Explanation

Hantavirus Hantaan IgG: what is measured?

Hantaan virus is a hantavirus carried by the striped field mouse and found mainly in Asia. People become infected by breathing in dust particles containing virus from rodent droppings. This test measures IgG antibodies against that virus. IgG appears later than IgM, usually in the second week of illness, and after that probably remains detectable for life. Hantaan virus does not circulate in the Netherlands; here it is almost always Puumala virus.

What can it detect?

A past infection with a hantavirus from the Hantaan serogroup, usually acquired in Asia
Support for the investigation of hantavirus hemorrhagic fever with kidney problems after a stay in an area where this virus occurs

Result

What does the result mean?

Positive result

A positive result means that antibodies were found that react to Hantaan virus in this test. In someone who has never been to Asia, this is usually not a true Hantaan virus infection: the different hantaviruses react strongly to each other's tests, so it is usually a cross-reaction, for example with Puumala virus, which does occur here. To really establish which virus it is, a neutralization test in a specialized laboratory is needed. Infections with Hantaan virus are generally more severe than those with Puumala virus.

Negative result

A negative result makes a past infection with a hantavirus from this group unlikely. In the first days of illness, a negative IgG does not rule out an infection, because IgG only appears after IgM. If a recent infection is suspected, IgM is the appropriate test, possibly with a second blood sample after at least fourteen days.

After an abnormal result

With a positive result and matching symptoms after a stay in an area where hantaviruses occur, assessment in the hospital follows, if needed with a neutralization test to determine the type of virus. Orthohantavirus infection is a notifiable disease in group C of the Dutch Public Health Act and must be reported to the GGD (municipal public health service) within one working day.

Reliability

How reliable is the test?

According to the LCI guideline (RIVM), serology is the appropriate method for hantavirus diagnostics, but type-specific serology is hampered by extensive cross-reactivity between the hantaviruses, also between serogroups. This test therefore cannot reliably distinguish whether it was Hantaan virus or another hantavirus. Because Hantaan virus does not circulate in the Netherlands, the chance of a true infection in someone without travel to Asia is very small, and a positive result is almost always a cross-reaction or a false positive.

What can affect the result?

Hantaan virus does not occur in the Netherlands; a positive result without a stay in Asia is almost always due to cross-reaction.
There is extensive cross-reactivity between hantaviruses; only a neutralization test in a specialized laboratory can determine the type.
IgG probably remains detectable for life after a past infection and says nothing about an active infection.
In the first days of illness, IgG may still be negative while there is an infection.

Who it is for

Who is the test useful for?

Useful for

May be useful with sudden fever with kidney symptoms or a bleeding tendency after a stay in Asia or another area where this virus occurs. For people who have only been in the Netherlands, this test is not useful: Hantaan virus does not circulate here, and when a hantavirus infection in the Netherlands is suspected, IgM and Puumala IgG say more. Also not useful as a general check-up in people without symptoms.

How common is it?

Hantaan virus mainly occurs in Asia; worldwide there are an estimated 100,000 cases of hantavirus hemorrhagic fever per year, 70 to 90 in 100 of them in China. This virus has not been found in the Netherlands: the notifications here, an average of 31 per year between 2018 and 2023, are almost all about Puumala virus. In addition, since 2016 six people in the Netherlands have been infected with Seoul virus, all of them keepers of pet rats or feeder rats.

The RIVM/LCI guideline on orthohantavirus infection

Drawbacks and risks

In the Netherlands, a positive result is almost always due to cross-reaction with another hantavirus and can cause unnecessary worry about a more severe illness than occurs here.
Unnecessary follow-up testing in a specialized laboratory with a result that does not fit the symptoms or exposure.

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