HUMAN PARASITOLOGY – UNIT 4 4.1 Opportunistic parasitic infections in people with HIV or AIDS
Owing to their weakened immune state, people living with HIV/AIDS are more vulnerable to infections. These so-called 'opportunistic infections' may not be fatal in a person without HIV infection; however, they are a major cause of morbidity and death among patients with low CD4 counts or who are in the advanced stages of AIDS. Opportunistic infections are caused by bacteria (e.g. tuberculosis, bacterial pneumonia), fungus (e.g. candidiasis, cryptococcosis, Pneumocystis jiroveci pneumonia), protozoan parasites (e.g. toxoplasmosis, cryptosporidiosis) and viruses (e.g. herpes simplex, herpes zoster).
In addition to opportunistic infections, people living with HIV/AIDS are susceptible to a number of HIV/AIDS-associated malignancies (cancers) such as Kaposi’s sarcoma, lymphoma, and squamous cell carcinoma. These, too, can have a devastating impact on the health status of people with HIV/AIDS, even those being treated with antiretroviral therapy.
(a) Bacterial Infections:
Children with HIV are at an increased risk of acquiring tuberculosis. Tuberculosis is a common cause of acute and chronic respiratory disease and death in HIV-infected children living in areas of high tuberculosis prevalence. Even with treatment, infected children with tuberculosis have a worse outcome than HIV-uninfected children. Hence preventing tuberculosis infection and disease in HIV-infected children is desirable and potentially an important public health intervention. Isoniazid, an anti-tuberculosis medication, has been used to effectively prevent tuberculosis in HIV-uninfected children, but there are currently no guidelines on the use of tuberculosis-preventive therapy in HIV-infected children. This review evaluates the impact of tuberculosis-preventive therapy on tuberculosis incidence and death in HIV-infected children.
(b) Fungal Infections
Pneumocystis jiroveci pneumonia in patients with HIV infection: Pneumocystis jiroveci pneumonia remains the most common opportunistic infection in patients infected with HIV, and mortality rate among co-infected people is 10% to 20% during the initial infection of Pneumocystis jiroveci pneumonia and increases substantially with the need for mechanical ventilation. In these patients’ corticosteroids adjunctive to standard treatment for Pneumocystis jiroveci pneumonia may prevent the need for mechanical ventilation and decrease mortality. This review assesses the effects of adjunctive corticosteroids on overall mortality and the need for mechanical ventilation in HIV-infected patients with Pneumocystis jiroveci pneumonia and substantial hypoxemia.
Oropharyngeal candidiasis associated with HIV infection in adults and children: Oral candidiasis associated with HIV infection occurs commonly and recurs frequently, often presenting as an initial manifestation of the disease. Left untreated, these lesions contribute considerably to the morbidity associated with HIV infection. Interventions aimed at preventing and treating HIV-associated oral candidal lesions form an integral component of maintaining the quality of life for affected individuals.
Vulvovaginal candidiasis in women with HIV infection: Vulvovaginal candidiasis is one of the most common fungal infections that recur frequently in HIV-infected women. Symptoms of vulvovaginal candidiasis are pruritis, discomfort, dyspareunia, and dysuria. Vulval infection presents as a morbiliform rash that may extend to the thighs. Vaginal infection is associated with white discharge, and plaques are seen on erythematous vaginal walls. Even though rarely or never resulting in systemic fungal infection or mortality, left untreated these lesions contribute considerably to the morbidity associated with HIV infection. Prevention and treatment of this condition is an essential part of maintaining the quality of life for these individuals.
(c) Protozoan Infections
Cryptosporidiosis in immunocompromised patients: Cryptosporidiosis is a disease that causes diarrhoea lasting about one to two weeks, sometimes extending up to two and a half months among the immunocompetent, and becoming a more severe life-threatening illness among immunocompromised individuals. Cryptosporidiosis is common in HIV-infected individuals. This review assesses the efficacy of interventions for the treatment and prevention of cryptosporidiosis among immunocompromised individuals.
Toxoplasmic encephalitis in HIV‐infected adults: Cerebral toxoplasmosis or toxoplasmic meningoencephalitis was one of the first opportunistic infections to be described in HIV-infected patients. Treatment of toxoplasmic meningoencephalitis has been relatively successful in comparison to other opportunistic infections, but the optimal management of toxoplasmic meningoencephalitis is important if the benefits of subsequently initiating highly active antiretroviral therapy are to be seen. This review assesses the most effective therapy for toxoplasmic meningoencephalitis in HIV-infected adults. Different treatment regimens have been compared with regard to clinical and radiological response, mortality, morbidity, and serious adverse events.
4.2 Sexually transmitted parasites
These STIs are caused by parasites passed from person-to-person during sexual activity. There are 3 in this category: Trichomoniasis, Pubic Lice and Scabies.
(a) Trichomoniasis (Trich) : Trichomoniasis, or trich (pronounced “trick”), is a common STI that usually has very few symptoms. It is caused by an infection of microscopic parasites called Trichomonas vaginalis. For women, these parasites may infect the vagina, urethra, bladder or cervix. In men, the infection is usually in the urethra, or under the foreskin of uncircumcised men. Trichomoniasis is spread through sexual contact with an infected person. Symptoms: Many people, particularly men, will not have symptoms of a trich infection. If symptoms do appear, they usually appear within one week of infection, though they can take up to six months. For some
people, symptoms may go away and then return later. About half of women will have symptoms of a trich infection. In men, trichomoniasis is rare and most men will not have symptoms. For women, symptoms may include: •Discharge from the vagina, •Vaginal odour, •Pain during intercourse or urination, •Irritation or itchiness of the vagina.
For men symptoms may include: •mild discharge, •irritation or redness at the top of the penis, •burning during urination, •Men may often become unknowing carriers of trich infections. Treatment is required to ensure that a trich infection is completely gone.
Prevention: The best way to help prevent Trichomoniasis is to use a condom each and every time. Testing : Testing may be done by physical examination or lab testing to detect the parasite. In some cases, the tiny sores caused by trichomoniasis may be detected during a routine pap test for women; however, pap smears do not specifically test for sexually transmitted infections.
Treatment : Typically, trichomoniasis can be treated with a single oral dose of an antibiotic called Metronidazole. However, Trichomonas can be reacquired easily so it is important that both partner(s) be treated together.
Impact if not treated : In rare cases, trichomoniasis can cause pelvic inflammatory disease (PID) in women, which can cause infertility, chronic pelvic pain or ectopic pregnancy. If a pregnant woman is infected with Trichomonas, it may cause premature delivery or low birth weight. Trich can cause small sores and inflammation, which can increase the risk of HIV transmission. Detection and treatment of a Trichomonas infection will help lower your risk of contracting HIV.
Prevention : Trichomoniasis is easily treated, but One’s partner(s) may not have symptoms. Also, if One is with a partner who’s infected, they can reinfect you after one had treatment. Telling a partner about a trichomoniasis infection may be embarrassing, but it’s important to be very honest with your partner(s). Let them know so that they can get tested and treated if necessary.
When to have sex again? : Ask your health care professional when receiving treatment about when you can have sex again. Do not have sex again if you or your partner(s) have not fully completed treatment, or if you are still displaying symptoms of infection. Remember, you can become reinfected immediately after your infection clears up. As always, it’s a very good idea to use condoms to help prevent sexually transmitted infections and trichomoniasis reinfection.
Public Lice in Female and Male
What are crabs/pubic lice? : Measuring in at about a millimetre tall, pubic lice (phthirus pubis) are tiny crab-like insects that nest in pubic hair. They bury their heads into the skin and live off human blood, laying their egg sacks (nits) near the base of the pubic hairs. A substance they secrete into the skin can cause intense itching, and the bites of adult lice turn small patches of skin to a bluish-grey colour. Unlike head lice, pubic lice have small, wide bodies and arms that resemble crabs. These lice can also be found in chest, armpit and facial hair, eyebrows and eyelashes.
How are crabs/public lice spread?: Pubic lice can be spread during intimate contact. They do this by crawling from one person to another, since they have no wings. Pubic lice also can live for one to two days in bedding, towels and clothing belonging to an infected individual, and these items can be a source of transmission. Lice are not related to poor hygiene. Anyone can get lice, though it’s most common among sexually active people and in situations where individuals are in close contact.
Prevention :
•Avoid sharing towels and clothing that have not been washed. •If it can’t be washed, vacuum it.
•When trying on underwear or a bathing suit at the store always wear something underneath.
Symptoms : Pubic lice and nits are small and can be difficult to spot. Infected individuals may experience: •Skin irritation and inflammation accompanied by itchiness and redness.
•Small blue spots on the skin where lice have bitten.
•Louse feces , fine black particles, in the infected person’s undergarments.
Testing: Healthcare professionals inspect the area for the crabs and the small greyish-white eggs they lay. Adult lice can easily be identified just by looking at the area with a magnifying glass, or viewing a sample of the area under a microscope.
Treatment :
Non-prescription shampoo that can be purchased at a pharmacy, clinic or doctor’s office. Usually one wash is all it takes. In cases where a second washing is needed, apply it four days after the first treatment. The pharmacist will be able to help you.
A fine-toothed comb or the fingernails can be used to scrape the eggs off the hairs. It’s important to tell recent sex partners so they can be treated at the same time.
Clothes, bedding, and other possible contaminated items should be washed in hot water or dry cleaned, or bagged for a week. Items that cannot be washed or bagged should be vacuumed. Shaving may not necessarily get rid of the problem
Impact if not treated : •It won’t go away on its own.
What to tell the partner: Pubic lice are easily treated, but your partner(s) may not know they have them. Telling a partner about pubic lice may be embarrassing, but it’s important to be very honest with your partner(s). All sexual partners who have had contact with an infected person in the month before diagnosis should be tested and treated to help prevent reinfestation. If you’re with a partner who’s infected, they can reinfect you after you’ve had treatment, so it’s best to get treated at the same time. When can I have sex again? : Ask your healthcare professional when receiving treatment about when you can have sex again. Do not have sex again if you or your partner(s) have not fully completed treatment, or if you are still displaying symptoms of infection. Remember, you can become reinfected immediately after your infection clears up.
Scabies
What are scabies?: Scabies are parasitic mites that dig holes (burrow) under the surface of the skin and lay eggs. The larvae that hatch move to new areas of the body and spread the infection. Mites prefer warm areas such as the folds of skin on the elbows, wrists, buttocks, knees, shoulder blades, waist, breasts, and penis, between the fingers, and under the nails.
How are scabies transmitted? : Scabies are spread through close contact with someone who is infected. Scabies can live for three days on clothing, towels and bedding. These can be a source of transmission, but that is much less likely than skin to skin contact.Mites are not related to poor hygiene. Anyone can get scabies, though it’s most common among sexually active people and in situations where individuals are in close contact.
Prevention :
•Avoid sharing unwashed towels and clothing. •If it can’t be washed, vacuum it.
•If you’re shopping for a bathing suit, wear your underclothes while trying things on in the change room.
What are the symptoms? :
Within three to four weeks of infestations an infected person could experience:
•Intense itchiness, especially at night-time or after bathing. This is caused by an allergic reaction to the mites’ feces.
•Reddish rash on fingers, wrists, armpits, waist, nipples, or penis.
•With reoccurrences, the same symptoms occur more rapidly within hours to days of a re-infestation. •Severe infections are commonly seen in people with compromised immune systems or HIV. The skin can become scaly or crusty, requiring more complex and aggressive treatment.
Testing and diagnosis : Diagnosing scabies can be difficult and timely, but a healthcare professional examines the area to determine if the patient is infected. A sample may be scraped from the skin and analyzed under a microscope if necessary.
Treatment :
•A special lotion the doctor prescribes is applied to the whole body.
•Some treatments are available without a prescription, ask your pharmacist
•Clothes, towels, bedding and other possible contaminated items should be washed with hot water or drycleaned, or bagged for three days to one week. This kills the mites.
•tems that cannot be cleaned should be vacuumed.
Impact if not treated
•Persistent scratching or irritated skin can cause a secondary bacterial infection.
What to tell the partner : All household contacts and recent sexual partners within the past month should be treated to prevent re-infestation. Scabies is easily treated, but your partner(s) may not have symptoms. Also, if you’re with a partner who’s infected, they can reinfect you after you’ve had treatment. Telling a partner about a scabies infection may be embarrassing, but it’s important to be very honest with your partner(s). Let them know so that they can get tested and treated if necessary.
When can one have sex again? Ask your healthcare professional when receiving treatment about when you can have sex again. Do not have sex again if you or your partner(s) have not fully completed treatment, or if you are still displaying symptoms of infection. Remember, you can become reinfected immediately after your infection clears up.
4.3 Parasitic infections in people with immunodeficiency, cancer and transplant recipients.
(a) Leiomyosarcoma and leiomyoma in children with HIV infection : Smooth muscle tumour composed of leiomyoma and leiomyosarcoma recently has been described in many HIV-infected children. Leiomyosarcoma has become the second most frequent malignancy in children with HIV infection or other immunodeficiency diseases in the United States. Although leiomyosarcoma accounts for only 2% to 4% of childhood soft tissue sarcomas, the prognosis is poor in HIV-infected patients compared with non-infected people. The development of Epstein–Barr virus-associated smooth muscle tumour in children with AIDS decreases health, reduces quality of life, and often
results in death. Some researchers, therefore, ascribe cause of death to smooth muscle tumour in the majority of these cases, not to AIDS. Currently, the optimal therapeutic strategy is controversial, and there is a need to identify the efficacy and safety of different interventions for AIDS-associated smooth muscle tumour on overall survival and disease-free survival in children. This review assesses the effectiveness of current therapeutic interventions for previously untreated children with AIDS-associated leiomyoma and leiomyosarcoma.
(b) AIDS‐associated Non‐Hodgkin´s Lymphoma : HIV infection is known to be associated with an increased risk of non-Hodgkin's lymphoma, but the treatment of non-Hodgkin's lymphoma is not standardized. The majority of lymphomas (>80%) occurring during immunosuppression are aggressive B-cell in origin and have a high-to-intermediate histology grade. This review assesses the clinical effectiveness and safety of single-agent or combination chemotherapy with or without immunochemotherapy (rituximab) and with or without highly active antiretroviral therapy on overall survival and disease-free survival for previously untreated patients with AIDS-related non-Hodgkin's lymphoma.
(c) AIDS‐associated Hodgkin´s lymphoma : Hodgkin's disease is the most common non-AIDS-defining malignancy in HIV-infected patients. Its unusually aggressive tumour behaviour includes a higher frequency of unfavourable histologic subtypes, high-stage and extranodal involvement by the time of presentation (anal canal, stomach), and poor therapeutic outcome, in comparison with Hodgkin's disease outside the HIV setting. The optimal therapeutic strategy is still controversial, and median overall survival is short, ranging from 12 to 18 months. This review assesses the effects of different interventions for treating AIDS-associated Hodgkin's disease, including chemotherapy, bone marrow transplantation, and gene therapy on overall survival and disease-free survival in treatment-naive adults with AIDS.
(d) Squamous cell carcinoma of the conjunctiva in HIV‐infected individuals : Squamous cell carcinoma of the conjunctiva is a rare, slow-growing tumour of the eye, normally affecting elderly men around 70 years of age. In Africa, however, the disease is different. The incidence is rising rapidly, affecting young persons (around 35 years of age), and usually affecting women. It is more aggressive, with a mean history of three months at presentation. This pattern is related to the co-existence of the HIV/AIDS pandemic, high human papillomavirus exposure, and solar radiation in the region. Various interventions exist, but despite therapy, there is a high recurrence rate (up to 43%) and poor cosmetic results in late disease. This review evaluates the effect of interventions for treating squamous cell carcinoma of the conjunctiva in HIV-infected individuals on local control, recurrence, death, time to recurrence, and adverse events.
