Akhtar Ahmed ( Department of Neurology, Dow Medical College and Civil Hospital, Karachi. )
Encephalitis is a common health hazard in this country. This is apparent to all clinicians dealing with adult and paediatric patients. Cases of cerebral palsy, mental retardation and epilepsy are often labelled post encephalitic. The report of the working group on the prevention and control of Japanese encephalitis that met in Tokyo, Japan in December 19831 in which members from 6 countries of South East Asia participated notes that Japanese encephalitis is a public health problem of increasing concern to the countries of South East Asia and the Western Pacific regions because of the occurrance of thousands of cases over the past decade with a high case fatality rate and expansion into new areas. Over 10,000 cases have been recorded in 1982, in Peoples Republic of China. In Republic of Korea an epidemic occurred in 1982, despite 80 per cent vaccine coverage in school children. In India Japanese encephalitis has been focally endemic in Karnataka and Andhra Perdesh states for decades. In 1978, Japanese encephalitis was recognised for the first time in Bthar and West Bengal. The annual occurrence of cases is estimated at 3000 to 4000. In Nepal Japanese encephalitis has been recognized as a new and major disease entity in the planes of southern Nepal. The working group recommended that encephalitis patients should be reported in each country. Unfortunately the extent of the problem is not generally recognized, and is the subject of personal conjecture and impressions gained from clinical practice. There is near total absence of access to facilities for diagnosis of virus encephalitis either by antibody estimations or by culture. Researchers at the National Institute of Health in Islamabad have been engaged in carrying out virus surveys and antibody estimations in patients but the extent and the nature of the problem of virus encephalitis still remains largely undefined in Pakistan. This issue contains 2-6 papers pertaining to various aspects of viral encephalitis. Some significant features appear to have emerged amongst the acute encephalitides reported by Takasu et al3. Thirty cases of acute encephalitis ar& documented. Of them 5 are probable Japanese encephalitis and 7 cases of herpes simplex encephalitis, however 2 of them had a sub acute course. Thus 12 of the 18 cases belong to one of these two groups. This is a fairly suggestive pattern. Clinicians would welcome this information. Cases diagnosed as sub acute scierosing pan encephalitis as reported by Ahmed in 19807 and cases since diagnosed by the same criteria all appear to have been serologically confirmed in this series. The paper by Kondo et al3 documents a very high incidence of cases of sub acute sclerosing pan encephalitis in Karachi. It is interesting to speculate about the cause of this high incidence which may be a reflection of prevalence of measles or contributed to perhaps by nutritional status. Their follow up case control study should be able to throw more light on this subject. Nakae et al4 have demonstrated a very high incidence of inflamatory disorders of the brain as reflected in mortality rates in Karachi. Incidently the table on mortality rates makes interesting reading. The seroepidemiological investigation by Sugamata et al6 of the patients and healthy volunteers has shown some interesting and some alarming data. The prevalence of antibody titres against arboviruses and including antibodies against Japanese encephalities virus is being reported for the first time in this country. The prevalence rates against herpes simplex and measles viruses which are spread by contact and droplet infection are alarming and reflect upon the poor public health situation. The report on the mosquitoe survey is again most interesting. The vector for Japanese encephalitis virus has been isolated from 5 spots in Karachi by Kamirnura et al5 Until now this vector was not generally recognized to exist in this part. Pigs are generally recognized to be the most important reservoirs for this virus and in their absence one wonders where the vector picks up the virus.
Many of the findings are new, while some of the findings had been suspected by doctors and workers in the field but together their documentation has for the first time defined the situation of virus encephalitis in and around Karachi.
1. Report of WHO Working Group on prevention and control of Japanese Encephalitis. Manila, WHO, 1984, p.1.
2. Takasu, T., Ahmed, A., Kono, R., Kondo, K., Sugamata, M., Chida, K. and Kamel, S. Neuroviro logical researches of encephalitis in and around Karachi; the clinical aspects. JPMA.,1986;36:159.
3. Kondo, K., Ahmed, A. and Takasu, T. Epidemiology of subacute scierosing pan encepha litis (SSPE) and other encephalitides in Karachi area; a progress note. JPMA., 1986; 36:169.
4. Nakae, K., Kondo, K., Takasu, T., Kamei, S. and Ahmed, A. Estimated mortality rate by sex-age and death causes in Karachi. JPMA., 1986: 36: 174.
5. Kamunura, K., Takasu, T., Ahmed, A. and Ahmed, A. A survey of Mosquitoes in Karachi area Pakistan. JPMA., 1986; 36:182.
6. Sugamata, M., Khano, R., Ahmed, A., and Takasu, T. Sero-Epidemiological research on viral encephalitis in Karachi, Pakistan-Preliminary report. JPMA., 1986; 36: 177.
7. Ahmed, A. Subacute Scierosing Pan-Encephalitis-A report of seven cases. JPMA., 1980; 30:249.