Mpox incidence across rural and urban areas in the US

By Tarun Sai LomteReviewed by Lily Ramsey, LLMMay 31 2023

A recent study published in Morbidity and Mortality Weekly Report explored the differences in rural and urban mpox incidence in the United States (US).

Study: Urban and Rural Mpox Incidence Among Persons Aged 15–64 Years — United States, May 10–December 31, 2022. Image Credit: DottedYeti/Shutterstock.com

Background

The US Centers for Disease Control and Prevention (CDC) recorded more than 29,000 mpox cases between May and December 2022, predominantly among cisgender adult males with recent sexual contact with males.

Urban-rural differences in health and diagnosis of human immunodeficiency virus (HIV) and other sexually transmitted infections are well established.

The study and findings

In the present study, researchers examined the differences in the urban and rural incidence of mpox in the US. Jurisdictional health departments reported data on probable and confirmed cases of mpox.

The study took this data from the National Notifiable Disease Surveillance System or a standardized case report form. Urbanicity was defined using the urban-rural classification scheme of the National Center for Health Statistics.

The urbanicity levels were large fringe, large central, medium, and small for metropolitan or urban counties and non-core and micropolitan for non-metropolitan or rural counties.

Micropolitan and non-core levels were merged into a single rural group due to small case numbers. Mpox incidence by each of these five urbanicity levels was estimated.

Analysis was restricted to individuals aged 15-64 because most cases (97.8%) were in this age group and to limit bias due to differential age distribution. Estimates were stratified by gender, race or ethnicity, and month. Risk ratios and 95% confidence intervals were computed between groups.

Most patients (71%) were from large central urban counties, and only 1.5% were reported in rural areas.

The median age and distribution of cases by age group were comparable across urbanicity levels. Over 95% of cases in large central urban counties and 94.7% in rural areas were among cisgender males. Cisgender females represented 2.3% and 4.6% of mpox cases in large central urban and rural areas, respectively.

Notably, the ethnic and racial distribution of mpox was different by urbanicity. Hispanic individuals represented around 34% and 26% in large central and fringe urban counties, respectively, compared to 14.3% in small urban areas and 15.1% in rural areas.

There were more cases among White individuals in rural and small urban counties than in other counties.

Mpox cases among Black persons ranged between 30% and 40% across large central and fringe urban areas. There were limited mpox cases in other ethnic and racial groups, so the relationship with urbanicity was not estimated.

Overall, the incidence of mpox was 13.5 cases per 100,000; however, estimates differed by urbanicity, with the highest in large central urban areas at 30.6 cases per 100,000, followed by large fringe urban, medium urban, small urban, and rural areas.

Further, mpox incidence peaked across all urbanicity levels in August and declined afterward. Mpox incidence was 27.2 and 0.7 cases per 100,000 in cisgender males and cisgender females, respectively.

The highest rates among cisgender males or females were in large central urban counties; rates were lower in small urban counties. Mpox incidence was higher among cisgender males than in cisgender females across all urbanicity levels, with the highest difference in incidence in large central urban counties and the lowest in rural areas.

Moreover, Black individuals had a higher incidence of mpox than White subjects in rural and urban counties, with the highest relative difference in rural areas.

Across all urbanicity levels, mpox incidence was higher in Hispanic individuals than in White people and Black people than in Hispanic individuals.

Conclusions

In sum, most mpox cases were reported in urban areas in the US, particularly in large central urban areas. Moreover, 95% of cases were among cisgender males. The proportions of mpox cases were similar among White, Hispanic, and Black persons in large central urban areas; however, Hispanic and Black individuals had a higher incidence than White persons.

By contrast, in rural counties, mpox cases were higher among White and Black individuals. Still, the incidence rates in Black and Hispanic individuals were six- and two-fold more elevated than in White individuals.

Overall, efforts to support and sustain mpox surveillance should continue across all urbanicity levels to ensure testing and treatment of all at-risk individuals.

The findings revealed racial and ethnic disparities that were higher in relative magnitude in small urban and rural areas but higher in absolute magnitude in urban areas.

This highlights the need for implementing equity-based vaccination focused on men who have sex with men (MSM), and gay and bisexual communities in urban areas.