Endemic Kaposi's sarcoma: incidence and risk factors in the West Nile District of Uganda

Endemic Kaposi's Sarcoma

Kaposi's sarcoma (KS) is a common neoplasm in Eastern and central Africa reflecting the spread of human gammaherpesvirus-8 (HHV-8), now considered a necessary causal agent for the development of KS. The endemic KS subtype can follow an aggressive clinical course with ulcerative skin lesions with soft tissue invasion or even bone or visceral involvement. In the latter cases, a thorough imaging work-up and better follow-up schedules are warranted. As KS is a chronic disease, the therapeutic goal is to obtain sustainable remission in cutaneous and visceral lesions and a good quality of life. Watchful monitoring may be sufficient in localized cutaneous forms. Potential therapeutic modalities for symptomatic advanced KS include systemic chemotherapies, immunomodulators, immune checkpoint inhibitors, and antiangiogenic drugs.

A prospective study of clinical outcomes of HIV-associated and HIV-negative Kaposi sarcoma in Uganda

OBJECTIVE

Improved understanding of the effect of HIV infection on Kaposi sarcoma (KS) presentation and outcomes will guide development of more effective KS staging and therapeutic approaches. We enrolled a prospective cohort of epidemic (HIV-positive; HIV + KS) and endemic (HIV-negative; HIV - KS) KS patients in Uganda to identify factors associated with survival and response.

METHODS

Adults with newly diagnosed KS presenting for care at the Uganda Cancer Institute (UCI) in Kampala, Uganda, between October 2012 and December 2019 were evaluated. Participants received chemotherapy per standard guidelines and were followed over 1 year to assess overall survival (OS) and treatment response.

RESULTS

Two hundred participants were enrolled; 166 (83%) had HIV + KS, and 176 (88%) were poor-risk tumor (T1) stage. One-year OS was 64% (95% confidence interval [CI] 57-71%), with the hazard of death nearly threefold higher for HIV + KS (hazard ratio [HR] = 2.93; P  = 0.023). Among HIV + KS, abnormal chest X-ray (HR = 2.81; P  = 0.007), lower CD4 + T-cell count (HR = 0.68 per 100 cells/μl; P  = 0.027), higher HIV viral load (HR = 2.22 per log 10  copies/ml; P  = 0.026), and higher plasma Kaposi sarcoma-associated herpesvirus (KSHV) copy number (HR = 1.79 per log 10  copies/ml; P  = 0.028) were associated with increased mortality. Among HIV - KS, factors associated with mortality included Karnofsky score <70 (HR = 9.17; P  = 0.045), abnormal chest X-ray (HR = 8.41; P  = 0.025), and higher plasma KSHV copy number (HR = 6.21 per log 10  copies/ml; P  < 0.001).

CONCLUSIONS

Although survival rates were better for HIV - KS than HIV + KS, the high mortality rate seen in both groups underscores the urgent need to identify new staging and therapeutic approaches. Factors associated with mortality, including high plasma KSHV, may serve as important targets of therapy.

Comparative transcriptome analysis of endemic and epidemic Kaposi's sarcoma (KS) lesions and the secondary role of HIV-1 in KS pathogenesis

In sub-Saharan Africa, endemic Kaposi's sarcoma (EnKS) is still prevalent despite high incidence of epidemic Kaposi's sarcoma (EpKS) resulting from the on-going HIV-1 epidemic. While KSHV is clearly the etiologic agent of KS, the mechanisms underlying KS development are not fully understood. For example, HIV-1 co-infection and concomitant immune dysfunction have been associated with EpKS development. However, the direct or indirect role(s) of HIV-1, and therefore of immune suppression, in EpKS remains unclear. How, or whether, EpKS is mechanistically distinct from EnKS is unknown. Thus, the absence of HIV-1 co-infection in EnKS provides a unique control for investigating and deciphering whether HIV-1 plays a direct or indirect role in the EpKS tumor microenvironment. We hypothesized that HIV-1 co-infection would induce transcriptome changes that differentiate EpKS from EnKS, thereby defining the direct intra-tumor role of HIV-1 in KS. Comparison of ART-treated and -naïve patients would further define the impact of ART on the KS transcriptome. We utilized RNA-seq followed by multiparameter bioinformatics analysis to compare transcriptomes from KS lesions to uninvolved control skin. We provide the first transcriptomic comparison of EpKS versus EnKS, ART-treated vs-naïve EpKS and male vs female EpKS to define the roles of HIV-1 co-infection, the impact of ART, and gender on KS gene expression profiles. Our findings suggest that ART-use and gender have minimal impact on transcriptome profiles of KS lesions. Gene expression profiles strongly correlated between EpKS and EnKS patients (Spearman r = 0.83, p<10-10). A subset of genes involved in tumorigenesis and inflammation/immune responses showed higher magnitude, but not unique dysregulation in EnKS compared to EpKS. While gender and ART had no detectable contribution, the trend toward higher magnitude of gene dysregulation in EnKS coupled with the absence of HIV-1 transcripts in EpKS may suggest an indirect or systemic effect of HIV-1 to promote KS tumorigenesis.

Viral and Immunological Analytes are Poor Predictors of the Clinical Treatment Response in Kaposi's Sarcoma Patients

Kaposi’s sarcoma-associated herpes virus (KSHV) is the etiologic agent for Kaposi’s sarcoma (KS). The prognostic utility of KSHV and HIV-1 (human immunodeficiency virus) viremia as well as immunological parameters in clinical management of participants with KS is unclear. The objective of this study was to investigate viral and immunological parameters as predictors of KS treatment responses in participants with KS from sub-Saharan Africa (SSA). Plasma KSHV-DNA, HIV-1 viral load, total anti-KSHV antibody, KSHV-neutralizing antibody (nAb), cytokine/chemokine levels, and T-cell differentiation subsets were quantified before and after KS treatment in 13 participants with KS and in 13 KSHV-infected asymptomatic control individuals. One-way analysis of variance and the Mann-Whitney t-test were used to assess differences between groups where p-values < 0.05 were considered significant. Subjects with patch and plaque KS lesions responded more favorably to treatment than those with nodular lesions. Pre-treatment and post-treatment levels of plasma KSHV-DNA, HIV-1 viral load, KSHV-Ab responses, cytokines, and T-cell populations did not predict the KS treatment response. Elevated KSHV-humoral and cytokine responses persisted in participants with KS despite a clinical KS response. While patch and plaque KS lesions were more common among treatment responders, none of the analyzed viral and immunological parameters distinguished responders from non-responders at baseline or after treatment.

Similar Immunological Profiles Between African Endemic and Human Immunodeficiency Virus Type 1-Associated Epidemic Kaposi Sarcoma (KS) Patients Reveal the Primary Role of KS-Associated Herpesvirus in KS Pathogenesis

BACKGROUND

Kaposi sarcoma (KS)-associated herpesvirus (KSHV) is etiologically linked to all KS forms, but mechanisms underlying KS development are unclear. The incidence of KS in human immunodeficiency virus type 1-infected (HIV-1+) individuals implicates immune dysregulation; however, the lack of characterization of KSHV immune responses in endemic KS makes the role of HIV-1 unclear. The study objective was to investigate the HIV-1 and KSHV roles in viral nucleic acid detection, antibody responses, and cytokine responses in polymerase chain reaction-confirmed epidemic KS and endemic KS patients and non-cancer controls from sub-Saharan Africa.

METHODS

KSHV viral DNA (vDNA), total anti-KSHV antibody, KSHV neutralizing antibody (nAb), and cytokines were quantified.

RESULTS

KSHV vDNA was detectable in tumors but variably in plasma and peripheral blood mononuclear cells. Consistent with elevated antibody-associated cytokines (interleukin [IL] 6, IL-5, and IL-10), nAb titers were higher in epidemic KS and endemic KS patients than in controls (P < .05). Despite HIV-1 coinfection in epidemic KS, nAb titers were similar between epidemic KS and endemic KS patients (P = 0.3).

CONCLUSIONS

Similarities in antibody and cytokine responses between epidemic and endemic KS patients suggest that KSHV drives KS pathogenesis, whereas HIV-1 exacerbates it.

Variability in the Incidence of Classic Kaposi's Sarcoma in the Veneto Region, Northern Italy

The incidence of Kaposi's sarcoma was estimated in the Veneto Region, Italy (age ≥50; 1990-96). Rates were higher in the coast and alpine valleys; in the latter there was an excess of cases for both sexes combined (SIR = 191.1; CI = 113.2-302.0). The hypothesis that birthplace/residency in areas abundant with bloodsucking insects may be a risk factor is discussed.

Metagenomic Virome Analysis of Culex Mosquitoes from Kenya and China

Many blood-feeding arthropods are known vectors of viruses that are a source of unprecedented global health concern. Mosquitoes are an integral part of these arthropod vectors. Advancements in next-generation sequencing and bioinformatics has expanded our knowledge on the richness of viruses harbored by arthropods. In the present study, we applied a metagenomic approach to determine the intercontinental virome diversity of Culex quinquefasciatus and Culex tritaeniorhynchus in Kwale, Kenya and provinces of Hubei and Yunnan in China. Our results showed that viromes from the three locations were strikingly diverse and comprised 30 virus families specific to vertebrates, invertebrates, plants, and protozoa as well as unclassified group of viruses. Though sampled at different times, both Kwale and Hubei mosquito viromes were dominated by vertebrate viruses, in contrast to the Yunnan mosquito virome, which was dominated by insect-specific viruses. However, each virome was unique in terms of virus proportions partly influenced by type of ingested meals (blood, nectar, plant sap, environment substrates). The dominant vertebrate virus family in the Kwale virome was Papillomaviridae (57%) while in Hubei it was Herpesviridae (30%) and the Yunnan virome was dominated by an unclassified viruses group (27%). Given that insect-specific viruses occur naturally in their hosts, they should be the basis for defining the viromes. Hence, the dominant insect-specific viruses in Kwale, Hubei, and Yunnan were Baculoviridae, Nimaviridae and Iflaviridae, respectively. Our study is preliminary but contributes to growing and much needed knowledge, as mosquito viromes could be manipulated to prevent and control pathogenic arboviruses.

Risk factors for seropositivity to Kaposi sarcoma-associated herpesvirus among children in Uganda

BACKGROUND

Determinants of Kaposi sarcoma-associated herpesvirus (KSHV) seropositivity among children living in sub-Saharan African populations where infection is endemic are not well understood. Local environmental factors, including other infectious agents, may be key.

METHODS

Within the context of a well-characterized birth cohort, we examined associations between various factors and antibodies against KSHV, measured in stored plasma samples from 1823 mother-child pairs in Entebbe, Uganda.

RESULTS

Seroprevalence increased with increasing age of the child (P = 0.0003) and was higher among those with KSHV seropositive mothers than in those without (12% vs 9%; odds ratio: 1.4, 95% confidence interval: 1.1 to 2.0). It was also higher among children with HIV infection (29% vs 10%; odds ratio: 3.1, 95% confidence interval: 1.2 to 8.3) or malaria parasitemia (30% vs 10%; odds ratio: 4.1, 95% confidence interval: 2.4 to 7.0) than in children without. These associations were not explained by socioeconomic status.

CONCLUSIONS

The finding that KSHV serostatus is associated with malaria parasitemia in children is novel. In a country endemic for KSHV, malaria may be a cofactor for KSHV infection or reactivation among children.

Distribution of 'promoter' sandflies associated with incidence of classic Kaposi's sarcoma

The patchy geographical distributions of classic Kaposi's sarcoma (KS) and human herpesvirus type 8 (HHV-8), better known as Kaposi's sarcoma-associated herpesvirus (KSHV) remain unexplained. It has been proposed that certain species of bloodsucking insects ('promoter arthropods') promote the reactivation of HHV-8/KSHV and facilitate both HHV-8/KSHV transmission and KS development. This hypothesis was tested by sampling the presence and density of human-biting Diptera with CDC light traps in two areas of Sardinia with contrasting incidence rates of classic KS. In total, 11,030 specimens (99.9% sandflies and 0.1% mosquitoes) belonging to 10 species were collected from 40 rural sites. Five of these species are considered to be possible promoter arthropods because of the irritation their bites cause: Phlebotomus perniciosus Newstead; Phlebotomus perfiliewi Parrot (Diptera: Psychodidae); Aedes berlandi Seguy; Culiseta annulata (Schrank) and Culex theileri Theobald (Diptera: Culicidae). Five species are probable 'non-promoters' because their bites are not particularly irritating: Culiseta longiareolata (Macquart); Culex pipiens s.l.; Anopheles algeriensis Theobald; Anopheles maculipennis s.l., and Anopheles plumbeus Stephens. A significant correlation was found between the geographical distribution of promoter arthropods and incidence rates of KS (Spearman's r = 0.59,P < 0.01). Promoter arthropods were more likely to be caught in areas with cutaneous leishmaniasis and a past high prevalence of malaria, and in areas of limestone, acid volcanic soil and cereal cultivation. The study supports the association between promoter arthropods and classic KS, which may explain the geographic variability of KS and HHV-8/KSHV, and highlights the links with a number of variables previously associated with the incidence of KS.

Role of environmental factors in the pathogenesis of classic and African-endemic Kaposi sarcoma

Kaposi sarcoma (KS) is a mesenchymal tumour associated with human herpesvirus-8 (HHV-8) infection. However, the incidence of HHV-8 infection is far higher than the prevalence of KS, suggesting that viral infection per se is not sufficient for the development of aggressive phenotype and that one or more additional cofactors are required. The great geographical variation in African-endemic and classic KS incidence points to a role for environmental factors in the etiology of Kaposi sarcoma. However, there are few unequivocably established environmental factors involved in KS pathogenesis. This review focuses on the environmental factors thought to be associated with KS, more particularly iron exposure and facilitation of transmission of HHV-8 infection by contact with blood-sucking arthropods.

Distribution of mosquito species in areas with high and low incidence of classic Kaposi's sarcoma and seroprevalence for HHV-8

The 'promoter-arthropod' hypothesis, which postulates that exposure to the bites of certain species of haematophagous arthropods is an environmental risk cofactor linked to human herpes virus 8 (HHV-8) and Kaposi's sarcoma, was investigated in the Po River valley, northern Italy. The presence and density of adult female mosquitoes (Diptera: Culicidae) was determined by CDC light trap catches in two adjacent districts, at variance with respect to Kaposi's sarcoma incidence and HHV-8 seroprevalence. A total of 3910 specimens belonging to 11 species was collected in 34 rural sites (six municipalities) representative of the two districts. Five of these species are considered to be possible 'promoters' because of the irritation their bites cause humans: Aedes vexans (Meigen) and Ae. caspius (Pallas) (87% of sampled promoters), Culex modestus Ficalbi, Culiseta annulata (Schrank) and Coquillettidia richiardii (Ficalbi). Six are probable 'non-promoters': Cx. pipiens s.l., Cx. martinii Medschid, Anopheles claviger (Meigen), An. maculipennis s.l., An. plumbeus Stephens and Uranotaenia unguiculata Edwards. The density of promoters by site was correlated with the incidence rates of Kaposi's sarcoma at the district level (Pearson's r = 0.33, P = 0.06) and at the municipal level (r = 0.50, P< 0.01). Similar correlations emerged for non-promoters (r = 0.48, P< 0.01 and r = 0.42, P = 0.01, respectively). The density of promoters was higher than that of non-promoters in sites with livestock (odds ratio, OR = 2.8, 95% CI 2.2-3.6) and in municipalities with Kaposi's sarcoma cases (OR = 2.5, 95% CI 1.7-3.5). The study provides additional evidence of the association between the density of some mosquito species and Kaposi's sarcoma.

Capacity building for the clinical investigation of AIDS malignancy in East Africa

PURPOSE

To build capacity in the resource-poor setting to support the clinical investigation and treatment of AIDS-related malignancies in a region of the world hardest hit by the AIDS pandemic.

METHODS

An initial MEDLINE database search for international collaborative partnerships dedicated to AIDS malignancies in developing countries failed to identify any leads. This search prompted us to report progress on our collaboration in this aspect of the epidemic. Building on the formal Uganda-Case Western Reserve University (Case) Research Collaboration dating back to 1987, established NIH-supported centers of research excellence at Case, and expanding activities in Kenya, scientific and training initiatives, research capital amongst our institutions are emerging to sustain a international research enterprise focused on AIDS and other viral-related malignancies.

RESULTS

A platform of clinical research trials with pragmatic design has been developed to further enhance clinical care and sustain training initiatives with partners in East Africa and the United States. An oral chemotherapy feasibility trial in AIDS lymphoma is near completion; a second lymphoma trial of byrostatin and vincristine is anticipated and a feasibility trial of indinavir for endemic Kaposi's sarcoma is planned.

CONCLUSIONS

In the absence of published reports of evolving international partnerships dedicated to AIDS malignancy in resource constrained settings, we feel it important for such progress on similar or related international collaborative pursuits to be published. The success of this effort is realized by the long-term international commitment of the collaborating investigators and institutions to sustain this effort in keeping with ethical and NIH standards for the conduct of research; the provision of formal training of investigators and research personnel on clinical problems our East African partners are faced with in practice and the development of pragmatic clinical trials and therapeutic intervention to facilitate technology transfer and enhance clinical practice.

Water, socioeconomic factors, and human herpesvirus 8 infection in Ugandan children and their mothers

BACKGROUND

Human herpesvirus 8 (HHV-8) infection is common in sub-Saharan Africa, but its distribution is uneven. Transmission occurs during childhood within families by unclear routes.

METHODS

We evaluated 600 Ugandan children with sickle cell disease and their mothers for factors associated with HHV-8 seropositivity in a cross-sectional study. HHV-8 serostatus was determined using an HHV-8 K8.1 glycoprotein enzyme immunoassay. Odds ratios for seropositivity were estimated using logistic regression, and factor analysis was used to identify clustering among socioeconomic variables.

RESULTS

One hundred seventeen (21%) of 561 children and 166 (34%) of 485 mothers with definite HHV-8 serostatus were seropositive. For children, seropositivity was associated with age, mother's HHV-8 serostatus (especially for children aged 6 years or younger), lower maternal education level, mother's income, and low-status father's occupation (P < 0.05 for all). Using communal standpipe or using surface water sources were both associated with seropositivity (OR 2.70, 95% CI 0.80-9.06 and 4.02, 95% CI 1.18-13.7, respectively) as compared to using private tap water. These associations remained, albeit attenuated, after adjusting for maternal education and child's age (P = 0.08). In factor analysis, low scores on environmental and family factors, which captured household and parental characteristics, respectively, were positively associated with seropositivity (P(trend) < 0.05 for both). For mothers, HHV-8 seropositivity was significantly associated with water source and maternal income.

CONCLUSIONS

HHV-8 infection in Ugandan children was associated with lower socioeconomic status and using surface water. Households with limited access to water may have less hygienic practices that increase risk for HHV-8 infection.

Identifying space-time disease clusters

A cluster of cases of disease that are close both in space and in time is suggestive of an infectious aetiology. We present statistical tests for space-time clusters of disease for the two situations where the population at risk is either known or unknown as a function of space and time. The tests are derived using standard statistical methodology from a simple mathematical model of disease spread, i.e. they are derived as score tests from a likelihood function in which the infection process is modelled as a point process whose intensity becomes greater near an infector. A problem for such tests is that, when investigating whether or not a disease may be of infectious origin, the space and time distances characterising closeness to an infection are very likely to be unknown. The proposed methodology copes with this difficulty in a statistically acceptable way, without requiring multiple tests whose interpretation would be doubtful. When the underlying population size is unknown, the test reduces to a modification of the Knox test. An example of its use is given as epidemiology, risk, space-time cluster, likelihood and Knox test.

Causality or coincidence: may the slow disappearance of helminths be responsible for the imbalances in immune control mechanisms?

Intestinal infection continues to be a problem worldwide and helminths, which currently infect billions of individuals, are primary culprits. The major burden of disease falls on the populations of developing countries, given that over the last four to five decades helminth infections are disappearing in industrialized societies. In developing countries, a major source of immunomodulatory signals in post-natal life are parasites, particularly helminths, which, unlike most bacteria and viruses, selectively stimulate Th2 function. Helminths and their eggs are probably the most potent stimulators of mucosal Th2 responses. Responses elicited by worms can modulate immune reactions to other parasites, bacterial, viral infections and several unrelated diseases. Bacterial and protozoal infections may also protect against atopy and asthma, through the induction of the Th1 regulatory responses. Today, people in developed countries often live in ultra-hygienic environments, avoiding exposure to viruses, bacteria, ectoparasites and endoparasites, particularly helminths. Perhaps failure to acquire worms and experience mucosal Th2 conditioning predisposes to unrelated diseases. In contrast to this hypothesis it has also been suggested that Th2 responses can make the host more susceptible to other important diseases and to contribute to the spread of them.

Risk factors for Kaposi's sarcoma: a case-control study of HIV-seronegative people in Uganda

As part of a larger investigation of cancer in Uganda, we conducted a case-control study of Kaposi's sarcoma in human immunodeficiency virus-1 (HIV)-seronegative adults presenting at hospitals in Kampala. Cases comprised 117 HIV-seronegative patients with Kaposi's sarcoma and controls comprised 1,282 HIV-seronegative patients with a provisional diagnosis of cancer other than Kaposi's sarcoma. Study participants were interviewed about social and lifestyle factors, tested for HIV and, if there was sufficient sera, for antibodies against Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8 [HHV8]), using an immunofluorescent assay. Independent effects of these factors were identified using unconditional logistic regression, after adjusting for age group (<30, 30-44, 45+) and sex. Antibody status for KSHV was available for 68% (80) of cases and for 45% (607) of controls. Among cases, 78% (91) were male and 57% (66) were over the age of 35. Cases were more likely than controls to be from tribal groups other than the Baganda (p = 0.05), to have higher household incomes (p = 0.003), to have left their home region at younger ages (p < 0.001), to own goats or pigs (p = 0.02) and to rarely or never use shoes (p < 0.001). Similar results were obtained when analyses were restricted to cases and controls with anti-KSHV antibodies. The seroprevalence of KSHV was 79% (63/80) in those with Kaposi's sarcoma as compared to 50% (302/607) in those without (chi(2) heterogeneity (1 df) = 21.0; p < 0.001) and the risk of the tumour increased with increasing anti-KSHV antibody titres (chi(2) trend (1 df) = 29.7; p < 0.001). The risk of Kaposi's sarcoma is clearly linked to antibody status for KSHV, but it would seem that in Uganda other factors are also important in the development of the tumour.

Human herpesvirus 8 (HHV-8) in the pathogenesis of Kaposi's sarcoma and other diseases

The discovery of Kaposi's Sarcoma-associated herpesvirus/human herpesvirus-8 (KSHV/ HHV-8) and subsequent studies of this virus have provided a body of evidence that support the concept that this is an etiologic agent for Kaposi's sarcoma (KS). Several studies have indicated that this virus may also be a causal agent for primary effusion lymphoma (PEL) and Castleman's disease as well. First generation serologic assays for HHV-8 have now been developed. The preponderance of data suggest that the incidence of HHV-8 infection is highest in populations at risk for KS: male homosexuals, immunosuppressed patients, and those who live in endemic regions. HHV-8 encodes for functional homologs of human proteins that may play a role in the development of disease. As we learn more about the steps by which this virus can lead to KS and/or other diseases, rational therapies and preventative strategies may be possible.

Risk factors for Kaposi's sarcoma in HIV-positive subjects in Uganda

BACKGROUND

Kaposi's sarcoma (KS) is associated epidemiologically with HIV infection and with human herpesvirus 8 (HHV-8 or KSHV). Both KS and HIV infection are common in Uganda. We conducted a case-control study of 458 HIV-seropositive. Ugandan adults with KS and 568 HIV-seropositive subjects without KS to examine risk factors for HIV-associated KS.

METHODS

We recruited newly diagnosed adult KS cases from five hospitals in Kampala, Uganda and controls from a large referral clinic for HIV infection at Mulago Hospital. All cases and controls were counselled and tested for HIV and answered an interviewer-administered questionnaire about their home, socio-economic conditions, lifestyle and sexual behaviour before they became ill. Only HIV-seropositive subjects were included in the analysis.

RESULTS

There were 295 males and 163 females with KS and 227 male and 341 female controls. Age distribution was similar but there was a higher proportion of cases (45%) than controls (29%) residing in rural regions of Uganda. KS cases were more likely than controls to have a higher level of education (X2 for trend, 4.8; P = 0.03), to have occupations associated with affluence [chi 2 for heterogeneity, 17.3 on 5 degrees of freedom (df); P = 0.004] and to come from larger settlements [adjusted odds ratio (OR) for settlements of > 1000 versus 10-99 houses, 1.8; 95% confidence interval (CI), 1.1-3.0]. Cases were more likely than controls to have high household income (chi 2 for trend, 32.6; P < 0.001) and other markers of urban or rural wealth such as owning several cows (chi 2 for trend, 9.5; P = 0.002). Cases were more likely to travel away from home (adjusted OR, 1.6; 95% CI, 1.1-2.3) and more likely to have spent increasing time in contact with water (chi 2 for trend, 12.3; P < 0.001). Few indices of sexual behaviour were related to risk of KS, including reported number of sexual partners. Cases were more likely than controls to be married to one rather than several spouses (adjusted OR, 1.6; 95% CI, 1.2-2.2) and to have reported a history of sexually transmitted diseases (STD) (adjusted OR, 1.6; 95% CI, 1.2-2.3).

CONCLUSIONS

Among HIV-infected subjects, KS cases are characterized by better education and greater affluence, compared with controls. Urban address, travel away from home, exposure to water, monogamous marriage and self-reported STD were also more frequent among KS cases than controls. The higher socio-economic status of persons with HIV and KS may be a marker for enhanced exposure to a possibly sexually transmitted agent, or for a delayed exposure to a childhood infection. The risk posed by exposure to water among KS cases requires further study.

Herpesvirus-like DNA sequences detected in endemic, classic, iatrogenic and epidemic Kaposi's sarcoma (KS) biopsies

The identification of Kaposi's sarcoma (KS) clusters in sub-equatorial Africa (endemic KS, AKS) and the high frequency of KS in sexually transmitted AIDS (epidemic KS, EKS), have previously suggested a role for infectious agents in the etiopathogenesis of KS. The recent identification of herpesvirus (HHV)-like DNA sequences in one case of EKS and their detection in > 90% of all tested EKS, prompted us to determine the prevalence of these viral sequences in all types of KS, such as AKS, EKS, classic KS (CKS) and iatrogenic KS (IKS). The presence of herpesvirus(HHV)-like DNA sequences has been examined in 61 KS skin tumors obtained from Greece, Italy, USA, Uganda and Kenya. All KS types (100%) were positive by polymerase chain reaction (PCR) and Southern-blot analysis, while 5 out of 6 (83%) and 4 out of 7 (57%) uninvolved autologous skin biopsies from AKS and CKS patients, respectively, were positive for HHV-like sequences. All samples from non-KS patients were negative, i.e. 17 human biopsies from healthy individuals or patients affected by other pathologies, 5 human cell lines and 15 peripheral blood mononuclear cells (PBMC) from HIV-positive subjects. These results suggest that HHV-like sequences play a major role in the pathogenesis of this neoplasm.

International variations in the incidence of childhood soft-tissue sarcomas

In the study of international childhood cancer incidence coordinated by the International Agency for Research on cancer, soft-tissue sarcomas comprised between 4 and 8% of all cancers between 0 and 14 years of age. Among predominantly white populations, the age-standardised annual incidence rate (ASR) for all soft-tissue sarcomas was between 5 and 9 per million. The most common histological subtypes were rhabdomyosarcoma (ASR 4-7 per million) and fibrosarcoma, including other malignant fibromatous tumours (ASR 1-2 per million). In the United States the incidence of rhabdomyosarcoma for black girls was only half that for white girls, while the rates for boys were similar in the two ethnic groups; fibrosarcoma had a higher incidence among black people than white people for both sexes. Throughout most of Asia, soft-tissue sarcomas almost invariably had a total ASR below 6 per million, rhabdomyosarcoma and fibrosarcoma again being the most common histological types. In Africa, incidence rates could not generally be calculated, but there were substantial numbers of registrations for rhabdomyosarcoma and fibrosarcoma. The majority of cases of Kaposi's sarcoma were in African children, and in eastern and southern Africa where Kaposi's sarcoma is endemic among adult men it comprised 25-50% of soft-tissue sarcomas and 2-10% of all childhood cancers; the sex ratio (M/F) was 2.2:1, in contrast to the overwhelming male predominance among adults. Variations between ethnic groups in the incidence of rhabdomyosarcoma and fibrosarcoma, together with their occurrence in a number of heritable syndromes, suggest that genetic predisposition is important in their aetiology. There was little evidence for an environmental aetiology in rhabdomyosarcoma and fibrosarcoma but an infectious agent may be responsible for childhood Kaposi's sarcoma.

Cancer in Kampala, Uganda, in 1989-91: changes in incidence in the era of AIDS

Re-establishment of the cancer registry in Kyadondo County, Uganda, has allowed estimation of incidence rates for the period September 1989 to December 1991. The results are compared with earlier data from the same area, and from other African cancer registries. The most striking feature is the emergence of Kaposi's sarcoma as the leading cancer in males (almost half of all registered cases) and the second most frequent (17.9%) in females. This parallels the evolution of the epidemic of AIDS. There were also marked increases in the incidence of both oesophageal and prostatic carcinoma, while the incidence of cancer of the penis and the urinary bladder declined, possibly as a result of improved standards of hygiene. In females, the incidence of cancer of the cervix has more than doubled since the 1950s, and is now among the highest recorded in the African continent.

Kaposi's sarcoma and non-Hodgkin's lymphoma in European AIDS cases. No excess risk of Kaposi's sarcoma in Mediterranean countries

Prior to the AIDS epidemic, Kaposi's sarcoma (non-AIDS-KS) in Europe was mainly a disease of elderly Mediterranean men. In 1989 AIDS data from 15 European countries were collected to study proportional trends in AIDS-related Kaposi's sarcoma (AIDS-KS) in order to determine whether specific factors in Southern Europe might be important in the development of KS among AIDS patients. Another AIDS-related cancer, non-Hodgkin's lymphoma (NHL) was included as a malignancy control. Of 22,367 AIDS cases reported, 3,779 (16.9%) were KS and 741 (3.3%) were NHL. A significant, continuous fall in the percentage of AIDS-KS was seen for both homosexual men and other members of exposure groups during the period 1981-89 (p-trend less than 0.0001). The proportion with AIDS-KS decreased from 40.5% in 1983 to 26.5% in 1988 in homosexual men and from 12.2 to 3.6% in other exposure groups, respectively. No significant change was observed in the proportion of NHL cases among any of the risk groups over time, although a tendency towards a slight increase was noted for homosexual men. Comparing proportional trends of KS and NHL geographically, no significant difference was found overall, by time or by exposure group. In conclusion, a specific decline is observed over time for AIDS-KS. However, if geographically-restricted factors are important in the development of non-AIDS-KS in Europe, the same factors do not appear to affect the risk of AIDS-KS.

Epidemiology of Kaposi's sarcoma in Sweden prior to the acquired immunodeficiency syndrome

We studied retrospectively 529 cases of Kaposi's sarcoma (KS) reported to the Swedish Cancer Registry between 1958 and 1982 to determine incidence rates, survival and rate ratios, together with the frequency and types of associated malignancies. The age-standardized (Swedish population 1970) incidence rate generally increased over the time period, with a mean of 0.27 cases per 100,000 population per year (males 0.40, females 0.14). The incidence rate ratio (based on 5-year intervals and relative to the earliest period) reached 2.06 for males and 3.76 for females in the 1968-1972 interval, while the actual peak occurred between 1971 and 1974 for both sexes. Poisson regression modelling suggested a transient shift in the age-specific male incidence rate pattern with a relative increase of the disease in younger age groups (p = 0.05) up to 1968-1972. The age-adjusted male:female ratio did not change significantly from 2.9 during the period of study. In relation to the general population, 18% fewer men and 24% fewer women were alive 10 years after the diagnosis had been made. Ninety-nine (19%) cases had other primaries, of which 17 were neoplasms of lymphocytic origin. Lymphoproliferative malignancy was 2.5 times (95% CI 1.38, 4.37) more common than expected in patients with KS (in particular in females) but a definite increase in other malignancies was not apparent. It is questionable whether immune dysfunction due to other malignant disease or drug therapy can account for the epidemiologic changes in KS, which began almost 2 decades prior to the AIDS epidemic in Sweden.

Clinical and histopathological aspects of Kaposi's sarcoma in Africa: relationship with HIV serology

From 1983 to 1987, 45 Kaposi's sarcomas (KS) were diagnosed at the University Hospital in Bangui; 37 cases were easily classified as either endemic or AIDS-related KS on clinical grounds and HIV serology. Moreover, probably due to the stage at which patients consulted and lesions were sampled, noticeable histopathological differences were observed between the two clinical presentations. But for 8/45 which we classified as "borderline KS", strong discrepancies occurred between clinical aspects, patient evolution, HIV serology and histopathology. In two cases, HIV-positive patients had typical endemic non-evolutive KS and have survived 15 and 36 months.

Connective tissue responses in blacks in relation to disease: further observations

Additional information is presented in support of the hypothesis (Polednak: Am. J. Phys. Anthropol. 41:49-58, 1974) that in some black populations certain connective-tissue responses, which are involved in protection against infection and repair after injury, also may predispose to specific chronic diseases. These diseases include some autoimmune disorders (i.e., systemic lupus erythematosus, sarcoidosis, and scleroderma) and various benign and malignant tumors involving connective-tissue cells. Complex interactions between genetic factors (HLA and non-HLA loci) and environmental agents may be involved both in the etiology of these autoimmune diseases and in population differences in the incidence of these diseases. A framework is reviewed whereby cellular responses to infectious agents, involving chiefly immunoglobulin-producing cells and macrophages, may have consequences in terms of pathogenesis of specific chronic diseases more common in some black populations. The possible role of natural selection in maintaining some of these diseases is also considered, along with the need for involvement of biomedical anthropologists in their investigation.

Kaposi's sarcoma: a trifactorial model

To explain the epidemiology of Kaposi's sarcoma, including its predominance in men, I present a theory based on three concurrent factors: immunodeficiency, exposure to a specific viral agent, and a recessive, highly prevalent X-linked regulatory gene. The X-linked locus is inferred from comparing the aberrant lymphaticovenous nature of immature lesions with absence of lymphaticovenous connections in XO karyotypes. The theory predicts that for heterosexual populations without sex differences in viral exposure or degree of immunodeficiency, the male-to-female ratio of Kaposi's sarcoma will equal the inverse of the lesion's frequency causative virus. In addition, an increased incidence of Kaposi's sarcoma is expected outside of the context of the acquired immunodeficiency syndrome as the causative virus is transmitted separately from the human immunodeficiency virus.

HLA studies of endemic African Kaposi's sarcoma patients and matched controls: no association with HLA-DR5

In the search for a genetic factor involved in the etiology of Kaposi's sarcoma, several studies have recently focused on a significantly increased HLA determinant, DR5, as well as a decreased DR3, among patients with both the classical and the AIDS-related form of Kaposi's sarcoma. To test the consistency of this phenomenon, we analysed the frequencies of HLA immunogenetic markers in 23 histologically confirmed Kaposi's sarcoma patients from Central Africa, where this tumor is endemic, and a local sex- and tribe-matched control group. No definite association was observed for any of the HLA antigens, including DR5 and DR3. We were not able to support the hypothesis that the same HLA-associated immune susceptibility factors are involved in all types of Kaposi's sarcoma.

AIDS in Africa: an epidemiologic paradigm

Cases of the acquired immune deficiency syndrome (AIDS) have been reported in countries throughout the world. Initial surveillance studies in Central Africa suggest an annual incidence of AIDS of 550 to 1000 cases per million adults. The male to female ratio of cases is 1:1, with age- and sex-specific rates greater in females less than 30 years of age and greater in males over age 40. Clinically, AIDS in Africans is often characterized by a diarrhea-wasting syndrome, opportunistic infections, such as tuberculosis, cryptococcosis, and cryptosporidiosis, or disseminated Kaposi's sarcoma. From 1 to 18% of healthy blood donors and pregnant women and as many as 27 to 88% of female prostitutes have antibodies to human immunodeficiency virus (HIV). The present annual incidence of infection is approximately 0.75% among the general population of Central and East Africa. The disease is transmitted predominantly by heterosexual activity, parenteral exposure to blood transfusions and unsterilized needles, and perinatally from infected mothers to their newborns, and will continue to spread rapidly where economic and cultural factors favor these modes of transmission. Prevention and control of HIV infection through educational programs and blood bank screening should be an immediate public health priority for all African countries.

Cancer in Haiti 1979-84: distribution of various forms of cancer according to geographical area and sex

Haiti exemplifies all of the problems of developing countries: poverty, hunger, reduced longevity, and an illiteracy rate of more than 75%. It is, therefore, not surprising that so little attention has been given to late-onset chronic diseases, particularly cancer. The results of a special survey of cancer cases first diagnosed in 1979-84 are presented, with relative proportions of cancers by site, according to age, sex and geographical area of origin (coastal vs. mountain). The major cancers recorded were: stomach and intestine, primary hepatic (especially in males), cervix, penis, and Kaposi's sarcoma (KS). There were 18 cases of KS, all of which occurred among AIDS patients. Among males, hepatic cancers accounted for a significantly larger percentage of cancer cases in the mountain vs. coastal origin group, while the reverse was true for penile cancer and KS. These preliminary data on cancer in Haiti are discussed with particular reference to dietary factors (for cancers of stomach, intestine, liver and cervix). The clarification and confirmation of these possible relationships between diet and cancer should provide an opportunity to elucidate environmental factors as causes of cancer.

HTLV-III serology distinguishes atypical and endemic Kaposi's sarcoma in Africa

Serum samples from African patients with Kaposi's sarcoma and acquired-immuno-deficiency-syndrome-related (AIDS-related) disorders and from normal subjects in Uganda and Zambia were tested for antibodies to the human T-lymphotropic retroviruses (HTLV) types I, II, and III. Nearly 90% of patients with AIDS-related disorders or with atypical, aggressive Kaposi's sarcoma were seropositive for HTLV-III in both countries, whereas only 17% of patients with classic endemic Kaposi's sarcoma were seropositive. Among the controls 20% were seropositive for HTLV-III in Uganda but only 2% in Zambia. None of the subjects tested had antibodies to HTLV-I or HTLV-II. These results are further evidence of the emergence of a clinically atypical form of Kaposi's sarcoma in Africans, which resembles that seen in American patients with AIDS, and which is associated with HTLV-III infection. The low frequency of antibodies to HTLV-III in the normal Zambian population together with the first appearance of HTLV-III-associated diseases during the past 2 years suggests that this virus is new to Zambia, although it may have been present in Uganda for longer.