Swine flue N1H1 Symptoms and expected severity

The signs of infection with swine flu are similar to other forms of influenza, and include a fever, coughing, headaches, pain in the muscles or joints, sore throat, chills, fatigue and runny nose. Diarrhea, vomiting and neurological problems have also been reported in some cases. A study concluded on May 5, published in the New England Journal of Medicine, found that 94% of confirmed patients had fever and 92% had cough.[206] People at higher risk of serious complications included people age 65 years and older, children younger than 5 years old, pregnant women, and people of any age with underlying medical conditions, such as asthma, diabetes, obesity, heart disease, or a weakened immune system (e.g., taking immunosuppressive medications or infected with HIV).[204][207] According to the CDC, more than 70% of hospitalizations in the U.S. have been people with such underlying conditions.[208]
Most cases mild
Evidence mounted through May 2009 that the symptoms were milder than health officials initially feared. As of May 27, 2009, most of the 342 confirmed cases in New York City had been mild and there had been only 23 confirmed deaths from the virus.[209] Similarly, Japan has reported 1,048, mostly mild flu cases, and no deaths,[210] with the government reopening schools as of May 23, stating that the "virus should be considered more like a seasonal flu."[211] In Mexico, where the outbreak began in April, Mexico City officials lowered their swine flu alert level as no new cases had been reported for a week.[212]

Symptoms that may require medical attention

Certain symptoms may require emergency medical attention. In children signs of respiratory distress, for instance, those might include blue lips and skin, dehydration, rapid breathing, excessive sleeping, seizures[213] and significant irritability that includes a lack of desire to be held. In adults, shortness of breath, pain in the chest or abdomen, sudden dizziness or confusion may indicate the need for emergency care. In both children and adults, persistent vomiting or the return of flu-like symptoms that include a fever and cough may require medical attention.

Underlying conditions may worsen symptoms

WHO reported that almost one-half of the patients hospitalized in the United States had underlying conditions.[214] "Among 30 patients hospitalized in California," stated the WHO report, "64 percent had underlying conditions and two of five pregnant women developed complications, including spontaneous abortion and premature rupture of membranes." And on June 5, health officials in six states that reported deaths from swine flu said that all six patients had been diagnosed with other health problems.[215]
However, doctors in New York suggested that people with "underlying conditions" who had flu symptoms should consult their doctors first. "Visiting an emergency room full of sick people may actually put them in more danger," wrote the New York Times. Dr. Steven J. Davidson, the chairman of emergency medicine department at Maimonides Medical Center in Brooklyn commented "Like the asthmatics, we’d really prefer that pregnant women would stay away from the emergency departments." Approximately one-third of New Yorkers have one of the underlying conditions recognized by the city.[207] However, no statistics for people with underlying conditions who die from seasonal flu have been reported by the media thus far.

Pneumonia

Influenza infection can cause pneumonia leading to death. This is typically described as either viral pneumonia, which has a rapid onset, often within one day after infection, or bacterial pneumonia, which often begins a week after infection after symptoms have begun to subside.[216]
Viral pneumonia has sometimes been attributed to "cytokine storm", in which an overly active immune response damages the lungs. Reports of deaths among healthy young people during the first weeks of the 2009 flu pandemic were attributed to this cause.[217]
Bacterial pneumonia is a secondary infection resulting from a weakened ability to clear common bacteria from the lower lungs, combined with reduced alveolar macrophage activity which makes it more difficult for the body to fight infection. Bacteria that cause pneumonia include Pneumococcus, Staphylococcus, and Hemophilus influenzae.[218] Bacterial pneumonia has been credited for a large proportion of deaths in the 1918 flu pandemic.[219]
Recent data has suggested that these two forms of pneumonia are not entirely unrelated. A study of 37,000 children in South Africa who received a pneumococcal vaccine (PncCV) found that they were on average one-third less likely to suffer viral pneumonia following infections with seven different respiratory viruses, as well as being protected from bacterial pneumonia afterward.[220]

Prevention

Personal hygiene

The Mayo Clinic has suggested personal measures to avoid seasonal flu infection which should be applicable to the 2009 pandemic: vaccination when available, thorough and frequent hand-washing, a balanced diet with fresh fruits and vegetables, whole grains, and lean protein, sufficient sleep, regular exercise, and avoiding crowds.

Airborne virus prevention

Masks may be of benefit in "crowded settings" or for people who are in "close contact" with infected persons, defined as 1 meter or less by the World Health Organization and 6 feet or less by the U.S. Occupational Safety and Health Administration. In these cases the CDC recommended respirators classified as N95, but it is unknown whether they would prevent swine flu infection.[222] According to mask manufacturer 3M, there are no "established exposure limits for biological agents" such as swine flu virus.
The UK Health Protection Agency considers facial masks unnecessary for the general public[223] and some experts feel it may lead to a false sense of security. Masks are not generally provided by airport security or airlines although the CDC recommends the use of surgical masks in some circumstances.[224] other U.S. officials stated in May that if the flu virus does in fact reach pandemic proportions, "there won't be enough face masks to go around."[225] A recent internal CDC briefing noted, "20,000 people die from novel 2009-H1N1 and everybody wants to wear a mask. 9 million people die from AIDS and no one wants to wear a condom."
Pork safe to eat
The leading international health agencies stressed that the "influenza viruses are not known to be transmissible to people through eating processed pork or other food products derived from pigs."

Airline hygiene precautions

U.S. airlines have made no major changes as of the beginning of June, but continued standing practices that include looking for passengers with symptoms of flu, measles or other infections, and rely on in-flight air filters to ensure that aircraft are sanitized. "We take our guidance from the professionals (such as the CDC)", stated an Air Transport Association spokesman. The CDC has not recommended that airline crews wear face masks or disposable overcoats. Alaska Airlines removed all pillows and blankets from its fleet in late April/early May.[228]

Outside the U.S. however, some airlines have modified hygiene procedures to minimize travel health risks on international flights. Asian carriers have stepped up cabin cleaning, installed state-of-the-art air filters and allowed in-flight staff to wear face masks, with some replacing used pillows, blankets, headset covers and headrest covers, while others have begun disinfecting the cabins of all aircraft. In China, some airline flight attendants are required to wear disposable facial masks, gloves and hats and even disposable overcoats during flights to select destinations.[229]
Singapore has been thermal-screening everyone coming into the country, with Singapore Airlines giving passengers traveling to the United States health kits that include a thermometer, masks and antiseptic towels. Its cabin and flight crews are getting mandatory temperature checks before flights. The government recently quarantined a passenger who was later found to have the flu along with about 60 other people on the same flight who were sitting within three rows.[229] A consultant for the microbiology division at National University Hospital in Singapore, said hygiene practices such as covering the nose and mouth when sneezing or coughing in confined areas may be the best way to limit infection and safety measures such as costly air filters may be of limited use for carriers.[229]
Further information: Influenza prevention and standard personal precautions against influenza
Containment


Chinese inspectors on an airplane, checking passengers for fevers, a common symptom of swine flu
On April 28, 2009, WHO's Dr. Keiji Fukuda said that it was too late to contain the swine flu. "Containment is not a feasible operation. Countries should now focus on mitigating the effect of the virus," he said.[230] He therefore did not recommend closing borders or restricting travel, stating that "with the virus being widespread... closing borders or restricting travel really has very little effects in stopping the movement of this virus."[230] However, on April 28, the U.S. CDC began "recommending that people avoid non-essential travel to Mexico."[231] Many other countries confirmed that inbound international passengers would be screened. Typical airport health screening involves asking passengers which countries they have visited and checking whether they feel or appear particularly unwell. Thermographic equipment was put into use at a number of airports to screen passengers.[232] A number of countries also advised against travel to known affected regions, while experts suggested that if those infected stay at home or seek medical care, public meeting places are closed, and anti-flu medications are made widely available, then in simulations the sickness is reduced by nearly two-thirds.

Quarantines

Some countries began quarantining foreign visitors suspected of having or being in contact with others who may have been infected.