Health authorities in the United States have issued guidance concerning swine flu and people with HIV.
On April 30th, the US Centers for Disease Control and Prevention (CDC) published information on what is currently known about the symptoms of swine flu, along with recommendations concerning its treatment and prevention.
Because there are limited data on swine flu, some of the guidance is based upon what is known about seasonal outbreaks of flu in people with HIV.
Background
Cases of swine flu (influenza A H1N1) in humans were first identified in April 2009. Much is still uncertain about the epidemiology of the infection and its clinical course.
There is not currently enough information to say which groups of patients will be at greater risk of complications caused by swine flu. However, it is known that people with HIV, especially those with a low CD4 cell count, have an increased risk of lower respiratory tract infections caused by both viruses and bacteria, or recurrent chest infections, as a consequence of seasonal flu.
Some studies examining the impact of annual winter outbreaks of flu on people with HIV have found that rates of hospitalisation are increased, that flu symptoms last for longer, and that there is increased mortality.
Although information from these studies is limited, the CDC is cautioning that it is “possible” that individuals with HIV, especially patients with a low CD4 cell count, may have a “higher risk for swine-origin influenza complications”.
Symptoms
It is expected that symptoms of swine flu in patients with HIV will be similar to those of normal influenza:
- Cough
- Sore throat
- Runny nose and sneezing
- Fever
- Headache
- Muscle pain
However, in some patients with HIV, especially those with a low CD4 cell count, the infection may progress more rapidly, and could be more likely to be complicated by secondary bacterial infections, for example pneumonia.
HIV-positive individuals in whom infection with swine flu is suspected should have appropriate laboratory tests to diagnose the infection.
It is recommended that “persons with HIV infection should remain vigilant for the signs and symptoms of influenza”. Patients who develop symptoms, or who come into contact with individuals who have confirmed, probable, or suspected cases of the infection, are recommended to consult their doctor “for evaluation and for possible anti-influenza treatment or prophylaxis”.
Treatment and prophylaxis
The virus involved in the current human outbreak of swine flu is sensitive to treatment with antiviral drugs in the neuraminidase inhibitor class. Drugs in this class include zanamivir and oseltamivir (Tamiflu). [The UK currently has supplies of these drugs in sufficient quantities to treat half the population.]
HIV-positive patients with confirmed, probable or suspected infection with swine flu are recommended to receive empiric treatment with such drugs.
Furthermore, HIV-positive individuals who have had close contact with individuals with confirmed or probable swine flu should receive prophylactic treatment with either of these drugs. Recommendations for prophylactic use of antiviral drugs in patients with HIV are the same as those for other groups with a higher risk of flu.
Treatment with antiviral drugs should be initiated as soon as possible after the symptoms of swine flu emerge. It is thought that the benefits of this treatment are greatest if it is provided within 48 hours of the emergence of symptoms. However, studies involving patients hospitalised because of seasonal flu suggest that starting treatment after symptoms have been present for over 48 hours may also be of benefit.
The recommended duration of treatment for patients with symptoms is five days. Prophylactic therapy should be taken for ten days after the last suspected exposure.
Treatment regimens with zanamivir and oseltamivir for people with HIV are the same as those for HIV-negative individuals. However, it is recommended that patients should be monitored closely to see if longer duration of treatment is warranted.
Recommendations regarding treatment and prophylaxis may, however, change as more clinical information becomes available.
There are no reported side-effects of treatment with zanamivir and oseltamivir, nor do these drugs interact with antiretrovirals.
Prevention
There is currently no vaccine against the human form of swine flu that is currently causing infections.
Prevention therefore relies on routine infection control procedures for flu. These include:
- Using a tissue to cover the mouth and nose when coughing and sneezing. This should then be thrown away.
- Frequent hand washing.
- Staying at home if ill except to go to the doctor.
- Minimal contact with household members who may have swine flu.
Avoidance of unnecessary social contacts and crowded places is also noted as a method of infection control.
Properly fitted facemasks and respirators can reduce the risk of flu, but the CDC stresses that they should be used along with other preventative measures. The only type of mask that protects against infection conforms to the European standard FFP3 and the US equivalent, N95, and this should be clearly indicated on the packaging.
Guidance on how to avoid infection with swine flu will be updated “as more information becomes available, including information of the risks of swine-origin influenza-related complications among HIV-infected adults and adolescents.”
Other measures to maintain health
The CDC guidelines note the importance of antiretroviral therapy and prophylactic treatment for other infections to the maintenance of good health in people with HIV. Their guidance stresses the importance of good adherence to such treatment.