February 20, 2002

'31'

        A local outbreak of a virulent, highly contagious fabrile illness, with pre-dominant chest symptoms, occurred in village Hat Koti, District Shimla, Himachal Pradesh, in the first week of February 2002. These cases presented with fever of rapid onset, chills, chest pain breathlessness, headache, prostration and haemoptysis. The local clinicians and the State nodal officer for Nation Surveillance Programme for Communicable Diseases (NSPCD), informed the Director, National Institute of Communicable Disease (NICD), Delhi on February 13, 2002 about the seriousness of this suspected outbreak. A total of 16 cases of such illness have been reported since the first case on February 4, 2002. Four of the infected persons have died till date; and, the remaining 12 patients under treatment are in a stable condition- five are under treatment at Civil Hospital, Rohru; and six are under treatment at PGIMER, Chandigarh; and one is under treatment at the Indira Gandhi Medical Institute, Shimla.

        Immediately, on receipt of information of this outbreak from the State health authorities, a team consisting of an Epidemiologist, a Microbiologist and an Entomologist from the NICD proceeded to the affected area on the morning of February 14, 2002. Simultaneously, the emergency medical requirements of the State were promptly met. This team visited the affected area of Shimla district between February 14 and 17, 2002, examined the patients in the hospitals where they were being treated, and held consultations with the doctors attending upon these patients. In the course of their visit, the team observed that all the cases of illness could be linked to residents of village Hat Koti, consisting of three houses. All the persons who were taken ill were relatives of first case detected, and had come into contact with the first reported patient. It was also observed by the NICD team that the first case reported had been on an extended hunting trip to the forests from January 21 and had taken ill immediately after his return to his village on February 2, 2002. The patient samples obtained from PGI, Chandigarh were brought back to Delhi on February 15, 2002 and were examined by the investigators of NICD.

        Culture isolates from two suspected cases; sputum specimens from two cases, lung autopsy from one case and one lung lavage material were examined in the laboratories of NICD. The stage-wise investigations reveal as under:

• Smear examination showed bipolar, short thin bacilli morphologically resembling Yersinia Pestis;
• Fluorescent antibody test was found positive for Yersinia Pestis;
• Molecular tests confirmed the presence of Yersinia Pestis specific Pla and F1 genes;
• The DNA fingerprint had identity with a known sequence of plague bacilli; and
• Bacteriophage lysis test for Yersinia Pestis was positive.

        The sequence of tests collectively confirmed that the cases were related to infection with Yersinia Pestis, commonly known as Pneumonic Plague. This conclusion is also supported by other clinical and epidemiological evidence. The procedure for identification and confirmation of the pathogen was in full conformity with the guidelines set out by the World Health Organisation for this exercise.

        The NICD team, which had gone to Himachal Pradesh to investigate the suspected outbreak, issued detailed guidelines to the local health administration for containing the spread of infection. The significant components of these guidelines were:

• Quarantine of the affected village.
• Chemoprophylaxis (using Doxycycline/Tetracycline/ Broad Spectrum antibiotics) administered to the close contacts of the patients, residents of the affected and neighbouring village and to doctors/paramedics and health workers (numbering about 7000 to 8000).
• Formalin (10%) fumigation in the affected villages, as well as in transport vehicles.
• IEC campaign for reassuring the general public not to panic, and also advise them to immediately report to health facilities in case there was fever, cough, etc.
• Door- to- door interaction with the population in the affected and adjoining village for dispensing antibiotics, obtaining information about the new cases and educating the people.

        Guidelines, as above, have also been issued to the Government of Uttaranchal, as one of the patients, who was a resident of that State, had acquired the infection on a visit to Hat Koti.

        All the persons taken ill, except one, have been from the hamlet in Hat Koti village where the first case occurred. The single exception is of a relative from Uttaranchal who contacted the infection while on a visit to the hamlet of Hat Koti. The last reported case is of February 8, 2002. The incubation period for plague bacteria being a maximum of 7 days, it is the considered assessment of the Public Health Experts of NICD, that the infection has been successfully confined to the area of its origin. However, the Public Health administration of Himachal Pradesh has been advised to maintain vigil, not only in the neighbouring areas the reported infection, but also in the State as a whole.