HIV Modifies the Effect of Tobacco Smoking on Oral Human Papillomavirus Infection

BACKGROUND

People living with HIV (PLWH) are more likely to smoke and harbor oral human papillomavirus (HPV) infections, putting them at higher risk for head and neck cancer. We investigated effects of HIV and smoking on oral HPV risk.

METHODS

Consecutive PLWH (n = 169) and at-risk HIV-negative individuals (n = 126) were recruited from 2 US health centers. Smoking history was collected using questionnaires. Participants provided oral rinse samples for HPV genotyping. We used multivariable logistic regression models with interaction terms for HIV to test for smoking effect on oral HPV.

RESULTS

PLWH were more likely to harbor oral HPV than HIV-negative individuals, including α (39% vs 28%), β (73% vs 63%), and γ-types (33% vs 20%). HIV infection positively modified the association between smoking and high-risk oral HPV: odds ratios for smoking 3.46 (95% confidence interval [CI], 1.01-11.94) and 1.59 (95% CI, .32-8.73) among PLWH and HIV-negative individuals, respectively, and relative excess risk due to interaction (RERI) 3.34 (95% CI, -1.51 to 8.18). RERI for HPV 16 was 1.79 (95% CI, -2.57 to 6.16) and 2.78 for β1-HPV (95% CI, -.08 to 5.65).

CONCLUSION

Results show tobacco smoking as a risk factor for oral HPV among PLWH.

Oral Human Papillomavirus Infection and Oral Lesions in HIV-Positive and HIV-Negative Dental Patients

We evaluated the risk factors associated with oral human papillomavirus (HPV) infection and oral lesions in 161 human immunodeficiency virus (HIV)-positive patients and 128 HIV-negative patients presenting for oral examination at 2 urban healthcare centers. Patients were interviewed on risk factors and provided oral-rinse samples for HPV DNA typing by polymerase chain reaction. Statistical associations were assessed by logistic regression. Oral HPV was prevalent in 32% and 16% of HIV-positive patients and HIV-negative patients, respectively, including high-risk HPV type 16 (8% and 2%, respectively; P = .049) and uncommon HPV types 32/42 (6% and 5%, respectively; P = .715). Among HIV-negative patients, significant risk factors for oral HPV included multiple sex partners (≥21 vs ≤5; odds ratio [OR], 9.1; 95% confidence interval [CI], 1.7-49.3), heavy tobacco smoking (>20 pack-years vs none; OR, 9.2; 95% CI, 1.4-59.4), and marijuana use (OR, 4.0; 95% CI, 1.3-12.4). Among HIV-positive patients, lower CD4(+) T-cell count only was associated with oral HPV detection (≤200 vs ≥500 cells/mm(3); OR, 4.5; 95% CI, 1.3-15.5). Detection of high-risk HPV was also associated with concurrent detection of potentially cancerous oral lesions among HIV-negative patients but not among HIV-positive patients. The observed risk factor associations with oral HPV in HIV-negative patients are consistent with sexual transmission and local immunity, whereas in HIV-positive patients, oral HPV detection is strongly associated with low CD4(+) T-cell counts.

Predictions of malaria vector distribution in Belize based on multispectral satellite data

Use of multispectral satellite data to predict arthropod-borne disease trouble spots is dependent on clear understandings of environmental factors that determine the presence of disease vectors. A blind test of remote sensing-based predictions for the spatial distribution of a malaria vector, Anopheles pseudopunctipennis, was conducted as a follow-up to two years of studies on vector-environmental relationships in Belize. Four of eight sites that were predicted to be high probability locations for presence of An. pseudopunctipennis were positive and all low probability sites (0 of 12) were negative. The absence of An. pseudopunctipennis at four high probability locations probably reflects the low densities that seem to characterize field populations of this species, i.e., the population densities were below the threshold of our sampling effort. Another important malaria vector, An. darlingi, was also present at all high probability sites and absent at all low probability sites. Anopheles darlingi, like An. pseudopunctipennis, is a riverine species. Prior to these collections at ecologically defined locations, this species was last detected in Belize in 1946.

Predictions of adult Anopheles albimanus densities in villages based on distances to remotely sensed larval habitats

Remote sensing is particularly helpful for assessing the location and extent of vegetation formations, such as herbaceous wetlands, that are difficult to examine on the ground. Marshes that are sparsely populated with emergent macrophytes and dense cyanobacterial mats have previously been identified as very productive Anopheles albimanus larval habitats. This type of habitat was detectable on a classified multispectral System Probatoire d'Observation de la Terre image of northern Belize as a mixture of two isoclasses. A similar spectral signature is characteristic for vegetation of river margins consisting of aquatic grasses and water hyacinth, which constitutes another productive larval habitat. Based on the distance between human settlements (sites) of various sizes and the nearest marsh/river exhibiting this particular class combination, we selected two groups of sites: those located closer than 500 m and those located more than 1,500 m from such habitats. Based on previous adult collections near larval habitats, we defined a landing rate of 0.5 mosquitoes/human/min from 6:30 PM to 8:00 PM as the threshold for high (> or = 0.5 mosquitoes/human/min) versus low (< 0.5 mosquitoes/human/min) densities of An. albimanus. Sites located less than 500 m from the habitat were predicted as having values higher than this threshold, while lower values were predicted for sites located greater than 1,500 m from the habitat. Predictions were verified by collections of mosquitoes landing on humans. The predictions were 100% accurate for sites in the > 1,500-m category and 89% accurate for sites in the < 500-m category.

Preliminary observations on the changing roles of malaria vectors in southern Belize

A survey for larval and adult Anopheles mosquitoes was conducted in Toledo District of southern Belize during August-September 1992. We surveyed for larvae in 145 habitats and conducted paired indoor-outdoor collections of adult mosquitoes landing on humans at 6 houses. In 1940-41, Kumm and Ram reported Anopheles darlingi females to be the most common Anopheles mosquitoes inside houses and reported no specimens of Anopheles vestitipennis in southern Belize. In our 1992 survey we found no An. darlingi mosquitoes either as adults or larvae. More An. vestitipennis females were captured indoors than outdoors, whereas most Anopheles albimanus and Anopheles apicimacula females were captured outdoors. All 3 species were represented occasionally in 145 collections of larvae from diverse habitats. Anopheles vestitipennis now appears to be a potentially important vector of malaria during the wet season in Toledo District.

Relationship of iron administration to susceptibility of newborn pigs to enterotoxic colibacillosis

To determine whether supplemental iron (Fe) administration to newborn pigs reared in concrete pens not only prevents anemia, but renders the pigs more susceptible to Escherichia coli-induced diarrheal disease, pigs were given a large or a small dose of Fe IM or orally before or after challenge exposure with E coli. The controls were challenge-exposed pigs not given Fe and pigs not challenge exposed (Fe-treated and nontreated groups). Although the mortality of the pigs challenge exposed with E coli and administered a large oral dose of Fe shortly after birth was greater than that of the challenge-exposed pigs given no Fe, differences in mortality were not noted between any of the groups tested when the Fe was injected IM. The Fe-treated survivors had severe diarrhea (oral Fe administration) or mild diarrhea (IM Fe administration) for longer periods than did the nontreated survivors. All challenge-exposed pigs treated with a large dose of Fe gained less weight than the nontreated pigs during the diarrheal period and for several days thereafter. Beyond this time period, the weight gain of the Fe-treated pigs was substantially greater than that of their nontreated littermates; the weight gain of the pigs given a small dose of Fe was intermediate. Hemoglobin and hematocrit values of the pigs shortly after birth and weekly thereafter revealed that within 2 weeks, both sets of values from the pigs treated with a large dose of Fe were within acceptable laboratory limits and substantially greater than the values obtained for the nontreated pigs, which were severely anemic.