The eye and tick-borne disease in the United States.

PURPOSE OF REVIEW: Tick-borne diseases are increasing in incidence and geographic distribution. Several diseases endemic to the United States have ophthalmic manifestations, including the most common tick-borne disease, Lyme borreliosis. As ocular complaints may lead a patient to seek medical evaluation, it is important to be aware of the systemic and ophthalmic manifestations of tick-borne diseases in order to make the correct diagnosis. RECENT FINDINGS: Vision-threatening ophthalmic manifestations are relatively common in Lyme disease and Rocky Mountain spotted fever. Ocular involvement is rare in babesiosis, tick-borne relapsing fever, Powassan encephalitis, ehrlichiosis, anaplasmosis, and Colorado tick fever.There are clear guidelines for diagnosis and treatment of Lyme disease; however, confusion and misinformation among the general public as well as controversy about chronic or late-stage Lyme disease can impact the evaluation of ophthalmic disease. Furthermore, there are many gaps in our knowledge regarding the pathophysiology of ocular borreliosis although it seems likely that Lyme uveitis is rare in the United States. SUMMARY: Knowledge of systemic and ophthalmic manifestations combined with an understanding of the epidemiology of disease vectors is crucial for the diagnosis of tick-borne diseases.

Colorado tick fever.

Colorado tick fever, also known as mountain fever and mountain tick fever, is a well-described, viral, tick-borne disease common to the Rocky Mountain region of the United States and Canada. The Rocky Mountain wood tick, Dermacentor andersoni, is the primary vector. The triad of high fever, severe myalgia, and headache is typical, but not specific. Although a self-limited disease in most cases, severe complications may occur. PCR techniques have been developed that allow the diagnosis to be established from the first day of symptoms. Ribavirin may merit consideration in the appropriate clinical setting.

Dermatologic manifestations of arthropod-borne diseases.

The arthropod-borne rickettsial, borrelial, and bacterial diseases of North America are a diverse group of disorders that produce a wide variety of cutaneous abnormalities. These dermatologic abnormalities are often valuable clinical clues that may reveal or suggest the correct diagnosis to the astute clinician. We review the usual and unusual dermatologic manifestations of Rocky Mountain spotted fever, murine and sylvatic typhus, rickettsialpox, ehrlichiosis, Lyme disease, tick-borne relapsing fever, Colorado tick fever, and tularemia. In some of these diseases, skin manifestations may be diagnostic; in others, dermatologic findings may be the initial and only clues that leads to the initiation of life-saving therapy. In other arthropod-borne infections, the appearance or evolution of the skin rash may be characteristic enough to suggest the proper diagnosis.

Virus-induced leukopenia: Colorado tick fever as a human model.

Eight patients with Colorado tick fever were studied to determine whether alterations in the production of granulopoietic stimulatory or inhibitory factors (or both) could be found in association with the leukopenic state of the disease. The studies demonstrate that in the patients with Colorado tick fever the mononuclear cell production of colony-stimulating factor is decreased and that there is an increase in circulating inhibitory factors in the serum of such patients. The depressed mononuclear cell colony-stimulating activity does not appear to be reversible by addition of either endotoxin or normal human serum. Characterization of these serum inhibitory factors may facilitate understanding of leukopenia in human disease.

Colorado tick fever: clinical, epidemiologic, and laboratory aspects of 228 cases in Colorado in 1973-1974.

During 1973 and 1974, we looked for cases of Colorado tick fever throughout Colorado; 228 cases were identified. Although 90% of the patients reported exposure to ticks before illness, only 52% were aware of an actual tick bite. Typical symptoms of fever, myalgia, and headache were common, but gastrointestinal symptoms were also prominent in 20% of the patients. Twenty percent were hospitalized; no deaths or permanent sequelae were noted. Persistent viremia (greater than or equal to 4 weeks) was found in about half of the cases; this finding was not associated with the occurrence of prolonged symptoms (greater than or equal to 3 weeks), which were also reported in half of the cases. One patient became reinfected with the virus. Increasing tourism in endemic areas and the frequent occurrence of prolonged or biphasic illnesses provide the potential for patients with Colorado tick fever to seek medical care anywhere in the United States.

Teratogenic effects of Colorado tick fever virus in mice.

The teratogenic effects in mice of Colorado tick fever (CTF) virus, a human pathogen, were demonstrated. Various routes of inoculation, gestational periods, and dosages of virus were studied. The incidence of stillbirth and neonatal death increased significantly after inoculation of pregnant mice with CTF virus. CTF virus crossed the placenta and replicated to high titers in the placental and fetal tissues. Mice that survived the first six weeks of life had neutralizing antibody to CTF virus. Neutralization tests, in which pregnant mice were inoculated with both CTF virus and specific antiserum to CTF virus, validated the teratogenic effects of CTF virus in mice.