malaria treatment for people

Behavioral Resistance: Mosquitoes Learn to Avoid Bed Nets

Malaria is a notoriously tricky infectious disease. Because of a unique genetic flexibility, it is able to change surface proteins, avoiding the immune response and greatly complicating vaccine development. Furthermore, the parasite is transmitted by mosquitoes, which are difficult to control. Insecticides work, but mosquitoes can develop resistance to them.

One method widely used to control malaria is for governments or charities to provide families with insecticide-treated bed nets. Overall, this strategy is very successful, and it has been credited with preventing some 451 million cases of malaria in the past 15 years. But bed nets are not successful everywhere. In some parts of the world, mosquitoes develop “behavioral resistance”; i.e., they learn to avoid bed nets by biting people earlier in the day.

A team led by Lisa Reimer of the Liverpool School of Tropical Medicine monitored mosquito behavior in villages in Papua New Guinea before (2008) and after (2009-2011) the distribution of bed nets. Data from one of the villages, Mauno, depicts a very noticeable shift in mosquito feeding behavior.

Before bed nets were distributed in 2008, the median biting time for mosquitoes was around midnight. After the distribution, the median time shifted back to 10 pm. Also, a greater proportion of mosquitoes took their dinner even earlier, from 7 to 9 pm.

Worryingly, it’s unclear whether the bed nets were effective at preventing malaria transmission. The number of bites per person per night dropped after the introduction of bed nets, but started to climb in subsequent years as mosquitoes began to adapt. Additionally, the prevalence of malaria infection in humans — arguably, the only statistic that actually matters — dropped in one village, remained the same in a second, and ticked up slightly (albeit insignificantly) in a third.

Despite the mixed results in Papua New Guinea, Dr Reimer believes that bed nets should continue to be used worldwide as part of a mosquito control strategy. However, she notes that behavioral resistance may prove just as vexing as insecticide resistance and, in some locations, may limit the efficacy of bed nets.

Thus, mosquitoes must be monitored for both behavioral and insecticide resistance, as the little creeps stubbornly refuse to die and may be cleverer than we thought.

Source: Edward K. Thomsen et al. “Mosquito behaviour change after distribution of bednets results in decreased protection against malaria exposure.”

Source : Acsh.org

Dengue cases in Mumbai highest in 6 years

MUMBAI: The number of dengue cases recorded in the city this year has been the highest in the last six years. However, the good news is that fatalities have declined significantly over the last three years.

According to figures recently released by the state, Mumbai has recorded 1,088 cases so far this year and four confirmed deaths. The last time dengue cases had crossed the 1,000mark was in 2012. Within the state too, the highest number of cases were reported from the city. Dengue infected 6,376 people and claimed 26 lives in Maharashtra between January 1 and November 21this year. Doctors say the increase in incidence is a reason for concern as it can lead to longer hospital stays, lost manhours and bigger hospital expenses. “Dengue causes mortality in merely 1%-3% of cases. It is the morbidity that needs to be looked into closely,” said infectious disease consultant Dr Om Srivastava. He said that patients this ye ar had complained of pro blems in resuming their routine lives long after they had recovered from the mosquitoborne illness.

A senior physician from KEM Hospital in Parel too added that patients came to the hospital three months after recovering from the disease with complaints of lethargy . “In a few cases, the symptoms had persisted from six weeks to three months,” the doctor said. Srivastava added that many patients fail to follow the post-recovery regimen like drinking water and taking adequate rest which prolong their suffering.

Source: Times Of India

UT researchers discover bacterial genes that could lead to effective malaria treatment.

Researchers at the University of Tennessee, Knoxville, have identified a set of bacterial genes that may help them find ways to lessen the severity of the disease malaria.

Their findings could also aid the research of fellow scientists working in malaria-stricken regions around the world.

The study was published in the journal Frontiers in Microbiology.

Collaborators in this work include Steven Wilhelm, the Kenneth and Blaire Mossman Professor in the UT Department of Microbiology; Shawn Campagna, UT associate professor of chemistry; Gary LeCleir, UT research assistant professor of microbiology; Joshua Stough, UT doctoral student in microbiology; and Nathan Schmidt, assistant professor of microbiology and immunology at the University of Louisville.

The research team earlier this year released a study that found the severity of malaria depends not only on the parasite or the host but also on the microbes in the infected organism. They examined the gut microbiomes of mice.

This new study is helping researchers better understand how gut bacteria work.

Stough analyzed hundreds of genes and eventually found that 32 bacterial genes and 38 mice genes have the characteristics–or phenotypes–that can affect malaria.

“We’re pretty excited because it means there is a limited number of genes to work with,” Wilhelm said. That discovery will make it easier to find a more effective malaria treatment for people.

Much of the study was carried out in Wilhelm’s UT lab.

When the research team released the first study in February, scientists around the world doing similar microbiome work expressed interest.

“The findings in this second study could allow scientists to look at data they’re collecting and try to draw comparisons to see if what we’re seeing is also happening in their samples from malaria-stricken regions,” Wilhelm said. “We’re collecting data in a way that can be used to answer other questions after the fact.”

Hundreds of children die every year from malaria. “If we can find a way to mitigate this disease, we can positively influence a large number of people,” Wilhelm said.

Source: http://www.news-medical.net/