WHO MEETING REPORTS GLOBAL H1N1 CLINICAL STATUS
Last week, WHO hosted a meeting in Washington, DC (14–16 October) to share findings and experiences with 100 clinicians, scientists, and public health professionals from the Americas, Europe, Asia, Africa, the Middle East and Oceania. The good news: The meeting confirmed that the overwhelming majority of persons worldwide infected with the new H1N1 virus continue to experience uncomplicated influenza-like illness, with full recovery within a week, even without medical treatment.
The flip side however is focused on the clinical course and management of small subsets of patients who rapidly develop very severe progressive pneumonia. In these patients, severe pneumonia is often associated with organ failure or marked worsening of underlying asthma or chronic obstructive airway disease.
The Clinical Picture
Primary viral pneumonia is the most common finding in severe cases and a frequent cause of death. Secondary bacterial infections have been found in approximately 30% of fatal cases. Respiratory failure and refractory shock have been the most common causes of death. Meeting presentations explored the pathology of this phenomenon in detail, with findings supported by work in experimental animals. These findings all confirm the ability of the new H1N1 virus to directly cause severe pneumonia.
Clinicians agreed that the clinical picture of these seriously ill patients is strikingly different from the disease pattern seen with seasonal influenza. While people with certain underlying medical conditions, including pregnancy, are known to be at increased risk, many severe cases occur in previously healthy young people. The clinical picture looks like this:
- The pattern of these severe cases begins with the patient deteriorating around 3 to 5 days after symptom onset.
- The decline is rapid, with many patients progressing to respiratory failure within 24 hours, requiring immediate admission to an intensive care unit.
- Upon admission, most patients need immediate respiratory support with mechanical ventilation.
- In some cases patients do not respond well to conventional ventilator support, further complicating the treatment.
One positive note, findings presented during the meeting concur that prompt treatment with the antiviral drugs, oseltamivir or zanamivir, reduces the severity of illness and improves the chances of survival. These findings strengthen previous WHO recommendations for early treatment with these drugs for patients who meet treatment criteria, even in the absence of a positive confirmatory test.
In addition to pneumonia directly caused by replication of the virus, evidence shows that pneumonia caused by co-infection with bacteria can also contribute to a severe, rapidly progressive illness. Bacteria frequently reported include Streptococcus pneumoniae and Staphylococcus aureus, including methicillin-resistant strains in some cases. As these bacterial co-infections are more frequent than initially recognized, clinicians stressed the need to consider empiric antimicrobial therapy for community-acquired pneumonia as an early treatment.
Groups At Greatest Risk
Participants noted the risk of severe or fatal illness is highest in these groups:
- Pregnant women, especially during the third trimester of pregnancy
- Children younger than 2 years of age
- People with chronic lung disease, including asthma
- Neurological disorders can increase the risk of severe disease in children.
- Obesity and especially morbid obesity have been present in a large portion of severe and fatal cases. Obesity has not been recognized as a risk factor in either past pandemics or seasonal influenza.
- Disadvantaged populations, such as minority groups and indigenous populations, are disproportionately affected by severe disease. Although the reasons for this heightened risk are not yet fully understood, theories being explored include the greater frequency of co-morbidities, such as diabetes and asthma, often seen in these groups, and lack of access to care.
Serious Disease In Women
One of those patients was Karen Ann Hays of Sacramento, Calif., an otherwise healthy nurse whose hobby was tackling grueling triathlons. Despite desperate measures to keep her alive, Hays, 51, died in July within days of coming down with swine flu. “I have seen more cases like this in the last three months than I have in the last 30 years,” said Peter Murphy, director of intensive care at the Mercy San Juan Medical Center in Carmichael, Calif., who tried to save Hays.
There appears to be no way to predict with certainty who may suffer serious, life-threatening complications, since some victims have had no other health problems. For instance, Stacey Hernandez Speegle, 30, of Madison, Calif., who died in July, “was in great shape. She was on the softball team. She had two young children. She was renovating her house,” said her mother, Tamara Brooks. “It’s just so hard to believe.” “There’s no question that women, and particularly young women, are getting hit disproportionately,” said Kumar. He noted that women tend to have more fat tissue, which can help stimulate a dangerous inflammatory response to infections.
PNEUMONIA VACCINE – WHAT IS IT? SHOULD YOU GET ONE?
The term pneumonia refers to any infection of the lung. The “pneumonia vaccine” is given to prevent one specific type of pneumonia–the pneumonia caused by the Pneumococcus (Streptococcus pneumoniae) bacterium. Pneumonia caused by Pneumococcus is the most common form of infection occurring outside of a hospital or institutional setting in the U.S. The pneumococcal vaccine is safe, it works, and one shot lasts most people up to 10 years. People who get the vaccine are protected against almost all of the bacteria that cause pneumococcal pneumonia and other pneumococcal diseases as well. The shot, which is covered by Medicare, can be a lifesaver.
Some experts say it may be best to get the shot before age 65–anytime after age 50–since the younger you are, the better the results. They also say people should have this shot even if they have had pneumonia before. There are many different kinds of pneumonia, and having one kind does not protect against the others. Most people need to get the shot only once. However some older people may need a booster; check with your doctor to find out if this is necessary.
HUMANS INFECTING PIGS IN MINNESOTA
I find these stories of cross species infections a bit disturbing. The more the disease moves back and forth, I wonder whether it provides a vehicle for mutation. Federal agriculture officials said Friday that pigs from the Minnesota State Fair had tested positive for H1N1, which would make them the first documented pig infections in the United States, if follow-up tests confirm the results. But there are no signs that the pigs were sick or that the animals had infected any humans.