A systematic review and meta-analysis of the prevalence of human papillomavirus infection in Indigenous populations - A Global Picture

BACKGROUND AND AIM

Recent trends have shown a decline in the rates of human papillomavirus (HPV)-associated cervical cancer in the vaccinated population but there has been a spike in the HPV-associated oropharyngeal, anal and penile cancers in the majority of the unvaccinated population which are young and middle-aged males. Indigenous populations at an international level carry a disproportionate burden of most diseases. The aim of this meta-analysis was to ascertain the worldwide prevalence of HPV infection in Indigenous populations stratified by sex and site and to document the most commonly reported HPV types.

METHODS

Published articles on HPV infection in Indigenous populations from PubMed, Scopus, EMBASE and Web of Science were systematically searched from inception until 23 December 2019.

RESULTS

A total of 41 studies were included in the final analysis. The pooled worldwide prevalence of HPV infection (for both oral and genital sites, both males and females) in Indigenous populations was 34.2% (95% CI: 28.9%-39.8%). Subgroup analysis (geographical) showed that the pooled prevalence for African Indigenous, American Indigenous and Asian-Oceanic Indigenous populations were 33.0% (95% CI: 12.8%-57.1%), 33.0% (95% CI: 27.4%-38.9%) and 33.3% (95% CI: 0.17.5%-51.3%), respectively.

CONCLUSION

There are not enough data on the burden of the infection carried by males especially with respect to highly suspicious sites like oropharynx. Also, we conclude an overall high prevalence of HPV infection in the Indigenous populations and increasing their susceptibility to benign and malignant manifestations of HPV.

Immunisation issues for Indigenous Australian children

Vaccination has provided major benefits to the health of indigenous children in the face of continuing poorer socioeconomic conditions but several issues have been identified for improvement. While indigenous children are vaccinated at high rates for the standard schedule vaccines, vaccination is more commonly delayed. Coverage for 'targeted' vaccines is substantially lower, and data on coverage for indigenous adolescents is non-existent. Improved identification of indigenous clients by immunisation providers and the expansion of the childhood register are required. The progressive removal of early-acting Haemophilus influenzae type b vaccines from schedules for indigenous children because of an international shortage raises the risk of disease re-emergence and highlights the need for vigilant surveillance including carriage. The expanded use of existing vaccines (influenza) and early adoption of new vaccines (higher valency pneumococcal conjugates) are needed to maximise benefits, in particular the potential to impact on non-invasive disease such as otitis media and non-bacteraemic pneumonia that are so prevalent in indigenous children.

Cervical cancer in Indigenous women: The case of Australia

Globally, health inequities between Indigenous and non-Indigenous populations exist. The disparity in health outcomes between Indigenous and non-Indigenous Australians is exemplified by cervical cancer. Current evidence suggests that Indigenous women have higher age standardised incidence and mortality than non-Indigenous women when adjusted for stage at diagnosis and co-morbidities; however, there is little information pertaining to national estimates of cervical cancer in Indigenous women. In this paper we review available evidence on the difference in occurrence and case fatality of cervical cancer among Indigenous and non-Indigenous Australian women. The Australian Bureau of Statistics, Australian Institute of Health and Welfare, and State- or Territory-based Cancer Registries were utilised to collect surveillance data. To corroborate existing data, further available journal literature was identified through Medline and Embase. All papers selected for review were cross-referenced to identify further relevant studies. The most recent national estimate of age-standardised cervical cancer incidence rate was 16.9 and 7.1 per 100,000 women-years in Indigenous and non-Indigenous women respectively (incidence ratio 2.4). The Indigenous age-standardised mortality rate was 9.9 per 100,000 women years (95% CI 7.1-13.3), over 5 times the non-Indigenous rate. Cervical cancer incidence, in both Indigenous and non-Indigenous women, has decreased since 1991. Despite the decline, age-standardised incidence among Indigenous women is still higher than non-Indigenous women. The pattern of cervical cancer incidence and survival corroborates the health inequities that exist in Australia. Indigenous women are more likely than non-Indigenous women to develop cervical cancer and are less likely to survive it. Similar patterns exist in Indigenous populations worldwide, such as New Zealander Maoris and Canadian Aboriginals, suggesting that high rates of cervical cancer incidence and mortality may be a symptom of social and economic inequity.

Human papillomavirus prevalence among indigenous and non-indigenous Australian women prior to a national HPV vaccination program

BACKGROUND

Indigenous women in Australia have a disproportionate burden of cervical cancer despite a national cervical screening program. Prior to introduction of a national human papilloma virus (HPV) vaccination program, we determined HPV genotype prevalence by Indigenous status and residence in remote areas.

METHODS

We recruited women aged 17 to 40 years presenting to community-based primary health services for routine Pap screening across Australia. A liquid-based cytology (LBC) cervical specimen was tested for HPV DNA using the AMPLICOR HPV-DNA test and a PGMY09/11-based HPV consensus PCR; positive specimens were typed by reverse hybridization. We calculated age-adjusted prevalence by weighting to relevant population data, and determined predictors of HPV-DNA positivity by age, Indigenous status and area of residence using logistic regression.

RESULTS

Of 2152 women (655 Indigenous), prevalence of the high-risk HPV genotypes was similar for Indigenous and non-Indigenous women (HPV 16 was 9.4% and 10.5%, respectively; HPV 18 was 4.1% and 3.8%, respectively), and did not differ by age group. In younger age groups, the prevalence of other genotypes also did not differ, but in those aged 31 to 40 years, HPV prevalence was higher for Indigenous women (35% versus 22.5%; P < 0.001), specifically HPV clades α5 (OR = 2.1, 95% CI 1.1 to 4.3) and α7, excluding type 18 (OR 1.9, 95% CI 1.1 to 3.3). In multivariate analysis, detection of any HPV genotype was strongly associated with smoking and Pap-test abnormalities, with both risk factors more common among Indigenous women.

CONCLUSION

Although we found no difference in the prevalence of HPV16/18 among Australian women by Indigenous status or, for Indigenous women, residence in remote regions, differences were found in the prevalence of risk factors and some other HPV genotypes. This reinforces the importance of cervical screening as a complement to vaccination for all women, and the value of baseline data on HPV genotype prevalence by Indigenous status and residence for the monitoring of vaccine impact.

Vaccine preventable diseases and vaccination policy for indigenous populations

There are many similarities regarding the health status of Indigenous people in the 4 English-speaking developed countries of North America and the Pacific (United States, Canada, Australia, New Zealand), where they are all now minority populations. Although vaccines have contributed to the reduction or elimination of disease disparities for many infections, Indigenous people continue to have higher morbidity and mortality from many chronic and infectious diseases compared with the general populations in their countries. This review summarizes the available data on the epidemiology of vaccine-preventable diseases in Indigenous populations in these 4 countries in the context of the vaccination strategies used and their impact, with the aim of identifying successful strategies with the potential for wider implementation.

Diagnosis of sexually transmitted infections (STI) using self-collected non-invasive specimens

Paramount in control of transmission of sexually transmitted infections (STIs) is their prompt recognition and appropriate treatment. In countries where definitive diagnoses are difficult, a 'syndromic approach' to management of STIs is recommended and practiced, yet many STIs have common symptoms or are asymptomatic and therefore go undetected and untreated. This is of particular concern with the recognition that HIV transmission is increased with co-existent STIs: the attributable risk for each STI varying with the prevalence within a particular population. Hence, HIV public health prevention approaches must include STI preventative strategies to be effective. Even then, microbiological screening is incorporated into STI control strategies; lack of access to appropriate services (especially in rural and remote areas), reluctance of at-risk populations to attend for treatment, fear of invasive genital examinations, and lower sensitivities of conventional diagnostic assays reduces the effectiveness of such programmes. Therefore, accurate, cost-effective, reliable diagnostic assays (preferably those which can be used in the field) are needed to impact on the incidence of the various STIs, as well as HIV. With the advent of molecular technologies, including target and signal amplification methods, diagnoses of STIs have been revolutionised and allow the use of non or minimally invasive sampling techniques, some of which are self-collected by the patient, e.g. first-void urine, cervico-vaginal lavage, low vaginal swabs, and tampons. Most studies evaluating such self-sampling with molecular diagnostic techniques have demonstrated an equivalent or superior detection of STIs as compared to conventional sampling and detection methods. These sampling methods can also be used to determine prevalence of STIs in various populations, but particularly those with difficult access to medical care. In this article, the utility of self-sampling collection devices for detection of various STIs, particularly in women, is reviewed as one step towards formulating appropriate strategies in control of STIs, and which are especially suited for remote areas.

Prevalence and typing of human papilloma virus (HPV) among female sex workers and outpatient women in southern Thailand

Background: Thai sex workers (SW) have high rates of sexually transmitted infections (STIs); however, detection and treatment is often complicated by accessibility to sensitive and accurate diagnostic tests. Self-sampling of women combined with molecular amplification techniques could help in accurate diagnosis, treatment and follow-up of such women. Detection of persistent high-risk human papilloma virus (HPV) in such populations could also be beneficial in identifying women who may need more frequent follow-up for cervical cytology screening. The current study aimed to examine the prevalence of HPV in this population and compare this with the lower-risk outpatient women (OPW) in Thailand. Methods: Four hundred and thirty OPW and 524 Thai SW were sampled by a self-administered tampon collection. Cells were extracted from tampons and, subsequently, women underwent routine vaginal examination for detection of other STIs. Detection of HPV was performed by polymerase chain reaction (PCR) using the L1 consensus primers, followed by L1 consensus probe using an in-house PCR-enzyme-linked immunosorbent assay (ELISA). All positive samples were typed using PCR-ELISA and type-specific oligonucleotide probes. Results: Overall, HPV was detected in 20/430 (4.6%) and 120/524 (22.9%) in OPW and SW respectively. Over 98% of samples produced a β-globin signal, indicating adequately collected samples. Human papilloma virus typing probes detected HPV16 or 18 in 14% and 26% of the positive samples from OPW and SW respectively. HPV31, 33, 35 or 39 were detected in 19% and 12% and HPV45, 51 or 52 in 9.5% and 4% of positive OPW and SW patients respectively. Low risk HPV6 or 11 were detected in 1% and 4.9% of OPW and SW respectively. Conclusion: There was a significantly higher HPV prevalence in Thai SW than OPW, with the majority (21%) of positive samples containing the oncogenic HPV16 or 18 DNA. The results indicate that PCR could serve as a rapid and easy method for identification of women who require more frequent screening for cervical cancer.

Prevalence of genital human papillomavirus DNA in a sample of senior school-aged women in the Australian Capital Territory

Background: A strong association between persistent infection with oncogenic types of human papillomavirus (HPV) and cervical cancer is well established. Small numbers of international studies examining adolescent HPV infection and the risk factors associated are published, but there is currently no evidence on the prevalence and risk factors for HPV in an Australian, sexually active female adolescent population. Methods: To provide prevalence and risk factors for HPV in a female sexually active, senior high school population in the Australian Capital Territory (ACT), a convenience sample of 161, 16–19-year-old females attending a senior high school was evaluated. The sample formed part of a larger sample recruited for a study of sexually transmitted infections and blood-borne viruses in senior high school students. A clinical record was used to collect information about sexual and other risk behaviours, while self-collected vaginal swabs were tested for HPV DNA detection and genotyping using polymerase chain reaction. Results: The prevalence of HPV DNA in this sample overall was 11.2%, with multiple genotypes in 38%. No statistically significant associations were found between HPV DNA and the number of male partners, age of coitarche, time since first sexually active, condom use, smoking or alcohol intake. Conclusions: This is the first Australian study that has examined the prevalence and risk factors for genital HPV in this demographic group. The prevalence of HPV infection is slightly lower than reported in similar age groups overseas and is lower than other Australian studies in older women and those attending sexual health centres. Of HPV-positive young women, high-risk genotypes were found in over half, with more than one-third of HPV existing as multiple genotypes. Large community-based prevalence studies are needed to guide the development of recommendations for the vaccination of young women against HPV and to support other health promotion initiatives.

Cancer incidence and survival for indigenous Australians in the Northern Territory

OBJECTIVE

To compare cancer incidence and survival for the Northern Territory (NT) Indigenous population with that of other Australians, and to assess NT Indigenous incidence time trends.

METHODS

Cancer registry data were used to calculate cancer incidence rate ratios (NT Indigenous to total Australian), the average annual change in NT Indigenous cancer incidence and the relative risk of cancer death after diagnosis of cancer (NT Indigenous to combined Western Australian and Tasmanian cases) for 1991-2001.

RESULTS

For NT Indigenous people, incidence rates were high for cancers of the liver, gallbladder, cervix, vulva and thyroid and, in younger people only, for cancers of the oropharynx, oesophagus, pancreas and lung, but low for cancers of the colon and rectum, breast, ovary, prostate, bladder, kidney, melanoma and lymphoma. Incidence rate ratios ranged from 0.1 for melanoma to 7.4 for liver cancer. Incidence increased for breast and pancreatic cancers. Survival was low for almost all specific cancers examined, and for all cancers combined (relative risk of death 1.9, 95% CI 1.7-2.1).

CONCLUSIONS

Compared with other Australians, NT Indigenous people have higher, and increasing, incidence for some cancers (particularly smoking-related cancers) and lower survival for most.

IMPLICATIONS

Cancer has a greater impact on NT Indigenous people than other Australians. Well-established cancer risk factors should be more effectively tackled in Indigenous people and known effective screening programs more effectively implemented. Research is urgently required into the reasons why survival from cancer in NT Indigenous people is so much lower than in other Australians.