Tickborne Diseases in Children in the United States
Total Page:16
File Type:pdf, Size:1020Kb
Tickborne Diseases in Children in the United States Jennifer S. Read, MD, MS, MPH, DTM&H*† *Department of Pediatrics, University of Vermont Medical Center, Burlington, VT †Infectious Disease Epidemiology, Vermont Department of Health, Burlington, VT Practice Gaps The most common tick-borne infections in the United States are Lyme disease, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever, and babesiosis. The epidemiology of these infections in the United States is integrally related to the geographic distribution and seasonality of the tick vector of each of the infections. Because these infections can be very serious and sometimes fatal, and because of the inherent delay in obtaining laboratory confirmation (especially with serologic assays requiring acute and convalescent titers), considering early implementation of empirical treatment based on the patient’s clinical presentation is extremely important. Prevention of acquisition of tick- borne diseases requires avoiding tick-infested areas or, if this is not possible or desired, implementing steps to decrease the likelihood of tick bites and the duration of tick attachment. Objectives After completing this article, readers should be able to: 1. Understand the etiologic organisms and the associated ticks responsible for transmission, the geographic distribution of and the reported infections associated with the ticks in the United States, and the seasonality and incubation periods of tick-borne infections in the United States. 2. Recognize the clinical manifestations and laboratory abnormalities associated with the infections, especially as they relate to children. AUTHOR DISCLOSURE Dr Read has disclosed 3. Plan for the diagnosis, treatment, and prevention of these infections. no financial relationships relevant to this article. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device. INTRODUCTION ABBREVIATIONS fl CSF cerebrospinal uid Vector-borne diseases, caused by microorganisms transmitted by insects and EM erythema chronicum migrans ticks, are major causes of morbidity and mortality globally. In the United States, IFA immunofluorescent antibody fi Ig immunoglobulin vector-borne diseases are occurring more frequently and represent a signi cant RMSF Rocky Mountain spotted fever public health concern. (1) The numbers of reported vector-borne disease cases in PCR polymerase chain reaction the United States (tick-borne, mosquito-borne, and flea-borne diseases) are Vol. 40 No. 8 AUGUST 2019 381 Downloaded from http://pedsinreview.aappublications.org/ at Health Sciences Library, Stony Brook University on June 3, 2020 shown in Table 1. (1) The reported incidence of vector-borne diseases most likely significantly underestimates the actual TABLE 1. Vector-borne Disease Cases Reported occurrence of these diseases; some individuals with vector- to the National Notifiable Disease borne infections may be asymptomatic or, if symptomatic, Surveillance System—US States and may not seek medical care. Territories, 2004–2016 This review addresses the most common tick-borne DISEASE NO. CASES diseases reported in the United States, (1) specifically, Lyme disease, ehrlichiosis and anaplasmosis, spotted fever rick- Tick-borne diseases ettsiosis, including Rocky Mountain spotted fever (RMSF), Lyme disease 402,502 and babesiosis. Specifically, the following are discussed: the Anaplasmosis/ 39,959 organisms and the associated ticks responsible for trans- ehrlichiosis mission; the geographic distribution of and the reported Spotted fever 37,376 infections associated with the ticks in the United States; rickettsiosis the seasonality of tick-borne infections in the United States; Babesiosis 9,631 the infections’ incubation periods; the clinical manifes- Tularemia 2,102 tations and laboratory abnormalities associated with the infections, especially as they relate to children; and the Powassan virus 101 diagnosis, treatment, and prevention of these infections. Subtotal 491,671 Mosquito-borne diseases LYME DISEASE Dengue viruses 46,692 Zika virus 41,680 Lyme disease is the most common tick-borne infection in the United States. (2) Over a 12-year period ending in 2016, West Nile virus 31,919 402,502 cases of Lyme disease were reported in the United Malaria 20,167 States. (1) Table 2 summarizes characteristics of Borrelia Chikungunya virus 9,081 burgdorferi sensu stricto (B burgdorferi), the causative organ- California serogroup 1,063 ism of Lyme disease in the United States. The first report in viruses the United States of the skin lesion characteristic of Lyme St Louis encephalitis 133 disease, erythema chronicum migrans (EM), was published virus in 1970. (3) Subsequently, the full spectrum of clini- Eastern equine 106 cal manifestations of Lyme disease, including EM, was encephalitis virus described in 1977. (4) B burgdorferi, a spirochete in the Yellow fever virus 1 family Spirochaetaceae, (5) was first isolated in 1982. (6) Subtotal 150,842 Another Borrelia species (Borrelia miyamotoi) was first iden- fi fi Flea-borne disease 89 ti ed in Japan in the 1990s, (7) and subsequently the rst (plague) case in the United States was described. (8) Total 642,602 B burgdorferi infection is transmitted by the blacklegged tick (Ixodes scapularis) (Fig 1) and the western blacklegged Adapted from Rosenberg R, Lindsey NP, Fischer M, et al. Vital signs: trends tick (Ixodes pacificus). (2) B miyamotoi is transmitted by the in reported vectorborne disease cases—United States and Territories, 2004-2016. MMWR Morb Mortal Wkly Rep. 2018;67(17):496–501. same tick vectors as B burgdorferi. (9)(10)(11)(12) The season- ality of Lyme disease is summarized in Table 2. (5) In the United States, most cases of Lyme disease are reported from 2 regions: 1) New England through the mid-Atlantic states early disseminated, and late. (5) Early localized disease and 2) the upper Midwest states (Table 2, Fig 2). (5)(13) B (2)(5)(13) is characterized by EM at the site of the tick bite miyamotoi infections have similar seasonality and distribu- and systemic manifestations. In children, EM is the most tion as Lyme disease cases. (9)(10)(12) common manifestation of Lyme disease. Some patients with The incubation period and clinical manifestations of, and large EM lesions are misdiagnosed as having cellulitis. Only the laboratory abnormalities associated with, Lyme disease a minority of patients have the classic bull’s-eye appearance are summarized in Table 3. (2)(5)(13) The clinical manifes- (concentric rings). Several weeks after the tick bite, the next tations of Lyme disease occur in 3 stages: early localized, stage of Lyme disease (early disseminated disease) (2)(5),(13) 382 Pediatrics in Review Downloaded from http://pedsinreview.aappublications.org/ at Health Sciences Library, Stony Brook University on June 3, 2020 TABLE 2. Tick-borne Diseases in Children in the United States: Organisms, Vectors, Seasonality, and Geographic Distribution DISEASE ORGANISM VECTOR SEASONALITY GEOGRAPHIC DISTRIBUTION Lyme disease Borrelia burgdorferi sensu Blacklegged tick (Ixodes Most early localized, early >90% of cases reported from stricto (B burgdorferi) scapularis) and the western disseminated disease: April– New England (Maine, New blacklegged tick (Ixodes October Hampshire, Vermont, pacificus) Connecticut, Rhode Island, Massachusetts) and the northeastern and mid- >50% during June and July Atlantic states (Delaware, Maryland, New Jersey, New York, Pennsylvania, Virginia) Less frequently, Lyme disease is reported from the upper Midwest (especially Minnesota and Wisconsin) Some cases have been reported from northern California, Oregon, and Washington Ehrlichiosis Ehrlichia chaffeensis Lone star tick (Amblyomma Most infections: April– Predominantly southeast, americanum) September south central, east coast states Peak incidence: May–July Highest incidence in Arkansas, Delaware, Missouri, Oklahoma, Tennessee, Virginia Ehrlichia ewingii Lone star tick (A americanum) Most infections: April– Mostly southeastern, south September central, midwestern states Peak incidence: May–July Ehrlichia muris–like Possibly blacklegged tick Highest incidence: April– Minnesota, Wisconsin organism (I scapularis) September Can occur year-round in areas with endemic disease Anaplasmosis Anaplasma Blacklegged tick (I scapularis) or Most infections: June– Most frequently reported from phagocytophilum western blacklegged tick November northeastern and upper (I pacificus) midwestern states RMSF Rickettsia rickettsii American dog tick (eastern, Highest incidence: April– Throughout most of the central, western United States) September (but, in areas with continental United States Rocky Mountain wood tick in endemic disease, can occur In 2002 –2012, 5 states Rocky Mountain states year-round) accounted for 63% of cases (Arkansas, Missouri, North Carolina, Oklahoma, Tennessee) Brown dog tick in southwestern Has become more common in United States and along US- parts of Arizona Mexico border Babesiosis Babesia microti and other Blacklegged tick (I scapularis) Most infections during late Northeast (especially Babesia species spring, summer, or fall Connecticut, Massachusetts, New Jersey, New York, Rhode Island; also, Maine, Pennsylvania) Upper Midwest (Minnesota and Wisconsin) may manifest as multiple EM lesions. Other clinical man- stages of infection. Several months may pass between a tick ifestations may occur (with or without multiple EM lesions), bite and late Lyme disease manifestations. Children with including neurologic, cardiac,