Identifying Active Foci of Malaria Tansmission

Elimination of malaria will need a tool to accurately point to the specific foci of active transmission. This will focus the intervention into the right location where it is needed. We can imagine high incidence of malaria as overlapping foci of malaria. Each foci has all the elements needed for the parasite to continue its cycle of life. This will need susceptible hosts, mosquito vector and human plasmodium species. Natural malaria transmission will not occur in the absence of one. The initial guide for the malaria worker to point out the foci of malaria transmission is the stratification of area as to non endemic and endemic areas. The size of these areas has to be within the flight range of the vector mosquito or within the smallest political unit possible. The next step is to classify the malaria cases in these areas as to he source i.e. indigenous or imported. After knowing the areas with indigenous cases, review the cases of that area in the past three months. Areas with the case/cases in the past three months are the foci with active transmission.

This method utilizes the incubation interval information of the parasite.
Incubation interval is the period from the gametocyte stage in one victim to the earliest appearance of gametocyte in the secondary victim. It is in the range of 25 to 35 days (pp.83,Malaria Elimination A field manual for low and moderate endemic countries, WHO, 2007). Once the foci of active transmission is pinpointed all locations of the parasite has to be attacked. These locations are in the blood at the clinical stage, in the liver at the hypnozoite stage, in the mosquito vector, in asymptomatic carrier, and in the liver at the pre-patent stage. These locations has to be addressed within the month. Unless all of these locations are addressed the parasite will be able to continue its life cycle refilling all the its former locations and transmission resumes. (This is related to the article written earlier with the title "Malaria Transmission Scoring System")

Malaria Control Sulu Experience

Sulu is a province in Mindanao, Philippines composed of islands. They are inhabited by several groups of indigenous populations mainly Tausug. Malaria in Sulu is classified as coastal malaria and the vector is Anopheles litorralis. It breeds in brackish water in areas covered by mangroves. There is no forest malaria in Sulu. Malaria control in Sulu is complicated by the distance between the islands and there is no regular transport in many of them. The main problem of malaria control in this area is logistics management as well as transport of malaria control personnel. Malaria in Sulu has been lowered significantly because of improve availability of logistics and currently the cases are in near elimination level. To eliminate malaria in the area careful logistics management as well as careful analysis of the need to deploy malaria personnel is the most critical decision. It has to be carefully planned in order to address the location of the parasite in the five locations as mentioned in the previous discussion.
Information dissemination is the most important at this stage. Every person has to be told that they need to be prevented from mosquito bite to prevent malaria. This message has to be in strategic location i.e areas where most of the population visit which is usually market places, piers and boats. This has to be complemented by the availability of diagnostic and treatment facilities located strategically.
Data form these diagnostic facilities has to be reviewed frequently in order to guide the deployment of malaria control personnel who will conduct indoor residual spraying and case finding activities either active case detection and bimonthly visit or by mass blood survey whichever is needed by the area. Malaria control or elimination in Sulu and other island provinces needs careful planning and sound management of implementation.

Malaria Problem of Sulu and Tawi Tawi Islands

Sulu and Tawi Tawi are island provinces in the southern Philippines. Both have island municipalities and barangays. Malaria in these provinces are classified as coastal malaria. They are transmitted by Anopheles litoralis mosquiotes. This mosquito breeds in coastal mangrove areas. They are early biters.
Most of the people live in the coastal areas. Houses are constructed on stilts along the shores. Motorized bancas are the usual mode of transportation. People here belong to the indigenous population groups of either Tausug, Samal and Badjao.
Malaria control in this group of island is faced by several problems. Foremost is the distance between the islands aggravated by peace and order problems in many islands. Another problem is the behavior of the vector i.e. peak biting density. The vector in the area is early biter hence mosquito net is quite inappropriate. This situation require extra effort in terms of program management particularly logistics and monitoring and evaluation. Please wait for the next issue.