Research on Sexually Transmitted Diseases

“Over 170 types of HPV have been identified, and they are designated by numbers.^[11][12][13]
Some HPV types, such as HPV-5, may establish infections that persist for the lifetime of the individual without ever manifesting any clinical symptoms. HPV types 1 and 2 can cause common warts in some infected individuals.^{[citation needed]} HPV types 6 and 11 can cause genital warts and respiratory papillomatosis.^[2] HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, and 82 are considered carcinogenic.^[14]” @Wikipedia: Human papillomavirus@

“Bivalent, quadrivalent, and 9-valent HPV vaccine all protect against HPV 16 and 18, the HPV types that cause about 66% of cervical cancers and the majority of other HPV-attributable cancers in the United States. 9-valent HPV vaccine targets five additional cancer-causing types, which account for about 15% of cervical cancers (12). Quadrivalent and 9-valent HPV vaccine also protect against HPV 6 and 11, the HPV types that cause anogenital warts.” @CDC: HPV Vaccine Information for Clinicians@

See:

@STD.gov List of All STDs and Their Symptoms@

@The STD Project’s List of All STDs@

@Wikipedia: Causes of sexually transmitted infections@

@Shrestha and Englund 2010@

The spreadsheet @GBD 2013 International Classification of Diseases codes mapped to the Global Burden of Disease cause list@ cells B94-100 lists the ICD10 codes associated with the STDs for which the overall DALY burden was calculated in the 2013 GBD. We looked up these codes on ICD10 data website to find out what sequelae were included in the impact calculation in the table above. We corresponded with a GBD representative who confirmed that the ICD codes listed in the @GBD 2013 International Classification of Diseases codes mapped to the Global Burden of Disease cause list@ constituted the disease impacts included in the overall disease burden assessment. Note that in one case, we were unable to find the ICD code referenced in the GBD spreadsheet: cells B93, B94, B95 and B97 reference ICD code M73, but we were unable to find that code on the ICD10 website. The list of codes from M70 to M79 does not seem to include M73. We do not know why we were unable to find the code.

We are uncertain about how the WHO GHO DALY burdens were calculated, and were unable to understand its process based on the information provided on the website (see @WHO GHO Data@). We reached out to a representative at the WHO GHO and have not received a response. Some information about the WHO GHO methodology and differences compared to the GBD 2010 approach are noted here (@WHO: Global Burden of Disease@).

We found that both sources included the impact of neonatal syphilis, the GBD did not include neonatal herpes, chlamydia, or gonorrhea (the DALY burden of each of these broken down by age group can be found at the @Global Burden of Disease Study 2013 (GBD 2013) Data Downloads – Full Results@ by selecting the diseases of interest as the ‘Causes’). The WHO GHO does not have a separate DALY estimate for herpes and very low estimates of the burden of chlamydia and gonorrhea in children under five (both diseases are listed as causing <30 DALYS per year in children under five, globally in the @WHO GHO DALYs by Cause@) to the extent that we doubt that this accurately captures the effects of the neonatal forms of these diseases.Below, we examine other effects of STDs which are not included in the assessments of the burdens given in the table above.

“Before the advent of highly active antiretroviral therapy (HAART), observational data demonstrated an association between non-ulcerative STDs, such as N. gonorrhoeae and C. trachomatis, and the risk of HIV transmission.7 HIV-infected women who had intercurrent N. gonorrhoeae, C. trachomatis, or T. vaginalis had increased rates of HIV detection in the cervix and vagina compared to HIV-infected women who did not have an STD, and HIV-infected men who had N. gonorrhoeae or C. trachomatis were more likely to have higher levels of HIV in the semen than mono-infected controls.8–11 For women, perturbations of the vaginal microflora associated with bacterial vaginosis have also been associated with increased HIV expression in the genital tract.12 In addition, HIV-infected individuals who experienced reactivations of HSV-2 can have high levels of HIV virus recovered from their genital tract ulcers.13” @Mayer and Venkatesh 2011@

“Two further cohort studies provide evidence for the possible role of human papillomavirus (HPV) in the sexual transmission of HIV. Auvert and colleagues used data from a male circumcision trial in South Africa to look at the association between HPV and HIV incidence. [24**]After controlling for other factors, there was no association between low-risk HPV and HIV, but there was a 4-fold increased risk in men with high-risk HPV, and the incidence increased with the number of high-risk HPV genotypes detected. A similar finding was reported among MSM in the USA, where increasing numbers of anal HPV types increased HIV risk. [25]” @Ward and Rönn 2010@

“A randomized cross-over trial of herpes simplex virus type 2 (HSV-2)-suppressive therapy (valacyclovir, 500 mg twice daily, or placebo for 8 weeks, a 2-week washout period, then the alternative therapy for 8 weeks) was conducted among 20 Peruvian women coinfected with HSV-2 and human immunodeficiency virus type 1 (HIV-1) who were not on antiretroviral therapy. Plasma samples (obtained weekly) and endocervical swab specimens (obtained thrice weekly) were collected for HIV-1 RNA polymerase chain reaction. Plasma HIV-1 level was significantly lower during the valacyclovir arm, compared with the placebo arm (−0.26 log10copies/mL, a 45% decrease [P<.001]), as was cervical HIV-1 level (−0.35 log10 copies/swab, a 55% decrease [P<001]).” @Baeten et al. 2008@ (Abstract)

“HSV was detected from 29% and 4.4% of swabs on placebo and valacyclovir, respectively (P<0.001). Valacyclovir significantly reduced the proportion of days with detectable seminal HIV-1 (63% during valacyclovir vs. 78% during placebo, p=0.04). The quantity of HIV-1 in semen was 0.25 log10 copies/mL lower (95%CI −0.40 to −0.10, p=0.001) during the valacyclovir arm compared with placebo, a 44% reduction. CD4 count (p=0.32) and seminal cellular CMV quantity (p=0.68) did not predict seminal plasma HIV-1 level.” @Zuckerman et al. 2009@ (Abstract)

• @Mayer and Venkatesh 2011@

• • • “Over the last decade and a half, there have been several large, multi-center clinical trials conducted in sub-Saharan Africa to evaluate whether the treatment of bacterial STDs could result in decreasing the incidence of HIV transmission and acquisition (see Table I).²² In the Mwanza trial, the only clearly successful STD intervention study, multiple communities in Tanzania were randomized to receive syndromic management of acute bacterial STDs with a regimen that was effective against N. gonorrhoeae, syphilis, and C. trachomatis.^23,24 The study was initiated in communities with an average HIV prevalence of 1%, and by the end of the study HIV prevalence was approximately 4% across the sites. By the end of the study, the syndromic management approach resulted in a 29% decrease in syphilis and a 49% reduction in incident urethritis. Although there were no changes in condom use or sexual risk behaviors, there was a statistically significant 38% reduction in HIV incidence. However, several subsequent large interventional STD trials conducted in East Africa were not successful in demonstrating that STD treatment could decrease HIV incidence. In the Rakai study conducted in rural Uganda, the investigators randomized communities to receive periodic mass treatment with a regimen that was effective against N. gonorroheae, C. trachomatis, T. vaginalis, and bacterial vaginosis, as well as syphilis.²⁵ Intervention teams went into villages every 9–10 months to offer the mass treatment. The investigators were able to demonstrate a 20% reduction in syphilis and a 41% reduction in incident T. vaginalis, both of which were statistically significant. However, there was no reduction in HIV incidence in the intervention communities. In contrast to the Mwanza study, the HIV epidemic was already much more well-established in this part of rural Uganda, with an HIV prevalence at the beginning of the study of over 16% in the male population.^26,27 Subsequent analyses by researchers in the Rakai group found that the two largest predictors of incident HIV infection among HIV discordant couples were the level of circulating plasma HIV RNA in the infected partner²⁸ and, independently, also the presence of prevalent and incident HSV-2 infection.²⁷ Similar to the Rakai trial, two other large scale clinical trials of STD interventions, one involving syndromic management of STDs as part of a community randomized trial in Masaka, Uganda, and one involving monthly antibiotic chemoprophylaxis conducted among Kenyan female sex workers, did not lead to a decrease in HIV incidence.^29,30” See also Table 1 for details on each study.
    • “In 2008, a large randomized controlled trial conducted among HIV uninfected, HSV-2 antibody-positive African women to prevent HIV acquisition, comparing acyclovir to placebo, had no impact.⁴⁷ Later that year, another large multi-center study among high-risk North and South American MSM and African women who were HIV-uninfected, HSV-2 seropositive failed to show a benefit of acyclovir prophylaxis in decreasing HIV incidence, but unlike the earlier study, this study did show a 47% reduction in genital ulcers.⁴⁸ More recently, a study of HSV-2 suppressive therapy among HIV-infected and HSV-2 seropositive Africans who were in HIV discordant relationships did not demonstrate a decrease in HIV transmission to their uninfected partners, but did show a decrease in genital ulcers by 73% and plasma HIV viral load by 0.25 log₁₀.^49,50 A reason for the failure of acyclovir to prevent HIV acquisition and transmission could be due to the relatively low dosage that was used (400 mg/twice daily), while in some settings a drug concentration several times higher may be used for optimal HSV-2 suppression, particularly in individuals who are already HIV co-infected.^51,52 Another reason for the lack of efficacy may be that although acyclovir decreases active clinical shedding of HIV, it may not be sufficiently potent to alter the inflammatory genital tract milieu, including micro-ulcerations, recruitment of cells that can bind or transmit HIV, or other mucosal changes that may potentiate HIV transmission.⁵³”
  • “There were three randomized controlled trials that met our inclusion criteria recruited HIV-negative participants with chancroid (two trials with 143 participants) and primary syphilis (one trial with 30 participants). The syphilis study, carried out in the US between 1995 and 1997, randomized participants to receive a single 2.0 g oral dose of azithromycin (11 participants); two 2.0 g oral doses of azithromycin administered six to eight days apart (eight participants); or benzathine penicillin G administered as either 2.4 million units intramuscular injection once or twice seven days apart (11 participants). No participant in the trial seroconverted during 12 months of follow-up. The chancroid trials, conducted in Kenya by 1990, found no significant differences in HIV seroconversion rates during four to 12 weeks of follow-up between 400 and 200 mg single oral doses of fleroxacin (one trial, 45 participants; RR 3.00; 95% CI 0.29 to 30.69), or between 400 mg fleroxacin and 800 mg sulfamethoxazole plus 160 mg trimethoprim (one trial, 98 participants; RR 0.33; 95% CI 0.04 to 3.09). Adverse events reported were mild to moderate in severity, and included Jarisch-Herxheimer reactions and gastrointestinal symptoms. The differences between the treatment arms in the incidence of adverse events were not significant. The quality of this evidence on the effectiveness of genital ulcer disease treatment in reducing sexual acquisition of HIV, according to GRADE methodology, is of very low quality.” @Mutua, M’Imunya, and Wiysonge 2012@
  • “In the mass treatment trial in rural southwestern Uganda, after three rounds of treatment of all community members for STIs, the adjusted rate ratio (aRR) of incident HIV infection was 0.97 (95% CI 0.81 – 1.2), indicating no effect of the intervention. The three STI management intervention studies were all conducted in rural parts of Africa. One study, in northern Tanzania, showed that the incidence of HIV infection in the intervention groups (strengthened syndromic management of STIs in primary care clinics) was 1.2% compared with 1.9% in the control groups (aRR = 0.58, 95% CI 0.42 – 0.79), corresponding to a 42% reduction (95% CI 21.0% – 58.0%) in HIV incidence in the intervention group. Another study, conducted in rural southwestern Uganda, showed that the aRR of behavioural intervention and STI management compared to control on HIV incidence was 1.00 (95% CI 0.63 – 1.58). In the third STI management trial, in eastern Zimbabwe, there was no effect of the intervention on HIV incidence (aRR = 1.3, 95% CI 0.92 – 1.8). These are consistent with data from the mass treatment trial showing no intervention effect. Overall, pooling the data of the four studies showed no significant effect of any intervention (rate ratio [RR] = 0.97, 95% CI 0.78 – 1.2).Combining the mass treatment trial and one of the STI management trials, we find that there is a significant 12.0% reduction in the prevalence of syphilis for those receiving a biomedical STI intervention (RR 0.88, 95% CI 0.80 – 0.96). For gonorrhoea, we find a statistically significant 51.0% reduction in its prevalence in those receiving any of these interventions (RR 0.49, 95% CI 0.31 – 0.77). Finally, for chlamydia, we found no significant difference between any biomedical intervention and control (RR 1.03, 95% CI 0.77 – 1.4).” @Ng et al. 2011@

Note that there is overlap between the studies examined in the reviews above.

For example, for HSV, the potential impact seems very large. This is because:

• In an observational study from 2002, researchers found that approximately 20% of cases of HIV at their study site appeared to be attributable to HSV-2 when 22% of the population was infected with HSV-2.[1] We have a very limited understanding of the reliability or methodology of these studies.
• In several studies from the 1990s and 2000s, the percentage of the population infected with HSV-2 in various countries was within a factor of 2-4 of that the HSV-2 prevalence in the observational study.[2] We do not know if genital HSV-1 has been linked to HIV transmission. We note that it seems possible that other factors (e.g. likelihood of engaging in sexual intercourse while experiencing an outbreak of genital herpes) could potentially drive differences in HSV-driven HIV transmission even in regions where HSV-2 infection prevalence rates are similar.
• The global burden of HIV is estimated to be approximately 80M DALYs.[3] 80M*0.2=16M DALYs that could potentially be attributable to HSV-driven HIV transmission. We don’t know whether HIV cases that are attributable to HSV are representative of HIV cases in general in terms of their DALY burden.

However, we note that if STDs increase HIV transmission, HSV may be responsible for a larger share of these transmission events than other STDs because it is highly prevalent.[4]

[1]“For 9 cohort and nested case-control studies that documented HSV-2 infection before HIV acquisition, the risk estimate was 2.1 (95% confidence interval, 1.4–3.2). Thus, the attributable risk percentage of HIV to HSV-2 was 52%, and the population attributable risk percentage was 19% in populations with 22% HSV-2 prevalence but increased to 47% in populations with 80% HSV-2 prevalence. For 22 case-control and cross-sectional studies, the risk estimate was 3.9 (95% confidence interval, 3.1–5.1), but the temporal sequence of the 2 infections cannot be documented.” @Wald and Link 2002@

[2] *”HSV-2 infections are markedly less frequent than HSV-1 infections, with 15%–80% of people in various populations infected (Corey and Wald, 1999). The rates of infection vary with country as well as levels of sexual activity. In some countries, such as Spain and the Philippines, the HSV-2 prevalence hovers around 10%, increasing to 20%–30% range for most European countries and the United States (Varela et al., 2001; Smith et al., 2001; Enders et al., 1998; Malkin et al., 2002). Developing countries bear a much higher burden of HSV-2 infection, with many populations in Africa having >50% prevalence in the general population (Weiss et al., 2001).” @Wald and Corey 2007@ (although we did not vet those prevalence estimates, and note that that many are over a decade old).

*”The estimated total number of people aged 15–49 years who were living with HSV-2 worldwide in 2003 is 536 million (Table 1). More women than men were infected, with an estimated 315 million infected women compared to 221 million infected men. The number infected increased with age, most markedly in the younger ages, until it peaked in the age stratum 35–39 years of age, after which it declined slightly.” @Looker Garnett and Schmid 2008@

[3] It was estimated to be 91,907,414 DALYs by the WHO in 2012 (see @WHO GHO DALYs by Cause@), and 69,363,400 DALYs by the GBD in 2013 (see @GBD 2013 DALYs from all causes@ cell C7). We used 80M as a rough average of the two estimates.

[4] For example: “A cohort study of women in two African countries, Zimbabwe and Uganda, followed 4439 women every 3 months for up to two years. [20**]With the exception of syphilis, which was uncommon, all the reproductive tract infections were associated with HIV in at least one statistical model. After controlling for demographic and behavioural factors, the strongest risk was from gonorrhoea, which conferred a 7-fold increase in HIV incidence, but the highest population attributable risk percent (PAR%) was for sero-prevalent HSV-2 (50.4%), with incident HSV-2 contributing 7.9%, gonorrhoea 5.3%, and bacterial vaginosis 17.2%.” @Ward and Rönn 2010@

• “We fitted a constant-incidence model to pooled HSV-1 prevalence data from literature searches for 6 World Health Organization regions and used 2012 population data to derive global numbers of 0-49-year-olds with prevalent and incident HSV-1 infection. To estimate genital HSV-1, we applied values for the proportion of incident infections that are genital.
  Findings
  We estimated that 3709 million people (range: 3440–3878 million) aged 0–49 years had prevalent HSV-1 infection in 2012 (67%), with highest prevalence in Africa, South-East Asia and Western Pacific. Assuming 50% of incident infections among 15-49-year-olds are genital, an estimated 140 million (range: 67–212 million) people had prevalent genital HSV-1 infection, most of which occurred in the Americas, Europe and Western Pacific.” @Looker et al. 2015@

@Looker Garnett and Schmid 2008@

“The large majority of persons with genital herpes do not know they have the disease and infection and reactivation are typically “asymptomatic” although, with teaching, most persons with positive HSV-2 serology (46 of 53, in one study) recognize genital lesions.”

“The estimated total number of people aged 15–49 years who were living with HSV-2 worldwide in 2003 is 536 million (Table 1). More women than men were infected, with an estimated 315 million infected women compared to 221 million infected men. The number infected increased with age, most markedly in the younger ages, until it peaked in the age stratum 35–39 years of age, after which it declined slightly.”

“There is no cure for herpes. Antiviral medications can, however, prevent or shorten outbreaks during the period of time the person takes the medication. In addition, daily suppressive therapy (i.e. daily use of antiviral medication) for herpes can reduce the likelihood of transmission to partners.

Several clinical trials have tested vaccines against genital herpes infection, but there is currently no commercially available vaccine that is protective against genital herpes infection. One vaccine trial showed efficacy among women whose partners were HSV-2 infected, but only among women who were not infected with HSV-1. No efficacy was observed among men whose partners were HSV-2 infected. A subsequent trial testing the same vaccine showed some protection from genital HSV-1 infection, but no protection from HSV-2 infection. 17” @Genital Herpes – CDC Fact Sheet (Detailed)@

“The updated Global Burden of Disease Study (GBD) estimates that genital HSV resulted in 311,600 years lived with disability (YLD) in 2013 (95% uncertainty interval 98,300–748,500) due to genital ulcer disease alone [18]. GBD 2013 likely underestimates the impact of genital HSV, as these YLD estimates do not include disability due to neonatal herpes nor the contribution of genital HSV to HIV susceptibility, which are the most devastating consequences of infection.” @Johnston, Gottlieb, and Wald 2016@

See also @GBD 2013 DALYs from all causes@, cell C80

The impacts of genital herpes included in this assessment can be found in the @GBD 2013 International Classification of Diseases codes mapped to the Global Burden of Disease cause list@ cell B99. See the ICD codes associated with the GBD genital herpes assessment here (@ICD 10 Data: Anogenital herpes@).

• “The frequency of neonatal herpes varies by region and is estimated to occur from 1 in 3200 to 1 in 15000 pregnancies (Sullivan-Bolyai et al., 1983a; Tookey and Peckham, 1996; Mindel et al., 2000; Brown et al., 2003; Gutierrez et al.,1999)” @Wald and Corey 2007@. We do not know what regions are represented in this estimate, and whether the frequency has changed since it was made.
• “The HSV-2 epidemic is of concern in part because of its potential to cause neonatal herpes.^11,24,49,97 Through pooling of prevalence values by age and sex in a random-effect model, followed by the use of a constant-incidence model, the worldwide prevalence of HSV-2 among 15- to 49-year-olds is estimated to be 536 million (16%).⁴⁸ NHANES data from 1999–2002 showed that 63% of pregnant women in the United States were seropositive for HSV-1, 22% for HSV-2, and 13% for both.⁹⁶ The incidence of neonatal HSV was estimated to be 5.9 per 100,000 live births in a nationwide surveillance program in Canada and ranged from 5.8 to 11.5 per 100,000 live births in the United States.14 Various manifestations of ocular infection occur in an estimated 13–20% of neonates with HSV.^54,61” @Farooq and Shukla 2012@

We did not vet these estimates or investigate the methodologies used in these studies.

• “Untreated neonatal HSV infection is associated with only a 40% survival rate, and even with the early initiation of high-dose intravenous acyclovir therapy, it results in considerable disability among survivors.” @Corey and Wald 2009@, p. 1376.
• “The mortality rate [of neonatal HSV infection] is relatively high (24%), and long-term sequelae may occur.” @Clinuvel: Herpes Simplex Virus@. We are uncertain about how this document arrived at the 24% figure, and could not find an explanation or source.
• Another study found a mortality rate of 0.8/100,000 live births in California from 1995-2003: “The overall incidence of neonatal herpes was 12.1 per 100,000 live births per year, with no observable change from 1995 to 2003. Neonatal herpes-related mortality, which was estimated to be 0.8 deaths per 100,000 live births, also did not show significant change over time.” @Morris et al. 2008@ (Abstract), indicating an overall mortality rate 6.6% (0.8 death rate from neonatal HSV/12.1 incidence of neonatal HSV) of neonatal HSV cases.

We would guess that the mortality rate might be higher in the developing world, where HSV may be more common and access to antivirals and diagnostic tools may be more limited, but we don’t know if this is true, and if so, how much higher it might be.

We use the following estimate of severe vision loss from HSV: “One way to estimate vision loss in HSV would be to determine the proportion of HSV keratitis cases that lead to blindness in the affected eye and extrapolate this to annual incidence rates. A Moor-fields Eye Hospital study found that of 152 patients with epithelial keratitis, only 3% had a final visual acuity less than 20/200.⁹³ Final visual acuity ranged from 20/60 to 20/200 in 24%, and 20/20 to 20/40 in 73%. Liesegang et al found a slightly lower incidence of vision impairment in ocular HSV (3 of 131 cases); impairment was defined as an acuity worse than 20/100, however, and the series included diseases other than keratitis.⁴⁷ Final visual acuity was 20/40 or better in 78% of eyes. A study at the Aravind Eye Hospital in India found that at least 2% had visual acuity worse than 20/1200, and 62% improved to better than 20/40.³¹ Norn et al found nearly 6% of eyes were worse than 20/200, although some were treated with idoxuridine or steroids.⁶⁴ In one series 20% of HSV uveitis cases led to severe vision loss; this did not include cases of uveitis without keratitis, which would be considered additive.⁵⁵ Although blindness can occur via ocular HSV without corneal involvement (e.g., acute retinal necrosis), these cases are much rarer.

There were several factors that needed to be considered in projecting the rates of vision loss from HSV keratitis (Table 6). Based on these issues, and adjusting the Moorfields data for the effect of long-term antiviral treatment (which reduces the rate of recurrence), we estimate that at least 1.5% of clinically significant HSV keratitis leads to vision worse than 20/200, the WHO definition of severe visual impairment in developed nations (Table 6). This is based on the assumption that a reduction in recurrence rate leads to a proportional decrease in visual impairment. It is slightly lower than the rate of visual impairment in the Rochester study, where acyclovir was available for only a portion of the study period. In the developing world, including Africa and India, it may be 3% or higher as access to treatment is often severely limited, and other risk factors may play a role. We are unable to estimate the proportion of cases leading to monocular blindness (lower than 20/400). Longer study periods might reveal higher rates of vision loss as there would be more time for recurrences.

Using the available data on visual prognosis, therefore, our conservative estimate is that HSV keratitis is the cause of roughly 40,000 new cases of severe monocular visual impairment or blindness annually in the world (Table 7).” @Farooq and Shukla 2012@. Table 7 includes data about HSV keratitis incidence. We have not vetted this estimate.

• “A herpetic infection of the brain thought to be caused by the transmission of virus from a peripheral site on the face following HSV-1 reactivation, along the trigeminal nerve axon, to the brain. HSV is the most common cause of viral encephalitis. When infecting the brain, the virus shows a preference for the temporal lobe.^[14] HSV-2 is the most common cause of Mollaret’s meningitis, a type of recurrent viral meningitis.” @Wikipedia: Herpes simplex@
• “Benign recurrent aseptic meningitis is a rare disorder described by Mollaret in 1944. When initially described, this form of aseptic meningitis had no identifiable infecting agent. New sophisticated diagnostic tools have now identified herpes simplex type 2 virus as the most commonly isolated agent. Antiviral treatment has been used successfully for prophylaxis and treatment.” @Farazmand Woolley and Kinghorn 2011@ (Abstract)

We were unable to find quantitative information about the prevalence and impact of Mollaret’s meningitis, but our impression from our reading is that it is rare.

@Human papillomavirus vaccines: WHO position paper, October 2014@

“Based on a meta-analysis, the adjusted HPV prevalence worldwide among women with normal cytological findings was estimated to be 11.7% (95% confidence interval (CI): 11.6–11.7%).² The highest adjusted prevalence was found in sub-Saharan African regions (24%; 95% CI: 23.1–25.0%), Latin America and the Caribbean (16.1%; 95% CI: 15.8–16.4%), Eastern Europe (14.2%; 95% CI: 14.1–14.4%), and south-eastern Asia (14%; 95% CI: 13.0–15.0). However, country-specific adjusted HPV prevalence in cervical specimens ranged from 1.6% to 41.9% worldwide. Age-specific HPV prevalence peaked at younger ages (<25 years) with a prevalence of 21.8% (95% CI: 21.3–22.3%, crude) and 24.0% (95% CI: 23.5– 24.5%, adjusted), with a lower prevalence plateau at middle-ages.”

“HPV prevalence in men: A systematic review of genital HPV among men in sub-Saharan Africa found that the prevalence of any HPV type ranges between 19.1% and 100%.⁵ The estimated pooled prevalence of any HPV was 78.2% (95% CI: 54.2–91.6%) among HIV-positive men and 49.4% (95% CI: 30.4–68.6%) among HIV-negative men (p=0.0632). No clear age trend was observed. The most common high-risk HPV types were HPV-16 and HPV-52, and HPV-6 was the most common low-risk HPV type in the general population.

A systematic review of genital HPV-DNA prevalence in men examined data generally limited to men >18 years of age from Europe and North America.⁶ The estimated HPV prevalence in men peaked at slightly older ages than in women and remained constant or decreased slightly with increasing age. HPV prevalence was high in all regions but varied from 1% to 84% among low-risk men, and from 2% to 93% among high-risk men (e.g. sexually transmitted infection (STI) clinic attendees, HIV-positive males, and male partners of women with HPV infection or abnormal cytology). HIV-positive men who have sex with men showed the highest prevalence. Anal HPV infections are very common in men who have sex with men, and almost universal among those who are HIV-infected.⁷

A multicentre clinical trial (conducted in 18 countries from Africa, Asia-Pacific, Europe, Latin America and North America) examined the baseline prevalence of penile, scrotal, and perineal/perianal HPV infection in heterosexual men. The prevalence of any HPV type was 18.7% at the penis, 13.1% at the scrotum, 7.9% at the perineal/perianal region, and 21.0% at any site. HPV was most prevalent in African men and least prevalent in men from the Asia-Pacific region. Age was not associated with risk of positivity for HPV types 6, 11, 16, 18, or any tested HPV types. Having at least 3 lifetime female sexual partners had the greatest impact on HPV prevalence: odds ratio (OR) 3.2 (95% CI: 2.1–4.9) for HPV types 6, 11, 16, and 18; and OR 4.5 (95% CI: 3.3–6.1) for all HPV types tested.⁸”

“Human papillomavirus (HPV) is a very common virus that infects epithelial tissue. More than 120 HPV types have been identified. Most HPV types infect cutaneous epithelial cells and cause common warts, such as those that occur on the hands and feet. Approximately 40 HPV types infect mucosal epithelial cells on the genitals, and the mouth and throat. Although most HPV infections are asymptomatic and resolve spontaneously or become undetectable, some HPV infections can persist and lead to cancer.
Persistent infections with high-risk (oncogenic) HPV types can cause cancers of the anus, cervix, penis, vulva, and vagina, as well as the oropharynx (defined as the back of the throat, including the base of the tongue and tonsils). The most common high-risk types are 16 and 18.

Infection with low-risk (non-oncogenic) HPV types can cause genital warts and rarely laryngeal papillomas. These types can also cause benign or low-grade cervical cell abnormalities. The most common low-risk HPV types are 6 and 11.” @CDC: HPV Vaccine Information for Clinicians@

“It is important to note that HPV vaccines are highly efficacious as a 3-dose schedule in women aged 18–26 years for prevention of CIN 3; data on efficacy for prevention of cervical cancer are pending.49” @Human papillomavirus vaccines: WHO position paper, October 2014@

We understand CIN 3 to refer to severely abnormal cervical intraepithelial neoplasia, a precursor to cervical cancer, based on this definition of CIN 3.

“Bivalent, quadrivalent, and 9-valent HPV vaccine all protect against HPV 16 and 18, the HPV types that cause about 66% of cervical cancers and the majority of other HPV-attributable cancers in the United States. 9-valent HPV vaccine targets five additional cancer-causing types, which account for about 15% of cervical cancers (12). Quadrivalent and 9-valent HPV vaccine also protect against HPV 6 and 11, the HPV types that cause anogenital warts.” @CDC: HPV Vaccine Information for Clinicians@

“Gardasil 9 is a vaccine approved for use in females ages 9 through 26 and males ages 9 through 15. It is approved for the prevention of cervical, vulvar, vaginal and anal cancers caused by HPV types 16, 18, 31, 33, 45, 52 and 58, and for the prevention of genital warts caused by HPV types 6 or 11. Gardasil 9 adds protection against five additional HPV types—31, 33, 45, 52 and 58— which cause approximately 20 percent of cervical cancers and are not covered by previously FDA-approved HPV vaccines.” @FDA News Release: Gardasil 9@

“Virtually all cases of cervical cancer are caused by HPV, and just two HPV types, 16 and 18, are responsible for about 70 percent of all cases (7,8).” @National Cancer Institute: HPV Vaccine Fact Sheet@

“HPV-16 and HPV-18 were the most common HPV types in invasive cervical cancer during the period 1940–2007 with no statistically significant variations in their adjusted-relative contributions from 1940–1959 to 2000–2007 (HPV-16 from 61.5 to 62.1%, and HPV18 from 6.9 to 7.2%).¹² HPV types 16, 18, 45, 31, 33, 52, and 58 account for approximately 90% of the squamous-cell carcinomas which are positive for HPV DNA.¹¹” @Human papillomavirus vaccines: WHO position paper, October 2014@

@Human papillomavirus vaccines: WHO position paper, October 2014@

“Cervical HPV infection can be diagnosed using tests based on HPV-DNA performed on cervical or vaginal swabs; HPV-induced changes in the cervical epithelium can be detected by cytology using a microscopic examination of exfoliated cells, known as the Papanicolaou (Pap) test. Testing for HPV DNA, cytology, and visual inspection with acetic acid are used for cervical cancer screening. In low-resource settings, visual inspection of the cervix with acetic acid is used to identify cervical lesions.^{29, 30} Anogenital warts are diagnosed by visual inspection including anoscopy.”

“Although there is no virus-specific treatment for HPV infection, the HPV-related diseases can be treated by tissue destructive measures. In low-income countries, precancerous lesions of the cervix are most commonly treated by cryotherapy.³¹ Surgical excision of the affected tissue is also effective (loop electrosurgical excision procedure) and necessary when the lesion is large.^{29, 31} Excision by cone biopsy is reserved for more advanced or recurrent cases, especially those involving disease in the endocervical canal. Screening and treatment for preinvasive disease of the cervix is highly successful in preventing progression to cervical cancer.²⁹”

“Cervical cancer is the fourth most common cancer in women, and the seventh overall, with an estimated 528,000 new cases in 2012. As with liver cancer, a large majority (around 85%) of the global burden occurs in the less developed regions, where it accounts for almost 12% of all female cancers. High-risk regions, with estimated ASRs over 30 per 100,000, include Eastern Africa (42.7), Melanesia (33.3), Southern (31.5) and Middle (30.6) Africa. Rates are lowest in Australia/New Zealand (5.5) and Western Asia (4.4). Cervical cancer remains the most common cancer in women in Eastern and Middle Africa.

There were an estimated 266,000 deaths from cervical cancer worldwide in 2012, accounting for 7.5% of all female cancer deaths. Almost nine out of ten (87%) cervical cancer deaths occur in the less developed regions. Mortality varies 18-fold between the different regions of the world, with rates ranging from less than 2 per 100,000 in Western Asia, Western Europe and Australia/New Zealand to more than 20 per 100,000 in Melanesia (20.6), Middle (22.2) and Eastern (27.6) Africa.” @Globocan Cervical Cancer Fact Sheet@

@GBD 2013 DALYs from all causes@ cell C101

The number of fatalities from cervical cancer and estimated DALY burden appear to be in agreement. 6,900,000 DALYs/528,000 cases of cervical cancer=13 DALYs/case of cervical cancer.

“Most anal squamous cell cancers (80%) are caused by HPV, usually HPV-16.18” @Human papillomavirus vaccines: WHO position paper, October 2014@

“IARC26 considers that there is convincing evidence that infection with HPV 16,18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 or 66 can lead to cervical cancer. For HPV 16, the evidence further supports a causal role in cancer of the vulva, vagina, penis, anus, oral cavity and oropharynx and a limited association with cancer of the larynx and periungual skin. HPV 18 also shows a limited association with cancer at most of these sites. Evidence for associations of HPV types of genus beta with squamous cell carcinoma of the skin is limited for the general population. There is some evidence that HPVs are involved in squamous cell carcinoma of the conjunctiva, but inadequate evidence for a role of HPVs in cancer of the esophagus, lung, colon, ovary, breast, prostate, urinary bladder and nasal and sinonasal cavities.

With respect to cancer of the cervix, oncogenic HPV may be detected by PCR in virtually all cases of cervix cancer, and it is generally accepted that the virus is necessary for development of cancer, and that all cases of this cancer can be ‘attributed’ to infection.10

With respect to squamous cell cancers of the vulva and vagina, carcinoma of the penis and anal cancer, published studies do not allow quantification of relative risk and infection prevalence, because they are generally small in size and usually do not include comparable measurement of prevalence of infection at these sites in normal subjects. To estimate AFs, approximate estimates of the proportion of cancer cases infected with HPV in various series are used.

The prevalence of HPV in vaginal cancer is about 60–65% in studies using PCR methodology.26, 27 About 20–50% of vulvar cancers contain oncogenic HPV DNA,28, 29 but only the basaloid and warty type that tends to be associated with vulvar intraepithelial neoplasia is caused by HPV infection (prevalence 75–100%), and only 2–23% of the keratinizing carcinomas harbour HPV.30 HPV-related vulvar cancer occurs in younger women than the typical keratinizing squamous histology related to chronic inflammatory precursors. Vulvar carcinomas are generally rather more frequent than cancers of the vagina; an overall HPV prevalence of about 40% in cancers of the lower genital tract in women is assumed. For anal cancer, in a large series of cases from Denmark and Sweden 95% and 83% of cancers involving the anal canal in women and men, respectively, were positive for oncogenic HPV31; the AF is taken to be 90% worldwide. For penile cancer, HPV DNA was found in 30% of 71 cases of penile cancer from Brazil32 and in 42% of 148 cases from the USA and Paraguay;33 the AF is assumed to be 40%.

HPV probably plays a role in the aetiology of a fraction of cancers of the oral cavity and pharynx,34 although the major risk factors are, of course, tobacco and alcohol. Several studies have investigated prevalence of HPV in cancers of the mouth and pharynx.35, 36 On average ˜40% of tumours were HPV-positive, but the prevalence varied widely with the population studied, subsites, type of specimen and detection method. HPV was detected most commonly in oropharynx and tonsil, but at every subsite, HPV 16 was the predominant type.37 The largest study so far is a multicentre case-control study in 9 countries, including more than 1,600 cases of cancers of the mouth and oropharynx and 1,700 controls.38 HPV DNA was detected in tumour specimens (cases) by PCR, and presence of antibodies against HPV 16 L1 and HPV 16 E6 and E7 was tested for by ELISA methods in cases and controls. HPV DNA was detected in 4 and 18% of cancers of the mouth and oropharynx, respectively (HPV 16 was found in 95% of the positive cases). As HPV DNA cannot be evaluated in controls, and there was a good correlation between HPV DNA in cancer biopsies and serum anti-E6/E7 antibodies, a comparison was made between HPV-positive cases who were positive for HPV DNA or E6/E7 antibody (6.4% mouth cancers, 15.3% oropharyngeal cancers), and HPV-positive control subjects positive for anti E6 or anti-E7 antibody (1.6%). The AFs, based on these figures, would be 5% for mouth cancers and 16% for cancers of the oropharynx. However, assessment of HPV DNA presence by PCR assay may lead to an overestimation of cases in which the virus is etiologically involved, as suggested by the lower proportion of cases with E6/E7 expression39––4.6% of oral cancers and 12% of oro-pharyngeal cancers in the IARC multinational study.38 The corresponding OR’s and AFs would be 2.9 and 3% for mouth cancers and 9.2 and 12% for oropharynx cancers. For the purpose of estimation, it is assumed that 3% of oral cavity cancers and 12% of cancers of the oropharynx are attributable to HPV.” @Parkin 2006@

See Table III of @Parkin 2006@. We divided the number of cases of cervical cancer by the total number of HPV-attributable cancers in Table III (492900/561200) and find that 87.8% of HPV-attributable cancers were cervical cancers in 2006. This implies that 12.2% of HPV-attributable cancers are not cervical cancers, but rather are cancers of the vulva, vagina, penis, anus, mouth, or oropharynx (as listed in the table).

We note that the relative proportions of HPV-attributable cancers may have changed since the publication of @Parkin 2006@, but we did not investigate this.

“In very rare cases, HPV may cause epidermodysplasia verruciformis in immunocompromised individuals. The virus, unchecked by the immune system, causes the overproduction of keratin by skin cells, resulting in lesions resembling warts or cutaneous horns.^[65]”

“After controlling for past sexual behaviors, vaccinated women had a lower risk of testing positive for the 4 types included in the HPV vaccine (6, 11, 16, or 18; Table 1). This association became stronger when the number of recent sexual partners was controlled for. However, vaccinated women had a higher prevalence of nonvaccine high-risk types than unvaccinated women (61.5% vs 39.7%, prevalence ratio 1.55, 95% CI 1.22-1.98). After adjusting for the number of recent sexual partners, the difference in prevalence of high-risk nonvaccine types was reduced, but remained significant.” @Guo et al. 2015@

But see:
“The bivalent vaccine induces strong neutralizing antibody responses (>50% seropositivity) to HPV-31, HPV- 33, HPV-45, and HPV-52. The quadrivalent vaccine induces neutralizing antibody responses to HPV-31, HPV- 33 and HPV-52. Serum-neutralizing antibody responses against non-vaccine HPV types have been reported to be broader and of a higher magnitude in the bivalent versus quadrivalent vaccine recipients. The clinical significance and longevity of this cross-protection are unclear.^{77, 78, 79} The vaccines appear to differ in their degree of cross protection.⁸⁰” @Human papillomavirus vaccines: WHO position paper, October 2014@

@Syphilis – CDC Fact Sheet (Detailed)@

“There are no home remedies or over-the-counter drugs that will cure syphilis, but syphilis is easy to cure in its early stages. A single intramuscular injection of long acting Benzathine penicillin G (2.4 million units administered intramuscularly) will cure a person who has primary, secondary or early latent syphilis. Three doses of long acting Benzathine penicillin G (2.4 million units administered intramuscularly) at weekly intervals is recommended for individuals with late latent syphilis or latent syphilis of unknown duration. Treatment will kill the syphilis bacterium and prevent further damage, but it will not repair damage already done.”

“Although data to support the use of alternatives to penicillin is limited, options for non-pregnant patients who are allergic to penicillin may include doxycycline, tetracycline, and for neurosyphilis, potentially ceftriaxone. These therapies should be used only in conjunction with close clinical and laboratory follow-up to ensure appropriate serological response and cure.”

Some examples of current organizations we are aware of in this space include:

• The National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (and its Division of STD Prevention (DSTDP)) of the CDC
• ProjectAccept
• Johns Hopkins Bloomberg School of Public Health Center for Sexually Transmitted Diseases
• American Sexual Health Association
• International Union against Sexually Transmitted Infections (IUSTI)
• American Public Health Association
• Infectious Diseases Society of America
• Family Health International
• UNAIDS/WHO Global HIV/AIDS & STD Surveillance
• The California Family Health Council

The HPV and Anal Cancer Foundation appears to be active (see @The HPV and Anal Cancer Foundation: Role and Impact@) and had in ~$760K in assets 2013 (see @990 Finder: HPV and Anal Cancer Foundation Form 990 2013@). We don’t know how much of that was for HPV R&D.

Specifically, we read that:

The National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP) of the CDC received ~$760M in funding in 2015 (@CDC Office of Financial Resources 2015 Annual Report@, pg 12) but it’s our impression that little or none of this was allocated the STD R&D.

The National Coalition of STD Directors had approximately $940k in assets in 2014: @990 Finder National Coalition of STD Directors Form 990 2013@ but it’s our impression that little or none of this was allocated the STD R&D.

The American Sexually Transmitted Diseases Association had approximately $883k in assets in 2014: @990 Finder American Sexually Transmitted Diseases Association Form 990 2014@

The Foundation for Research into Sexually Transmitted Diseases had $1.8M in 2014:@990 Finder The Foundation for Research into Sexually Transmitted Diseases Form 990 2013@

“[N]on–HIV STIs received GBP 139 million across 378 studies” in the period from 1997-2013, according to @Head et al. 2015@

• In “Fiscal Year”, unselected “active projects” and selected “2015”
• In “Text Search” entered “herpes simplex”
• In “Limit Project search to” selected “Project Title”
• Clicked “Submit Query”
• Clicked “Data and Visualize”
• Repeated this process, instead selecting “Project Title” “Project Terms” and “Project Abstracts” rather than just “Project Title”

See @NIH Reporter- Herpes simplex funding, project titles only@ cell C7 and @NIH Reporter- Herpes simplex funding, project titles, terms, and abstracts@ cell C20

• In “Fiscal Year”, unselected “active projects” and selected “2015”
• In “Text Search” entered “hpv”
• In “Limit Project search to” selected “Project Title”
• Clicked “Submit Query”
• Clicked “Data and Visualize”
• Repeated this process, instead selecting “Project Title” “Project Terms” and “Project Abstracts” rather than just “Project Title”

See @NIH Reporter- HPV funding, project titles only@ cell C10 and @NIH Reporter- HPV funding, project titles, terms, and abstracts@ cell C27

• In “Fiscal Year”, unselected “active projects” and selected “2015”
• In “Text Search” entered “syphilis”
• In “Limit Project search to” selected “Project Title”
• Clicked “Submit Query”
• Clicked “Data and Visualize”
• Repeated this process, instead selecting “Project Title” “Project Terms” and “Project Abstracts” rather than just “Project Title”

See @NIH Reporter- Syphilis funding, project titles only@ cell C6 and @NIH Reporter- Syphilis funding, project titles, terms, and abstracts@ cell C15