H5N1 Bird flu (avian flu) did kill some family members in Peshawar, north-west Pakistan last year, the World Health Organization (WHO) has confirmed after carrying out tests at its WHO H5 Reference Laboratory in Cairo, Egypt, and the WHO Collaborating Centre for Reference and Research on Influenza in Atlanta, USA.

Last year the north-west and southern areas of Pakistan were hit by bird flu. Tens of thousands of birds were destroyed in an attempt to stem the spread of the disease. Last Thursday WHO confirmed that people had died as a result of bird flu infection.

However, according to WHO “The preliminary risk assessment found no evidence of sustained or community human to human transmission.” In other words, the infection did not extend into the community.

In an interview with the BBC, Mukhtiar Zaman Afridi, Head of Isolation Ward, Khyber Teaching Hospital, Peshawar, where the patients were being treated, said that an infected poultry worker seems to have passed the infection on to relatives. The patient then made a full recovery. Unfortunately, his brother became infected and later died. Two more brothers became infected, one of whom died while the other made a full recovery. As only the first infected person had had contact with sick/dead birds, the others must have got the bird flu from him or each other.

Here are the results of the four cases of the family cluster in Peshawar

Case 1 (Index case, first infected person)
Onset date – 29 Oct 07
Outcome – Fully recovered
Exposure – Direct contact with sick/dead birds
Status – Confirmed (serology)

Case 2 (brother)
Onset date – 12 Nov 07
Outcome – Dead (19 Nov 07)
Exposure – Close contact with Case 1, no known contact with sick/dead birds
Status – Probably (no sample available)

Case 3 (brother)
Onset date – 21 Nov 07
Outcome – Dead (28 Nov 07)
Exposure – Close contact with Case 1&2, no known contact with sick/dead birds)
Status – Confirmed (PCR)

Case 4 (brother)
Onset date – 21 Nov 07
Outcome – Fully recovered
Exposure – Close contact with Case 1&2, no known contact with sick/dead birds
Status – Confirmed (serology)

*Serology – the technique of determining antigens or antibodies in serum

What is Bird Flu (Avian Influenza)

Bird flu (avian influenza) is a disease cause by viruses. It is a contagious disease which infects only birds, and occasionally pigs. The avian influenza viruses attack specific species – they have sometimes jumped the species barrier and infected people. However, this has been extremely rare, and continues to be rare.

As far as farmed birds are concerned (poultry), there are two main types of avian influenza – one is fairly mild while the other is deadly (for birds).

Mild

Low pathogenic forms of bird flu may cause a bird to have more ruffled feathers and lay fewer eggs. This form is often undetected among farmed poultry (in many cases the bird is infected, and then gets better and nobody noticed).

Deadly (H5N1)

The highly pathogenic form of bird flu is much more dangerous. It has a mortality rate of virtually 100% and spreads very rapidly among flocks of birds. A bird infected with the more virulent type of bird flu (the highly pathogenic form) experiences deterioration of many internal organs.

Written by – Christian Nordqvist