An article to help you understand microfilariae examination

Microfilariae are long, thin nematodes that live in humans and animals. They are the larval stage of filarial worms. Filarial worms are parasitic worms that are mainly transmitted to humans through mosquito bites. Microfilariae are usually between 150-400 microns in length, with a sheath and many nuclei. The nuclei are round or oval in shape, uniform in size, neatly arranged, separated from each other, and clearly countable. The life cycle of microfilariae in the human body consists of two stages: one in which they develop into infective larvae in the mosquito and the other in which they develop into adults in the human body. The adult worms mainly live in the lymphatic vessels, producing microfilariae that are spread throughout the body through the blood circulation.

1. According to different morphologies and characteristics, microfilariae can be divided into different types such as Bancrofti microfilariae and Malayan microfilariae.

2. Diagnostic significance

1. Diagnostic value: Examination of microfilariae in peripheral blood can diagnose filariasis. Microfilariae are the pathogens of filariasis.

2. Detection time: Blood is usually collected between 10 pm and 2 am. The number of microfilariae in the peripheral blood is the highest during this time period, which is conducive to improving the detection rate.

3. Living habits

1. Host: Microfilariae mainly parasitize in the blood or tissue fluid of the final host. When they appear in the microvessels under the host's skin, they may enter the body of the blood-sucking mosquito and become sheathed larvae to spread.

2. Activity pattern: Microfilariae move to peripheral blood vessels at certain times of the day. When they appear in the microvessels under the host's skin, they may enter the body of blood-sucking mosquitoes and become sheathed larvae to spread the disease.

4. Blood microfilariae examination method:

1. Thick blood film method: This is the most commonly used method, which detects microfilariae by making a thick blood film on a slide, then staining and observing under a microscope. This method is simple and easy, but it requires high technical skills from the operator.

2. Thin blood film method: Similar to the thick blood film method, but the prepared blood film is thinner. This method can improve the detection rate of microfilariae, but the operation technology requirements are also higher.

3. Direct smear method: fresh peripheral blood is directly smeared on a slide, then stained and observed under a microscope. This method is simple and fast, but it requires a high number of microfilariae.

4. Centrifugal concentration method: fresh peripheral blood is centrifuged to precipitate red blood cells, and then the supernatant is taken for staining and microscopic observation. This method can increase the detection rate of microfilariae, but the operation process is more complicated.

5. Immunological detection methods: including indirect fluorescent antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA), etc. These methods use specific antibodies to recognize microfilariae antigens, thereby achieving the detection of microfilariae. These methods are highly sensitive and specific, but require professional laboratory equipment and technology.

5. Harm of Microfilariae to Human Body

Microfilariae are the larval stage of filarial worms, which mainly parasitize in the human body. The presence of microfilariae can cause a series of symptoms and diseases. Their harm to the human body mainly includes the following aspects:

1. Cause disease: Microfilariae reproduce and migrate in the human body, causing a series of symptoms and diseases, such as lymphangitis, lymphadenitis, elephantiasis, etc. Among them, elephantiasis is one of the most serious consequences, and the patient's skin will become rough and thick, and even cracks and ulcers will appear.

2. Affect blood circulation: When microfilariae move in the blood, they will affect blood circulation, causing poor blood flow and triggering symptoms such as anemia and edema.

3. Impact on the immune system: The presence of microfilariae will stimulate the human body to produce an immune response. Long-term immune response may cause damage to the immune system and reduce the body's resistance to other diseases.

4. Impact on quality of life: Due to the symptoms and diseases caused by microfilariae, the patient's quality of life will be seriously affected, such as pain, fatigue, and difficulty in movement.

In general, microfilariae are the pathogens of filariasis, and research on them will help people better understand and prevent filariasis. In daily life, people should pay attention to personal protection. Avoiding mosquito bites is the key to preventing filariasis. Mosquito repellents, mosquito nets and other anti-mosquito measures can be used to reduce the risk of infection with filariasis. For patients who have been infected with microfilariae, timely diagnosis and treatment should be carried out to prevent them from causing greater harm to the human body. Anti-parasitic drugs can be used for treatment. At the same time, strengthening environmental hygiene and eliminating mosquito breeding grounds are also important means to control microfilariasis.

【Image source: Baidu】

First author: Li Chunhong

Unit: Zhanjiang Fourth People's Hospital