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India, which was once a major polio hotspot, has reported no new cases of the disease in just over 12 months, ever since a two-year old female case on 13th January, 2011, in the state of West Bengal. According to WHO (World Health Organization), India used to be known as the planet's "epicenter" of polio. WHO scientists say that as soon as all remaining lab investigations come back negative, India will be officially recognized as a nation that has stopped indigenous transmission of wild poliovirus, leaving just three countries with existing indigenous transmissions - Pakistan, Nigeria and Afghanistan. Despite this major achievement, scientists say India must not become complacent. Childhood immunity against wild poliovirus must be religiously maintained, as should nationwide surveillance. Unfortunately, and also rather worryingly, Pakistan and Afghanistan have had rising numbers of reported poliovirus infections over the last 12 months. Poliovirus found its way from Pakistan into China, re-infecting the country after it had been polio-free for over a decade. Nigeria, DR Congo, and Chad continue having active polio transmission. There have also been sporadic outbreaks in Central and West Africa over the past year. Polio will remain a global threat as long as it exists somewhere in the world, says WHO. Health experts and leaders throughout the world praised India for its dedication and commitment to the eradication of polio, as well as the millions of health workers, including vaccinators, community mobilizers, Rotarians, caregivers and parents who have been behind this drive over the last decade. Over 170 million kids under 5 are vaccinated annually in India - this includes 70 million in very high-risk areas. A total of almost 1 billion polio vaccine doses per year have been administered in the country to people of all ages.
Background. Knowledge of factors that affect per-act infectivity of human immunodeficiency virus type 1 (HIV-1) is important for designing HIV-1 prevention interventions and for the mathematical modeling of the spread of HIV-1.
Methods. The researchers analyzed data from a prospective study of African HIV-1–serodiscordant couples. They assessed transmissions for linkage within the study partnership, based on HIV-1 sequencing. The primary exposure measure was the HIV-1–seropositive partners’ reports of number of sex acts and condom use with their study partner.
Results. Of 3297 couples experiencing 86 linked HIV-1 transmissions, the unadjusted per-act risks of unprotected male-to-female (MTF) and female-to-male (FTM) transmission were 0.0019 (95% confidence interval [CI], .0010–.0037) and 0.0010 (95% CI, .00060–.0017), respectively. After adjusting for plasma HIV-1 RNA of the HIV-1–infected partner and herpes simplex virus type 2 serostatus and age of the HIV-1–uninfected partner, we calculated the relative risk (RR) for MTF versus FTM transmission to be 1.03 (P = .93). Each log10 increase in plasma HIV-1 RNA increased the per-act risk of transmission by 2.9-fold (95% CI, 2.2–3.8). Self-reported condom use reduced the per-act risk by 78% (RR = 0.22 [95% CI, .11–.42]).
Conclusions. Modifiable risk factors for HIV-1 transmission were plasma HIV-1 RNA level and condom use, and, in HIV-1–uninfected partners, herpes simplex virus 2 infection, genital ulcers, Trichomonas vaginalis, vaginitis or cervicitis, and male circumcision.