Vector-Borne Illnesses and Pregnancy

This resource provides guidance for both healthcare providers and patients on vector-borne illnesses during pregnancy. It was developed by the Society for Maternal-Fetal Medicine (SMFM) Committee on Infectious Diseases and Emerging Threats. 

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What are vector-borne illnesses?

Vector-borne illnesses are caused by a pathogen, such as a virus or bacteria, that is transmitted by an insect carrier. Emerging threats include, but are not limited to, Chikungunya, Dengue, Oropouche, and Zika viruses. Because many of these diseases have no cure and treatment is largely supportive, prevention is critical. Prevention strategies are largely focused on the insect vector. With climate change, increasing temperatures allow disease-carrying insects to thrive and survive in new regions and put vulnerable populations at greater risk, especially pregnant people. 

What are the risks in pregnancy?

Perinatal infection with a vector-borne pathogen can lead to adverse outcomes including preterm delivery, low fetal birth weight, congenital malformations, and increased risks for maternal, fetal and neonatal mortality.

How can I assess patients?

A comprehensive clinical assessment should include screening for travel history or sick contacts, evaluation of signs and symptoms, and assessment for activities in areas of potential exposure to vector-borne illnesses. Symptoms often resemble non-specific viral syndromes but may have distinguishing features, e.g., severe arthralgia (Chikungunya), mucosal bleeding (Dengue), scleral injection (Zika), or retro-orbital pain (Oropouche).

How do I diagnose vector-borne illnesses in pregnancy?

Diagnosis requires a high index of suspicion. Polymerase chain reaction (PCR) and antibody testing may be appropriate to determine exposure and the presence of co-infection. PCR testing can be used for acute infection. Serologic studies are available totest for vector borne illness exposures or prior infection.

Recommended Diagnostic Testing and Surveillance Reporting Guidelines

Abbreviations: IFA, Indirect immunofluorescence antibody; MAC-ELISA, IgM antibody capture enzymelinked immunosorbent assay; NAAT, Nucleic acid amplification test; NAT, Neutralizing antibody test; NND, Nationally Notifiable Disease; PRNT, Plaque Reduction Neutralization Test; RT-PCR, Real-time polymerase chain reaction.

Are vaccines available to protect against vector-borne illnesses?

Currently, there are no vaccines available against the Oropouche and Zika viruses. The vaccine against the Dengue virus is not available in most jurisdictions of the United States, though it is available in Puerto Rico. There is one vaccine available in the United States to protect against chikungunya, a virus-like particle (VLP) vaccine (called VIMKUNYA). 

Patient counseling that includes an evaluation of the risks and benefits of vaccination, as well as bite prevention measures is essential.

What treatment options are available?

There are currently no treatments or antiviral medications against these viruses. Management depends on the severity of illness. Mild cases involve supportive care, including adequate hydration and over-the-counter analgesics and antipyretics. With dengue, there is a chance that the illness progresses to shock and death. High level of suspicion and supportive care is warranted.

How can I counsel patients to prevent exposure?

Patient counseling can start with reconsidering nonessential travel to areas with a Level 2 advisory or higher on the CDC’s Travel Health Notices board. Avoiding travel to high-risk areas can reduce the risk of maternal-to-fetal transmission of these vector-borne illnesses. If the patient chooses to travel or engage in outdoor activity in affected areas, it is essential to use physical protectants, such as protective clothing and Environmental Protection Agency (EPA)-approved insect repellents. 

What are pregnancy-safe repellents?

The EPA recommends using N, N-diethyl-meta-toluamide (DEET), picaridin, IR3535, oil of lemon eucalyptus, and para-menthane-diol. The EPA has studied these insect repellents for their effectiveness and safety profile for use in pregnancy.