Confirm the diagnosis, interview the case patient and visit the patient’s home
The case patient and/or family members (if the patient is too ill to be interviewed or has died), should be interviewed within the first 24–48 hours of the investigation to collect basic demographic, clinical, and epidemiological information. First, the date of the case patient’s illness onset needs to be ascertained. Exposures to potential sources of A(H5N1) in the 7 days before illness onset2 should then be sought. If the diagnosis of A(H5N1) infection has not been confirmed, collection and testing of appropriate clinical samples from the case patients(s) is an immediate priority (see section 4).
Information that is essential for local and national authorities to manage the investigation should be collected including:
• Patient ID number/cluster number (if applicable)
• Date of illness onset
• Date of initial report
• Date of initial WHO notification
• Patient details (e.g. name, home address, home/mobile telephone numbers)
• Demographic information (e.g. date of birth/age, sex)
• Travel history in 7 days before the onset of symptoms
• Occupation (note if health-care worker or laboratory worker)
• H5 laboratory diagnosis
− date of sampling
− name of national laboratory: type of test, type of sample
− name of WHO reference laboratory (if applicable): type of test, type of sample
− test results
• Contact with confirmed or suspect human H5 cases in the 7 days before symptom onset
− relationship with contact (first/last date of contact)
− type of contact (speaking distance, slept in same room, touched, provided bedside care, other)
• Exposure history to animals (chickens and other animals) and their environment in the 7 days before symptom onset
− setting (e.g. farm, backyard, household, visit of live/wet market, hunting, traditional medicine, other)
− type of animal exposure (e.g. de-feathered, slaughtered, butchered, prepared, cleaned cages, shared living space, handled/used droppings as fertilizers, handled, played with, other)
− occupational exposure to animal and/or animal products (e.g. slaughterer, farm worker, factory worker, poultry seller, veterinarian, culler, laboratory worker)
− consumption of raw or undercooked animal products (e.g. meat, eggs, blood, liver)
− H5N1 outbreak in animals in the area
− first/last date of contact
• Clinical data
− symptoms on day of onset
− days of illness before initial presentation
− symptoms at initial presentation
− illness onset during antiviral prophylaxis
− hospitalization, including first date of admission and duration
− pre-existing conditions
• Laboratory data
− white blood cell count and differential
− haemoglobin/platelets
− Aspartate amino transferase (AST) /Amino alanine transferase (ALT) and creatinine
− chest radiograph results
• Antiviral treatment
• Other treatment (e.g. oxygen, intubation, antibiotics, steroids)
• Secondary complications (e.g. bacteraemia, bacterial pneumonia, shock, renal failure, coagulopathy)
• Outcome (dead/alive).
It is important that investigators obtain and verify first-hand as much information as possible. This usually includes visiting the case patient’s home during which a number of key actions should be undertaken:
• Confirm the family/household composition and identify contacts of the case patient (see section 3) including:
− Household and other contacts in work, school, and community settings who had close3 unprotected (i.e., not wearing PPE) contact in the 1 day before4 through 14 days5 after the case patient’s symptom onset
− Contacts in traditional and non-traditional in- and out-patient health-care settings before initiation of appropriate infection control measures.
• Inquire about possible bird/animal exposures for the case patient in the 7 days before illness onset including exposure6 to ill or dead poultry, wild birds, contaminated environments (e.g. exposure to poultry droppings including fertilizers or contaminated sewage, bathing in ponds/canals where domestic or wild birds can be found, etc.), and other animals regardless of their clinical status, especially those that may have consumed dead poultry (e.g. cats, dogs, and civets).
• Inquire about illness or deaths in birds, cats, swine, or other animals in the household and neighbouring area.
• Examine the house and its surroundings for evidence of domestic poultry (e.g. feathers, scratch marks on the floor or furniture, bird droppings, cages, poultry bones/carcasses). Note if poultry and other animals were allowed to enter the house, had access to household water and food storage areas, and if persons, especially children, were exposed to poultry or interior or exterior environmental surfaces potentially contaminated by poultry.
• Map or photograph the house and its surroundings. Indicate its location with respect to homes of other relatives or neighbours, farms (backyard and commercial), markets and nearby bodies of water that birds could inhabit.
• Collect animal and/or environmental samples and map/note locations (see section 7).
The use of PPE by investigators during home visits should be guided by the overarching priority to protect the health of investigators. Decisions can be guided by the health status of household members (e.g. asymptomatic versus actively coughing) and activities that are undertaken (e.g. collection of human or animal specimens). Investigators may elect to interview persons outdoors and not in a closed interior setting, avoid direct face-to-face contact, etc. Appropriate PPE should be worn when in contact with symptomatic persons and in situations where humanto-human transmission is suspected (6,7).