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Researchers at Vanderbilt University have identified a new family of odor sensors that mosquitoes use to locate their prey. Their discovery could help explain the puzzling mechanisms behind the mosquito’s sense of smell and further the discovery of new deterrents and traps. Funded by NIAID, the study was published in the journal PLoS Biology in August 2010.

Mosquitoes’ olfactory system, or sense of smell, is crucial for their survival. Mosquitoes use it to identify mates and locate a host. While its importance is well-accepted, the exact mechanisms behind the mosquito’s olfactory system are poorly understood.

For about ten years, scientists have been examining Anopheles gambiae, the primary vector of malaria, and studying a set of odor sensors called AgORs (A. gambiae odorant receptors). Now, the Vanderbilt team, led by Laurence Zwiebel, Ph.D., has discovered a new set of receptors, AgIRs (A. gambiaevariant ionotropic receptors) by examining the larval olfactory system.

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Emerging and resurging vector-borne diseases cause significant
morbidity and mortality, especially in the developing world. We
focus on how advances in mapping, Geographic Information System,
and Decision Support System technologies, and progress in spatial
and space-time modeling, can be harnessed to prevent and control
these diseases. Major themes, which are addressed using examples
from tick-borne Lyme disease; flea-borne plague; and
mosquito-borne dengue, malaria, and West Nile virus disease,
include (a) selection of spatial and space-time modeling
techniques, (b) importance of using high-quality and biologically
or epidemiologically relevant data, (c) incorporation of new
technologies into operational vector and disease control
programs, (d) transfer of map-based information to stakeholders,
and (e) adaptation of technology solutions for use in
resource-poor environments. We see great potential for the use of
new technologies and approaches to more effectively target
limited surveillance, prevention, and control resources and to
reduce vector-borne and other infectious diseases. Expected final
online publication date for the Annual Review of Entomology
Volume 56 is December 03, 2010. 

Plasmodium vivax is responsible for a significant portion of malaria cases worldwide, especially in Asia and Latin America, where geo-helminthiasis have a high prevalence. Impact of the interaction between vivax malaria and intestinal helminthes has been poorly explored. The objective of this study was to evaluate the influence of intestinal helminthiasis on the concentration of hemoglobin in children with Plasmodium vivax malaria in rural areas in the municipality of Careiro, in the Western Brazilian Amazon.

Connie Bennett

Special to AOL News

(May 28) — We’re in the midst of a terrifying epidemic, although you wouldn’t know it to talk to most doctors and health specialists.

The disease is growing at a rate faster than AIDS. From 2006 to 2008 alone, the number of cases jumped a whopping 77 percent. In 2008 alone, the Centers for Disease Control and Prevention listed 28,921 “confirmed” and 6,277 “probable” cases of the disease, but there could be as many as 420,000 because of underreporting.

Prominent victims include Parker Posey, Richard Gere, President George W. Bush, Alice Walker and Christie Brinkley.

If any other disease had stricken so many people, the medical community would be scurrying for knowledge, scrambling for cures or rushing to warn patients (think swine flu).

But that’s not the case with Lyme disease — a disease carried by ticks.

Instead, ill-informed doctors are often flummoxed when patients complain of fatigue, headaches, fever or chills, muscle or joint pain, mental confusion, swollen lymph nodes and neurological symptoms. It’s an appalling display of indifference.

As Lyme Disease Awareness Month comes to a close and Memorial Day travelers flock to grassy, tick-infested holiday spots across America, vacationers and physicians alike need to be on the alert for freckle-sized menaces that are responsible for the fastest-growing, most misdiagnosed infectious disease in the country. The CDC has a map that shows where the ticks are most prevalent.

For my part, I was lucky because my smart nutritionist friend, JJ Virgin, immediately grew suspicious when, almost overnight, I became an exhausted, headache-ridden, nightmare-plagued, memory-challenged zombie suffering from vertigo, sleeping problems, swollen glands, achy eyes, sensitivity to light and noise, fever, chills and a sore neck.

New Haven, Conn. — A protein found in the saliva of ticks helps protect mice from developing Lyme disease, Yale researchers have discovered. The findings, published in the November 19 issue of Cell Host & Microbe, may spur development of a new vaccine against infection from Lyme disease, which is spread through tick bites.

Traditionally, vaccines have directly targeted specific pathogens. This is the first time that antibodies against a protein in the saliva of a pathogen’s transmitting agent (in this case, the tick) has been shown to confer immunity when administered protectively as a vaccine.

The Lyme bacterium known as Borrelia burgdorferi is transmitted by ticks. When it moves through the tick, it is coated with a tick salivary protein known as Salp15. The Yale team injected Salp15 into healthy mice and found that it significantly protected them from getting Lyme disease. When combined with outer surface proteins of B. burgdorferi, the protection was even greater.

Lead author Erol Fikrig, M.D. of Yale School of Medicine and Howard Hughes Medical Institute said, “The interaction between the Lyme disease agent and ticks is very complex, and the bacteria uses a tick salivary protein to facilitate infection of the mammalian host. By interfering with this important interaction, we can influence infection by the Lyme disease agent.”

Several years ago there was a Lyme vaccine on the market that utilized just the outer surface proteins of the bacteria. It was taken off the market in 2002, and to date no other antigen has been tested in phase III clinical trials.

The authors believe this new strategy of targeting the saliva – the “vector molecule” that a microbe requires to infect a host – may be applicable not just to Lyme disease but to other insect-borne pathogens that also cause human illness.

“We believe that it is likely that many arthropod-borne infection agents of medical importance use vector proteins as they move to the mammalian host,” Fikrig explained. “If so, then this paradigm, described with the Lyme disease agent, is likely to be applicable to these illnesses. Currently, we are working to determine if this strategy is likely to be important for West Nile virus infection, dengue fever, and malaria, among other diseases.”

Other researchers were Jianfeng Dai, Penghua Wang, Sarojini Adusumilli, Carmen J. Booth and Sukanya Narasimhan of Yale School of Medicine, and Juan Anguita of the University of Massachusetts. This work was support by grants from the National Institutes of Health.

 http://opa.yale.edu/news/article.aspx?id=7083
 
FOUND IN: Health & Medicine

PRESS CONTACT: Helen Dodson 203-436-3984

A rapid test for malaria that has a high sensitivity and specificity “could potentially avert more than 100,000 malaria-related deaths each year and save nearly $200 million that is spent on unnecessary treatments annually,” Dr. Davis C. Nwakanma from the Medical Research Council, Fajara, Banjul, Gambia and his team and colleagues estimate.

Dr. Nwakanma and his team his team compared the diagnostic accuracy of nested and quantitative PCR testing of saliva, urine and blood with the gold standard blood smear microscopy in 386 Gambian out-patients with suspected malaria.

Saliva PCR for malaria returned a sensitivity and specificity of 73% and 97%, respectively, and a correlation of 0.58 with blood microscopy, the researchers report in the June1st issue of The Journal of Infectious Diseases. The correlation of blood and urine PCR for estimation of malarial parasite density was 0.94 and 0.20 as compared to the gold standard, they add.

“Presently, the saliva testing assay may be applied in malaria research but not for deciding the treatment options for patients because of sensitivity and time-to-assay-completion issues,” Dr. Nwakanma told Reuters Health.

“Saliva could be used for rapid testing, as a new generation of point of care DNA-based tests are currently being developed by several research groups, Dr. Colin Sutherland from the London School of Hygiene and Tropical Medicine, and author of a related editorial told Reuters Health. “However, some adaptation to the use of saliva as starting material in these tests would be needed, and it is uncertain how sensitive such tests would be.”

“Saliva sampling is a promising less-invasive approach,” the researchers conclude.

J Infect Dis 2009;199:1561-1563,1567-1574.

Findings from another study indicate that inoculation of intact sporozoites can induce protection against malaria challenge. Both studies are reported in The New England Journal of Medicine for July 30.

Recent research suggests that artemisinin-based therapies are losing their efficacy against falciparum malaria on the Thai-Cambodian border, a site where antimalarial-drug resistance has been described in the past.

In the first study, Dr. Arjen M. Dondorp, from Mahidol University, Bangkok, and colleagues assessed the response to artesunate with or without mefloquine in 40 patients living in western Cambodia and 40 in northwestern Thailand.

The time to parasitic clearance was significantly longer in the Cambodian patients: 84 vs. 48 hours in Thai patients (p < 0.001). In vitro testing, however, did not show reduced sensitivity to artesunate.

“Measures for containment are now urgently needed to limit the spread of these parasites from western Cambodia and to prevent a major threat to current plans for eliminating malaria,” the authors conclude.

In the second study, Dr. Robert Sauerwein, from Radboud University, Nijmegen, the Netherlands, and colleagues examined sporozoite inoculation, via mosquito bite, as a means of inducing immunity against malaria.

Ten healthy subjects received bites from infected mosquitos (vaccine group) and 5 received bites from uninfected mosquitos (control group), once a month for 3 months. Chloroquine prophylaxis was given to both groups during this immunization phase. One month after stopping chloroquine, all of the subjects underwent malaria challenge with mosquitos infected with P. falciparum.

The subjects in the vaccine group were fully protected against malaria challenge, whereas all subjects in the control group developed parasitemia. No serious adverse events were seen in either group.

Although the described study protocol does not represent a vaccine strategy that can be widely implemented, “the induction of sterile protection against a homologous malaria challenge suggests that the concept of a whole-parasite malaria vaccine warrants further consideration,” the authors conclude.
N Engl J Med 2009;361:455-477.