Vectors

Diseases Transmitted through Flies

Diseases Transmitted through Flies:
Kinds of Flies Transmitting Infections Diseases:

 

​Flies Description​ Diseases Vectored​
Sand Flies​ Sand flies are blood-feeders. They are weak fliers, tending to move from host to host in short “hopping” flights. Their bodies are so small (3 mm) they are hard to detect until after they begin biting. Their bite generates intense discomfort for several days.​ Leishmaniasis​
Black Flies​ Black flies are specialized for breeding in running water from small trickles to large rivers. They also vector a nematode that can live in the human body for up to fifteen years destroying tissue in internal organs, most notably in the eye thereby causing blindness.​ River Blindness (Onchocerciasis)​
Tsetse Flies​ This winged pathogen causes “African Sleeping Sickness” to humans through biting. Tsetse flies live at ponds and banks of rivers.​ Sleeping Sickness​
 

 

i. Leishmaniasis
Leishmaniasis is an infectious disease affecting men, through over 20 species of parasites infecting mammals, including man. These parasites lead to symptoms ranging from simple self-healing skin ulcers to damaging various body organs and severe life-threatening diseases.
Clinical symptoms:
Symptoms vary according to the kind of infection. Depending on the place of infection, there are three types of Leishmaniasis:

1- Cutaneous Leishmaniasis:
This kind on infection affects the skin only and not internal organs. It takes the form of simple or acute skin lesions. The onset of symptoms takes the form of a redding and itching caused by the fly bite. Several weeks afterwards, it may grow and develop into an ulcer excreting pus, or remaining dry. Exposed parts of the body (such as the face, arms, legs and feet) are vulnerable to infection.
Inflammation of the sores and ulcers could take place as a result of a bacterial infection, or in case the infected person suffers immunodeficiency. In such cases, ulcers remain unhealed for longer time, leaving unsightly scars.
 
2- Visceral Leishmaniasis
Symptoms begin to appear after the bite of the sand fly; the infected person suffers high temperature, sweating, general weakness, malaise, diarrhea, weight loss, and symptoms like those of anemia.
That is to be added to swelling of spleen, liver and lymph nodes. With the development of the disease, the skin turns dark, especially the forehead, hands, feet and belly.

 

Symptoms are akin to those associated with malaria, tuberculosis, and brucella. Therefore, lab tests have to be conducted to verify of the diagnosis.

 

3- Mucocutaneous Leishmaniasis:
It is caused by the bite of the sand fly, and begins with simple skin ulcers, but these can spread to give hideous tissue destruction-especially of the nose and mouth. Symptoms are concentrated in the respiratory system. They may develop to nosebleeds and sinus congestion, and then further develop to ulcers in the nasal tissue, which lately extend to the larynx and pharynx. In the advanced cases, pneumonia might take place.

 


Treatment of Leishmaniasis
• Simple Cutaneous Leishmaniasis will usually heal without treatment, leaving the person immune to further infection with that species of Leishmaniasis. Treatment of the ulcers may take as long time as two years. They may leave unsightly scars. Treatment, thus, should start before the development of ulcers.
• Cutaneous Leishmaniasis could be treated by the Antimony V (either intramuscular or intravenous), or locally inside the ulcer. Right now, other drugs are used, such as Amphotericin B and Allaloberinol, among other, in the cases that do not respond to Antimony V drugs.
• For treatment, ulcers might be exposed to high temperature, radiation or cooling.
• As for visceral Leishmaniasis, it should be treated early to prevent the development of the case, and reduce the ulcers, and thus reduce the resistance of the disease. These cases are treated by Antimony V drugs intramuscularly, intravenously or locally inside ulcer, or through other drugs like Amphotericin B and Allaloberinol.
 
Prevention of Leishmaniasis infection:
• Being cautious when getting into gardens and farms in the early morning, and in the evening, and making sure to cover limbs.
• Using insecticides at gardens, farms and ponds.
• Paying attention to the cleanliness of animals such as dogs and cats.
• Using repellents and insecticides.
• Using bed nets for children.
i. River Blindness (Onchocerciasis):
Onchocerciasis is also caused by nematodes, but its vectors are black flies, relatives of mosquitoes that breed in clean, running water. The adult worms that cause Onchocerciasis cause the body to form hard lumps or nodules of fibrotic tissue under the skin. Parasitic nematode worms of the family filariidae. The work lives at the human body for as long as fifteen years and when they die, the immune system resists the dead tissue. These
symptoms appear:
• Acute itching.
• Changes in the skin color.
• Hard lumps or nodules of fibrotic tissue under the skin.
• Damage of the cells and tissue of the eye, causing blindness.

Treatment of river blindness
Close attention should be paid to treatment to prevent the development of complications on the skin and eye.
A well-tolerated drug, ivermectin, can kill the microfilaria and temporarily inhibit the ability of the adult female worms to reproduce. Also, Doxycycline is useful to combat adult worms.

 

Prevention of river blindness:
1. No vaccinations or drugs are available for preventing the infection of this disease.
2. Avoid the bites of the flies are the best way of protection; through:

  • Bed nets
  • Covering the body, by wearing full-sleeve clothes. 
  •  Using insecticides and repellents.

i. sleeping sickness:
Sleeping sickness, also called the African trypanosomiasis, is a parasitic disease transmitted by the sting of the tsetse fly which mostly thrives in the African tree-mixed Savanna regions and forest habitats.  
The human African trypanosomiasis takes two forms according to the parasite causing the disease:
•  Trypanosoma brucei: this form of the disease spreads in west and middle of Africa.
• T. B. Rhodesiense: this from of the disease is rampant in the east and south of Africa.
 
What is its symptom?
First Stage:
It is called the lymph blood stage. Trypanosomatidae propagates in the tissues under the skin, blood, lymphatic nodes, and it is characterized by bouts of fever, headache, joint pains, and itch.
Second Stage:
It is called the nerve stage where the parasites penetrate the blood brain barrier and afflict the central nerve system along with the appearance of the disease symptoms, such as:
• Behavior change and disturbances
• Lack of concentration
• Sleeping disorders
• Causing death if not treated
What is the drug prescribed for the sleeping sickness?
Treatment is identified according to the stage in which the disease is diagnosed
 

​Stage Drug Used​
First Stage​ • Pentamidine
• Suramin
Second Stage​ • Melarsoprol
• Eflornithine

 

 

 

 

How is the sleeping sickness prevented?
• No vaccines or drugs are forthcoming for preventing the disease.
• Avoiding the fly stings is the optimal form of prevention by: 

  • Using net sleeping
  •  Covering the body by wearing long-sleeved clothing.
  •  Applying the insect repellent cream to the skin.
Last Update : 07 May 2014 01:26 PM
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