Intestinal Parasites and HIV Infection

ABSTRACTS & COMMENTARY

Synopsis: Opportunistic infections with intracellular intestinal protozoa (i.e., Cryptosporidium parvum, Cyclospora cayatanensis, Isospora belli, and the various species of microsporidia) are well documented to cause uncontrollable, debilitating diarrhea in patients with AIDS worldwide. Little has been reported on the presence of other protozoan and helminth infections in HIV seropositive individuals in developing countries.

Sources: Lindo JE, et al. Intestinal parasitic infections in human immunodeficiency virus (HIV)-positive and HIV-negative individuals in San Pedro Sula, Honduras. Am J Trop Med Hyg 1998;58:431-435; Chintu C, et al. Human immunodeficiency virus-associated diarrhea and wasting in Zambia: Selected risk factors and clinical associations. Am J Trop Med Hyg. 1998;59:38-41.

Reports indicate that up to 50% of persons living in Central and South America are infected with intestinal parasites including Entamoeba histolytica, Giardia lamblia, Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercoralis, and hookworm. Slim disease, a chronic diarrhea and wasting syndrome, occurs in approximately 50% of patients with AIDS in Africa. Tuberculosis is the only other medical complication that may be equally as important for African HIV-infected patients. One might expect non-opportunistic parasites to contribute to the morbidity of HIV-infected patients living in developing countries, given the high prevalence of intestinal parasites in general. Both opportunistic and non-opportunistic parasites may contribute to serious nutritional deficiencies in AIDS patients and HIV-infected individuals, such as stunting, wasting, protein losing enteropathy (common with T. trichiura infection), iron deficiency anemia (hookworm infections), anorexia, and malabsorption (associated with S. stercoralis).

Honduras has the largest number of HIV-infected persons in Central America. The epidemiology of intestinal parasites in AIDS patients living in Honduras had not been well documented until recently. A report in the American Journal of Tropical Medicine and Hygiene reviews interesting findings from a cross-sectional study of the frequency and distribution of intestinal parasites in HIV-seropositive and HIV-seronegative individuals from San Pedro Sula, Honduras. A subsequent report examined the clinical features of diarrhea and wasting in HIV-infected patients in Zambia, an area that has one of the highest rates of HIV infection in the world.

Fifty-two HIV-seropositive patients, 16 of whom had diarrhea, and 48 HIV-seronegative individuals, were recruited from four Hondouran hospitals and a correctional institution setting where patients sought medical attention for diarrhea and/or HIV care. All those who reported symptoms of diarrhea agreed to participate, eliminating selection bias from this study. HIV testing was performed on all patients regardless of their reported HIV status (Abbott Diagnostics; microhemagglutination assay, Chicago, IL). The definition of AIDS in this cohort was based upon the presence of HIV-related opportunistic infections including tuberculosis, rather than simply low CD4 counts.

Of those who were HIV-infected, 20 of 52 individuals also had an AIDS diagnosis; only four HIV-seropositive persons with diarrhea had AIDS. Seven HIV-seropositive persons with diarrhea did not have an AIDS diagnosis. No difference in the frequency of symptoms was shown between the patients who were HIV positive vs. those who had AIDS. Interestingly, of the HIV-infected group, pathogenic intestinal parasites were diagnosed more frequently among persons who did not have diarrhea than among those who did.

All individuals in the HIV-seronegative group had self-reported diarrhea at the start of the study, and less than half (16 of 52) of the HIV-seropositive patients had diarrhea at the time of enrollment. There were no statistically significant differences in the mean age of the HIV-positive group compared to the HIV-negative group; however, there were significantly more male participants in the HIV-positive group.

The table shows the distribution of intestinal parasites detected. In the total study population, 58% harbored at least one parasite. Only 49% of stools from HIV-infected persons harbored intestinal parasites, compared with 64.6% of HIV-negative individuals; 15.4% of HIV-positive persons were infected with two or more parasites, but 32.3% of HIV-negative persons had multiple infections. This represents a trend toward harboring one or multiple parasites within the HIV-seronegative group of patients, when compared with those who were HIV seropositive.

Table

Distribution of Intestinal Parasites in HIV-Positive and -Negative Patients in San Pedro Sula, Honduras

Helminths

HIV-positive (n = 52)

HIV-negative (n = 48)

Trichuris trichiura

11 (21.2%)

19 (39.6%)

Hookworm

9 (17.3%)

4 (8.3%)

Strongyloides stercoralis

4 (7.7%)

0

Ascaris lumbricoides

1 (1.9%)

10 (20.8%)

Taenia sp.

1 (1.9%)

0

Hymenolepis nana

1 (1.9%)

0

Protozoans

   

Entamoeba histolytica

3 (5.8%)

7 (14.6%)

Giardia lamblia

1 (1.9%)

6 (12.5%)

Cryptosporidium parvum

4 (7.7%)

0

Cyclospora caytenensis

1 (1.9%)

0

Entamoeba coli

4 (7.7%)

2 (4.2%)

Chilomastix mesnili

1 (1.9%)

1 (2.1%)

Blastocystis hominis

1 (1.9%)

0

Iodamoeba butschlii

0

1 (2.1%)

Balantidium coli

0

1 (2.1%)

Dientamoeba fragilis

0

1 (2.1%)

    Adapted from: Lindo JE, et al. Am J Trop Med Hyg 1998;58:433.

In terms of specific parasites, these HIV-seronegative individuals were significantly more likely to have G. lamblia, 10 times more likely to have A. lumbricoides, and twice as likely to have T. trichiura than their HIV-positive counterparts. Hookworm, Entamoeba coli, and E. histolytica demonstrated similar prevalence rates, which were not significantly different. Microsporidia were not detected in either group. Four cases of Cryptosporidium parvum and S. stercoralis and one case of Cyclospora cayatanensis were detected exclusively in HIV-positive persons.

COMMENT BY MARIA D. MILENO, MD

Some clear trends in the prevalence of specific parasites infecting patients from Honduras are described here, which may help to guide diagnosis and therapy for HIV-infected patients and to advise such travelers. Common parasitic infections, such as giardiasis and ascariasis, appear unchanged in the presence of HIV infection with regard to their disease severity.1 Previous studies in Zambia, Zaire, and Tanzania,2 have revealed the presence of intracellular and mucosal parasites in the HIV-positive individuals, with a higher prevalence of extracellular and lumenal parasites in those who are HIV negative. Possible reasons for these patterns of parasite distribution include HIV enteropathy, or infection by the HIV virus throughout the gastrointestinal tract, which causes significant structural and functional impairment leading to diarrheal symptoms independent of the presence of enteric pathogens. HIV-associated gastrointestinal pathology may actually produce an unfavorable environment for the establishment and survival of other enteric pathogens, specifically those that are extracellular and luminal. Therapy directed against HIV using highly active antiretroviral therapy (HAART) is important in the management of symptoms due to HIV enteropathy. Improving the immune system can also mitigate disease due to other opportunistic parasitic infections, such as C. parvum.1,3 It is not known how the non-opportunistic group might be affected.

Another study conducted in Lusaka, Zambia, described important associations with chronic diarrhea in patients with HIV infection in that region. Specific pathogens were not identified. Selected clinical features associated with HIV infection in children and adults include the following features. In children, weight loss and clinical tuberculosis were clearly associated with HIV infection, and HIV-infected children were diagnosed more frequently as having marasmus. In adults, chronic diarrhea, weight loss, lymphadenopathy, and skin eruption were statistically related to the presence of HIV infection. Weight loss, wasting, and death in 262 HIV-infected children and adults occurred more commonly in persons between 31 and 45 years old and were significantly related to chronic diarrhea and the presence of persistent cough. Increased mortality was associated with chronic diarrhea and the presence of lymphadenopathy, after adjusting for other risk factors. While parasitologic diagnosis was not a part of this analysis, a significant degree of morbidity due to concomitant diarrhea in HIV-infected persons was confirmed. Of note, since 1993, three foodborne outbreaks of cryptosporidiosis have been reported in the United States.4 It cannot be overemphasized that patients with HIV infection are at risk for diarrheal pathogens; even those who reside here can get sick in their own backyard. A focus on safe water for drinking and proper food preparation may prevent enteric infections.

References

    1. Mileno MD, Bia FJ. The Compromised Traveler. Infect Dis Clin North Am 1998;12:369-412.

    2. Gomez Morales MA, et al. Opportunistic and non-opportunistic parasites in HIV-positive and negative patients with diarrhea in Tanzania. Tropical Med Parasitol 1995;46:109-114.

    3. Ramratnam B, et al. A practical approach to managing diarrhea in the HIV-infected person. The AIDS Reader 1997;Nov/Dec:87-94.

    4. Centers for Disease Control and Prevention. Foodborne outbreak of cryptosporidiosis-Spokane, WA, 1997. MMWR Morb Mortal Wkly Rep 1998;47:565-567.