What is Hantavirus? What Are Its Symptoms? How Is It Diagnosed and Treated?

Hantavirus is a rare but serious infectious disease with a mortality rate that can reach 30-50%. Transmitted to humans via rodents, this virus can pose a life-threatening danger if not intervened in time. Questions such as what is hantavirus, what are its symptoms, and how is it transmitted are of vital importance. The disease can present with two different clinical pictures: Hantavirus Pulmonary Syndrome and Hemorrhagic Fever. In this article, you will find the answer to whether there is a treatment for hantavirus and ways to protect against it.

What is Hantavirus?

Characteristics of the Hantavirus Family

Belonging to the Bunyaviridae family, hantavirus is a group of enveloped viruses with a single-stranded RNA structure. Around 45 types of hantaviruses have been identified to date, and at least 20 of them have been shown to be infectious agents in humans.

The most striking feature of the virus is its ability to persist for many years in its natural hosts, rodents, without causing any disease symptoms. Rodents, especially mice and rats, appear completely healthy while carrying this virus. However, they can shed the virus into the environment for months through their urine and feces.

Each hantavirus type is carried by its own specific rodent species. Therefore, the type of virus varies depending on the geographical region.

Hantavirus Types and Geographical Distribution

Hantaviruses are divided into two main groups based on their geographical location. Viruses found in the Americas are called "New World" hantaviruses. Sin Nombre virus, Andes virus, Laguna Negra virus, and New York virus fall into this group.

Viruses found in Europe and Asia are known as "Old World" hantaviruses. Hantaan virus, Seoul virus, Dobrava virus, and Puumala virus are in this category. Hantaan and Seoul viruses in Asia, and Puumala and Dobrava viruses in Europe are the main infectious agents.

Especially in China, more than half of the 150,000 HFRS cases per year are seen. In the United States, 890 cases were recorded from 1993 to 2023.

Hantavirus Pulmonary Syndrome (HPS)

New World hantaviruses cause Hantavirus Pulmonary Syndrome, which targets the lungs. This condition is common in the Americas, and the fatality rate is around 30%.

The incubation period of HPS ranges from 9 to 33 days, with an average of 14-17 days. The disease begins with flu-like symptoms. Symptoms such as fever, chills, and muscle pain appear in the first days.

Permeability increases in the capillary system of the lungs, and pulmonary edema develops as a result of fluid leakage. This situation leads to sudden-onset severe respiratory distress. Approximately 38% of those infected die.

Hemorrhagic Fever with Renal Syndrome (HFRS)

Old World hantaviruses lead to the HFRS condition, which affects the kidneys and vascular system. Infection caused by Hantaan and Dobrava viruses has a more severe course, with a fatality rate between 5-10%.

In contrast, infection caused by Puumala virus has a milder course, with a fatality rate of around 0.1%. Hypotension is seen in 11-40% of patients and oliguria in 40-60%.

Kidney damage is prominent in HFRS. In Hantaan and Dobrava infections, the need for hemodialysis arises in 30-40% of cases. The hemodialysis rate in Puumala infection is around 5-7%.

What Are the Symptoms of Hantavirus?

After the virus enters the body, symptoms do not appear immediately. The incubation period generally ranges from 1 to 5 weeks. In most cases, this period is around 2-3 weeks. The disease begins with mild flu-like complaints and can turn into serious conditions in the following days.

Early Stage Symptoms

Symptoms seen in the first days can easily be mistaken for the flu or a common cold. Fever and chills start suddenly and are difficult to reduce. Severe pain is felt in large muscle groups, especially the hips, back, and shoulders.

Fatigue and weakness are prominent. Most patients feel too exhausted to get out of bed. Headache and dizziness are common.

Digestive system symptoms also appear during this period. Nausea, vomiting, and abdominal pain may be experienced. Diarrhea is observed in some patients. These symptoms can cause the disease to be confused with appendicitis or a stomach infection.

Respiratory System Symptoms

4 to 10 days after the onset of the disease, the situation changes. The Hantavirus Pulmonary Syndrome condition affecting the lungs develops. Vascular permeability increases, and fluid accumulation begins in the lungs.

Coughing appears and is usually dry in character. Shortness of breath progresses rapidly. Patients describe a feeling of tightness or pressure in their chests. Breathing becomes progressively more difficult.

Oxygen intake is impaired due to pulmonary edema. Blood pressure drops, and heart rate becomes irregular. At this stage, the condition can suddenly worsen and become life-threatening. The need for intensive care may arise within a few hours.

Kidney and Circulatory System Symptoms

In types common in Europe and Asia, kidney involvement is at the forefront. Distinct kidney and lower back pain is felt. A decrease in urine output begins. This condition is called oliguria and is a harbinger of kidney failure.

Swelling develops in the face, hands, and feet. Because the vessel walls are damaged, the tendency to bleed increases. Bleeding in the gums, nose, or skin can be observed. Blood may be detected in the urine.

Redness in the eyes and bleedings in the form of small red dots on the skin appear. Low blood pressure and circulatory disorders develop.

Late-Stage Complications

The risk of bleeding increases due to thrombocytopenia. If pulmonary edema progresses, respiratory failure develops. The heart becomes unable to provide adequate oxygen to the body.

Kidney functions are severely impaired. The condition of oliguria can progress to anuria, meaning the complete cessation of urine production. Supportive care and close monitoring under hospital conditions are mandatory.

How is Hantavirus Transmitted?

Rodents are the natural carriers of hantavirus. Mice and rats do not get sick themselves while carrying this virus. However, they spread the virus to the environment throughout their lives via their urine, feces, and saliva.

Ways of Transmission from Rodents

The most common route of transmission is the inhalation of dust formed by the drying of infected rodent waste. This waste dries and attaches to dust particles. When a warehouse or attic is swept, virus-laden dust kicks up into the air. When you inhale this dust, the virus reaches your lungs directly.

Outdoors, sunlight and wind disrupt the structure of the virus in a short time. In contrast, unventilated and dark environments allow the virus to remain viable. In indoor environments, the virus can remain intact for months.

Contact with contaminated surfaces also poses a risk. If you touch a surface contaminated with rodent secretions and then touch your mouth, nose, or eyes without washing your hands, the virus can enter your body. In addition, the consumption of food or water contaminated with rodent waste causes transmission.

Rodent bites are a rare route of transmission. However, in the event that a mouse carrying the virus bites you, the virus directly mixes into the blood via saliva.

Risky Environments and Situations

Closed areas such as warehouses, pantries, barns, basements, and garages carry high risk. Unused houses, agricultural areas, and closed structures in forested regions are also among dangerous environments.

Particularly in winter months, woodpiles and unused cabins where mice take shelter are risky areas. The risk of transmission increases in areas that have not been ventilated for a long time and are open to rodent entry. If there is a presence of rodents, feces traces, or nest remnants in these environments, you need to be careful.

The moment a door is opened and the dust inside is aerated, the virus can reach your respiratory tract. Actions such as wind, sweeping, or walking cause virus-laden particles to mix into the air.

Person-to-Person Transmission Status

Hantavirus generally does not transmit easily from person to person. The biological structure of the virus does not possess an adaptation to jump from person to person.

Very rare records of human-to-human transmission exist only in the Andes virus type seen in South America. These transmissions have occurred in closed family-type cases and very close contacts. This situation is not the case for hantavirus types seen in Turkey, Europe, and Asia.

Therefore, the primary risk in terms of transmission is your contact with infected rodents or environmental areas contaminated with their secretions.

How is Hantavirus Diagnosed?

Diagnosing hantavirus can be quite challenging in the early stages. The fact that symptoms show similarities with the flu and other viral infections complicates the diagnostic process. However, the correct diagnostic approach becomes lifesaving.

Clinical Evaluation and Anamnesis

The first step of the diagnostic process is to take a detailed patient history. Your doctor will ask whether you have had contact with rodents recently. A history of being in rural areas, working in agricultural fields, or entering unused closed areas are important clues supporting the diagnosis.

When being in risky environments and certain symptoms come together, the suspicion of hantavirus infection arises. Especially if you are experiencing fever, muscle pain, shortness of breath, or kidney problems, a history of rodent contact is of critical importance.

If your urea value is above 40 mg/dL and your creatinine value is above 1.6 mg/dL in a secondary healthcare institution, a blood sample is taken for the diagnosis of hantavirus infection. These laboratory values indicate impairment in kidney functions.

Laboratory Tests and Serological Examinations

For definitive diagnosis, antibodies formed against the virus are investigated. Your immune system produces IgM and IgG type antibodies against the infection. IgM antibodies are detected in the early period of the infection, and IgG antibodies are detected in the later period or in past infections.

Serological tests are the methods most frequently used in diagnosis. The ELISA test is widely preferred today. In addition, indirect immunofluorescence test and immunoblot methods can also be used. The presence and level of antibodies formed against the virus are determined with these tests.

Molecular diagnostic methods include the PCR test. This test can directly detect the genetic material of the virus. It is very useful in making a diagnosis in the early period. The PCR test can look for virus RNA in your blood, urine, or tissue samples.

However, the reliability of the PCR test depends on the stage of the disease. After antibodies start to form, the amount of virus in the blood decreases rapidly. Therefore, negative PCR results should be interpreted with caution.

Important findings also emerge in routine blood tests. A drop in your platelet count, an increase in white blood cells, and a high hematocrit can be seen. An increase can be detected in your liver enzyme values, ALT and AST. Protein or blood can be detected in urine tests.

Imaging Methods

Imaging methods are resorted to in cases with suspected lung involvement. A chest X-ray can show fluid accumulation in the lungs or changes related to the infection. Computed tomography provides more detailed examination and determines the degree of lung damage.

If there is an impairment in kidney functions, ultrasonography can be performed. This method evaluates structural changes and fluid accumulations in the kidneys. Imaging results serve as a guide in monitoring the course of the disease and treatment planning.

Which test will be chosen is determined according to the stage of the disease, the duration of symptoms, and the clinical picture. When all these evaluations come together, a definitive diagnosis is reached.

How is Hantavirus Treated?

Today, there is no specific antiviral drug or vaccine for hantavirus infection. The treatment process is entirely based on supportive care. However, early intervention and correct supportive treatment significantly increase survival rates.

Supportive Treatment Approaches

The basis of treatment is to protect the physiological balance of your body. Fluid and electrolyte support is the most critical part of this process. Fluids given via the intravenous route regulate your blood pressure and support your kidney functions. The fluid amount is adjusted delicately because excessive or insufficient fluid can negatively affect your organ functions.

Your blood pressure is continuously monitored. If low blood pressure develops, special medications and fluid therapy are applied. Your body's oxygen need is met, and your fever is reduced. Antipyretic medications such as paracetamol help alleviate your symptoms.

The treatment of secondary infections is also important. When your immune system weakens, bacterial infections can develop. In this case, antibiotic therapy is initiated. Healthcare professionals monitor your condition very closely.

Respiratory Support and Intensive Care

Respiratory support is of vital importance in patients who develop hantavirus pulmonary syndrome. When fluid accumulation begins in your lungs, your oxygen level drops. At this stage, oxygen therapy is initiated immediately. Oxygen is given via a mask or nasal cannula.

If respiratory failure has progressed, mechanical ventilation may be required. The ventilator device supports your breathing by pumping oxygen into your lungs. Intubation is applied in severe cases. This intervention prevents hypoxia in your lungs and protects your vital functions.

Admission to the intensive care unit may be necessary. Here, your pulse, blood pressure, respiration, and fever are monitored regularly. Early access to intensive care significantly increases survival rates in patients who develop cardiopulmonary syndrome. Impairments and complications in your heart functions are tracked moment by moment.

Protection of Kidney Functions

Fluid balance plays a critical role in cases with kidney involvement. Your urea, creatinine, and electrolyte values are tracked with your blood tests. Your urine output is measured, and your kidney functions are evaluated. If kidney failure develops, you may need dialysis treatment.

Dialysis can be applied temporarily or permanently. This treatment cleans harmful wastes and toxins accumulated in your body. The hemodialysis machine filters your blood and removes excess fluid. Dialysis support during the period when your kidneys are healing positively affects your health status.

Treatment Process and Follow-up

Your treatment duration varies according to the severity of the disease. In mild cases, staying in the hospital for a few days may be sufficient. However, in severe conditions, the treatment process can extend to weeks. Your organ functions are monitored closely.

Preventive interventions are made against complications. If acidosis develops, corrective treatment is applied. If your serum lactate level rises, the reason for this is investigated. Every development is evaluated instantly, and your treatment plan is updated.

Your check-ups continue even after you are discharged. Your kidney functions and respiratory capacity are monitored. It is checked whether permanent damage has developed. Your recovery process continues to be followed outside the hospital.

Frequently Asked Questions About Hantavirus

Is hantavirus transmitted from person to person?

No, hantavirus generally does not transmit from person to person. The structure of the virus is not suitable for easy transfer among humans. The main source of transmission is rodents and environments contaminated with their secretions.

However, there is only one exception to this rule. Family-type human-to-human transfer has been reported in very rare and exceptional situations in the Andes virus type seen in South America. These transmissions have occurred in closed environments and very close family-type contacts.

Transmission from person to person is not in question for hantavirus types seen in Turkey, Europe, and Asia. Therefore, it is not expected to cause an international epidemic and pandemic. Research has also shown that the virus is not transmitted via blood transfusion.

Since transmission may occur in the event of direct contact of body fluids such as blood and urine of the patient with the mucous membrane, it is recommended that healthcare personnel comply with standard protection precautions. In contrast, precautions such as quarantining patients are not necessary.

Is there a treatment for hantavirus?

There is no approved specific antiviral drug that will completely eradicate the virus. A protective vaccine against hantavirus is also not currently available. Vaccine studies are ongoing in some countries, but there is no vaccine that has entered widespread use yet.

It has been observed that some broad-spectrum antiviral agents such as ribavirin can provide partial benefit, especially in kidney forms caught in the very early stage of the disease. Intravenous ribavirin has been reported to be successful in Korea and some other countries. However, this treatment is not standard in every case and has limited efficacy.

The mainstay of treatment consists of supportive care aimed at controlling symptoms. Early diagnosis, rapid transport to a tertiary health center under appropriate conditions, and good supportive care increase the chance of survival.

Is hantavirus seen in Turkey?

Yes, hantavirus is found in Turkey. Although the global discovery of the disease dates back to former years, its official detection at the microbiological level within our country's borders coincides with a relatively recent period. The proof of hantavirus cases in Turkey with definitive laboratory findings and their entry into the literature corresponds to the early months of 2009.

The first clinically and serologically verified hantavirus outbreak in humans was detected in the Zonguldak-Bartın region in February 2009. Since that date, a limited number of hantavirus cases have been reported in Turkey in past years.

Rodent genera recorded as being hantavirus carriers are Microtus, Apodemus, Rattus, and Myodes, and 21 species belonging to these genera are distributed in Turkey. Cases have generally been associated with rodent contact. Rare cases originating from rodents are reported in various regions, especially in the Western Black Sea.

What should be done to protect from hantavirus?

Cutting off contact with natural sources of the virus in nature from the root is the only way to protect. It is necessary for all segments of society, especially individuals working in rural areas or warehouses, to be conscious about hantavirus and to apply hygiene rules without compromise.

The most important element in protection is ensuring rodent control in people's living spaces. Keeping rodents away from homes and other buildings is of vital importance. Food and beverages must be stored in closed cabinets where rodents cannot enter.

Contact with rodents and the excretions of these animals, such as feces, secretions, and urine, should be avoided. Dead rodents should not be touched with bare hands; gloves must be worn or a tool such as tongs should be used.

Methods that kick up dust, such as brooms and vacuum cleaners, should be avoided in cleaning. Wiping and washing methods should be used after moistening risky areas primarily with water containing 10% bleach. Moisten infected areas before cleaning them prevents dust laden with viruses from mixing into the air.