1. Malaria Control By Kim Harbal and Tashi Sherpa

2. Ways to Control Malaria? Definitive Host Intermediate Hosts Hosts

3. DEFINITIVE HOST The definitive host is the female Anopheles mosquito The definitive host is the female Anopheles mosquito There are approximately 400 species of Anopheles, but only 30-40 transmit malaria There are approximately 400 species of Anopheles, but only 30-40 transmit malaria Once mosquito’s contract Plasmodium, they are infective for life Once mosquito’s contract Plasmodium, they are infective for life They also are stimulated to feed more frequently, thus increasing the chance of transmission They also are stimulated to feed more frequently, thus increasing the chance of transmission There are three ways to prevent the Anopheles from spreading Malaria There are three ways to prevent the Anopheles from spreading Malaria – Prevent breeding – Prevent entry and bites – Modifying populations of Anopheles

4. Breeding Prevention Basic facts Basic facts – Females lay 50-200 eggs at a time in water – From egg to adult it takes anywhere from 5-14 days Destroying larval habitats is vital to their control Destroying larval habitats is vital to their control – Anywhere there is standing water such as swamps, marshes, barrels, cans, and even rain pools For some species, habitat elimination is For some species, habitat elimination is not possible so there are chemical alternatives – Suffocating larvae and pupae by applying oils on the water surfaces – Applying toxins from the bacterium Bacillus thuringiensis – Using methroprene, a substance that inhibits insect growth – The fish, Gambusia affinis, which can control the larval populations Source reduction is very difficult because larval habitats can be very small and widely dispersed Source reduction is very difficult because larval habitats can be very small and widely dispersed

5. Preventing Entry and Bites Insecticide treated bed nets (ITN) Insecticide treated bed nets (ITN) – Untreated nets are not recommended because mosquitoes may pass through the net during the night and feed on the host – It has been found that ITNs greatly enhance protection from mosquitoes because they either kill or repel them – If a majority of the community uses ITNs then the numbers and longevity of mosquitoes will be reduced – ITNs lead to a 19% reduction in child mortality and 40-60% reduction in infection according to the CDC – However, due to cost many families can not afford one

6. Indoor Residual Spraying Indoor Residual Spraying – This involves coating the walls and other surfaces of the house with a residual insecticide – These insecticides last several months and when mosquitoes come in contact with the surface they will hopefully be killed – This prevents the transmission of the infection – IRS with DDT is the cheapest and most effective form of control – “DDT and effective medications have reduced South Africa’s annual malaria death toll from 458 in 2000 to 89 in 2006,” according to the American Chemical Society

7. – However, DDT has many setbacks; it can accumulate in humans and other mammals, has higher concentrations as it goes up the food chain, pollutant, has high toxicity (especially to aquatic life), has been banned by many countries, and could be used on crops – Africans are afraid of using it because of the fear of the European Union ceasing food exports – There are many other insecticides that might be used as substitutes for DDT, but they are not as cheap and do not last as long – Insecticides are very useful in the control of malaria, but many mosquitoes have shown resistance to more benign insecticides; even DDT has shown resistance from some species

8. Modifying Populations of Anopheles Sterile insect technique Sterile insect technique – Method of biological control, whereby millions of sterile Anopheles mosquitoes are released – The released insects are normally males because these males can compete with wild males for the female – If a sterile male mates with a female there will be no offspring – This could help reduce the number of mosquitoes in each generation Genetic modification Genetic modification – Develop mosquitoes that are Plasmodium-resistant

9. INTERMEDIATE HOST The intermediate host is primarily humans, but can also include other mammals The intermediate host is primarily humans, but can also include other mammals There are several ways to protect or treat humans There are several ways to protect or treat humans – Protecting the unaffected – Treating the affected – Vaccines ?

10. Protecting the Unaffected Important protective measures include the use of window screens, ITNs, repellents, and wearing long pants and long- sleeved shirts. Important protective measures include the use of window screens, ITNs, repellents, and wearing long pants and long- sleeved shirts. Travelers and high risk individuals should be started on chemoprophylaxis, which involves taking antimalarial drugs every week to suppress malaria Travelers and high risk individuals should be started on chemoprophylaxis, which involves taking antimalarial drugs every week to suppress malaria Using antimalarial drugs does not prevent initial infections, but prevents the development of malaria parasites in the blood Using antimalarial drugs does not prevent initial infections, but prevents the development of malaria parasites in the blood Pregnant woman should receive intermittent preventative treatments with antimalarial drugs during the 2 nd and 3 rd trimester Pregnant woman should receive intermittent preventative treatments with antimalarial drugs during the 2 nd and 3 rd trimester

11. Treating the Affected The following monotherapy drugs are used to treat malaria The following monotherapy drugs are used to treat malaria – Chloroquine – Quinine – Mefloquine – Primaquine – Sulfadoxine-pyrimethamine Artemisinin-based combination therapies (ACTs) are also used, which contain a derivative of the plant Artemisia annua Artemisinin-based combination therapies (ACTs) are also used, which contain a derivative of the plant Artemisia annua The World Health Organization has recommended that a switch to ACTs should be made in all countries where the malaria parasite has developed resistance to chloroquine. The World Health Organization has recommended that a switch to ACTs should be made in all countries where the malaria parasite has developed resistance to chloroquine.

12. Drug resistance Drug resistance – Most monotherapy drugs have found great resistance from the Plasmodium species – Combination therapies are very effective, but already have found some resistance Financial issues Financial issues – Many poor countries do not have the infrastructure or the sources to disperse these drugs – ACTs cost up to twenty times as much as older medications, they remain unaffordable in many malaria-endemic countries – The cost of treating a malaria-infected person in an endemic country is between $0.25 and $2.40.

13. Vaccines A vaccine has not been found, but it is under intense investigation A vaccine has not been found, but it is under intense investigation A successful malaria vaccine must protect vaccinees against multiple stages and multiple strains as well as stimulate multiple effectors of the immune response A successful malaria vaccine must protect vaccinees against multiple stages and multiple strains as well as stimulate multiple effectors of the immune response – Each stage has different antigens – Antibodies against one stage will be unaffective in another stage – The sporozoite can produce several different protein coats

14. References Foundations of Parasitology Foundations of Parasitology CDC CDC –http://www.cdc.gov/malaria/controlprevention/vector_control.htm http://www.cdc.gov/malaria/controlprevention/vector_control.htm Roll Back Malaria Roll Back Malaria –http://www.rollbackmalaria.org/ http://www.rollbackmalaria.org/ DDT, Global Strategies, and a Malaria Control Crisis in South America DDT, Global Strategies, and a Malaria Control Crisis in South America –http://www.cdc.gov/ncidod/EID/vol3no3/roberts.htm http://www.cdc.gov/ncidod/EID/vol3no3/roberts.htm Africa at home Africa at home –http://africa-at-home.web.cern.ch/africa%2Dat%2Dhome/malaria.html http://africa-at-home.web.cern.ch/africa%2Dat%2Dhome/malaria.html American Chemical Society American Chemical Society –http://pubs.acs.org/cen/government/84/8430gov1.html http://pubs.acs.org/cen/government/84/8430gov1.html Science and Technology Magazine Science and Technology Magazine –http://www.21stcenturysciencetech.com/articles/Fall02/DDT.html http://www.21stcenturysciencetech.com/articles/Fall02/DDT.html Malaria site Malaria site –http://www.malariasite.com/malaria/ControlOfMalaria.htm http://www.malariasite.com/malaria/ControlOfMalaria.htm