CDC EIS Officers Presented Emerging Vector-borne Disease Research at Recent Conference

“Vector-borne diseases are among the most complex of all infectious diseases to prevent and control. Not only is it difficult to predict the habits of mosquitoes, ticks, and fleas, but most vector-borne viruses or bacteria infect animals as well as humans,” according to the Centers for Disease Control and Prevention (CDC). Six officers of the CDC’s Epidemic Intelligence Service (EIS) presented their recent research findings on May 3 in the Vectorborne Diseases session of the 65th Annual Epidemic Intelligence Service (EIS) Conference in Atlanta, Georgia. A summary of the presentations is included below:

The chikungunya virus (CHIKV), transmitted by mosquitoes, emerged in the United States Virgin Islands (USVI) in June 2014, and that same year, 380 locally transmitted and 19 travel-associated cases were reported.

Over one week in February 2015, Cara C. Cherry, DVM, MPH, and her colleagues surveyed Virgin Islands National Park visitors 18 years of age and above at 10 park locations with a questionnaire assessing their CHIKV knowledge, attitudes, and health information-seeking practices, as well as their travel details and demographics.

Of the 443 people who completed the survey, 208 (47%) were aware of CHIKV. During trip preparation, 126 (28%) of them investigated USVI-specific health concerns, and 102 of the 126 (81%) were aware of CHIKV. Visitors who were aware of CHIKV were more likely to apply insect repellent ([134 of 207; 65%] vs [111 of 231; 48%]; P<0.001), wear long pants and long-sleeved shirts ([84 of 203; 41%] vs [57 of 227; 25%]; P<0.001), and wear clothing treated with insect repellent ([36 of 204; 18%] vs [22 of 227; 10%]; P=0.02).

Based on their findings, the authors advised that tourists need to be educated about their travel-related CHIKV risks.

Jefferson M. Jones, MD, MPH, and his co-authors detected no locally acquired Dengue virus (DENV) cases along the border of Yuma County, Arizona and Sonora, Mexico; but their entomologic findings and the frequent border crossings during Dengue outbreaks make Dengue possible to occur in Yuma County.

From September through December 2014, during a Dengue epidemic in Sonora caused by Aedes species mosquitoes, 95 travel-associated Dengue cases were reported in Arizona. Seventy-five percent of the cases were among Yuma County residents. The researchers investigated households within 50 meters of patients’ Yuma County residences. All residents within that area were offered a questionnaire and Dengue diagnostic testing by reverse transcription polymerase chain reaction (RT-PCR) and anti-DENV IgM Enzyme-Linked Immunosorbent Assay (ELISA). In addition, their houses and yards were tested for mosquito breeding sites.

Of the 194 participants in 113 households, four participants had traveled to Mexico within the previous three months and had detectable anti-DENV IgM antibody, but none reported a recent febrile illness; 152 (78%) reported travelling to Mexico at least monthly; and 42 (37%) households reported mosquitoes in their home. The researchers advised travelers to avoid contact with mosquitoes and to kill them if possible.

Ian D. Plumb, MD, and his group studied an unusual cluster of endocarditis due to Bartonella quintana, which is transmitted to humans by body lice and prevalent among people who are homeless, in Anchorage, Alaska. The authors reviewed the charts of patients with Bartonella infection in Anchorage hospitals from 2009 through 2014; and since August 2015, they collected lice from clothing of patients examined at one emergency department, and performed PCR for Bartonella using 2 molecular targets (gltA and ITS). They identified 7 cases confirmed by PCR from 2012 through 2014-5, 2 with positive serology only. All occurred in men over 40, including 6 Anchorage residents, 4 homeless, 3 who used the same shelter, and 3 with louse infestation. Six had valvular cardiac failure and 2 died. All surviving patients needed valve replacement and antimicrobial therapy. Of 55 lice collected from 21 patients to date, 4 lice from 2 patients tested positive for B. quintana. The authors recommend Bartonella testing in men with possible lice exposure and unexplained valvular insufficiency and they called for more research.

Heather Venkat, DVM, MPH, and her colleagues evaluated a BioSense syndrome-based query for West Nile Virus (WNV). They found that the platform used by the Arizona Department of Health Services (ADHS) was too broad to reveal trends for this leading cause of domestically acquired arboviral disease in the United States which can lead to neuroinvasive disease and death.

The authors recorded hospital emergency department and inpatient visits over ten months in 2015 and chief complaints or diagnoses of: fever, chills, headache, rash, vertigo, muscle pain, joint pain, nausea, vomiting, stiff neck, altered mental status, seizures, limb or muscle weakness, encephalitis, or loss of consciousness. They compared WNV BioSense cases with reported lab-confirmed WNV cases and identified the correlations between WNV BioSense and reported WNV cases.

Searching for 2 or more symptoms detected 141,920 WNV BioSense cases, 3 or more symptoms detected 38,093 cases, and 4 or more symptoms detected 5,790 cases. By contrast, 91 lab-confirmed WNV cases were reported. The correlation between trends of WNV BioSense cases with 2 or more WNV symptoms and lab-confirmed WNV cases was not significant (F-test=0.92; P=0.43), and the authors suggested adding more subtle distinctions, weighted criteria, and more hospital involvement to better predict outbreaks.

“For Rickettsia species and other tickborne diseases, there is disease in more of the state than expected. Tick disease is traveling westward,” Jessica A. Nadeau, PhD, MPH, said in her talk about her group’s study of spotted fever group Rickettsia (SFGR) in Kansas. Overall, 83% of persons were considered to be exposed while in their county of residence and 17% exposed while traveling to another county in the state. In 2012 through 2015, most ill persons were in the eastern portion of the state.

The researchers evaluated human SFGR cases reported to the Kansas Department of Health and Environment with onset between January 2012 and October 2015 and canine specimens submitted to the Kansas State Veterinary Diagnostic Laboratory during the same period. Lab tests dates for positive human SFGR serologic tests and positive canine SFGR serologic or polymerase chain reaction tests were compared to determine the first reported case for each county.

Exposure for 514 reported human cases occurred in 58 of the 105 Kansas counties, and in 17 counties for 90 cases in dogs. Exposure for human and canine cases was detected in 14 counties, with dog cases preceding human cases in 4 counties, by an average of 4 months; and canine cases were found in 3 counties with no reported human cases.

“Due to the high mortality of some Rickettsia species, treatment with doxycycline both for non-pregnant adults and children should be started prior to receiving results of confirmatory testing. Due to lack of in-office testing and ease of treatment, many dogs may receive doxycycline empirically without confirmatory testing,” Dr. Nadeau said, and she advised identifying counties at risk to help target tick-borne disease prevention.

Natalie A. Kwit, DVM, MPH and her co-authors assessed employer-insured patients with Lyme disease diagnosed with carditis, meningitis, facial palsy, and arthritis. They used MarketScan^® insurance claims databases that contain diagnosis and treatment information for roughly 40 million employer-insured Americans under 65 and their dependents in the US and the District of Columbia. (https://marketscan.truvenhealth.com/marketscanportal/)

“Each year, an estimated 300,000 Americans are diagnosed with Lyme disease, a zoonotic infection caused by Borrelia burgdorferi and transmitted by certain species of Ixodes, blacklegged ticks,” Dr. Kwit said in her talk.

The researchers identified 93,981 patients diagnosed with Lyme disease. Their median age was 41 years and 51% were female. The mean annual incidence was 51 per 100,000 persons, and 3,406 (3.6%) patients had codiagnoses consistent with disseminated Lyme disease: 348 (0.3%) carditis, 451 (0.5%) meningitis, 447 (0.5%) facial palsy, and 2,160 (2.3%) arthritis. More than one disseminated co-diagnosis was reported in 174 patients and 35% of patients with disseminated disease were hospitalized.

Males between 17 and 33 were at significantly higher risk of both carditis (odds ratio [OR] 2.09; 95% confidence interval [CI], 1.87 to 2.30) and facial palsy (OR 1.26; 95% CI, 1.04 to 1.48); meningitis risk was highest among children of either sex aged 0 through 16 years (OR 1.90; 95% CI, 1.73 to 2.06); and arthritis most strongly affected females 34 to 50 (OR 1.18; 95% CI, 1.09 to 1.27).

Although the MarketScan^® database may not be represent the entire US population and its codes designed for insurance reimbursement may not always reflect true disease, these findings may be used to help diagnose and prevent Lyme disease, the authors suggested.

Lorraine L. Janeczko, MPH, is a medical science writer who creates news, continuing medical education and feature content in a wide range of specialties for clinicians, researchers and other readers. She has completed a Master of Public Health degree through the Department of Epidemiology of the Johns Hopkins Bloomberg School of Public Health and a Dana Postdoctoral Fellowship in Preventive Public Health Ophthalmology from the Wilmer Eye Institute, the Johns Hopkins University School of Medicine and the Bloomberg School.

SOURCE: EIS 2016 Conference Program, pp 54-57: Concurrent Session F1: Vectorborne Diseases

Studies Presented:

Cara C. Cherry, DVM, MPH, EIS officer, Office of Public Health Scientific Services, Knowledge and Use of Prevention Practices for Chikungunya Virus Among Visitors — Virgin Islands National Park, 2015

Jefferson M. Jones, MD, MPH, EIS officer, Office of Public Health Scientific Services, Binational Dengue Outbreak Along the United States-Mexico Border — Yuma County, Arizona and Sonora, Mexico, 2014

Ian D. Plumb, MD, EIS officer, Office of Infectious Diseases, Endocarditis from Bartonella quintana in Anchorage, 2012—2014

Heather Venkat, DVM, MPH, EIS officer, Office of Public Health Scientific Services, Evaluation of a Query for Identifying West Nile Virus Symptoms Using Arizona’s BioSense Platform Data —2015

Jessica A. Nadeau, PhD, MPH, EIS officer, Office of Public Health Scientific Services, Risk Factors for Disseminated Lyme Disease — United States, 2005—2013

Natalie A. Kwit, DVM, MPH, EIS officer, National Center for Emerging and Zoonotic Infectious Diseases, Risk Factors for Disseminated Lyme Disease — United States, 2005—2013