Kakaire A. Kirunda
11 June 2008
As the fight against malaria gains ground, studies are showing that mosquitoes that transmit the disease are beginning to gain resistance against the commonly used pyrethroid insecticides. "Generally, the results showed a trend of increase in mosquito resistance status with cross-resistance against all the three pyrethroid insecticides.
This study reveals for the first time the development of pyrethroid resistance in malaria vector Anopheles gambiae s.l. in Western Uganda," according to the findings published in the Malaria Journal on May 26.
The study was conducted by three scientists from the Fort Portal-based Mountains of the Moon University, the Medical Department of Kabarole District and the Medical Research Council in Entebbe.
The trio embarked on the study at a time when Pyrethroid insecticide-treated mosquito nets were massively being scaled-up for malaria prevention particularly in children under five years of age and pregnant mothers in Sub-Saharan Africa.
But this is amid serious concern of the likely evolution of widespread pyrethroid resistance in the malaria transmitting Anopheles gambiae s.l. due to the extensive use of pyrethroid insecticide-treated mosquito nets.
It was against this backdrop that researchers John Rubaihayo, Ephraim Tukesiga and Andrew Abaasa sought to ascertain the status of pyrethroid resistance in malaria causing mosquitoes in western Uganda. Being cost-effective, highly insecticidal at low dosage and highly biodegradable with low mammalian toxicity, pyrethroid insecticides were recommended by WHO Pesticides Evaluation Scheme (Whopes) for large-scale use on mosquito bed nets for malaria prevention.
For purposes of the western Ugandan study in Kamwenge District, wild mosquitoes (1-2 days old) were exposed in 10 replicates to new nets impregnated with K-othrine, Solfac EW50 and Fendona 6SC and observed under normal room temperature and humidity.
A similar set of mosquitoes collected from the control area 80 km away were exposed to a deltamethrin 25mg/m2 impregnated net at the same time and under the same conditions. The 10-year mean knockdown time and mortality rates for each of the three pyrethroid insecticides were then compared.
Results
The study findings indicated that it was taking longer than it should for the mosquitoes to be killed after coming into contact with the insecticide treated nets. The overall results showed that it was now taking four times longer for the insects to succumb, an indication of reduced susceptibility to pyrethroid insecticides.
Following the findings, the study authors are now recommending that the impact of these developments on malaria control efforts be closely monitored and alternative fabric treatments considered before this problem curtails community wide implementation of this malaria control strategy in Uganda.
The findings come at a time when malaria is still the leading cause of childhood and maternal ill health and death in the country, according to WHO.
And statistics from the Ministry of Health show that the burden of malaria is unacceptably high, accounting for 20-40 percent of outpatient attendance at health facilities, 14 percent of in-patient deaths and 20-23 percent of childhood mortality.
It is further estimated that there are 70,000-110,000 malaria-specific deaths every year and $24.7 is being spent on each individual per annum to treat malaria. Matters have not been helped by the evolution of both drug and insecticide resistance to the commonly used anti-malarials and insecticides respectively.
Citing the study Malaria: Current and future prospects for control, the authors of the western Uganda research noted that a number of novel technologies have been developed to combat malaria including insecticide treated nets and malaria vaccines but the vaccines have shown limited efficacy and need further development.
Read comments. Write your own.
Copyright © 2008 The Monitor. All rights reserved. Distributed by AllAfrica Global Media (allAfrica.com). To contact the copyright holder directly for corrections — or for permission to republish or make other authorized use of this material, click here.
AllAfrica aggregates and indexes content from over 125 African news organizations, plus more than 200 other sources, who are responsible for their own reporting and views. Articles and commentaries that identify allAfrica.com as the publisher are produced or commissioned by AllAfrica.
How to kill pests without killing yourself or the earth......
There are about 50 to 60 million insect species on earth - we have named only about 1 million and there are only about 1 thousand pest species - already over 50% of these thousand pests are already resistant to our volatile, dangerous, synthetic pesticide POISONS. We accidentally lose about 25,000 to 100,000 species of insects, plants and animals every year due to "man's footprint". But, after poisoning the entire world and contaminating every living thing for over 60 years with these dangerous and ineffective pesticide POISONS we have not even controlled much less eliminated even one pest species and every year we use/misuse more and more pesticide POISONS to try to "keep up"! Even with all of this expensive and unnecessary pollution - we lose more and more crops and lives to these thousand pests every year.
We are losing the war against these thousand pests mainly because we insist on using only synthetic pesticide POISONS and fertilizers There has been a severe "knowledge drought" - a worldwide decline in agricultural R&D, especially in production research and safe, more effective pest control since the advent of synthetic pesticide POISONS and fertilizers. Today we are like lemmings running to the sea insisting that is the "right way". The greatest challenge facing humanity this century is the necessity for us to double our global food production with less land, less water, less nutrients, less science, frequent droughts, more and more contamination and ever-increasing pest damage.
National Poison Prevention Week, March 18-24,2007 was created to highlight the dangers of poisoning and how to prevent it. One study shows that about 70,000 children in the USA were involved in common household pesticide-related (acute) poisonings or exposures in 2004. At least two peer-reviewed studies have described associations between autism rates and pesticides (D'Amelio et al 2005; Roberts EM et al 2007 in EHP). It is estimated that 300,000 farm workers suffer acute pesticide poisoning each year just in the United States - No one is checking chronic contamination. In order to try to help "stem the tide", I have just finished re-writing my IPM encyclopedia entitled: THE BEST CONTROL II, that contains over 2,800 safe and far more effective alternatives to pesticide POISONS. This latest copyrighted work is about 1,800 pages in length and is now being updated at my new website at http://www.thebestcontrol2.com .
This new website at http://www.thebestcontrol2.com has been basically updated; all we have left to update is Chapter 39 and to renumber the pages. All of these copyrighted items are free for you to read and/or download. There is simply no need to POISON yourself or your family or to have any pest problems.
Stephen L. Tvedten 2530 Hayes Street Marne, Michigan 49435 1-616-677-1261 When a man who is honestly mistaken hears the truth, he will either quit being mistaken or cease to be honest.
"An invasion of armies can be resisted, but not an idea whose time has come." --Victor Hugo "Our lives begin to end the day we become silent about things that matter." -- Martin Luther King Jr.