The United States Naval Medical Research Unit #2 (NAMRU-2), has worked with the Indonesian National Institute of Health Research and Development (LITBANGKES) under the Indonesian Ministry of Health (DEPKES), since about 1970 on a variety of projects, including Avian Influenza. Since 1999, NAMRU-2, DEPKES, and the US CDC have maintained a hospital-based influenza surveillance network at sites across the Indonesian archipelago. NAMRU-2 analyzes about 700 influenza samples a month and about 100 samples a month strictly for avian influenza. NAMRU-2 has tested every human AI case in Indonesia since human cases first appeared.
From January to December 2005, NAMRU-2 has identified 18 cases of H5N1 in Indonesia, all of which were confirmed internationally. A number of family clusters were observed in Indonesia and the possibility of human to human transmission could not be excluded in at least two of these clusters. Small clusters with possible limited human to human transmission is a worrying development, as is the fact that many of the human H5N1 isolates have been obtained from cases without a clear exposure.
Molecular analysis of the H5N1 isolates has shown that human viruses are clustering and most have a distinct genetic difference from the poultry viruses. The number of cases is accelerating with 45 deaths in 2006 as compared to 13 deaths in 2005. The seriousness of the Indonesian situation, and recently publicized failures in national contingency planning for an AI outbreak highlight the need for oil and gas industry to engage in detailed contingency planning arrangements.
This paper will review the NAMRU-2's sampling and analysis program drawing some broad conclusions from the results as well as highlighting the need for ongoing influenza surveillance in Indonesia and improvements in national crisis management and contingency planning.
Human illness due to highly pathogenic (HPAI) avian influenza A (H5N1) virus was first documented in 1997, following H5N1 poultry outbreaks in Hong Kong where 18 H5N1 cases with 6 deaths were detected.1 Between late 2003 and early 2004, unprecedented outbreaks of HPAI H5N1 virus among poultry re-emerged in Asia.2 From January 2004 through June 29, 2007, 317 human cases and 191 deaths had been reported to the World Health Organization (WHO) in twelve countries.3 Most cases are believed to have resulted from sporadic avian-to-human transmission through direct exposure to H5N1-infected poultry.
The occurrence of H5N1 cases among family members was first documented in Hong Kong in 1997 in which two confirmed cases were cousins.4 In early 2003, two H5N1 cases were identified among a Hong Kong family that had recently traveled to southern China.5 Other H5N1 case clusters were observed in 2004–05, but without sufficient information to ascertain if human-to-human transmission had occurred.6 The best evidence to date of probable limited human-to-human transmission of H5N1 virus was from a hospitalized child to her mother and aunt in Thailand in 2004.7 Emergence of an H5N1 virus with greater transmissibility among humans could result from re-assortment of avian with human influenza A viral genes and or the acquisition of mutations in one or more avian influenza genes, including those that confer a change in the receptor binding specificity of the H5 hemagglutinin or enhance transmission among humans. Since an increase in case clustering could signal the beginning of a pandemic, detailed investigation of all H5N1 case clusters is critically important.
Since 2003, poultry outbreaks of H5N1 have been reported throughout Indonesia, especially on the islands of Java, Sumatra, Bali and Sulawesi. Most provinces have been affected by these outbreaks, prompting culling activities.8 During June 28 to July 7, 2005, three of five immediate family members were admitted to hospitals near Jakarta with severe respiratory disease. Within two weeks, all three patients had died and H5N1 virus infection was confirmed in one case. Over the next two years 80 deaths in 101 additional human H5N1 cases and at least 10 family clusters were identified amongst these. In this report, we describe the epidemiology, clinical, and virological findings associated with clusters of H5N1 cases in Indonesia that occurred from June through October 2005 and the large cluster that occurred in May.