First human infection with Influenza A H5N1 confirmed in Bangladesh

The first human case of influenza A H5N1 recognized in Bangladesh and was notified to WHO by Bangladesh Government on 22 May, 2008. The case occurred in a 15 month old child from Dhaka. He developed fever and difficulty breathing, but recovered completely.  His likely exposure was to a chicken that was slaughtered in his household.Physicians who see patients with serious respiratory illness should take a history of exposure to sick poultry and contact IEDCR if they suspect highly pathogenic avian influenza.

We report the first case of human infection with influenza A, H5N1 confirmed in Bangladesh.  The case was identified as part of the population based surveillance in urban Dhaka.  Upon laboratory confirmation of the case an investigation team re-evaluated the affected child and family and investigated potential sources for the infection.

The World Health Organization and the Food and Agriculture Organization monitor strains of influenza circulating globally to identify dangerous emerging strains with the hope that early recognition and intervention a high mortality pandemic can be avoided.Strains of Influenza A, H5N1, first identified in Hong Kong in 1997 have been circulating in Asia since 2001.These strains have caused high mortality outbreaks among poultry throughout Asia, and in many countries in Europe and Africa.  The H5N1 virus is a adapted to birds, the natural host of influenza viruses.  However, these strains occasionally infect humans.Among the 383 human cases of H5N1 recognized and reported to the World Health Organization by 28 May 2008, 241 (63%) had died.If the H5N1 virus develops the capacity to efficiently transmit from person to person, this could cause a deadly pandemic.

The government of Bangladesh confirmed the presence of influenza A, H5N1 virus in poultry in March 2007 and since then poultry outbreaks of H5N1 have been confirmed in 47 of the 64 districts in Bangladesh.  ICDDR,B collaborates with the Government of Bangladesh on human surveillance for influenza under two broad activities, national hospital surveillance in 12 hospitals across the country and population based surveillance in a low income community in urban Dhaka.

Kamalapur is a densely populated, low-income community in Dhaka city. Since March 2004, approximately 5000 households with children under the age of 5 years are under active surveillance for respiratory illness. Each week a field worker visited participating households and referred children to the clinic who had signs of serious respiratory illness. Participating families were encouraged to bring their children to the clinic if they developed signs or symptoms of illness on days that the field worker did not come to visit them in the home. In the clinic physicians performed a standardized exam, and ordered additional studies based on specific findings. Every fifth child from the surveillance area who met the criteria for acute infectious respiratory illness had a nasopharyngeal wash specimen collected. An aliquot of the nasopharyngeal washes was placed on tissue culture in the Virology Laboratory of ICDDR,B, and incubated. If cytopathic effect was noted, the tissue culture supernatant was collected and a haemagglutination inhibition test conducted using the standard WHO influenza reagent kits for Influenza A (H1N1), Influenza A (H3N2), Influenza B Shanghai and Influenza B/Hong Kong.

A 15 month old Kamalapur resident developed cough and runny nose on 22 January 2008. By 27 January his breathing was labored. On 29 January his mother brought him to the ICDDR,B clinic in Kamalapur. On examination the child had a temperature of 38.1 °C, a respiratory rate of 40 breaths per minute, pulse of 124, weight for age was the 78th percentile and there were no abnormal sounds on chest auscultation. Because the child was part of the active surveillance system, a chest radiograph was obtained. The child was also selected as one of the one in every 5 children selected for nasopharyngeal wash and influenza culture.

The initial clinical impression was enteric fever. The child was treated with amoxicillin. The chest radiograph was later interpreted as showing an alveolar infiltrate. Because the child was in the surveillance system, a field worker visited him daily at his home. He was also seen in the clinic for follow-up on 31 January, 5 February, 10 February and 13 February. Although the mother reported the child had fever at home as late as 7 February, an elevated temperature was not identified after the initial clinic visit. The child completed a 13 day course of amoxicillin. On his last clinic visit on 13 February the child was clinically well. The final clinical diagnosis was upper respiratory tract infection. The child was re-evaluated on 22 May and remained clinically well.

The culture of the child’s nasopharyngeal wash specimen showed cytopathic effect typical of influenza virus, reacted against antibody to influenza A, but the specimen did not agglutinate with H1 or H3 antisera. The specimen was forwarded to the Centers for Disease Control in Atlanta, Georgia for further characterization. At the Centers for Disease Control the isolate was confirmed as a highly pathogenic Influenza A, H5N1, by anti-sera agglutination and real time PCR. The viral genome was sequenced. It was a clade 2.2 virus.

The infected child lived with his mother, sister, and father in a one room residence in the Kamalapur community. The child’s father bought a live broiler chicken from a poultry shop located 50 meters from the residence at 11:00 am at some time in January. He kept the chicken near the door of their one room house where the affected child was sleeping. At 12:00 pm, the child’s mother with the help of her next door neighbor slaughtered the chicken inside the bathroom near the tap. While they were slaughtering the chicken, the child was sleeping and immediately after the processing of the chicken, the child awoke. Neither the mother nor the neighbor washed their hands. The mother handed the child to the neighbor. The mother gathered all the entrails, organs and other wastes of the chicken in a polythene bag, tied a knot in that bag and kept it near the main entrance of the house. The waste bag remained there for about two hours.

The poultry shop where the father bought the chicken sold an average of 15 chickens per day. The owner purchased chickens from the Jatrabari whole sale market in Dhaka. One day during the first three weeks in January he recalled that three of the chickens that he purchased died on the same day. This was quite an unusual event. Poultry wholesalers at the Jatrabari whole sale poultry market report purchasing their poultry mostly from Savar, Gazipur, Norshingdi, Munshigonj, Brahmanbaria, and Commilla outside Dhaka. During January they recalled that deaths among poultry in cages occurred commonly averaging among 5 – 10% of chickens each day. Fifty outbreaks of H5N1 were confirmed in Bangladesh in January.

The mother also reported that the child ate a soft boiled egg each day in January. None of the child’s family members reported illness during the time that the index child was ill nor in the following two weeks.

Reported by:
Institute for Epidemiology Disease Control and Research (IEDCR), Ministry of Health and Family Welfare, Government of the People’s Republic of Bangladesh

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