Treatment and Prevention of Toxoplasmosis

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Toxoplasmosis (also known as "toxo") in an infectious disease caused by a single-celled parasite known as Toxoplasma gondii. In the vast majority of cases, a toxo infection will be mild and resolve on its own without treatment. If treatment is needed, it would typically involve one or more antibiotic or antimalarial drugs able to clear the infection.

However, during pregnancy or in people with compromised immune systems, aggressive treatment may be required to either control or prevent infection and avoid serious complications of infection. This is especially true in cases of advanced HIV infection.

Acute Treatment

In people with normal immune systems, up to 90 percent of T. gondii infections will have no symptoms at all. Those that do will often be mild and easily mistaken for the flu, even by a doctor. On the off chance toxo is diagnosed, the doctor will most often recommend bed rest and maybe an over-the-counter (OTC) pain reliever like Tylenol (acetaminophen) or Advil (ibuprofen).

Treatment is primarily recommended for people with compromised immune systems who don’t have the immune defenses to fight off an infection. These mainly include people with advanced HIV infection but can also involve organ transplant recipients and people undergoing cancer chemotherapy (both of whom commonly take immune suppressive drugs).

Recommended Therapies

To treat an acute (active) infection, doctors will prescribe antibiotics and other medications able to clear the infection and prevent the disease from progressing. The most commonly prescribed medications include:

  • Pyrimethamine, an antimalarial drug considered the most effective agent in treating an acute toxo infection
  • Sulfadiazine, an antibiotic drug used in combination with pyrimethamine
  • Clindamycin, an alternative antibiotic used alongside pyrimethamine
  • Minocycline, an antibiotic used only when a person is resistant to both sulfadiazine and clindamycin
  • Folinic acid used as a supplement to reduce the risk of thrombocytopenia (low platelets)

The six-week therapy would involve a daily dose of pyrimethamine, four daily doses of the chosen antibiotic, and a daily dose of folinic acid. To prevent recurrence, the antibiotic drug trimethoprim and sulfamethoxazole (TMP-SMX) would be taken once daily for four weeks.

In Pregnancy

Tthe transmission of T. gondii from mother to child is rare unless the mother has HIV and is severely immune compromised. Among these mothers, treatment is commonly prescribed to prevent fetal infection.

Scientists remain less certain about mothers with normal immune function. Even if a toxo infection were to occur, there remains considerable debate as to how effective antibiotics are in preventing transmission, particularly since it can be difficult to diagnose toxoplasmosis during pregnancy.

To this end, specialist care should be sought if you are pregnant and are at increased risk of toxoplasmosis. Treatment is typically prescribed as follows:

  • If an acute infection occurs during the first trimester, spiramycin would be prescribed from the time of diagnosis to the time of delivery.
  • After the first trimester (or if fetal infection has been confirmed), pyrimethamine, sulfadiazine, and folinic acid would be used from diagnosis to delivery.

Pediatric Recommendations

Treatment is strongly recommended for newborns whose HIV-positive mothers were diagnosed with T. gondii during pregnancy. This is true whether or not the mother had symptoms or was given preventive therapy. The duration of treatment (pyrimethamine, sulfadiazine, and folinic acid) can vary but may last for as long as 12 months.

If the infant or child is diagnosed with toxoplasmosis and HIV, TMP-SMX would be prescribed along with HIV therapy. The TMP-SMX would be used to prevent toxoplasmic encephalitis (the most severe complication of congenital toxoplasmosis) and continued until such time as the HIV drugs are able to normalize the baby’s immune system.

In the event of toxoplasmic encephalitis, corticosteroids would be prescribed to reduce brain inflammation. Anticonvulsive drugs may also be used to prevent seizures.

In People With HIV

Toxoplasmosis in people with HIV can cause serious, and potentially life-threatening, illnesses affecting the brain, eyes, and lungs. In most cases, the disease will be caused by the reactivation of a past infection rather than a new one.

Without the immune defenses to control the infection, a person can quickly succumb to the illness unless immediate measures are taken to restore the immune function, clear the T. gondii infection, and treat the disease complication.

Antiretroviral Therapy

Toxoplasmosis in people with HIV is considered opportunistic because it can only cause disease when the immune system is too weak to stop it.

To this end, the only way to recover from toxoplasmosis is to restore the body immune defenses. Antiretroviral drugs do this by interfering with HIV's ability to replicate. While they cannot cure the disease, they keep the viral population as low as possible so that it can no longer infect and kill the immune cells that are meant to protect us.

Commonly prescribed in a combination of three drugs, antiretroviral therapy can restore the immune function even in severely ill people, often within the span of a few months. Treatment would be continued for a lifetime and include regular doctor visits to monitor your immune status and check for possible side effects.

Antibiotic Therapy

The treatment of a reactivated T. gondii infection is similar to that of an acute infection and may include:

  • Pyrimethamine, sulfadiazine, and folinic acid
  • Pyrimethamine, clindamycin, and folinic acid
  • Atovaquone (a potent antifungal) used in combination with pyrimethamine and folinic acid
  • Azithromycin (another common antibiotic), pyrimethamine, and folinic acid
  • Atovaquone and sulfadiazine

Once the infection is cleared, TMP-SMX would be prescribed to prevent recurrence and continued until such time as the antiretroviral drugs can restore immune function.

Treating Disease Complications

The three most common complications of toxoplasmosis in people with HIV are ocular toxoplasmosis (affecting the eyes), CNS toxoplasmosis (affecting the brain and nervous system), and pulmonary toxoplasmosis. The treatment of each would be directed by the severity of symptom and the health status of the affected individual.

Treatment options for ocular toxoplasmosis may include:

  • Systemic corticosteroids to help alleviate inflammation
  • Injections of corticosteroids and clindamycin into the eye
  • The surgical implantation of clindamycin pellets into the eye

Treatment options for CNS toxoplasmosis may include:

  • Systemic corticosteroids to reduce inflammation of the brain and central nervous system (CNS)
  • Anticonvulsive drugs to treat seizures

Treatment options for pulmonary toxoplasmosis may include:

  • Systemic corticosteroids to alleviate inflammation
  • TMX-SMP to treat an active pneumocystis infection of the lungs

Prophylactic Therapies

If you have HIV, prophylactic (preventive) medications may be prescribed if your immune system is compromised.

This can be determined by your CD4 count which measures the number of defensive CD4 T-cells your blood. In a healthy individual, the CD4 count would be between 800 and 1,500. In persons with a compromised immune system, that number would drop below 200.

To prevent toxoplasmosis, TMP-SMX would be prescribed in a daily dose as your CD4 count approaches the "danger zone" of 100. Along with your antiretroviral medication, you would continue taking TMP-SMX until such time as your CD4 count is well above 200 and is able to stay there. You can then stop the antibiotic and continue to take your HIV drugs.

Tools for Prevention

If you are pregnant or have a compromised immune system, you would need to take steps to avoid exposure to T. gondii in your daily life. These safeguards can protect you from toxoplasmosis far better than all of the treatments in the world.

Some of the most effective preventive measures include:

  • Wearing a pair of disposable gloves when cleaning the cat litter box or, better yet, having someone else do it
  • Wearing gloves when you are outdoor gardening
  • Cooking your meat, poultry, and fish well done
  • Peeling and washing any vegetables or fruits that come from the garden or farmer's market
  • Cleaning cutting boards, knives, or surfaces raw meat may have come into contact with
  • Avoiding unpurified water of any sort
  • Keeping your cat indoors
  • Feeding your cat only canned or dried food and avoiding raw or undercooked meats
  • Covering your child’s sandbox
  • Washing your hands thoroughly with hot water and soap after gardening, playing with your cat, preparing food, or cleaning the sandbox
  • Teaching your children proper handwashing skills
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