In Kerala, malaria had been eradicated as early as in 1965

Environmental Factors of Malaria Persistence:
A study at Valiyathura, Thiruvananthapuram city (Abstract)

S. Rema Devi, S. Dass*

In Kerala, malaria had been eradicated as early as in 1965. But imported malaria used to occur even thereafter; and indigenous malaria showed signs of resurgence from 1969 onwards. Recently an increasing trend of both imported and indigenous malaria cases were observed. Malaria began to occur in epidemic proportions in the coastal areas of Thiruvananthapuram city since 1994, an area which had till then been a non-endemic area for this disease.Moreover, the disease persisted in the area during 1995 and 1996 despite control measures implemented by the health care personnel of the State Government. The present study was carried out in Valiyathura to explore the environmental factors influencing the persistence of malaria in this coastal area.

A cross-sectional survey was conducted covering 300 households in 11 sectors (out of a total of 24 sectors) in Valiyathura area during 1997 identified as high-risk area by the Health Services Department. An equal number of houses were drawn as control from the adjoining Poonthura ward of Thiruvananthapuram Corporation, which was non-endemic to malaria. A systematic random sampling technique was followed in the selection of households. The tools for data collection were a pre-tested interview schedule and qualitative methods like focus group discussion and open-ended interviews. The period of study was from January to December in 1997.

The background characteristics of Valiyathura and Poonthura areas are similar. Both are coastal areas lying adjacent with similar distributions of religion, family size, and family type. The majority of the adult population in both the areas is engaged in fishing. But sharp contrast exists between them in the prevalence of malaria. The prevalence of malaria cases observed in the study area during a recall period of three months, was 6.3 per cent and the corresponding figure for the control area was only 0.17 per cent.

Climatological factors are common to both the areas and hence they do not explain the difference in the prevalence of malaria between the two areas. Prevalence of malaria was found higher in the study in which housing conditions were poor in the majority of households (54.7 per cent Vs 35.3 per cent). Presence of a significantly large number of wells in the study area indicates higher risk of malaria. Socio-economic background reported frequently as a risk factor for malaria is found to have little significance in this area. Habit of sleeping outdoors during night and transmigration of working population to endemic areas outside the State might have increased the risk of malaria, but the relationship observed between the two is weak and insignificant.

Regarding the use of personal protective measures, no significant difference was noticed between the study area and control area. The study revealed fairly high levels of community awareness regarding malaria among the study population, more in the study area than in the control area. This could have been due to the increased exposure of the residents of the study area to IEC activities.

It was found that certain flaws in the formulation and implementation of the strategy for controlling malaria and the indifferent attitudes of the local population had contributed to the ineffectiveness of the interventions of the Health Department till about the end of 1996. The new strategy, which is being implemented as an integrated parasitic and vector control measures in a systematic manner since 1997 has proved effective. The attitude of the entire local population towards treatment and control of malaria has changed from one of apathy to that of extreme compliance and co-operation.

The present study points out certain important environmental factors, which influenced the persistence of the disease in the study area. The current rigorous control activities have successfully interrupted the transmission of disease and brought down the number of malaria cases drastically. But these rigorous measures are more like treating symptoms than curing disease. While it is essential to continue the activities as a short-term measure, preventive strategy should be developed and executed on a long-term basis to eradicate the factors.

Recommendations

In the light of the present study, we put forward the following recommendations.

(i) The large number of wells in the study area has been identified as a potential breeding ground and resting-place for Anophels stephensi, the vector mosquito responsible for malaria in this urban area. The wells, together with the poor housing conditions in the area, are responsible for the high density of vectors for effective transmission. Since it is not feasible to modify the housing conditions in the area given their living conditions and occupational patterns, the alternative is to provide protected pipe water supply and fill up the wells in the area. This could be achieved in a phased manner. This is justifiable as an eco-friendly vector control method since DDT and BHC are reported to be environmental pollutants.

(ii) There is regular import of vectors from cities like Mumbai, Delhi, and Chennai through aircraft landing at Thiruvananthapuram Airport, as evidenced by the larval collections in and around the airport. Moreover, transmigration of fisherfolk leads to continuous import of parasite from endemic areas. Hence the existing surveillance system should be continued as any lapse in the present system may lead to focal outbreaks of malaria as it did in previous years.

(iii) Alternative strategies like having a basic health infrastructure on the lines of the primary health centres in rural areas should be thought of in the underprivileged urban areas since the present set-up for surveillance and control could not be continued indefinitely. It should be possible to integrate the existing system of surveillance, detection, and treatment of malaria with the proposed system.

(iv) The community should be made aware of the possibility of contracting infection during episodes of transmigration and of the need to report to the health facility in case of any history of fever surfacing again.

(v) The airport health authorities should take stringent measures to disinsectise both incoming and outgoing aircrafts and cargo.

* S. Rema Devi is Associate Professor at Department of Community Medicine, Medical College, Thiruvananthapuram. S. Dass is Reader at Department of Community Medicine, Academy of Medical Sciences, Pariyaram, Kannur.