04/24/2007 05:33 pm ET | Updated May 25, 2011

Chlamydia, Largest Bacterial Cause of Sexually Transmitted Disease, Insidious Under the Radar Screen

Chlamydia is the single largest bacterial cause of sexually-transmitted infections in the US with 3-5 million new infections per year, as well as in the world with an estimated 92-100 million people infected every year. This bacterial infection is responsible for many severe, progressive sequelae: women's reproductive organs - pelvic inflammatory disease (PID) and infertility; the eyes - trachoma, corneal opacity, ulceration and blindness. Indeed, the bacterium is the cause of trachoma that is the largest cause of preventable blindness in the world. Chlamydia is also a co-factor for transmission of HIV, and women infected with Chlamydia have a five times higher probability of contracting HIV when exposed to the virus. The disease burden of Chlamydia, thus, is disproportionately high on women and children.

According to the US Federal Centers for Disease Control and Prevention (CDC), 85-90% of those infected go through an asymptomatic phase where the individual can be a carrier. Severe and sometimes irreversible complications such as PID and infertility, therefore present as the first symptoms of this genital infection. Up to 40% of US women with untreated Chlamydia infections develop PID and about 20% of those may become infertile.

A key to the long-term success of control measures, prevention of infection, and even prevention of serious sequelae is to immunize early. The highest rates of infection are in the adolescents, and there are biological and immunological factors behind that reality that go beyond behavior. Hence, there is a compelling reason to plan to vaccinate when the immune system is naïve to Chlamydia and before permanent damage can occur to the reproductive system.

Education, abstinence, screening and 20-40 years old antibiotics are the best possible intervention methods available today against this quiet endemic lurking behind the veil of sensitivity and privacy. However, correlation is apparent between the increased screening and rising incidence in the few countries that have implemented widespread screening, the US, UK, Sweden, and as yet no decline in incidence is discernable. The more screening takes place, the more cases are found, and there is a sign of limitation in that strategy and current intervention tools.

No clinical trials of Chlamydia vaccines have been conducted for about 40 years, and this makes current treatment highly dependent on antibiotics that need to be prescribed frequently because of repeated re-infection.

Overall, in the US alone, 19 million new sexually-transmitted infection (STI) cases occur each year, half of that concentrated in the 15-24 year olds. Since the US has the highest STI rates in the industrialized world, the potential exists for public support for vaccines against STIs.

Further, health sciences R&D is generally supported in the private sector when there is an overlap between medical need and business opportunity. But in this constellation of diseases caused by Chlamydia, humanitarian need of blindness prevention, in addition to the HIV co-factor role, infertility, PID - provide additional passionate philanthropic rationale for wealthy individuals and foundations to support this vaccine development in addition to what the private sector and government can do.

Let us hope that philanthropists will step up to accelerate medical, scientific and public health work against this neglected disease.