor-made for the global eradication of rinderpest, and technology transfer to Africa and Asia.

Rinderpest is an acute and highly contagious viral disease of ruminants, often resulting in greater than 90% mortality. We previously reported the development of first- and second-generation recombinant vaccinia virus vaccines which provide complete protection against rinderpest virus (RPV) and peste-des-petits ruminants virus (PPRV). These vaccines are safe even for immunodeficient mice and macaques with acquired immunodeficiency syndrome. We developed a third-generation recombinant vaccinia virus vaccine (v2RVFH) that expresses the fusion and haemagglutinin genes of RPV under strong synthetic vaccinia virus promoters. Cattle vaccinated intramuscularly with as little as 10(3) plaque-forming units (PFU) of v2RVFH were completely protected from rinderpest. Vaccinated animals did not develop pock lesions or transmit v2RVFH to contact animals. Cattle vaccinated with a standard dose of 10(8) PFU of v2RVFH developed long-term, sterilizing immunity against rinderpest. Thus, v2RVFH is safe, efficacious, heat stable, inexpensive, easily administered, and allows serological differentiation between vaccinated and infected animals. To aid in diagnosis and differentiation of vaccinated from infected animals, we developed indirect ELISAs (iELISAs) that use baculovirus-expressed RPV or PPRV nucleoprotein as coating antigens. A single larva contains enough viral antigen to test more than 10,000 serum samples, in duplicate. African scientists trained at the ILMB successfully transferred the iELISA kit technology to more than 30 countries in Africa, providing a model for technology transfer among developing countries. Vaccination with v2RVFH, in conjunction with the iELISA kits, greatly enhances the prospects for global eradication of rinderpest, as developing nations achieve independence in control efforts.