Marburg Toll in Angola Balloons to 255
Recombinomics Commentary
April 17, 2005
>> The Angolan Ministry of Health has announced that the death toll from the epidemic of Marburg hemorrhagic fever has jumped to 233 from a total of 255 cases recorded in Angola until Saturday.
According to a press release issued here by the ministry on Sunday, all the reported cases of the Ebola-like disease had originated in the northwestern province of Uige, though patients have died elsewhere, including Luanda, Zaire, Malange, Kuangza Norte, Kuanza South and Cabinda provinces. <<
The rising death toll in the absence of patients in the isolation wards in Uige and Luanda supports the observation that patients are dying in neighborhoods and avoiding hospitals. These numbers would also suggest that infected individuals are moving out of the area. However, it is difficult to see why such movement would not result in transmission in the new areas, because the families would not be trained in infection control. The large number of fatal Marburg cases in health care workers indicates that transmission associated with close contact with dead or dying patients is quite efficient.
The increase in patients follows a period of reclassification of Marburg cases. Health reports from last week suggested the requirements for inclusion in the case tally were being tightened. All of the new reported cases in Uige for April 13 were laboratory confirmed, suggesting lab confirmation may be a new requirement for inclusion as a reported case. That requirement may be more easily met in Uige, since there is now a new lab set up with rapid turnaround of testing data. However, a lab confirmation requirement may produce a significant undercount, especially in more distant provinces. Sample collection may be absent in some cases, and in others transport of collected samples to testing facilities may produce sample degradation and false negatives.
The reclassification did eliminate cases from Kwanza Sul, where there were cases clustered in 3 adjacent municipalities. The reported cases in Zaire were also eliminated administratively by reclassifying them.
Efforts to manage an outbreak by simply administratively eliminating cases because of unrealistic requirements can lead to gross undercounts and undetected spread of virus. The analogies with the bird flu management in southeast Asia have some striking parallels. The bird flu undercounts were driven by several factors, including unreported data, untested patients, and using tests with poor sensitivity. False negatives due to poor testing procedure or sample degradation also contributed to the gross undercount.
The data management practices have been particularly disastrous in Vietnam, which is likely to be the epicenter of the next flu pandemic, which may have already begun. In spite of almost daily press releases citing provinces that were bird flu free because of no detectable virus, a recent report indicated that 71% of the ducks in all 11 provinces in the Mekong Delta were positive for H5N1, as were about 25% of the chickens. These numbers were so high, that management via culling was considered to be a poor option.
Similarly, the size of human clusters continues to grow. Confirmatory data from the largest clusters is being withheld while 1000 samples are sent to the CDC for analysis. Since these samples were collected over 3 weeks ago, it would seem that most of the samples are positive, and CDC is analyzing sequences to identify which molecular changes are correlating with which clinical diseases. However, it seems quite clear that while Vietnam was administratively eliminating the virus, the H5N1 virus itself became so entrenched that the number of options has diminished.
Unfortunately, the administrative management of Marburg via press release and reclassification appears to be on the same misdirected path. The approach eliminates reports of virus that don't match models or wishful thinking, while the virus continues to spread beyond control.
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