Can acute HIV infection be mistaken for influenza ?

Dear Ask The Doctor: I know I just posted this question but I made an error, and am unable to edit the original question. I meant to say that a nasal swab was taken and the doctor said it showed influenza, not a saliva swab. I re-wrote the question below to correct it: Hi, I had unprotected vaginal sex with a prostitute in Thailand. This was on a Thursday night like maybe after 12 midnight. When I pulled out there was blood on the head of my penis. Then around 3 days later saturday night, Sunday morning I started to feel not so well. I went to a doctor on the Sunday, and he said I had fever. He gave me antibiotics but I was still not better after taking the antibiotics for 2 days. I went back to the doctor 2 days later, he did a nasal swab and told me it was influenza. I also had a small amount of fluid in my lungs. He gave me tammiflu and the fever got better after a few days. I was just wondering what the chances are that the doctor mistakingly diagnosed me with influenza when it was actually acute hiv infection? The doctor did take a nasal swab, so after doing that test is it still possible to mistake acute hiv for influenza? Or is it not possible to make that mistake after a nasal swab of mucous is checked? Also, the encounter was on a Thursday night, and I started having symptoms around 3 days later. Is that too soon to develop symptoms from hiv after an encounter? I've read that 2 to 4 weeks is the norm, but can it happen sooner, like after 3 days? I also had a small amount of fluid in my lungs when I initially was diagnosed with influenza. I'm smoker but I've never had pneumonia before. About a month later after I had the influenza I developed a more worse case of pneumonia. I was also a smoker during this time, but could the pneumonia a month later indicate I do have HIV? Thanks in advance.

Dear Michael: Yes is too soon for HIV testing, and a positive test for Influenza means that you have Influenza virus, which does not rule out the possibility that you might get infected with HIV, given the fact that you were engaged in high risk sexual behaviors as: sex with persons who exchange sex for money and/or drugs and with an unknown HIV status. A person may get infected very fast (within a day or two), but you have to wait a while before an HIV test will produce an accurate result. The period of time you should wait before taking an HIV test will depend on the type of test that you are taking. In the majority of cases, the standard test that will be offered at an HIV testing center will be an HIV antibody Test. The HIV antibody Test detects antibodies to the virus in your blood. For most of the people these antibodies take 6 weeks to 3 months to develop, sometimes, in very rare cases, may take up to 6 months. For this reason, getting tested before 3 months have passed may result in an unclear test result, as the infected person may not yet have developed antibodies to HIV. These 3 – 6 months are known as the 'window period'. Many people do not show symptoms after they first get infected with HIV. Others have a flu-like illness within several days to weeks after exposure to the virus. They complain of: fever, headache, tiredness, and swollen nodes in the neck. These symptoms usually disappear within a few weeks. After that, the person feels normal and has no symptoms. This asymptomatic phase may lasts for years. The development of the disease is different among individuals. This state may last from a few months to more than 10 years. Even though the person has no symptoms, is contagious and can pass HIV to others.  So, I recommend waiting for at least 4-6 weeks after the last time you were at risk before taking the test. Some test centers may recommend testing again at 6 months, just to be extra sure, though in most cases this is not necessary.