Most people develop these clinical manifestations years after being infected. The swelling and the decreased function of the lymph system make it difficult for the body to fight germs and infections. Affected persons will have more bacterial infections in the skin and lymph system. This causes hardening and thickening of the skin, which is called elephantiasis. Many of these bacterial infections can be prevented with appropriate skin hygiene and care for wounds.
Men can develop hydrocele or swelling of the scrotum due to infection with one of the species of parasites that causes LF, specifically W. Filarial infection can also cause tropical pulmonary eosinophilia syndrome. Eosinophilia is a higher than normal level of disease-fighting white blood cells, called eosinophils. This syndrome is typically found in infected persons in Asia. Clinical manifestations of tropical pulmonary eosinophilia syndrome include cough, shortness of breath, and wheezing.
The eosinophilia is often accompanied by high levels of Immunoglobulin E IgE and antifilarial antibodies. The standard method for diagnosing active infection is the examination of blood under the microscope to identify the microscopic worms, called microfilariae. This is not always feasible because in most parts of the world, microfilariae are nocturnally periodic, which means that they only circulate in the blood at night.
For this reason, the blood collection has to be done at night to coincide with the appearance of the microfilariae in the blood. Serologic techniques provide an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis. Because lymphedema may develop many years after infection, lab tests are often negative with these patients. Avoiding mosquito bites is the best form of prevention.
The mosquitoes that carry the microscopic worms usually bite between the hours of dusk and dawn. If you live in or travel to an area with lymphatic filariasis:. People infected with adult worms can take a yearly dose of medicine, called diethylcarbamazine DEC , that kills the microscopic worms circulating in the blood. While this drug does not kill all of the adult worms, it does prevent infected people from giving the disease to someone else.
And since these worms can live for a decade , and can release thousands of new larvae every day , their hosts must resign themselves to years of regular treatments. The answer involves a bacterium called Wolbachia , which colonizes the cells of up to 40 percent of insect species. And beyond its normal insect hosts, it also lives in filarial nematodes. No one is entirely sure what it does in the worms, but it is clearly essential.
The nematodes cannot complete their life cycles without these microbes. When the worms die, they release their Wolbachia into their hosts. In lab tests, he and others showed that removing the bacteria with antibiotics has fatal results for the worms. The larvae fail to mature. The existing adults stop reproducing. And after some time, their cells start to self-destruct. The process is slow, taking up to 18 months, but a slow death is still a death.
And since these worms have no Wolbachia to release, they can be slaughtered with impunity. In the s, Taylor and his colleagues showed that an antibiotic called doxycycline could eliminate Wolbachia from people with filariasis. In Ghana, Achim Hoerauf from the Bernhard Nocht Institute for Tropical Medicine found that doxycycline could sterilize female nematodes in villagers with river blindness.
A decline in lymphatic function makes it difficult for the body to fight infections from other bacteria, eventually leading to elephantiasis. Lymphedema advances rapidly and is associated with acute pain, fever, cold chills, and deformation of infected areas of the body.
There are two ways to diagnose lymphatic filariasis. One is verification of the presence or absence of microfilariae in the blood using a microscope. Since microfilariae generally move to peripheral blood at night, blood drawing must be done at night. The other method is a serological test antibody titers in blood serum. Whichever method is used, there have been a number of cases where lymphedema nevertheless developed several years after a patient was found negative, underscoring the difficulty of accurately diagnosing lymphatic filariasis.
Anthelmintics and other drugs for the treatment of lymphatic filariasis include diethylcarbamazine DEC , albendazole, and ivermectin. Of these three, the most effective against both microfilariae and adult worms with the fewest side effects is DEC. It is possible, however, that lymphedema and elephantiasis continue to develop even after the filariae are destroyed. Basic measures to prevent the symptoms from getting worse include sanitizing the swollen area and exercising to improve the flow of lymph fluid.
The most effective preventive measure against lymphatic filariasis is to avoid mosquito bites. It is best to wear long-sleeved shirts and long pants and to apply a mosquito repellent to exposed skin. Mosquito nets over bedding and other sleeping areas are also effective. It is therefore important to maintain hygiene in the home.
0コメント