If I knew for sure what was going on with the reported human bird flu outbreak in Pakistan’s northwest border region I’d tell you. At this point it appears no one knows for sure — not WHO, not CDC, not even the Pakistani authorities. The region where the cases are reported is near the Afghan border and is not under firm government control. The unsettled political situation merely adds to the usual confusion inevitable in the early days of any outbreak. We are all looking for a pandemic signal embedded in a lot of noise, difficult enough, but we don’t even know what the signal sounds or looks like. It is now Sunday evening in Geneva and after midnight in Pakistan, so this is as good a time as any for a summary. I doubt more information will be available before tomorrow (Monday, December 17, 2007).
As best I can tell from scanning the reports, this is the current status. I am synthesizing and using my best judgments among conflicting and confusing news and official reports. Some of this may change. At this point there appears there are two (or three, depending on how you count) groups of cases, one a family cluster involving four brothers and two cousins (with two deaths); the other involving three workers involved in culling infected poultry,including a man, his niece and a third unrelated person who, however, worked at the same farm as the index case.
The index case was one of five brothers, an agricultural official who worked on a culling operation on an infected poultry farm and fell ill in October. He has since recovered. Two younger brothers who visited and nursed him in the hospital, however, fell ill and died. Both were students at an agricultural school, so may also have been exposed there. One was said to have been confirmed to be infected with H5N1 by testing at Pakistan’s National Laboratory. Specimens are being sent to a WHO reference laboratory for definitive confirmation. The other died and was buried before there was suspicion of H5N1 infection. A third brother, a primary school teacher who also visited the index case, developed mild symptoms and has recovered. Testing on him was not complete. A fourth brother, living in the US, traveled to Pakistan for the funerals of his siblings. There are conflicting reports whether he showed any symptoms. Upon his return to the US (Nassau Country, New York) he notified his doctor of a potential exposure and voluntarily quarantined himself in his home. Subsequent testing by CDC and the New York Health Department showed he had not been infected (his son was also negative for infection). Two cousins of the family are also reported to have had mild symptoms and to have tested positive. We have no exposure information on them at this time. They have since recovered. The three cull workers also have recovered. Finally, a doctor involved in the care of the index case was well but a non-standard diagnostic test (not specified) showed she may have been infected.
Meanwhile there is time for fingerpointing in Pakistan, which I take to be a good thing. That usually happens when people aren’t so fully occupied with the crisis they have no time for anything else (see excellent reporting over at Avian Flu Diary [link fixed; ht GMan). The politics of this region are complex and multiple agendas are in play simultaneously. Reports of some additional suspect cases are not only expected but desirable. In this setting there should be high index of suspicion, with a diagnosis of H5N1 in an exposed person with flu-like symptoms a rebuttable presumption of avian influenza. It will take some time to sort all of this out. WHO and CDC are collaborating with Pakistani authorities. Some additional diagnostic confirmations may come tomorrow (Monday) or Tuesday.
To sum up, as best we can tell there are possibly nine cases and two deaths (one buried before testing could be done). We are told three of the cases (brothers) visited or tended the index case in the hospital. Thus this cluster is suspicious for person to person transmission of the disease. While there were two fatalities, most of the cases have recovered, very different from the pattern in Indonesia where most cases have a fatal outcome. The Indonesian case fatality ratio [CFR] is 80% and the overall CFR just over 60% but it is driven by the very bad outcomes in Indonesia. The CFR outside Indonesia is just over 51%. Vietnam’s CFR is less than 50% and Egypt and Turkey lower still (see latest WHO compilation of confirmed cases), so the apparently better outcomes so far in Pakistan may not be so unusual. There is always the possibility that this is a milder but more transmissible variant.
Meanwhile it is reported that Tamiflu has been rushed to the area “for treatment and prophylactic purposes.” We don’t know who is being treated or prophylaxed, if anyone. Pakistani hospitals and clinics have been put on alert. Like everyone else, we’ll await further developments.