(See attached) Beatty et al investigated the transmission of mosquito- and waterborne illness in Gonaive, Haiti following Hurricane Jeanne. The time period of study was November 15 to December 22, 2004, which is within range of dengue seasonal transmission.
Hurricane Jeanne was gathering strength when it hit Hispaniola Island, only becoming a Category 3 hurricane after passing over the island to later become the deadliest hurricane of 2004. In reviewing the records of what happened, it is not clear whether it was a hurricane or a tropical storm when it released 330mm of precipitation in the Haitian mountains that later flooded the Artibonite Valley and Gonaives. Mudslides were documented. A total of 80,000 were estimated to be affected out of 250,000 inhabitants in Gonaives, which is the third most population-dense area in Haiti. By October, it was believed 3,000 people died in Gonaives alone. Most of the houses were huts that were under ten feet of water at street level, displacing 200,000. One hospital was reported to be knee-deep in mud. The most vulnerable and poorest neighborhood in Gonaives, Raboteau, reportedly flooded even in light rain and was badly affected. Livestock and crops were washed away, a disaster the region is still trying to recover from to this day. Other towns were affected such as Port-de-Paix, Gros Morne and Chansolme. It is noteworthy that floods the prior May had already killed 3,000 in Mapou and other areas of southwest Haiti.
The most common clinical diagnoses they encountered were acute respiratory illness (30%), malaria (29%), pneumonia (18%), and typhoid (11%). They diagnosed 2 cases of dengue and found high pediatric seroprevalence, indicating prior community transmission. A 13 year old child and an infant were found to have dual infections with acute malaria and West Nile virus. This became the first documentation of active West Nile virus in Haiti. Curiously, no location-specific infectious disease baseline was reported or discussed in detail to enable contextualization of the results.
The authors concluded, "An outbreak of mosquitoborne disease was not detected during the period of surveillance... Our data are consistent with previously published reports, which indicate that the incidence of arboviral infections rarely increases after water-related disasters... However, malaria outbreaks are common in such settings."
This highlights an important point of clarification in our assessments that will be updated in the next SitRep. When we report anticipated increase in risk of transmission for dengue, it is an expression of an endemic seasonal increase, not necessarily due to any additional risk caused by the earthquake. We will probe this issue in greater depth in future posts.
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