In response to report of an episode of an unknown disease in human beings & goats of Gombli village, in Thiruvellure district of Tamil Nadu, a team from NICD carried out the epidemiological investigation during the period 23rd - 27th March 2002. The objectives of the team were to find out the cause of disease, its source, probable mode of spread and to suggest suitable preventive and control measures for further spread of disease. The salient observations of the team were as follows:

1. A total of 8 human cases with two deaths were reported within a period of six weeks i.e. 1-02-02 to 14-03-2. All these cases were male in the age range 17-55. The duration of illness varied from 12 hours to 32 days. AThemajority of cases presented with neurological manifestations varying from mild tingling & numbness to weakness of limbs. The weakness of limbs was ascending, progressive & flaccid type. Few cases had sensory disturbances below D8/D10 level. The fever was also found in 60% of the cases. The bladder and bowel dysfunction was also noted in some of the cases. The peripheral nerves conduction studies were also normal. The CSF findings showed increase in protein & cells. The possibility of intoxication due to contaminated alcohol consumption, adultration in cooking medium, contaminated drinking water, use of insecticides and pesticides was ruled out by case investigation.

   
   

2. Earlier an outbreak of unknown disease in goats was also reported between 3rd January to 14thMarch  2002 in the same village. During the outbreak about 200 goats had died during the prograssive stage of illness. The predominant symptoms found in the goats included salivation, discharge from nostrils & weekness of limbs. The duration of illness in goats was 4-5 days. The mortality in the diseased goats was hundred percent and over mortality of 20% was observed among the total goat population of the village. The surrounding villages did not report any unusual increase in orbidity and mortality among goats.

   
   

3. The team observed that all the human cases occured within a radius of 150 meters. The spot mapping indicated that human cases were located near the houses where deaths of goat took place. The outbreak of deaths in goats was observed during the 3rd week of February & peak of human cases was noted in the first & second week of March 2002.

   
   

4. The etiology of human cases & cause of mortality in goats, the presence of similar symptoms of weakness of limbs in the goats & humans indicate the possibility of common Neurotropic viral aetiology. The focal distribution of human cases & deaths in goats points towards the involvement of vector/direct contact.

   
   

5. The team collected six paired sera samples, and four stool samples frm six cases. Twenty-three  serun samples have been collected from the control population of the village. One serum serum sample of diseased animal, eight sera samples from healthy animals and one postmortem specimen of brain tissue were also collected from laboratory analysis.

   
   

6. The clinical & epidemiological evidence together indiacte the possibility of unknown disease as an acute infective encephalomyelitis of viral origin.