Novel emerging infectious diseases in pregnancy

Last two decades have seen epidemics of several infectious diseases which were previously not so prevalent worldwide. Pregnant mothers are especially prone to many infections because of anatomical and physiological changes that accompany pregnancy. The immune tolerance to semiallogenic fetus is because of down regulation of immunity, which puts the pregnant women at high risk of other infectious diseases reports a paper published in May 2017 issue of Journal Obstetrics and Gynecology.

The world has seen epidemics of four major and other minor emerging infectious diseases in the last two decades such as severe acute respiratory syndrome, the 2009 H1N1 pandemic influenza, Ebola virus, and, most recently, the Zika virus. Each of this infection has unique implications in pregnant women that are distinctly different from general population.

Each of this infectious disease has different clinical course, complications and future implications when occurring in pregnant women and requires special technique and skills and coordination at national and international levels to contain the outbreak, some basic principles are common to all for diagnosing and limiting the spread of these diseases.

A number of epidemiological factors have contributed towards emergence and widespread occurrence of these infection in pregnant women like global travel, development of microbial resistance and barriers towards vaccinations in pregnant women in-spite of increasing evidence of distinct benefits to mother and fetus.

Although the general principles of disease containment are common to all, some disease specific measures for treatment and prevention of individual infections in pregnancy are:

SARS: During the severe acute respiratory syndrome (SARS) outbreak by coronavirus in 2003, standard non-pharmaceutical measures were applied, and global containment was achieved in 5 months.

Influenza: All pregnant women should get influenza vaccine every year as soon as it is available and should not wait for the unpredictable influenza season to start. It is safe in all the trimester. The rapid influenza tests currently available has low sensitivity resulting in many false negative results. Hence, to err on the side of safety it is always recommended to prescribe oseltamivir as precaution and is recommended both by Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists.

Ebola virus: Women are always at high risk for contracting Ebola during an epidemic as they are the primary caregivers to other infectious family members. Women who are pregnant with the virus during acute Ebola epidemic usually transmit virus to the fetus, leading to intrauterine fetal death, stillbirth, or neonatal death. Ebola virus is also excreted in breast milk.

They also transmit the virus to healthcare providers and caregivers during labor or abortion. Standard precaution including the use of personal protective equipment (PPE) during labor and delivery for protection against blood and body fluids should be used along with rigorous hand hygiene, appropriate waste, sharps and laundry management and cleaning and decontamination.

WHO states that women who get pregnant after having being recovered from Ebola infection are not infectious but standard precautions and use of PPE should be implemented all the time during handling such patients. 

Zika virus: Zika virus is a flavivirus that has potential for sexual and vector born transmission by Aedes (Stegomyia) species of mosquitoes. It was declared as a public health emergency by the World Health Organization from 2016. A pregnant woman is susceptible to Zika virus in all three trimesters. Maternal Zika infection is associated with a range of adverse neonatal complications, most important of which is microcephaly. Peripartum transmission is also known to occur.

In absence of antiviral vaccine, CDC recommends that all pregnant women should postpone their travel to Zika infected areas and those who are in such areas should avoid mosquito bite especially during the day.

Pregnant women with laboratory-confirmed Zika virus infection can be offered amniocentesis to test for Zika virus RNA by RT-PCR after 15 weeks of gestation.

Deliveries of mothers with positive Zika infection should take place at specialized center.   

No specific antiviral treatment is available.

Abstract

Expert Discussion

WHO guide to Ebola disease in pregnancy

Media courtesy: InfectiousDiseaseAdvisor and Coherent news.

A secret weapon against Zika and other mosquito born disease.

Zika Virus disease is a nationally notifiable condition in US. As of June 2017, there were 1,997 pregnant women with laboratory evidence of Zika.

There were 8 pregnancy losses and 88 infants born with Microcephaly in US, with the worldwide estimate being 2,300.

Zika is spread mostly by the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus), although sexual transmission has also been documented.

Although, Zika virus no longer constitutes an international public health emergency but according to WHO ‘Zika is here to stay.’

"Although Zika's spread has waned, it still holds the potential for an explosive epidemic. If it were to reemerge in the Americas or jump to another part of the world, it would significantly threaten a new generation of children born with disabilities such as microcephaly." said Lawrence Gostin, a global health law expert from Georgetown University.

In this Ted Talk Molecular biologist Nina Fedoroff takes us around the world to understand Zika's origins and how it spread, proposing a controversial way to stop the virus -- and other deadly diseases -- by preventing infected mosquitoes from multiplying.

Maternal ZIKA virus infection linked to fetal and placental malformations, apart from Microcephaly.

The World Health Organization has declared the Zika virus an international public health emergency, with a prediction of about four million people being infected at the end of the year.

WHO has issued a travel warning for pregnant women advising them not to travel to areas with continuing outbreaks of Zika virus due to the potential risk of birth defects.

Sexual transmission appears to be more common than previously thought of. "Pregnant women whose sexual partners live in or travel to areas with Zika virus outbreaks should ensure safe sexual practices or abstain from sex for the duration of their pregnancy," the WHO said, based on advice from its Emergency Committee of independent experts.

According to a preliminary report of case series  from Rio de Janeiro, Brazil, published online March 4 issue of the New England Journal of Medicine, ZIKA is also linked to fetal death, placental insufficiency, IUGR and Nervous system malformation.

Dr. Patrícia Brasil, MD, the principal investigator of the study  “our findings provide further support for a link between maternal ZIKV infection and fetal and placental abnormalities that is not unlike that of other viruses that are known to cause congenital infections characterized by intrauterine growth restriction and placental insufficiency.”

In September, 2015 researchers in Brazil identified dengue like fever, which was later identified as ZIKV. In the same month the ZIKV was linked to microcepahy, cases in Brazil rocketed to 3,500 from 147, the average for the same time last year (2014).

The link was first detected when Brazilian health authorities found traces of the Zika virus in a deceased infant born with microcephaly or in amniotic fluid of mothers delivering microcephalic infants.

In the present study, the researchers enrolled pregnant women of any gestation, who presented with a rash that had developed within the previous 5 days. Out of 88 women, 72 (82%) women tested positive ZIKV in blood and/or urine by reverse-transcriptase polymerase chain reaction assays. The researchers followed the women prospectively with clinical examinations and serial ultrasound. All the study participants were generally healthy with no h/o congenital malformations.

Clinically the women presented with a macular or maculopapular rash, pruritus (94%) arthalgia (65%), conjuntival redness (58%). Fever was not a significant symptom with only one third of women reporting it.

All the ZIKV negative as well as positive women had ultrasound. USG showed abnormalities in 12 of ZIKV positive women while those women who are negative showed normal USG.  Sonographically detected abnormalities include:

• intrauterine growth restriction, with or without accompanying microcephaly(5)
• cerebral calcification (4)
• CNS alterations (n = 2)
• Oligohydramnios and anhydramnios (2)
• Abnormal arterial flow in the cerebral or umbilical arteries(4)
• additional malformations, including agenesis of the vermis, Blake’s pouch cyst, and potentially a club foot, in addition to cerebral calcifications, intrauterine growth restriction, and microcephaly(1)

Abnormalities were present in fetuses of women irrespective of there gestational age at ZIKV infection, although those women infected in first trimester show signs of insult during embryogenesis. CNS abnormalities seen in fetuses infected as late as 27 weeks.

Six live births and two still births occurred during the follow up and confirmed the Sonography findings.

The authors suggest that “many aspects of ZIKV infection are similar to those of rubella, particularly rash, arthralgias, pruritus, and lymphadenopathy in the mother without high fever.” But, it is worrisome that there is no population immunity for ZIKV as compared to rubella U.S. pandemic of 1959–1965, when only 17.5% of women of childbearing age lacked rubella antibodies.

In summary the study findings provide support to the hypothesis of link between maternal ZIKV infection and fetal and placental abnormalities. The women infected with ZIKV should be followed up closely with serial ultrasonography to evaluate for signs of placental insufficiency, given the risks of fetal death and intrauterine growth restriction.

References:

http://www.who.int/mediacentre/news/statements/2016/zika-ec/en

http://www.nejm.org/doi/full/10.1056/NEJMoa1602412?query=featured_home#t=articleDiscussion