The greater Manila dengue hemorrhagic fever epidemic of 1966

In a study of 408 clinically-diagnosed cases of hemorrhagic fever, from the 1966 Greater Manila epidemic, the largest on record in the Philippines, 217 were confirmed as dengue infections, and 54 strains of dengue virus of three types were recovered. The disease afffected mostly children aged 5 to 14 years, but adults were also significantly involved. Distribution was largely central-urban and outer-urban, with fewer cases in rural areas. Correlation of data for incidence and distribution of positive cases and strains of dengue virus isolated indicated that the epidemic extended from May to October, peaked in July and August, and was caused by dengue type 3. Dengue types 2 and 4 appeared to maintain a low endemic level throughout the period of study. There was no evidence that dengue type 1 or other arboviruses were involved. All cases of hemorrhagic fever with shock, except possibly two, had secondary antibody responses, but no other correlation of antibody response to severity of disease could be made.(Summary)

Dengue hemorrhagic fever in Malaysia: the 1973 epidemic.

The first major Malaysian epidemic of dengue hemorrhagic fever with severe manifestations occurred in 1973, with 969 reported cases and 54 deaths. In a detailed study of 138 clinically diagnosed and laboratory confirmed cases at the General Hospital in Kuala Lumpur, hemorrhagic manifestations were observed in 68.7% and shock in 18.1% of the patients. The cases occurred mainly from May to September, largely in urban and suburban areas of the majority of the states in the country. A main focus of infection was Jinjang, a heavily populated outlying district of Kuala Lumpur, where unusually high incidences of morbidity, severe disease and mortality were seen. Severe disease was seen mostly in children under the age of 15 years, although a significant number of adults suffered milder illnesses. The Chinese population was chiefly affected, due to their living in crowded, low-income housing where the vector, Aedes aegypti, occurred in the greatest numbers. All four dengue types were recovered during the epidemic period, although dengue 3 (DEN-3) was incriminated as the major epidemic type. Entomological data revealed high indices of A. aegypti throughout the country and left little doubt that this epidemic was aegypti transmitted. Spraying and fogging operations were carried out in attempts to control vector populations.

Alphaviruses in Peninsular Malaysia: II. Serological evidence of human infection.

A serum survey of several characteristic groups of humans in urban, rural, and forested areas of Peninsular Malaysia for evidence of infection with three alphaviruses (Sindbis, getah, and chikungunya) was made on 4384 specimens collected between 1965 and 1969. Analysis of the serological results indicated that 1) persons residing in predominantly rural and forested areas have higher frequencies of specific alphavirus antibody of all three viruses than persons residing in urban areas, 2) human infection with chikungunya virus appears to be at a low level of activity but is widespread, although more common and recent in the northern part of the country, and 3) Sindbis and getah viruses probably do not represent a threat to the public health, but chikungunya virus remains a potential menance and may be responsible for future epidemics transmitted by A. aegypti and A. albopictus mosquitoes.

Alphaviruses in Peninusular Malaysia: I. Virus isolations and animal serology.

A survey of the activity of three alphaviruses (Sindbis, getah and chikungunya) in Peninsular Malaysia was conducted between 1962 and 1970. Serum samples were examined from 3,917 vertebrates representing a wide variety of wild and domestic animals throughout the peninsula for hemagglutination-inhibiting and neutralizing antibodies. A total of 548,939 mosquitoes were collected from different habitats, including jungle, rural, suburban and urban areas, and the majority of the females taken were examined for the presence of virus. Two strains of Sindbis virus and one strain of getah virus were isolated from pools of Culex mosquitoes collected in and around domestic animal shelters. Analysis of the serological results indicated that, 1) getah virus is associated principally with large domestic animals, particularly swine, 2) Sindbis virus is associated with large domestic animals and birds, especially domestic ducks, and 3) chikungunya virus, which has not yet been isolated in Malaysia, appeared to be present at a very low level of activity, probably with wild monkeys as the vertebrate hosts.