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Aedes albopictus

Within 2 years, scientists manage to wipe out mosquitoes on two Chinese islands

In a time period of only two years, scientists have almost wiped out the most invasive mosquito in the world from two islands in Guangzhou, China. The mosquito species, Asian tiger is a carrier of highly infectious diseases such as Zika, chikungunya and dengue affecting millions of people all over the world. It is very difficult to control.

Over the last forty years, this mosquito has reached to all other continents on Earth excluding Antarctica from its home in Asia. It has caused a heavy impact on public health due to the limited availability of vaccines and treatments for the diseases it spreads. However, with an exciting field test of a mosquito control technique, this can be changed. Researchers used two existing methods to decrease the population of Asian tiger up to 94 percent on the Chinese river islands. In some instances, even one viable egg was not found for 13 weeks. The findings have been published in the Nature journal.

Peter Armbruster, mosquito ecologist while reviewing the work said that the results were quite remarkable and it shows the potential of a new tool to fight infectious diseases that are spread by mosquitoes.

The double combination approach involves a radiation dose for sterilizing the mosquitoes along with a bacterial strain from the Wolbachia genus preventing the hatching of mosquito eggs. When these two methods are applied together on the lab-grown mosquitoes, they work very effectively than when used alone.

Radiation based techniques used at present work with the release of sterile male insects who mate with the females decreasing the population size. However, radiation makes them less competitive sexually and are prone to die quickly. Other methods using bacteria are less harmful but they work only if the male mosquito grown in the lab is infected. When both male and female have a bacterial infection, they cancel each other out producing a healthy offspring.

Sifting through male and female insects is highly painstaking, as although the researchers put all the effort, Wolbachia-infected females get released accidentally 0.3 percent of the time which undermines the whole mission.

However, in the new solution, Wolbachia-infected mosquitoes are reared in the lab who are then subjected to low radiation which makes the females sterile while the males can still reproduce. This not only works theoretically but also works in reality. Getting rid of the sex testing, the team was able to produce and release huge numbers of these mosquitoes grown in the lab, nearly two hundred million in the city having the largest dengue transmission rate in China.

After two years, the team found a decrease of 97 percent in the mosquito bites by the local population. The average number of wild adult females caught per trap reduced by 83 to 94 percent, with none found for a period of six weeks. Authors say the remaining mosquitoes on the island migrated from outside, suggesting that the region would not be free of mosquitoes for a long period of time. However, if the technique is implemented on a larger scale it is possible to make the place free from the Asian tiger mosquitoes.

Zhiyong Xi, a molecular genetics professor at Michigan State University said that their study predicted the total future costs of a completely operational intervention using this approach would be nearly 108 US dollars per hectare per year which is cheaper than other mosquito-control techniques.

Research Paper: https://www.nature.com/articles/s41586-019-1407-9


Salmonella Infection (salmonellosis) and Animals

What is Salmonella

Salmonella germs can live in the intestinal tract of many different animals. Salmonellosis (sal-mohn-el-OH-sis) is a bacterial disease caused by the bacterium Salmonella. Most people have diarrhoea, fever, and stomach pain that start 1 to 3 days after they get infected. These symptoms usually go away after 1 week. Sometimes, people have to see a health care provider or go to the hospital because the diarrhoea is severe or the infection has spread from the intestines to the bloodstream, and then to other body sites.

Important Tip!

Protect yourself against getting Salmonella from animals. Simply wash your hands with running water and soap after any contact with animal faeces (stool)

Can animals make me sick?

Yes, although Salmonella is most commonly transmitted through contaminated food, Salmonella is also one of many zoonotic pathogens that can be spread between people and animals. Animals can carry Salmonella and pass it in their faeces or stool. Salmonella germs are shed in animals’ faeces and can easily contaminate their bodies (fur, feathers, and scales) and anything in areas where these animals live and roam. Therefore, people can also get a Salmonella infection if they do not wash their hands after contact with animals or their environment, such as touching contaminated animal bedding or tank water.

Many Salmonella infections occur in people who have contact with certain types of animals — or “risky” pets. These include reptiles (turtles, snakes, and lizards), amphibians (frogs and toads), and poultry (chicks, chickens, ducks ducklings, geese, turkeys). Also, pocket pets (guinea pigs and rodents like hamsters), dogs, cats, birds (including pet and wild birds), horses, and farm animals (goats, calves, sheep) can pass Salmonella to people. It is important to know that these animals can carry Salmonella germs and still appear healthy and clean. Additionally, reptiles and amphibians that live in tanks or aquariums can contaminate the water with Salmonella, which can lead to illness in people. You should also know that some pet products, like pet foods and treats, can be contaminated with Salmonella and other germs. Pet food and treats might include dry dog or cat food, dog biscuits, pig ears, beef hooves, and rodents used to feed reptiles including frozen feeder rodents.

Who is most at risk for serious illness?

Some people are more likely than others to get salmonellosis. A person’s age and health status may affect his or her immune system, increasing the chances of getting sick. People who are more likely to get salmonellosis include infants, children younger than 5 years old, older persons, and people with weakened immune systems such as people with HIV/AIDS or organ transplant patients and people receiving treatment for cancer.

How can I protect myself from getting Salmonella?

  • Wash your hands thoroughly with soap and water right after touching animals, their food (e.g., dry dog or cat food, frozen feeder rodents, etc.) or treats (e.g., rawhide bones, pig ears, biscuits, etc.) or anything in the area where they live and roam.
  • Running water and soap are best. Use hand sanitizers if running water and soap are not available. Be sure to wash your hands with soap and water as soon as a sink is available. Directions for washing hands can be found here. Adults should always supervise hand washing for young children.
  • Do not let children younger than 5 years of age, older individuals, or people with weakened immune systems handle or touch high-risk animals (e.g., turtles, water frogs, chicks, ducklings), or anything in the area where they live and roam, including water from containers or aquariums.
  • Keep live poultry, amphibians, and reptiles out of homes and facilities with children younger than 5 years old or people with weakened immune systems.
  • Don’t eat or drink around high-risk animals (e.g., turtles, water frogs, chicks, ducklings), or in areas where they live and roam. Keep animals away from areas where food and drink are prepared, served, or stored, such as kitchens or outdoor patios.
  • Use soap or a disinfectant to thoroughly clean any surfaces that have been in contact with animals. Children older than 5 years of age should perform this task only under adult supervision.
  • Habitats and their contents, such as food and water bowls, should be carefully cleaned outdoors, if possible. If bathtubs must be used for these purposes, they should be thoroughly cleaned and disinfected with a bleach solution afterward.
  • High-risk individuals should avoid cleaning habitats and their contents, but if unavoidable, they should use disposable gloves when cleaning and do not dispose of water in sinks used for food preparation or for obtaining drinking water.

Source: https://www.cdc.gov