Promotion of insecticide-treated mosquito nets in Myanmar.

A simple health promotion message administered by village midwives raised bednet usage to over 60% in trial hamlets in north Shan State, Myanmar. Treatment of the nets in the study villages produced a reduction in malaria cases. Most villagers were prepared to buy their nets at market prices and were willing to pay for the cost of re-treatment of nets, but very poor, members of the Wa ethnic group required a half-price subsidy for them to afford them. The use of insecticide treated bednets was felt to be appropriate for undeveloped and remote areas of the country where malaria control was difficult.

Entomological and epidemiological investigations of malaria transmission in relation to population movements in forest areas of north-west Thailand.

Transmission of forest-related malaria was observed entomologically and epidemiologically for 2 transmission seasons in 1990 and 1991 in 5 villages of Mae Sariang district, Mae Hong Son Province, north-west Thailand. The entomological study included collections of mosquitos and determination of infection rate by using enzyme-linked immunosorbent assay in the residential villages and the farm huts. The epidemiological study included fortnightly visits to 30% of the households to interview and record movement activities and illness of villagers. Circumsporozoite proteins, in most cases of Plasmodium falciparum, were detected in Anopheles minimus species A, An. dirus s.l., An. maculatus s.s. and An. sawadwongporni in residential villages and/or farm huts, suggesting transmission could occur there. Movement of people away from their residences occurred throughout the year for several reasons with a sharp peak in July for agricultural activity, mainly ploughing and planting for rice cultivation. The relative risk of infection for people engaged in agricultural activity was 3 times that of people living in the residential villages. Although a higher biting density of vectors was generally evident at the farm huts, the estimated inoculation rates in the 2 settings were similar. Movement for forest activity increased after harvesting rice in the cool dry season and carried the highest malaria risk, suggesting different epidemiological and probably entomological conditions which need further investigation. The significance is discussed of discrepancies between the case classification system used by this study and that used by malaria sector staff.

The economic impact of Plasmodium falciparum malaria on education investment: a Pacific Island case study.

A small but intensive study was carried out adopting a simple method which attempts to quantify the economic consequences Plasmodium falciparum malaria on education investment through school pupil absenteeism in a community in Solomon Islands. In a randomized sample of 4,920 cases of P. falciparum malaria in a community, 2,886 occurred in children of primary school age group of 7 to 13 years. On average a case gave rise to a mean school absenteeism of 5.3 days. In the final analysis a total of 11,028 pupil days schooling were lost due to the sampled cases of malaria caused by the species. This is equivalent to 55.14 school pupil years as a child is expected to attend school for 200 days in a year. A primary school teacher with an average annual salary of US$3,990.00 is expected to teach 6,500 school pupil days a year. When this is adopted as an economic indicator for investment in education the loss is calculated to be US$6,769.57 or equivalent to US$1.38 per case. When this is applied nationally, assuming that rates are similar for 79,203 cases of P. falciparum reported in 1990, the total consequence for investment in education is US$108,966.00, which is equivalent to 27.31 teachers being paid for not teaching, an unacceptable impact for a small nation like the Solomon Islands.

Theoretical considerations in the vector control of filariasis.

In order to assist in assessing progress of vector control of filariasis a theoretical model is constructed, using retrospective data on infected persons removed to a vector-free situation. This shows that the decrease of microfilaraemia is not regular, but is gradual for the first 3 years and then more rapid, reaching zero at about 10 years. An estimate is made of the level to which the vector must be reduced before transmission of filariasis ceases, showing that the degree of efficiency required is considerably less than for malaria.

Vector control of filariasis in the Solomon Islands.

In Solomon Islands, filariasis is caused by the nocturnally perodic form of Wuchereria bancrofti and is transmitted by the same vectors of malaria. This study explores the control of this disease as an additional effect of the Malaria Eradication Programme.