Imagine the shock of a mother fighting off dengue fever mere hours before welcoming her baby into the world—and then discovering traces of the virus in her breast milk. This isn't hypothetical; it's a groundbreaking case from China that raises urgent questions about breastfeeding safety during outbreaks. But here's where it gets interesting: Could this shift our entire approach to maternal-infant health in dengue-prone areas?
Detection of Dengue Virus RNA in Breast Milk Following Peripartum Infection — Guangzhou City, Guangdong Province, China, 2024
Detection of Dengue Virus RNA in Breast Milk Following Peripartum Infection — Guangzhou City, Guangdong Province, China, 2024
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Summary
What is already known about this topic?
Dengue fever, a mosquito-borne illness caused by the dengue virus, spreads mainly through bites from Aedes mosquitoes. Most people experience no symptoms or just mild fever, but in some cases, it can escalate to serious issues like dengue hemorrhagic fever or shock syndrome. Doctors typically diagnose it by spotting the virus's genetic material, proteins, or immune responses in blood samples taken from patients.
What is added by this report?
In this instance, a woman who fell ill with dengue just one day before giving birth showed evidence of the virus's RNA, NS1 protein, and IgM antibodies in her breast milk up to 10 days after symptoms started. By day 15, the RNA and NS1 were gone, but IgM lingered until day 22, hinting at a possible chance of passing the virus through breastfeeding if done too soon.
What are the implications for public health practice?
To minimize risks, mothers should hold off on breastfeeding for at least 22 days after symptoms begin, only resuming once tests confirm the virus's RNA and IgM are no longer present in the milk, and the baby shows no signs of infection. Families of expectant mothers with potential dengue symptoms should rush to get tested for NS1 antigen, especially during peak mosquito seasons in affected regions.
Author Affiliations
- Guangzhou Liwan Center for Disease Control and Prevention, Guangzhou City, Guangdong Province, China
- Bomi Center for Disease Control and Prevention, Nyingchi City, Xizang Autonomous Region, China
Corresponding author:
Shuxian Pan, lwcdcyz@gz.gov.cn
Funding: Supported by the Guangzhou Health Science and Technology Project (20241A010094)
Online Date: October 24, 2025
Issue Date: October 24, 2025
doi: 10.46234/ccdcw2025.229 (https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2025.229)
- & Joint first authors.
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Introduction
By examining a woman infected with dengue who showed symptoms just one day prior to childbirth, this investigation assessed the potential danger of passing the virus from mother to child via breastfeeding. Weighing the pros and cons of nursing in such scenarios, the study aims to shape clearer guidelines for mothers dealing with dengue during pregnancy.
Methods
Milk samples from the mother were gathered on days 10, 15, and 22 following the start of her symptoms. Researchers combined fieldwork with detailed lab tests on blood and milk specimens, then sequenced the full virus genome using advanced nanopore technology to get a complete picture.
Results
Ten days into her illness, the breast milk tested positive for dengue virus RNA, NS1 protein, and IgM antibodies (with a nucleic acid cycle threshold value of 35.58), but IgG was absent. By day 15, the RNA, NS1, and IgG were no longer detectable, though IgM persisted until day 22. Full-genome sequencing revealed the strain was nearly identical (99.90% homology) to a 2023 Guangdong isolate (PP563845.1), suggesting a local connection.
Conclusion
Nursing in the early postpartum period for women contracting dengue late in pregnancy might carry the risk of transmitting the virus. It's advisable to wait 22 days post-symptom onset, ensuring both the virus's genetic material and IgM antibodies are cleared from the milk before starting.
Dengue fever is a viral illness triggered by the dengue virus, spread predominantly by Aedes mosquitoes, often resolving on its own. Although many cases are silent or involve only light fevers, a portion can worsen into severe forms like hemorrhagic fever or shock—conditions where blood vessels leak and organs struggle. Guangdong's warm, humid climate provides an ideal breeding ground for these mosquitoes, sustaining ongoing outbreaks. Since Guangzhou recorded its initial case in 1978, the city has been a hotspot in China. The virus comes in four types: DENV1 through DENV4.
While experts have mapped out dengue's usual spread, less is known about detecting it in breast milk. This gap inspired our exploration into whether colostrum (the first milk produced) from a late-pregnancy infection could vertically transmit the virus to the newborn, potentially refining advice on when and how to breastfeed safely.
Our patient, a 35-year-old unemployed woman from near Guangzhou living with her mother and husband, spiked a fever of 37.8°C on November 21, 2024. Her family members had dengue earlier that month and were treated locally. She was admitted the next day with a higher temperature (38.9°C), rapid pulse (136 beats per minute), breathing rate of 22 breaths per minute, low blood pressure (94/64 mmHg), white blood cell count of 6.66×10^9/L, and platelet count of 205×10^9/L, but no rash. An investigation showed she hadn't traveled far in the prior two weeks, sticking to her home area. Her house featured mosquito nets, plants, and a rooftop garden, with frequent insect bites reported. That day, she delivered a baby boy via cesarean section under epidural anesthesia. Her temperature swung between 35.8°C and 39.4°C afterward, but a chest X-ray confirmed no pneumonia.
Breast milk was sampled on days 10, 15, and 22 post-symptom onset. Her blood test on November 22 showed positive RNA (cycle threshold: 24.9) and NS1, but no IgM or IgG. The infant tested negative for NS1, IgM, and IgG on November 23, and follow-ups on November 28 also came back clean, though the baby had small skin spots (petechiae) without fever. On day 10 (November 30), the milk was positive for RNA, NS1, and IgM (cycle threshold: 35.58), but IgG was negative. By day 15 (December 5), RNA, NS1, and IgG were absent, yet IgM remained until day 22 (December 12). She left the hospital on November 28, with lab values improving to a white blood cell count of 7.99×10^9/L and platelets at 471×10^9/L. Nursing wasn't recommended until all markers were negative, as shown in the table.
Table 1. Results of dengue virus serological and breast milk tests in mother patient.
| Sampling date | Project | Sera | Breast milk |
|---|---|---|---|
| | | Nucleic acid | NS1 | IgM | IgG | Nucleic acid | NS1 | IgM | IgG |
| November 22 (2 days post-onset) | | Positive (Ct: 24.9) | Positive | Negative | Negative | / | / | / | / |
| November 30 (10 days post-onset) | | / | / | / | / | Positive (Ct: 35.58) | Positive | Positive | Negative |
| December 5 (15 days post-onset) | | / | / | / | / | Negative | Negative | Positive | Negative |
| December 12 (22 days post-onset) | | / | / | / | / | Negative | Negative | Negative | Negative |
Note: /, No detection.
The patient was confirmed to have DENV serotype-1 via RT-PCR. Nanopore sequencing produced a 10.7 kb genome. It matched 92.46% with a reference sequence (NC001477.1) and 99.90% with the 2023 Guangdong isolate (PP563845.1), differing by just one amino acid (L617S) in the E protein. Phylogenetically, it aligned closely (98.86%–99.90%) with Southeast Asian strains, pointing to possible imported origins.
Figure 1. Phylogenetic analyses of DENV1 from the patient.
To our knowledge, this marks China's first documented case of dengue RNA persisting in postpartum breast milk, spotted within 10 days of maternal symptoms. Combining epidemiology and lab data, it underscores twin dangers: direct vertical spread during pregnancy and indirect exposure through feeding.
Previous research echoes this. For instance, a study by Arragain et al. found dengue genetic material in breast milk 1–14 days after onset, implying it could infect newborns. Similarly, Barthel et al. detailed a case where the virus appeared in maternal blood, infant blood, and milk, heightening breastfeeding worries. Wang et al. noted that late-gestation infections might not cause severe infant illness but still risk transmission. Reports also show that vertical cases can lead to shared IgM responses in mother and baby. Moreover, IgM from other viruses like HIV, Zika, and cytomegalovirus can transfer via milk, potentially harming infants.
Our tests revealed IgM positive but IgG negative in the milk at day 10, with IgM lasting to day 15—a sign of an evolving immune reaction. The WHO and UNICEF urge starting breastfeeding within an hour of birth and continuing exclusively for six months. Yet, our findings warn of transmission risks while RNA is present. Based on this case, wait 22 days, verify milk clearance, and ensure the baby is symptom-free and infection-free. Interestingly, Lee et al. discovered that IgG antibodies in milk might prolong a 'disease enhancement' period in animal models but also shield against matching viruses. Plus, early research highlighted anti-dengue fats in breast milk, suggesting nursing could protect infants in endemic zones despite the risks.
And this is the part most people miss: Balancing breastfeeding's well-known benefits—like boosting immunity and bonding—with these viral threats. But here's where it gets controversial—does pausing for 22 days outweigh the emotional and nutritional toll, especially in resource-poor settings? Is there a safer way to pasteurize milk or provide alternatives?
This report has limitations. We couldn't prove direct transmission since the baby wasn't fed and tested negative. No placenta or cord blood samples limited deeper insights. The infant's petechiae (possibly from vascular issues in severe cases) weren't fully explored for dengue. As a single case, it may not apply universally. More research is needed for a complete risk-benefit view.
In summary, late-pregnancy dengue might enable viral passage through early breastfeeding. From this example, delay nursing until 22 days post-onset, after ruling out infections in both parties. In endemic seasons, pregnant women's households should seek NS1 testing promptly. Future guidelines should include lab checks to protect mothers and babies.
Acknowledgments
The patient for participating in the study.
Ethical Approval
Approval from the institutional review board of Guangzhou Center for Disease Control and Prevention (No.: PJ2025004) on May 28th, 2025.
Conflicts of Interest
No conflicts of interest.
References (15) (https://weekly.chinacdc.cn/en/article/app/id/5b4b15b3-3e0e-4820-8d81-e0811b145a83/reference)
Citation:
What do you think about this discovery? Does it challenge your views on breastfeeding during illnesses? Is the 22-day waiting period reasonable, or could shorter alternatives work with monitoring? Share your opinions in the comments—do you agree with delaying for safety, or do you see it as overcautious? Let's discuss!
