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A rapid mapping technique for the prevalence and distribution of onchocerciasis: a Cameroon case study.

A rapid and cheap method for mapping the endemicity levels of onchocerciasis in both forest and savanna areas, where the vectors are members of the Simulium damnosum complex, is described. The selection of the study communities is based on a general understanding of the vectors' ecology and biassed towards those at highest risk of onchocerciasis, although there must be adequate geographical coverage. In a case study in Cameroon, prevalences were determined, using the non-invasive nodule palpation technique, in samples, each of 30-50 adult males, from 49 villages in six study areas in Cameroon. The method proved effective in the rapid mapping of onchocerciasis distribution in all areas studied, in which the distribution patterns varied from the classical linear to diffuse, and in one area with an anomalous distribution. The method should prove of value in the design of national onchocerciasis control programmes.

Adult↗

Determinants of infant and early childhood mortality in Cameroon: the role of socioeconomic factors, housing characteristics, and immunization status.

This study examines factors impinging on the survival of children in Cameroon using longitudinal data collected by the United Nations Demographic Training and Research Institute of Yaoundé, Cameroon. It deals especially with the role of socioeconomic factors (mother's education, employment, marital status, ethnicity, and household income), housing characteristics (construction materials, power source, source of water supply, extent of crowding), and immunization status on infant and child mortality. Two-state parametric and nonparametric hazards models for the risk of death at any time within the course of the study are used, with and without accounting for unmeasured heterogeneity. Overall, overcrowding has robust deleterious effects on infant and child survival. As regards the effects of socioeconomic variables, the robustness of the effects of household income and ethnic differentials are unchanged, even after controlling for unmeasured heterogeneity; the deleterious effects of marital status are also apparent, but these effects are largely explained by unmeasured covariates. The data also suggest that the protective effects of full immunization status are robust and not contaminated by confounding factors, at least in the first 16 months of life. These findings provide solid ground to support immunization programs and efforts as a means to reduce significantly infant and child mortality.

Cameroon↗

V118I substitution in the reverse transcriptase gene of HIV type 1 CRF02_AG strains infecting drug-naive individuals in Cameroon.

We describe the resistance-associated substitutions that are present in the reverse transcriptase (RT) genes of HIV-1 CRF02_AG strains infecting drug-naive villagers of Cameroon. The 11 sequences analyzed were previously subtyped as CRF02_AG in the gag, pro, and env genes, and this work revealed that most (10/11) had a concordant subtype (CRF02_AG) in the pol gene, while one sequence had discordant subtype (A1) in the pol gene. Classification of the CRF02_AG sequences was further confirmed by recombination breakpoint analysis, which revealed a mosaic composition similar to the reference strain IbNG. Analysis of the RT genes for resistance-associated substitutions revealed two sequences containing a V118I substitution. Even though no other resistance-associated substitutions were found, the presence of V118I, which is implicated in resistance to reverse transcriptase inhibitors, in CRF02_AG strains infecting drug-naive individuals should be considered when introducing these antiretrovirals in areas where CRF02_AG is the predominant subtype, such as Cameroon.

Amino Acid Substitution↗

HIV type 1 genetic variability in the northern part of Cameroon.

In 1995, 53 blood samples from Muslim patients with AIDS, or who were thought to have AIDS, were collected in the main hospitals of Adamaoua Province, in the northern part of Cameroon. The variable env C2V3 region of HIV-1 was amplified by nested PCR and phylogenetically analyzed. The results indicated that of 15 amplified samples, 1 belonged to HIV-1 group O, 1 to HIV-1 subtype D, 1 to subtype G, 2 to subtype H, and 10 to subtype A. Furthermore, the northern Cameroonian subtype A could be divided into at least two subclusters as shown by the env tree as well as by two remarkably conserved hexameric amino acid sequences in the apex of V3 (GPGQAF in one subcluster and GPGQTF in the other). This distinction suggests that the HIV-1 subtype A circulating in northern Cameroon evolved from two main sources. More recently, three HIV-1 strains from Nigeria (IBNG) and Djibouti (DJ263 and DJ264), previously reported on the basis of their env C2V3 sequences as subtype A, were found to have a similar A/G mosaic structure alongside their full-length sequence and were tentatively designated as members of a new subtype called "IBNG." Interestingly, within the northern Cameroonian subtype A described, the isolates of the second subcluster clustered distinctly with these A/G mosaic strains, strongly suggesting that they may be members of the IBNG subtype.

Amino Acid Sequence↗

A new HTLV type II subtype A isolate in an HIV type 1-infected prostitute from Cameroon, Central Africa.

Among 332 female sex workers in Douala, Cameroon, 113 were HIV-1 seropositive, 3 were HTLV-I seropositive, and only 1 had specific anti-HTLV-II antibodies. By cocultivation with BJAB cells, an HTLV-II was isolated from the peripheral blood mononuclear cells of this 32-year-old woman coinfected by HIV-1. This new African HTLV-II isolate (PH230PCAM) belongs to the molecular subtype A, exhibiting, however, a nucleotide variability of 2.4% and 0.8%, vis-à-vis the MO prototype, in the LTR and in the gp21 env gene, respectively. These data, as well as the previous findings of another HTLV-II subtype A in a Ghanean prostitute, suggest that this viral subtype had been imported into Africa, while the HTLV-II subtype B, described in remote areas of Zaire, Gabon, and Cameroon, could be a genuine African HTLV-II, present in this continent for a long period of time.

Adult↗

HIV infections in northwestern Cameroon: identification of HIV type 1 group O and dual HIV type 1 group M and group O infections.

HIV-1 strain diversity was examined in a study population that consisted of hospital and clinic patients from seven cities and villages located in the northwestern regions of Cameroon. Specimens were screened using a serological algorithm designed to identify HIV-1 group M, N, and O, and SIVcpz-like infections followed by RT-PCR amplification to characterize the infecting virus. The results show that the HIV epidemic in northwest Cameroon is dominated by HIV-1 group M CRF02_AG infections (57%). Additional group M subtypes present include A, D, F2, G, and CRF01_AE. Based on discordant subtype classification between gag and env sequences, a high percentage (23%) of viral strains appear to be unique intersubtype recombinants with the majority (88%) involving recombination with CRF02_AG. Group O prevalence is low accounting for only 0.4% of HIV infections. However, group O strain diversity is high; isolates from clades I, IV, and V, as well as unclassified and recombinant strains, were found. Three dual infections by HIV-1 group M and group O were identified and characterized. In two specimens, both group M and O sequences were amplified in gag, pol, and env suggesting the presence of both viruses. Analysis of the third specimen shows the presence of a group O virus and an intergroup M/O recombinant virus. Finally, no infections due to HIV-1 group N or SIVcpz-like strains were found in the study population.

Amino Acid Sequence↗

HIV-1 Group N: evidence of ongoing transmission in Cameroon.

An HIV-1 group N infection, 02CM-DJO0135, was identified among specimens collected in 2002 at the D'Joungolo Hospital, Yaoundé, Cameroon. Sequences were obtained from viral RNA extracted from plasma for regions of LTR-gag, pol-vif, and env. The virus amplified from the specimen is closely related to a previously reported group N virus, 02CM-DJO0131, that was also collected at this hospital in 2002. Although the viral sequences for the two isolates differ, their close relationship suggests that the two specimens are linked. No patient histories are available for 02CM-DJO0131 and 02CM-DJO0135; the specimens could have been drawn from a husband/wife, mother/child, or a single individual. However, differences in seroreactivity indicate that it is unlikely that the specimens were drawn from the same patient. This report documents the second case that suggests linkage between group N-infected individuals and indicates that there is ongoing transmission of HIV-1 group N in Cameroon.

Cameroon↗

An evaluation of vital registers as sources of data for infant mortality rates in Cameroon.

BACKGROUND: Infant mortality rates have been widely used as indicators of health status and the availability, utilization and effectiveness of health services. Two principal sources of data for infant mortality rates are vital registers and censuses. This study was designed to evaluate the accuracy of vital registers as sources of data for infant mortality rates in Cameroon. METHODS: A household census of births and infant deaths that occurred in Buea Subdivision between 1 November 1991 and 31 October 1992 was conducted to determine the proportion that were registered and the reasons why the remainder were not registered. RESULTS: The registration coverage was found to be 62% for births and 4% for infant deaths. The most frequently reported reasons for not registering births were lack of money, lack of time and a complicated registration procedure. For infant deaths the reasons were lack of knowledge and no perceived benefits. CONCLUSIONS: Vital registers of birth and death are not an accurate source of data for infant mortality rates in Cameroon. Motivation for birth and death registration appear to be dependent on the perceived benefits. A mechanism of registration that uses medical institutions may substantially increase registration coverage for births and infant deaths.

Birth Certificates↗

Dracunculiasis in Cameroon at the threshold of elimination.

BACKGROUND: Dracunculiasis is endemic in Mayo Sava Division in the Far North Province of Cameroon. Transmission occurs during the rainy season with a peak in the months of July and August. METHODS: A combination of interventions consisting of active surveillance, social mobilization, health education, distribution of filters, construction of new water sources, chemical treatment of unsafe water sources with temephos, and case containment were applied in Mayo Sava in 1990-1995 by the national Guinea Worm Elimination Programme (GWEP). Dracunculiasis cases were detected by village health workers, confirmed by health outreach teams and reported weekly to the GWEP. RESULTS: A decline in the incidence of dracunculiasis by 98.1% from 778 cases in 1990 to 15 in 1995, and in the number of endemic villages by 92.7% from 82 in 1990 to 6 in 1995 was achieved. The proportion of cases identified < or =24 hours of worm emergence increased from 19% in 1991 to 73.6% in 1993. Over 1500 nylon monofilament filters were distributed yearly to endemic villages lacking safe drinking water sources, while 81 new water sources were constructed (boreholes, wells and dikes), 55% in 1992-1993. The success of GWEP is attributed mainly to: intensive and simultaneous implementation of interventions in highly endemic villages in the first 3 years of the programme, case containment, and cash reward. CONCLUSIONS: Cameroon is on the threshold of eliminating dracunculiasis from Mayo Sava but the major remaining obstacle is the ever increasing threat of re-infestation from neighbouring countries.

Adult↗

Health impacts of macroeconomic crises and policies: determinants of variation in childhood malnutrition trends in Cameroon.

BACKGROUND: It is generally hypothesized that macro economic shocks worsen child health by lowering household economic status and limiting access to health care, but this proposition seldom has been tested empirically. We examined the effects of economic crises and adjustment programmes during the 1990s in Cameroon on childhood malnutrition in population subgroups and evaluated the household and health system mediators of these effects. METHODS: We used pooled cross-sectional data from two Demographic and Health Surveys conducted in 1991 and 1998. In multivariate analysis, we stratified data on child sex and age, maternal education, and place and region of residence. We used a linear regression model to estimate the net effects of changes in average household economic status and maternal health seeking behaviour (MHSB) on changes in the prevalence of malnutrition for each stratum, adjusting for all other variables. RESULTS: The prevalence of malnutrition in children younger than 3 years increased from 16 to 23% (P < 0.001) between 1991 and 1998. The increase in urban areas, from 13 to 15% (P = 0.391), mostly occurred in children of low-educated mothers. The increase in rural areas, from 19 to 25% (P < 0.001), mostly occurred in boys, children older than 6 months of age, those born to low-educated mothers, and those of low economic status. In urban areas, the advantage associated with higher maternal education was robust to all controls, and declines in economic status and MHSB were the mediators of increasing malnutrition. In rural areas, increase in malnutrition was higher in children with lower baseline economic status; decline in MHSB was a significant mediator of worsening nutritional status. CONCLUSIONS: The negative nutritional effects during economic crises and adjustment programmes of the 1990s in Cameroon were largest among children of low socioeconomic status. Declines in household economic status and access to health care were the mediators of increasing malnutrition.

Age Distribution↗

Species and populations of the Anopheles gambiae complex in Cameroon with special emphasis on chromosomal and molecular forms of Anopheles gambiae s.s.

We studied the geographical distribution of species, chromosomal, and molecular forms of the Anopheles gambiae Giles (Diptera: Culicidae) complex in 23 sites in Cameroon, Central Africa. Almost all the specimens collected in the four northern-most arid sites were Anopheles arabiensis. Anopheles melas was found in a rural locality surrounded by mangrove swamps, on the Atlantic Coast. In total, 1,525 An. gambiae s.s. females were identified down to their molecular form, and inversion polymorphisms on polytene chromosomes were scored from 186 half-gravid females. The Forest chromosomal form, with standard arrangements almost fixed on both arms of chromosome-2, was the only one observed in the southern, more humid localities. Karyotypes typical of Savanna and Mopti were recorded northwards, in the humid savannas of the Adamawa Province. The molecular forms M and S were widespread throughout Cameroon, and assort independently from the chromosomal forms. S-form populations were characterized by karyotypes typical of Forest and Savanna chromosomal forms, and M-form populations were characterized by karyotypes typical of Forest, Savanna, and Mopti. No M/S hybrid patterns were detected, although M and S mosquitoes were sympatric in 15 sites, providing further evidence for positive assortative mating within molecular forms. The observed ecogeographical distribution of M and S was peculiar: the ecological parameters involved in this distribution still need to be clarified as well as the possible role of competitive exclusion between chromosomally homosequential molecular forms. No difference was observed in host preference or in Plasmodium falciparum infection rates between sympatric M and S populations.

Animals↗

Serological and virological characterization of HIV-1 group O infection in Cameroon.

OBJECTIVES: To study the presence of HIV-1 group O infection among HIV-infected people in Cameroon and to further characterize the HIV-1 group O infections. DESIGN AND METHODS: During a 2-year survey (1994-1995), all samples tested positive in screening methods in the National Reference and Public Health Laboratory, Centre Pasteur, Yaoundé, Cameroon were identified as HIV-1 group M, HIV-1 group O or HIV-2 by using a serological algorithm. HIV-1 group M and HIV-1 group O were distinguished on the basis of competitive enzyme-linked immunosorbent assay (ELISA) reactivity against gp41 group M recombinant protein. HIV-1 group O infections were confirmed by using group O-specific V3 synthetic peptides. HIV-1 group O strains were isolated by lymphocyte cocultures, proviral DNA was amplified with specific primers, and sequencing was performed on the C2V3 and gag regions. RESULTS: Of the 8,331 screened samples, 3,193 were HIV-reactive, 2,376 (74%) of which were considered to belong to group M. The 817 (26%) that had reacted poorly or not at all against group M gp41 were further characterized: 10 were confirmed as HIV-2 and 82 as HIV-1 group O, the others being indeterminate (n = 285) or negative (n = 440). The frequency of group O relative to group M ranged from 1% in Far North province to 6.3% in the capital. There was no difference in sex, age or frequency of clinical manifestations between group M and group O infections. Group O infection was confirmed in a subset of cases by polymerase chain reaction (n = 14), with perfect concordance. Sequencing and phylogenetic analyses confirmed the high variability inside group O. CONCLUSIONS: Group O and group M epidemiological patterns are known to be similar so the reason for the lower prevalence of group O remains to be found. The wide distribution of group O infection in all Cameroonian provinces underlines the importance of further characterizing the epidemic spread and diffusion of this group.

Amino Acid Sequence↗

Prevalence and risk factors for human herpesvirus 8 infection in northern Cameroon.

BACKGROUND: The modes of transmission of HHV-8 are still unclear. GOAL: To evaluate the distribution and transmission of HHV-8 infection. DESIGN: Serosurvey conducted in a Cameroon hospital among 292 persons, including children (5-10 years), adolescents (15-20 years), and adults (30-40 years). Antibodies against lytic and latent antigens to HHV-8 were detected by immunofluorescence assay; antibodies against Epstein-Barr virus viral antigens were detected by enzyme-linked immunoabsorbent assay. RESULTS: The prevalence of HHV-8 antilytic antibodies remained stable and was 39.8% among children, 51.5% among adolescents, and 61.8% among adults. Epstein-Barr virus seroprevalence was high among children, and remained stable among adolescents and adults. A history of sexually transmitted diseases was an independent determinant of HHV-8 infection (adjusted odds ratio 2.47; 95% CI 1.09-4.91). CONCLUSION: The high prevalence of HHV-8 infection among children indicates nonsexual modes of transmission in Cameroon, with sexual transmission occurring among adolescents and adults.

Adolescent↗

Mobility, sexual behavior, and HIV infection in an urban population in Cameroon.

Several studies, notably from rural areas, have shown an association between mobility and HIV infection. However, reasons for this association are poorly documented. In this study, we examined the relationship between mobility, sexual behavior, and HIV infection in an urban population of Cameroon. A representative sample of 896 men and 1017 women were interviewed and tested for HIV infection and other sexually transmitted infections in Yaoundé in 1997. Mobile and nonmobile people were compared with respect to sociodemographic attributes, risk exposure, condom use, and prevalence of HIV infection, using descriptive statistics and multivariate logistic regression. Seventy-three percent of men and 68% of women reported at least 1 trip outside of Yaoundé in the preceding 12 months. Among men, the prevalence of HIV infection increased with time away from town. Men who declared no absence were 5 times less likely to be infected than were those away for >31 days (1.4% vs. 7.6%, respectively; adjusted odds ratio, 0.23; 95% confidence interval, 0.07-0.82). Furthermore, mobile men reported more risky sexual behaviors (ie, more partners and more one-off contacts). For women, the pattern was less clear: differences in the prevalence of HIV infection were less marked for nonmobile than for mobile women (6.9% vs. 9.8%, respectively; P > 0.1). This study suggests that characteristics of male mobility may be an important feature of the HIV epidemic in Cameroon.

Adolescent↗

Evaluation of four simple/rapid assays and two fourth-generation ELISAs for the identification of HIV infection on a serum panel representing the HIV-1 group M genetic diversity in Cameroon.

The performance of 4 rapid and simple assays: Camstix-HIV 1+2 (Camdiagnostix, Yaounde, Cameroon); Determine HIV 1+2+0 (Abbott Laboratories, Tokyo, Japan); Genie II HIV-1/HIV-2 (Bio-Rad, Marnes la Coquette, France); ImmunoComb II HIV 1 & 2 BiSpot (Orgenics, Yavne, Israel); and 2 fourth-generation ELISAs: Enzygnost HIV Integral (Dade Behring, Marburg, Germany) and Genscreen plus HIV Ag-Ab (Bio-Rad, Marnes la Coquette, France) currently used in Cameroon to detect HIV infections were evaluated on a local serum panel. A total of 503 samples were collected, using the Camstix-HIV 1+2 assay. Overall, 280 samples were confirmed HIV positive, 181 were negative, and 42 were indeterminate. All positive samples belonged to group M: CRF02_AG (73.5%), A1 (7.1%), A2 (1.2%), G (4.7%), F2 (5.1%), D (1.6%), CRF11 (1.6%), CRF06 (1.2%), and CRF01_AE (1.6%). Sensitivity, specificity, test efficiency, and positive and negative predictive values were calculated both including and excluding indeterminate samples. Except for Genie II and ImmunoComb II (98.9 and 99.3%, respectively), sensitivities were 100% for the remaining 4 tests. Specificities, efficiencies, and positive predictive values of all assays were negatively affected by the addition of HIV-indeterminate samples in the calculations. These data show the importance of prior test evaluations on local serum panels and in field conditions before a national policy for HIV screening is decided on and stress also the need to use tests and algorithms that can reduce the high number of HIV-indeterminate results in Africa.

AIDS Serodiagnosis↗

Knowledge and attitudes concerning medical genetics amongst physicians and medical students in Cameroon (sub-Saharan Africa).

PURPOSE: Little is known about physician's knowledge of, and attitudes toward genetics in sub-Saharan Africa. METHODS: Survey of 101 pre-clinical, 95 clinical medical students, and 110 physicians, in Cameroon. RESULTS: The awareness of DNA diagnosis was poor: 0, 2.2, and 1.2%, respectively, for sickle cell anemia. The majority of the respondents considered genetic counseling as indispensable (97.6, 98.9 and 100%); and prenatal diagnosis as acceptable. The acceptance of medical abortion increased with the level of medical education (62.6, 74.7 and 90.7%). Sickle cell anemia was considered as a "serious disease" by a greater majority of respondents than Down syndrome (P < 0.001). But, in all three groups, the acceptance of termination of affected pregnancy "if the respondent's own child was affected" was lower for sickle cell anemia than Down syndrome (22.4 versus 40.2%, 10.8 versus 29.3% and 36.1 versus 70.4%). CONCLUSIONS: The data suggest a poor knowledge of genetic tests among medical students and physicians. This cohort appears to accept the principles of medical genetics. Our data emphasized a need to introduce genetics and to develop research on its ethical and social implications in Cameroon.

Abortion, Therapeutic↗

Integrating prevention of mother-to-child HIV transmission into routine antenatal care: the key to program expansion in Cameroon.

With funds from Elizabeth Glaser Pediatric AIDS Foundation, the Cameroon Baptist Convention Health Board implemented a program to prevent mother-to-child transmission of HIV-1 (PMTCT) as part of its routine antenatal care, with single-dose maternal and infant peripartum nevirapine (NVP) prophylaxis of HIV-positive mothers and their babies. Nurses, midwives, nurse aides, and trained birth attendants counseled pregnant women, obtained risk factor data, and offered free HIV testing with same-day results. From February 2000 through December 2004, this program rapidly expanded to 115 facilities in 6 of Cameroon's 10 provinces, not only to large hospitals but to remote health centers staffed by trained birth attendants. We trained 690 health workers in PMTCT and counseled 68,635 women, 91.9% of whom accepted HIV testing. Of 63,094 women tested, 8.7% were HIV-1-positive. Independent risk factors for HIV-1 infection included young age at first sexual intercourse, multiple sex partners, and positive syphilis serology (P < 0.001 for each). We counseled 98.7% of positive and negative mothers on a posttest basis. Of 5550 HIV-positive mothers, we counseled 5433 (97.9%) on single-dose NVP prophylaxis. Consistent training and programmatic support contributed to rapid upscaling and high uptake and counseling rates.

Adolescent↗

Cross-clade reactivity of HIV-1-specific T-cell responses in HIV-1-infected individuals from Botswana and Cameroon.

An effective HIV type 1 (HIV-1) vaccine will likely require elicitation of broadly reactive cell-mediated immune (CMI) responses against divergent HIV-1 clades. We compared anti-HIV-1 T-cell immune responses among 363 unvaccinated adults infected with diverse HIV-1 clades. Response rates to clade B Gag and/or clade B Nef in Botswana (95%) and Cameroon (98%) were similar when compared with those in countries previously studied, including Brazil (92%), Thailand (96%), South Africa (96%), Malawi (100%), and the United States (100%). Substantial cross-clade cell-mediated immune responses in Botswana and Cameroon confirm previous findings in a larger, more genetically diverse collection of HIV-1 samples.

Adolescent↗