Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 24, Number 9—September 2018
Research Letter

Case of Microcephaly after Congenital Infection with Asian Lineage Zika Virus, Thailand

Thidathip Wongsurawat1, Niracha Athipanyasilp1, Piroon Jenjaroenpun, Se-Ran Jun, Bualan Kaewnapan, Trudy M. Wassenaar, Nattawat Leelahakorn, Nasikarn Angkasekwinai, Wannee Kantakamalakul, David W. Ussery, Ruengpung Sutthent, Intawat Nookaew2Comments to Author , and Navin Horthongkham2Comments to Author 
Author affiliations: University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA (T. Wongsurawat, P. Jenjaroenpun, S.-R. Jun, D.W. Ussery, I. Nookaew); Siriraj Hospital, Mahidol University, Bangkok, Thailand (N. Athipanyasilp, B. Kaewnapan, N. Leelahakorn, N. Angkasekwinai, W. Kantakamalakul, R. Sutthent, N. Horthongkham); Molecular Microbiology and Genomics Consultants, Zotzenheim, Germany (T.M. Wassenaar)

Cite This Article


We sequenced the virus genomes from 3 pregnant women in Thailand with Zika virus diagnoses. All had infections with the Asian lineage. The woman infected at gestational week 9, and not those infected at weeks 20 and 24, had a fetus with microcephaly. Asian lineage Zika viruses can cause microcephaly.

Although Zika virus has circulated in Asia longer than in the Americas, only 3 confirmed cases of congenital Zika virus infection with microcephaly have been reported in Asia (2 Thailand, 1 Vietnam) (1). As of June 2018, the genomic sequences of the viruses from these 3 cases have not been reported; thus, whether these cases were caused by an Asian lineage or an imported American lineage is unknown.

Several mechanisms involving virus genome sequences have been proposed to explain how Zika virus might cause microcephaly (2). Liang et al. (3) showed in vitro that replication of both the African (strains MR766 and IbH30656) and American (strain H/PF/2013) lineage viruses suppress Akt phosphorylation; this suppression is caused by an accumulation of mutations in the Zika virus genome that increase the number of phosphorylation sites on virus proteins that compete with host proteins for phosphorylation. Yuan et al. proposed that a serine to asparagine substitution (S17N) in the premembrane protein (stably conserved in the American lineage but not in the Asian) contributes to the onset of microcephaly (4). An increased frequency of retinoic acid response elements in the American lineage genome versus the Asian lineage genome has also been observed (2). We question these explanations because we report a confirmed case of congenital Zika virus infection with microcephaly in Thailand caused by an Asian lineage virus.

We sequenced 7 Zika virus genomes obtained from 5 patients, including 3 pregnant women (PW1–3), in 2016 and 2017. PW1 had fever, maculopapular rash, and mild conjunctivitis at 24 weeks of gestation. Her urine sample was positive for Zika virus (BKK05, GenBank accession no. MG807647), and she gave birth to an infant without birth defects at full term. PW2 had a suspected Zika virus infection at 9 weeks’ gestation with high fever, maculopapular rash, and mild conjunctivitis. At 16 weeks, a sample of the amniotic fluid was positive for Zika virus (BKK03, GenBank accession no. MG548660). The pregnancy was terminated at 17 weeks. Autopsy of the fetus demonstrated a head circumference of 12.5 cm (less than the third percentile for this gestational age); Zika virus was detected in the brain (BKK02, GenBank accession no. MF996804) and placenta (BKK04, GenBank accession no. MG548661). No other etiologic agents associated with birth defects (cytomegalovirus, herpes simplex virus types 1 and 2, rubella virus, syphilis virus, Toxoplasma gondii, Treponema pallidum) were detectable by real-time PCR. PW2 had detectable hepatitis B viral surface antigen but no concurrent medical conditions. These findings suggest that Zika virus was the causative agent of this case of microcephaly. PW3 had a maculopapular rash without fever or conjunctivitis and received a Zika virus diagnosis at 20 weeks’ gestation. Her urine sample was positive for Zika virus (BKK07, GenBank accession no. MH013290), and she gave birth to a healthy infant at full term. The last 2 samples were from a 6-year-old child with mild fever and maculopapular rash (BKK06, GenBank accession no. MG807647) and a 64-year-old man with fever and maculopapular rash (BKK01, GenBank accession no. KY272987).


Thumbnail of Maximum-likelihood phylogenetic analysis of nonredundant Zika virus genomes including 7 isolates from patients in Thailand, 2016–2017, and amino acid changes corresponding with 3 evolutionary events (2). Circles indicate the Zika virus isolates from this report; the Zika virus strains used by Liang et al. (3) are indicated by asterisks and Yuan et al. (4) by squares. The key amino acid residue changes corresponding with the 3 evolutionary events (2) are shown, and the conserved amin

Figure. Maximum-likelihood phylogenetic analysis of nonredundant Zika virus genomes including 7 isolates from patients in Thailand, 2016–2017, and amino acid changes corresponding with 3 evolutionary events (2). Circles indicate the...

We retrieved 121 nonredundant Zika virus genomes (444 viruses, 99.9% nucleic acid identity cutoff) from GenBank to compare these isolates by phylogenetic analysis. All 7 BKK Zika virus isolates grouped within the Asian lineage (Figure). Virus from the amniotic fluid (BKK03), fetal brain (BKK02), and placenta (BKK04) of PW2 closely resembled each other (5 mismatches in BKK04 and 6 in BKK03, overall 99.898% identity). These 3 isolates were separated on the tree from their closest neighbor, a 2016 isolate from Singapore, by 40 mismatches. The number of retinoic acid response elements and predicted phosphorylation sites in BKK01–BKK07 was the same as the number in other Asian lineage Zika viruses (2). Also, the S17N substitution in premembrane was absent in all 7 isolates. Thus, all 3 proposed mechanisms failed to explain the case of congenital Zika virus infection with microcephaly in PW2. This case clinically resembled that of a woman in Finland infected during week 11 of pregnancy while traveling in Mexico, Guatemala, and Belize (5); in that case, Zika virus was detected in the brain of the aborted fetus at week 21.

The 3 cases in pregnant women described here support the hypothesis that the timing of Zika virus infection during pregnancy might be a key contributor to the development of microcephaly during congenital Zika virus infection. PW2 was infected around week 9 of gestation, during embryonic neurulation and cortical neurogenesis, which lay the foundation for the developing brain. Infection during week 20 (for PW3) and 24 (for PW1) of gestation did not led to microcephaly. Our observations are in agreement with reports involving American lineage Zika viruses that show a high risk for microcephaly when infection occurs before week 21 (6), during weeks 7–14 (7), or during the first trimester (810). Our findings show that Zika viruses circulating in Asia can cause microcephaly, just like American strains.

Dr. Wongsurawat is a postdoctoral research fellow at the Arkansas Center for Genomic Epidemiology & Medicine in Little Rock, Arkansas, USA. Her primary research interests are applying next-generation and third-generation sequencing technologies to perform DNA and RNA viral genome and metagenome sequencing.



This work was funded in part by Siriraj Research (grant no. RO16034012), the Helen Adams & Arkansas Research Alliance Endowed Chair, and the National Institute of General Medical Sciences of the National Institutes of Health (award no. P20GM125503).



  1. Lim  SK, Lim  JK, Yoon  IK. An update on Zika virus in Asia. Infect Chemother. 2017;49:91100. DOIPubMedGoogle Scholar
  2. Jun  SR, Wassenaar  TM, Wanchai  V, Patumcharoenpol  P, Nookaew  I, Ussery  DW. Suggested mechanisms for Zika virus causing microcephaly: what do the genomes tell us? BMC Bioinformatics. 2017;18(Suppl 14):471. DOIPubMedGoogle Scholar
  3. Liang  Q, Luo  Z, Zeng  J, Chen  W, Foo  SS, Lee  SA, et al. Zika virus NS4A and NS4B proteins deregulate akt-mTOR signaling in human fetal neural stem cells to inhibit neurogenesis and induce autophagy. Cell Stem Cell. 2016;19:66371. DOIPubMedGoogle Scholar
  4. Yuan  L, Huang  XY, Liu  ZY, Zhang  F, Zhu  XL, Yu  JY, et al. A single mutation in the prM protein of Zika virus contributes to fetal microcephaly. Science. 2017;358:9336. DOIPubMedGoogle Scholar
  5. Driggers  RW, Ho  CY, Korhonen  EM, Kuivanen  S, Jääskeläinen  AJ, Smura  T, et al. Zika virus infection with prolonged maternal viremia and fetal brain abnormalities. N Engl J Med. 2016;374:214251. DOIPubMedGoogle Scholar
  6. Sohan  K, Cyrus  CA. Ultrasonographic observations of the fetal brain in the first 100 pregnant women with Zika virus infection in Trinidad and Tobago. Int J Gynaecol Obstet. 2017;139:27883. DOIPubMedGoogle Scholar
  7. Parra-Saavedra  M, Reefhuis  J, Piraquive  JP, Gilboa  SM, Badell  ML, Moore  CA, et al. Serial head and brain imaging of 17 fetuses with confirmed Zika virus infection in Colombia, South America. Obstet Gynecol. 2017;130:20712. DOIPubMedGoogle Scholar
  8. Kleber de Oliveira  W, Cortez-Escalante  J, De Oliveira  WT, do Carmo  GM, Henriques  CM, Coelho  GE, et al. Increase in reported prevalence of microcephaly in infants born to women living in areas with confirmed Zika virus transmission during the first trimester of pregnancy—Brazil, 2015. MMWR Morb Mortal Wkly Rep. 2016;65:2427. DOIPubMedGoogle Scholar
  9. Cuevas  EL, Tong  VT, Rozo  N, Valencia  D, Pacheco  O, Gilboa  SM, et al. Preliminary report of microcephaly potentially associated with Zika virus infection during pregnancy—Colombia, January–November 2016. MMWR Morb Mortal Wkly Rep. 2016;65:140913. DOIPubMedGoogle Scholar
  10. Reynolds  MR, Jones  AM, Petersen  EE, Lee  EH, Rice  ME, Bingham  A, et al.; U.S. Zika Pregnancy Registry Collaboration. Vital Signs: Update on Zika virus–associated birth defects and evaluation of all U.S. infants with congenital Zika virus exposure—U.S. Zika Pregnancy Registry, 2016. MMWR Morb Mortal Wkly Rep. 2017;66:36673. DOIPubMedGoogle Scholar




Cite This Article

DOI: 10.3201/eid2409.180416

Original Publication Date: July 31, 2018

1These first authors contributed equally to this article.

2These senior authors contributed equally to this article.

Table of Contents – Volume 24, Number 9—September 2018

EID Search Options
presentation_01 Advanced Article Search – Search articles by author and/or keyword.
presentation_01 Articles by Country Search – Search articles by the topic country.
presentation_01 Article Type Search – Search articles by article type and issue.



Please use the form below to submit correspondence to the authors or contact them at the following address:

Intawat Nookaew, Department of Biomedical Informatics and Department of Physiology and Biophysics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; ; Navin Horthongkham, Department of Microbiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Wanglang Road, Bangkoknoi Bangkok, 10700 Thailand

Send To

10000 character(s) remaining.


Page created: August 17, 2018
Page updated: August 17, 2018
Page reviewed: August 17, 2018
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.