Infectious Diseases

Insect and Tick-Borne Illnesses

Infectious diseases from mosquito, tick, and flea bites have tripled in the United States with many new diseases being discovered in recent years. 

Our infectious disease specialists have expertise in treating the wide variety of insect and tick-borne diseases. You may have been infected while traveling abroad, or have been bitten locally. Prompt medical attention can reduce the impact of the disease—and our specialists will make sure that you receive the very best care possible.

Stay Informed About Your Health

The Mount Sinai Health System is committed to providing accurate, scientific information about insect- and tick-borne illnesses. The health and safety of our patients, their families, and our employees are of utmost importance, and we are actively monitoring evolving circumstances surrounding new threats, such as the Zika virus. The information on this page is intended as a resource for patients, community physicians, and other health care partners.

Insects such as mosquitos and  ticks can transmit a variety of diseases. Here are some diseases that you can contract through a tick bite:

  • Lyme disease
  • Zika virus
  • Rocky Mountain spotted fever
  • Colorado tick fever
  • Tularemia
  • Ehrlichiosis

Some of the diseases that mosquitoes carry include:

  • West Nile virus
  • Eastern equine encephalitis
  • Malaria

What is Lyme Disease?

Lyme disease is caused by bacteria called Borrelia burgdorferi (B burgdorferi). Blacklegged ticks (also called deer ticks) can carry these bacteria. Not all species of ticks can carry these bacteria. Immature ticks are called nymphs, and they are about the size of a pinhead. Nymphs pick up bacteria when they feed on small rodents, such as mice, infected with B burgdorferi. You can get the disease if you are bitten by an infected tick.

People bitten by a tick should be watched closely for at least 30 days to see if a rash or symptoms develop. 

A single dose of the antibiotic doxycycline may be given to someone soon after being bitten by a tick, when all of these conditions are true:

  • The person has a tick that can carry Lyme disease attached to his or her body
  • A nurse or doctor has looked at and identified the tick
  • The tick is thought to have been attached to the person for at least 36 hours
  • The person is able to start taking the antibiotic within 72 hours of removing the tick
  • The person is at least 8 years old and is not pregnant or breastfeeding
  • The local rate of ticks carrying B burgdorferi is 20% or higher

What is Zika Virus?

Zika virus is primarily transmitted through infected mosquitos; however, sexual transmission has been described. It is a mosquito-transmitted infection related to dengue, yellow fever, chikungunya, and West Nile virus and is common in Africa and Asia. It did not begin spreading widely in the Western Hemisphere until May 2015, when an outbreak occurred in Brazil.

What are the signs and symptoms of Zika virus?

  • The most common symptoms of Zika virus disease are mild, and include fever, rash, joint pain, and conjunctivitis (red eyes).
  • The incubation period (the time from exposure to symptoms) for Zika virus disease is thought to be a few days to a week.
  • There is no vaccine to prevent disease, and there is no antiviral treatment for a Zika virus infection.
  • Patients with general inquiries or concerns about Zika should contact their primary care physician.

What are the dangers of Zika virus to pregnant women?

Zika presents the greatest risk to pregnant women because the virus can spread from the mother to her baby. This may increase a baby’s risk of developing microcephaly, a condition in which the baby’s head size is smaller than normal due to abnormal brain development. It can also increase the risk of miscarriage and stillbirth.

Pregnant women who are concerned they might have been exposed to the Zika virus should contact their obstetricians immediately. If you are considering pregnancy and are concerned that you might have been exposed or are considering travel to a region where the Zika virus has been reported, talk with your primary care physician or gynecologist before trying to conceive. The Centers for Disease Control and Prevention (CDC) advises women who are pregnant to consider postponing travel to these areas. If you have traveled to an area with Zika virus transmission, we advise you to wait eight weeks before trying to conceive. If your male partner has traveled to an area where Zika virus is present, consider talking to your doctor about testing for the disease before trying to conceive.

Is protection available against Zika?

There is no vaccine to prevent the Zika virus or medicine to treat the infection. If you must travel to an affected region, you should protect yourself against mosquito bites. The type of mosquito that transmits the Zika virus is most likely to bite in the daytime. Wear long sleeves and pants while outdoors and use an insect repellent that is registered with the Environmental Protection Agency, such as one containing DEET. 

Zika outbreaks have been reported in Mexico; Central America; South America; in the Caribbean, including Puerto Rico, Aruba, Bonaire, and the U.S. Virgin Islands; Cape Verde, off the coast of Africa; the Pacific Islands of American Samoa, Samoa, and Tonga; and parts of Florida. For the most up-to-date information, please visit the Centers for Disease Control and Prevention (CDC) Zika web site.

Resources for the latest Zika virus information

Knowledge regarding the details of the Zika virus is evolving, and we continue to work closely with the New York City Department of Health and the New York State Department of Health to ensure we are following current recommendations for patient evaluation and care. Please visit the following websites for the most up-to-date Zika virus information.


Malaria is a parasitic disease that involves high fevers, shaking chills, flu-like symptoms, and anemia. Malaria, especially falciparum malaria, is a medical emergency that requires a hospital stay. Chloroquine is often used as an anti-malarial drug. But chloroquine-resistant infections are common in some parts of the world. Learn more about malaria.