By Dr Than Lwin Tun
Hantavirus is a group of viruses that can cause serious illness in humans. It is mainly spread through contact with infected rodents, especially their urine, droppings, or saliva.
The virus is named after the Hantan River in South Korea, where more than 3,000 troops fell seriously ill after becoming infected with it during the 1950-1953 Korean War, the FOPH says.
Hantaviruses can infect and cause serious disease in people worldwide. People get Hantavirus from contact with rodents like rats and mice, especially when exposed to their urine, droppings, and saliva. It can also spread through a bite or scratch from a rodent, but this is rare.
Hantaviruses cause two syndromes. Hantaviruses found in the Western Hemisphere, including the US, can cause Hantavirus pulmonary syndrome (HPS). The most common Hantavirus that causes HPS in the US is spread by the deer mouse.
Haemorrhagic fever with renal syndrome (HFRS) is a group of clinically similar illnesses caused by Hantaviruses found mostly in Europe and Asia. However, Seoul virus, a type of Hantavirus that causes HFRS, is found worldwide, including in the United States.
Transmission
People usually get infected by breathing in air contaminated with tiny particles from rodent waste. Less commonly, it can spread through bites or direct contact with infected animals.
Types of Illness
Hantavirus infections can lead to two major diseases:
i. Hantavirus Pulmonary Syndrome (HPS): A severe respiratory illness that affects the lungs and can be life-threatening.
ii. Haemorrhagic Fever with Renal Syndrome (HFRS): A condition that mainly affects the kidneys and can cause bleeding problems.
Signs and Symptoms
Hantavirus Pulmonary Syndrome (HPS)
HPS is a severe and potentially deadly disease that affects the lungs. Symptoms of HPS usually start to show 1 to 8 weeks after contact with an infected rodent. Early symptoms can include:
- Fatigue
- Fever
- muscle aches, especially in the large muscle groups like the thighs, hips, back, and sometimes shoulders
- About half of all HPS patients also experience:
- Headaches
- Dizziness
- Chills
- abdominal problems, like nausea, vomiting, diarrhoea, and abdominal pain
Four to 10 days after the initial phase of illness, the late symptoms of HPS appear. These symptoms include coughing and shortness of breath. Patients might experience tightness in the chest as the lungs fill with fluid.
HPS can be deadly. Thirty-eight per cent of people who develop respiratory symptoms may die from the disease.
Haemorrhagic Fever with Renal Syndrome (HFRS)
HFRS is a severe and sometimes deadly disease that affects the kidneys. Symptoms of HFRS usually develop within one to two weeks after exposure. In rare cases, they may take up to eight weeks to develop. Initial symptoms begin suddenly and include:
- intense headaches
- back and abdominal pain
- fever/chills
- nausea
- blurred vision
- People may have flushing of the face, inflammation or redness of the eyes, or a rash. Later symptoms can include:
- low blood pressure
- lack of blood flow (acute shock)
- internal bleeding (vascular leakage)
- acute kidney failure, which can cause severe fluid overload
The severity of the disease varies depending on the virus causing the infection. Hantaan and Dobrava virus infections usually cause severe symptoms, where 5-15 per cent of cases are fatal. In contrast, Seoul, Saaremaa, and Puumala virus infections are usually more moderate, with less than one percent dying from the disease. Complete recovery can take several weeks to months.
Case definitions
The World Health Organization (WHO) suggested the following outbreak case definition: –
Suspected Case
A person who presents with a febrile illness (Fever > 38.5 °C [103 °F] oral) with an acute respiratory distress syndrome requiring supplemental oxygen AND bilateral diffuse infiltrates developed within 72 hours of hospitalization in a previously healthy person
Unexplained illness resulting in death, plus an autopsy examination demonstrating noncardiogenic pulmonary oedema without an identifiable specific cause of death
Confirmed Case
A suspected case laboratory confirmed with:
The presence of hantavirus-specific IgM antibodies or a four-fold or greater increase in IgG antibody titers or hantavirus-specific IgG seroconversion.
- A positive reverse transcriptase-polymerase chain reaction (RT-PCR) result for Hantavirus RNA.
- Positive immunohistochemical results for Hantavirus antigens.
Reducing Risk
Eliminate or minimize contact with rodents in your home, workplace, or campsite to reduce your risk of exposure to Hantaviruses. Seal holes and gaps in your home or garage to keep rodents from entering these spaces. Place traps in and around your home to decrease rodent infestation. Clean up any easy-to-get food that might attract rodents.
Treatment and Recovery
There is no specific treatment for Hantavirus infection. Patients should receive supportive care, including rest, hydration, and treatment of symptoms.
HPS can cause breathing difficulties, and patients may need breathing support, such as intubation. Intubation is a medical procedure where a tube is placed in the lungs from the mouth to help the patient get oxygen.
HFRS can disrupt kidney function. Patients with HFRS may need dialysis to remove toxins from the blood and maintain the right balance of fluids in the body when the kidneys aren’t working well.
In addition, Hantavirus is a rare but dangerous infection transmitted from rodents to humans. Preventing exposure to rodents is the most effective way to stay safe.
References
www.cdc.gov
www.who.int
www.rte.ie