Population-based denominators matter: Bias in U.S. Virgin Islands COVID-19 vaccination coverage under changing population counts.

PURPOSE: The U.S. Virgin Islands (USVI) receives an updated population count once every 10 years and used 2010 decennial census population counts to estimate COVID-19 vaccination coverage during the COVID-19 emergency response. We investigated whether using outdated (2010) or modeled (2020 international database [IDB]) population counts biased vaccination coverage estimates used to inform public health priorities during the 2020-2022 COVID-19 response. METHODS: We estimated percentage of USVI residents with a completed primary COVID-19 vaccination series during December 16, 2020-September 20, 2022. Vaccination coverage was calculated as number of persons who completed the vaccination series divided by 2010 and 2020 decennial census population counts and 2020 IDB intercensal estimate. RESULTS: COVID-19 vaccination coverage using the 2020 population count was 12 % points higher than coverage using 2010 denominator (2010 denominator: 51 %; 2020 denominator: 63 %). Vaccination coverage estimated using 2020 IDB was approximately equal with the 2010 decennial census estimate (52 %). CONCLUSIONS: Using 2010 and modeled population counts underestimated 2020 USVI COVID-19 vaccination coverage given the 18 % population decline during 2010-2020, potentially limiting USVI's ability to assess vaccination progress. Identifying mechanisms for more reliable population enumeration or improved estimate modeling are essential for accurately guiding USVI public health decision-making.

Acceptability of a Chikungunya Virus Vaccine, United States Virgin Islands.

Chikungunya virus, a mosquito-borne alphavirus, causes acute febrile illness with polyarthralgia. Groups at risk for severe disease include neonates, people with underlying medical conditions, and those aged ≥ 65 years. Several chikungunya vaccines are in late clinical development with licensure expected in the United States during 2023. We administered a questionnaire to randomly selected households in the U.S. Virgin Islands (USVI) to assess interest in a hypothetical chikungunya vaccine. Estimates were calibrated to age and sex of USVI population, and univariate and multivariable analyses were performed. Of 966 participants, 520 (adjusted 56%, 95% CI = 51-60%) were interested in receiving the vaccine. Of 446 participants not interested in vaccination, 203 (adjusted 47%, 95% CI = 41-52%) cited safety concerns as the reason. Educational efforts addressing vaccine safety concerns and risk factors for severe disease would likely improve vaccine acceptability and uptake among those most at risk.

2021 U.S. Virgin Islands Zika health brigade: Providing recommended pediatric health screenings for children born to mothers with laboratory evidence of possible Zika virus infection during pregnancy.

BACKGROUND: The United States Virgin Islands (USVI) Department of Health (DOH) conducted a second Zika health brigade (ZHB) in 2021 to provide recommended Zika-related pediatric health screenings, including vision, hearing, neurologic, and developmental screenings, for children in the USVI. This was replicated after the success of the first ZHB in 2018, which provided recommended Zika-related pediatric health screenings to 88 infants and children exposed to Zika virus (ZIKV) during pregnancy. METHODS: Ten specialty pediatric care providers were recruited and traveled to the USVI to conduct the screenings. USVI DOH scheduled appointments for children included in CDC's U.S. Zika Pregnancy and Infant Registry (USZPIR). During the ZHB, participants were examined by pediatric ophthalmologists, pediatric audiologists, and pediatric neurologists. We report the percentage of participants who were referred for additional follow-up care or given follow-up recommendations in the 2021 ZHB and compare these referrals and recommendations to those given in the 2018 ZHB. RESULTS: Thirty-three children born to mothers with laboratory evidence of ZIKV infection during pregnancy completed screenings at the 2021 ZHB, of which 15 (45%) children were referred for additional follow-up care. Ophthalmological screenings resulted in the highest number of new referrals for a specialty provider among ZHB participants, with 6 (18%) children receiving referrals for that specialty. Speech therapy was the most common therapy referral, with 10 (30%) children referred, of which 9 (90%) were among those who attended the 2018 ZHB. CONCLUSIONS: Thirty-three children in a jurisdiction with reduced access to healthcare specialists received recommended Zika-related pediatric health screenings at the ZHB. New and continuing medical and developmental concerns were identified and appropriate referrals for follow-up care and services were provided. The ZHB model was successful in creating connections to health services not previously received by the participants.

Microbial Characterization, Factors Contributing to Contamination, and Household Use of Cistern Water, U.S. Virgin Islands.

Households in the United States Virgin Islands (USVI) heavily rely on roof-harvested rainwater stored in cisterns for their daily activities. However, there are insufficient data on cistern water microbiological and physicochemical characteristics to inform appropriate cistern water management. Cistern and kitchen tap water samples were collected from 399 geographically representative households across St. Croix, St. Thomas, and St. John and an administered survey captured household site and cistern characteristics and water use behaviors. Water samples were analyzed for Escherichia coli by culture, and a subset of cistern water samples (N = 47) were analyzed for Salmonella, Naegleria fowleri, pathogenic Leptospira, Cryptosporidium, Giardia, and human-specific fecal contamination using real-time polymerase chain reaction (PCR). Associations between E. coli cistern contamination and cistern and site characteristics were evaluated to better understand possible mechanisms of contamination. E. coli was detected in 80% of cistern water samples and in 58% of kitchen tap samples. For the subset of samples tested by PCR, at least one of the pathogens was detected in 66% of cisterns. Our results suggest that covering overflow pipes with screens, decreasing animal presence at the household, and preventing animals or insects from entering the cisterns can decrease the likelihood of E. coli contamination in USVI cistern water.

Spatial, Sociodemographic, and Weather Analysis of the Zika Virus Outbreak: U.S. Virgin Islands, January 2016-January 2018.

Background: The first Zika virus outbreak in U.S. Virgin Islands identified 1031 confirmed noncongenital Zika disease (n = 967) and infection (n = 64) cases during January 2016-January 2018; most cases (89%) occurred during July-December 2016. Methods and Results: The epidemic followed a continued point-source outbreak pattern. Evaluation of sociodemographic risk factors revealed that estates with higher unemployment, more houses connected to the public water system, and more newly built houses were significantly less likely to have Zika virus disease and infection cases. Increased temperature was associated with higher case counts, which suggests a seasonal association of this outbreak. Conclusion: Vector surveillance and control measures are needed to prevent future outbreaks.

Seroprevalence, distribution, and risk factors for human leptospirosis in the United States Virgin Islands.

BACKGROUND: The first documented human leptospirosis cases in the U.S. Virgin Islands (USVI) occurred following 2017 Hurricanes Irma and Maria. We conducted a representative serosurvey in USVI to estimate the seroprevalence and distribution of human leptospirosis and evaluate local risk factors associated with seropositivity. METHODOLOGY/PRINCIPAL FINDINGS: A stratified, two-stage cluster sampling design was used and consisted of three island strata and random selection of census blocks and then households. All eligible members of selected households were invited to participate (≥5 years old, resided in USVI ≥6 months and ≥6 months/year). Household and individual-level questionnaires were completed, and serum collected from each enrolled individual. Microscopic agglutination test serology was conducted, and bivariate and logistic regression analyses completed to identify risk factors for seropositivity. In March 2019, 1,161 individuals were enrolled from 918 households in St. Croix, St. Thomas, and St. John. The territory-wide weighted seroprevalence was 4.0% (95% CI:2.3-5.7). Characteristics/exposures independently associated with seropositivity using logistic regression included contact with cows (OR: 39.5; 95% CI: 9.0-172.7), seeing rodents/rodent evidence or contact with rodents (OR: 2.6; 95% CI: 1.1-5.9), and increasing age (OR: 1.02; 95% CI: 1.002-1.04); full or partial Caucasian/White race was negatively correlated with seropositivity (OR: 0.02, 95% CI: 0.04-0.7). Bivariate analysis showed self-reported jaundice since the 2017 hurricanes (pRR: 5.7; 95% CI: 1.0-33.4) was associated with seropositivity and using a cover/lid on cisterns/rainwater collection containers (pRR: 0.3; 95% CI: 0.08-0.8) was protective against seropositivity. CONCLUSIONS/SIGNIFICANCE: Leptospirosis seropositivity of 4% across USVI demonstrates an important human disease that was previously unrecognized and emphasizes the importance of continued leptospirosis surveillance and investigation. Local risk factors identified may help guide future human and animal leptospirosis studies in USVI, strengthen leptospirosis public health surveillance and treatment timeliness, and inform targeted education, prevention, and control efforts.

A Cross-Sectional Household Survey in the US Virgin Islands (2019) Reveals Cisterns as Challenging Peridomestic Aedes aegypti Habitats.

Most residences in the United States Virgin Islands (USVI) rely on household rainwater-catchment systems and subterranean cisterns for long-term water storage that may provide suitable habitats for mosquitoes of public health relevance. We conducted a household cistern survey (n = 164) on the islands of St. Croix, St. John, and St. Thomas in 2019. The survey revealed that 45.7% (95% CI: 38.3-53.4%) of cisterns contained mosquitoes (adult and/or immature mosquitoes). Aedes aegypti, a vector of chikungunya, dengue, and Zika viruses in the USVI, was found in 27.4% (95% CI: 21.2-34.7%) of cisterns and accounted for 83.3% of the total mosquitoes identified in the study. The odds of detecting mosquitoes in a cistern were 5.45 times higher at locations where the residents reported that they had observed adult mosquitoes coming out of their cisterns (95% CI: 2.25-14.21), suggesting that vector control personnel should consider resident complaints about mosquitoes in their cistern as valid and likely reliable self-assessments. Resident mosquito management practices in cisterns did not correspond with decreased odds of mosquito detection. We conclude that cisterns in the USVI commonly provide habitat for immature and adult Ae. aegypti, which may decrease the effectiveness of area-wide mosquito control strategies. Additional studies are necessary to evaluate the importance of these cisterns as they relate to mosquito production and arbovirus transmission risk, and to assess physical and chemical control methods.

Assessing rodents as carriers of pathogenic Leptospira species in the U.S. Virgin Islands and their risk to animal and public health.

Leptospirosis is a global zoonotic disease caused by pathogenic bacteria of the genus Leptospira. We sought to determine if rodents in U.S. Virgin Islands (USVI) are carriers of Leptospira. In total, 140 rodents were sampled, including 112 Mus musculus and 28 Rattus rattus. A positive carrier status was identified for 64/140 (45.7%); 49 (35.0%) were positive by dark-field microscopy, 60 (42.9%) by culture, 63 (45.0%) by fluorescent antibody testing, and 61 (43.6%) by real-time polymerase chain reaction (rtPCR). Molecular typing indicated that 48 isolates were L. borgpetersenii and 3 were L. kirschneri; the remaining nine comprised mixed species. In the single culture-negative sample that was rtPCR positive, genotyping directly from the kidney identified L. interrogans. Serotyping of L. borgpetersenii isolates identified serogroup Ballum and L. kirschneri isolates as serogroup Icterohaemorrhagiae. These results demonstrate that rodents are significant Leptospira carriers and adds to understanding the ecoepidemiology of leptospirosis in USVI.

Mongooses (Urva auropunctata) as reservoir hosts of Leptospira species in the United States Virgin Islands, 2019-2020.

During 2019-2020, the Virgin Islands Department of Health investigated potential animal reservoirs of Leptospira spp., the bacteria that cause leptospirosis. In this cross-sectional study, we investigated Leptospira spp. exposure and carriage in the small Indian mongoose (Urva auropunctata, syn: Herpestes auropunctatus), an invasive animal species. This study was conducted across the three main islands of the U.S. Virgin Islands (USVI), which are St. Croix, St. Thomas, and St. John. We used the microscopic agglutination test (MAT), fluorescent antibody test (FAT), real-time polymerase chain reaction (lipl32 rt-PCR), and bacterial culture to evaluate serum and kidney specimens and compared the sensitivity, specificity, positive predictive value, and negative predictive value of these laboratory methods. Mongooses (n = 274) were live-trapped at 31 field sites in ten regions across USVI and humanely euthanized for Leptospira spp. testing. Bacterial isolates were sequenced and evaluated for species and phylogenetic analysis using the ppk gene. Anti-Leptospira spp. antibodies were detected in 34% (87/256) of mongooses. Reactions were observed with the following serogroups: Sejroe, Icterohaemorrhagiae, Pyrogenes, Mini, Cynopteri, Australis, Hebdomadis, Autumnalis, Mankarso, Pomona, and Ballum. Of the kidney specimens examined, 5.8% (16/270) were FAT-positive, 10% (27/274) were culture-positive, and 12.4% (34/274) were positive by rt-PCR. Of the Leptospira spp. isolated from mongooses, 25 were L. borgpetersenii, one was L. interrogans, and one was L. kirschneri. Positive predictive values of FAT and rt-PCR testing for predicting successful isolation of Leptospira by culture were 88% and 65%, respectively. The isolation and identification of Leptospira spp. in mongooses highlights the potential role of mongooses as a wildlife reservoir of leptospirosis; mongooses could be a source of Leptospira spp. infections for other wildlife, domestic animals, and humans.

Determination of freedom-from-rabies for small Indian mongoose populations in the United States Virgin Islands, 2019-2020.

Mongooses, a nonnative species, are a known reservoir of rabies virus in the Caribbean region. A cross-sectional study of mongooses at 41 field sites on the US Virgin Islands of St. Croix, St. John, and St. Thomas captured 312 mongooses (32% capture rate). We determined the absence of rabies virus by antigen testing and rabies virus exposure by antibody testing in mongoose populations on all three islands. USVI is the first Caribbean state to determine freedom-from-rabies for its mongoose populations with a scientifically-led robust cross-sectional study. Ongoing surveillance activities will determine if other domestic and wildlife populations in USVI are rabies-free.

Exposure and Carriage of Pathogenic Leptospira in Livestock in St. Croix, U.S. Virgin Islands.

From 2019-2020, the Virgin Islands Department of Health (VIDOH) investigated potential animal reservoirs of Leptospira spp., the pathogenic bacteria that cause leptospirosis. We examined Leptospira exposure and carriage in livestock on the island of St. Croix, United States Virgin Islands (USVI). We utilized the microscopic agglutination test (MAT) to evaluate the sera, and the fluorescent antibody test (FAT), real time polymerase chain reaction (rt-PCR), and bacterial culture to evaluate urine specimens from livestock (n = 126): 28 cattle, 19 goats, 46 pigs, and 33 sheep. Seropositivity was 37.6% (47/125) with agglutinating antibodies to the following serogroups identified: Australis, Djasiman, Icterohaemorrhagiae, Ballum, Sejroe, Cynopteri, Autumnalis, Hebdomadis, Pomona, Canicola, Grippotyphosa, and Pyrogenes. Urine from 4 animals (4.0%, 4/101) was positive by rt-PCR for lipL32: 2 sheep, 1 goat, and 1 bull. Sequencing of secY amplicons identified L. interrogans in 1 sheep and 1 bull. Livestock in USVI harbor pathogenic Leptospira bacteria and could play a role in the zoonotic cycle of leptospirosis.

Ocular Findings and Visual Function in Children Examined during the Zika Health Brigade in the US Virgin Islands, March 2018.

Among children born with laboratory-confirmed Zika virus (ZIKV) infection, visual impairment (VI) can occur despite normal ocular structure. The objective of this report is to describe ocular findings and visual function among children examined during the Department of Health Zika Health Brigade (ZHB) in the United States Virgin Islands in March 2018. This analysis is based on a retrospective chart review of children eligible to participate in the ZHB (i.e., part of the US Zika Pregnancy and Infant Registry) and who were examined by ophthalmologists. Eighty-eight children attended the ZHB. This report includes 81 children [48 (59.3%) males] whose charts were located [average gestational age = 37.6 weeks (range: 27.6-41.3) and average adjusted age at examination = 9.1 months (range: 0.9-21.9)]. Of those examined, 5/81 (6.2%) had microcephaly at birth, 2/81 (2.5%) had a structural eye abnormality, and 19/72 (26.4%) had VI. Among children with normal ocular structure and neurologic examination, 13/51 (25.5%) had VI. Despite a low incidence of abnormal ocular structure and microcephaly, about a quarter of children examined had VI. Our findings emphasize that ophthalmological examinations should be performed in all children with suspicion for antenatal ZIKV infection, even children with normal ocular structure and neurologic examination.

2018 Zika Health Brigade: Delivering Critical Health Screening in the U.S. Virgin Islands.

In 2017, Hurricanes Irma and Maria caused significant damage to the United States Virgin Islands (USVI), heightening the challenges many residents faced in accessing adequate healthcare and receiving recommended Zika virus screening services. To address this challenge, the USVI Department of Health (DOH) requested technical assistance from the Centers for Disease Control and Prevention (CDC), the Health Resources and Services Administration (HRSA), and the American Academy of Pediatrics (AAP) to organize a health brigade to bring needed medical care to an underserved population. It also established the development of important partnerships between federal and private partners as well as between clinical providers and public health entities such as the Epidemiology & Disease Reporting, Maternal Child Health (MCH), and Infant and Toddlers Programs within the DOH, and local clinicians. This health brigade model could be replicated to ensure recommended evaluations are delivered to populations that may have unmet medical needs due to the complexity of the conditions and/or rural location.

Burkholderia pseudomallei in Soil, US Virgin Islands, 2019.

The distribution of Burkholderia pseudomallei in the Caribbean is poorly understood. We isolated B. pseudomallei from US Virgin Islands soil. The soil isolate was genetically similar to other isolates from the Caribbean, suggesting that B. pseudomallei might have been introduced to the islands multiple times through severe weather events.

Population-Based Surveillance for Birth Defects Potentially Related to Zika Virus Infection - 22 States and Territories, January 2016-June 2017.

Zika virus infection during pregnancy can cause congenital brain and eye abnormalities and is associated with neurodevelopmental abnormalities (1-3). In areas of the United States that experienced local Zika virus transmission, the prevalence of birth defects potentially related to Zika virus infection during pregnancy increased in the second half of 2016 compared with the first half (4). To update the previous report, CDC analyzed population-based surveillance data from 22 states and territories to estimate the prevalence of birth defects potentially related to Zika virus infection, regardless of laboratory evidence of or exposure to Zika virus, among pregnancies completed during January 1, 2016-June 30, 2017. Jurisdictions were categorized as those 1) with widespread local transmission of Zika virus; 2) with limited local transmission of Zika virus; and 3) without local transmission of Zika virus. Among 2,004,630 live births, 3,359 infants and fetuses with birth defects potentially related to Zika virus infection during pregnancy were identified (1.7 per 1,000 live births, 95% confidence interval [CI] = 1.6-1.7). In areas with widespread local Zika virus transmission, the prevalence of birth defects potentially related to Zika virus infection during pregnancy was significantly higher during the quarters comprising July 2016-March 2017 (July-September 2016 = 3.0; October-December 2016 = 4.0; and January-March 2017 = 5.6 per 1,000 live births) compared with the reference period (January-March 2016) (1.3 per 1,000). These findings suggest a fourfold increase (prevalence ratio [PR] = 4.1, 95% CI = 2.1-8.4) in birth defects potentially related to Zika virus in widespread local transmission areas during January-March 2017 compared with that during January-March 2016, with the highest prevalence (7.0 per 1,000 live births) in February 2017. Population-based birth defects surveillance is critical for identifying infants and fetuses with birth defects potentially related to Zika virus regardless of whether Zika virus testing was conducted, especially given the high prevalence of asymptomatic disease. These data can be used to inform follow-up care and services as well as strengthen surveillance.

Melioidosis after Hurricanes Irma and Maria, St. Thomas/St. John District, US Virgin Islands, October 2017.

We report 2 cases of melioidosis in women with diabetes admitted to an emergency department in the US Virgin Islands during October 2017. These cases emerged after Hurricanes Irma and Maria and did not have a definitively identified source. Poor outcomes were observed when septicemia and pulmonary involvement were present.

Community Assessments for Public Health Emergency Response (CASPERs)-US Virgin Islands, 2017-2018.

Objectives. To assess preparedness levels of communities to help public health and others plan for disasters or emergencies and tailor messaging to increase community preparedness.Methods. US Virgin Islands Department of Health conducted a Community Assessment for Public Health Emergency Response (CASPER) in June 2017, 2 hurricane response CASPERs in November 2017, and a recovery CASPER in February 2018. CASPER is a 2-stage cluster sampling method designed to provide household-based information about a community's needs in a timely, inexpensive, and representative manner.Results. Roughly the same amount of households reported having a 3-day supply of food and water before and 3 months after the hurricanes. During the response, approximately a third of households resupplied between 3 and 6 days and an additional approximately 40% between days 7 and 14.Conclusions. On the basis of the CASPERs, we were able to track whether households had an emergency preparedness kit, whether they used it during the storms (and what was missing), and if they resupplied their kit in recovery.Public Health Implications. CASPER is a promising tool to measure community preparedness to help state, local, tribal, and territorial jurisdictions plan for disasters or emergencies.

First Reported Human Cases of Leptospirosis in the United States Virgin Islands in the Aftermath of Hurricanes Irma and Maria, September-November 2017.

OBJECTIVE: Following Hurricanes Irma and Maria, the first case of human leptospirosis ever identified in the US Virgin Islands (USVI) was reported to the Virgin Islands Department of Health. Leptospirosis is a potentially fatal bacterial disease caused by Leptospira species found in animal urine and urine-contaminated water and soil. Outbreaks can occur following extreme weather events. METHOD: Additional cases of leptospirosis were identified in the 2.5 months post-hurricanes by reviewing emergency department (ED) records from territorial hospitals for patients demonstrating leptospirosis-consistent symptoms, testing symptomatic patients previously enrolled in the USVI arbovirus surveillance system (VIASS), and adding leptospirosis testing prospectively to VIASS. Available patient sera underwent local rapid diagnostic testing for anti-Leptospira IgM followed by confirmatory microscopic agglutination testing at the US Centers for Disease Control and Prevention. Water was collected from cisterns with epidemiologic links to confirmed cases and tested by real-time PCR (qPCR) for pathogenic Leptospira spp. RESULTS: Sixteen retrospectively identified symptomatic patients were enrolled in VIASS; 15 with available samples tested negative. Based on review of 5226 ED charts, 6 patients were further investigated; of these, 5 were tested of which 1 was positive. Prospective leptospirosis surveillance tested 57 additional patients; of these, 1 was positive. Water from 1 of 5 tested cisterns was found positive by qPCR. CONCLUSIONS: This investigation documents the first 3 cases of leptospirosis reported in the USVI and demonstrates how VIASS successfully was adapted to establish leptospirosis surveillance. Contaminated cistern water was identified as a potential source for Leptospira spp. transmission, highlighting the need for additional post-hurricane remediation and disinfection guidance.