A Case of Ancylostoma ceylanicum Infection Occurring in an Australian Soldier Returned from Solomon Islands

A 26-year-old male member of the Australian Defense Force presented with a history of central abdominal pain of 4 weeks duration and peripheral eosinophilia consistent with eosinophilic enteritis. Acute hookworm disease was diagnosed as the cause. Adult worms recovered from feces after therapy with albendazole were morphologically consistent with Ancylostoma ceylanicum. As the patient had been deployed with the Regional Assistance Mission to Solomon Islands for 6 months prior to this presentation, it is very likely that the A. ceylanicum was acquired in Solomon Islands. Until now, it has been assumed that any Ancylostoma spp. recovered from humans in Solomon Islands is A. duodenale. However, this case demonstrates that human hookworm infection acquired in the Solomon Islands could be caused by A. ceylanicum.

Ancient migration routes of Austronesian-speaking populations in oceanic Southeast Asia and Melanesia might mimic the spread of nasopharyngeal carcinoma / 癌症

Mitochondrial DNA (mtDNA) and non-recombining Y chromosome (NRY) are inherited uni-parentally from mother to daughter or from father to son respectively. Their polymorphism has initially been studied throughout populations of the world to demonstrate the "Out of Africa" hypothesis. Here, to correlate the distribution of nasopharyngeal carcinoma (NPC) in different populations of insular Asia, we analyze the mtDNA information (lineages) obtained from genotyping of the hyper variable region (HVS I & II) among 1400 individuals from island Southeast Asia (ISEA), Taiwan and Fujian and supplemented with the analysis of relevant coding region polymorphisms. Lineages that best represented a clade (a branch of the genetic tree) in the phylogeny were further analyzed using complete genomic mtDNA sequencing. Finally, these complete mtDNA sequences were used to construct a most parsimonious tree which now constitutes the most up-to-date mtDNA dataset available on ISEA and Taiwan. This analysis has exposed new insights of the evolutionary history of insular Asia and has strong implications in assessing possible correlations with linguistic, archaeology, demography and the NPC distribution in populations within these regions. To obtain a more objective and balanced genetic point of view, slowly evolving biallelic Y single nucleotide polymorphism (Y-SNP) was also analyzed. As in the first step above, the technique was first applied to determine affinities (macro analysis) between populations of insular Asia. Secondly, sixteen Y short tandem repeats (Y-STR) were used as they allow deeper insight (micro analysis) into the relationship between individuals of a same region. Together, mtDNA and NRY allowed a better definition of the relational, demographic, cultural and genetic components that constitute the make up of the present day peoples of ISEA. Outstanding findings were obtained on the routes of migration that occurred along with the spread of NPC during the settlement of insular Asia. The results of this analysis will be discussed using a conceptual approach.

Alpha+ -thalassaemia and malaria in Melanesia: epidemiological perspectives

In 1948 Haldane first proposed that the high frequencies of thalassaemias in malaria-endemic regions were due to natural selection by malaria. Some of the highest frequencies of alpha+ -thalassaemia are found in the Pacific region of Melanesia. Consequently, Melanesia has provided a unique opportunity for an extensive study of the association between alpha+ -thalassaemia and malaria. Here we review the emergence of alpha+ -thalassaemia in this region and the research that has been carried out, both from the historical perspective and the most recent developments, which may give insight into the selection of alpha+ -thalassaemia by malaria.

Epidemiology of Cervical Cancer

Invasive cancer of the cervix is considered a preventable disease because it has a long preinvasive state, cervical cytology screening programs are currently available, and the treatment of pre-invasive lesions is effective. Cancer of the cervix is the second most common cancer among women worldwide, with an estimated 493,000 new cases and 274,000 deaths in 2002. The highest incidence rates are observed in sub-Saharan Africa, Melanesia, Latin America and the Caribbean, South-Central Asia, and South East Asia. In Korea, cervical cancer is the fifth most common cancer among women with over 3,000 new cases every year. Age-standardized incidence rate (ASR) is 15.5 per 100,000, which is lower than those in developing countries but higher than in western countries such as Europe and North America. The patients' mean parity is 2.59, and the range of age in peak incidence is 40~49 years (29.8%), followed by 50~59 years (21.9%). As the age goes on, more advanced stage cancer is frequent. Squamous cell carcinoma is the most common cell type, and adenocarcinoma is more frequent among those under 60 years old. Operation (56.0%) is the major treatment modality under stage IIa, and concurrent chemoradiation (31.6%) is the major treatment over stage IIb. The 5year survival rate is 73.9%. It is generally thought that human papillomavirus (HPV) test and HPV vaccine might play an important role in lowering the incidence of cervical cancer, and continuous epidemiologic studies will support its usefulness and efficacy.

AIDS in Papua New Guinea: situation in the Pacific.

There has long been reason to anticipate a major heterosexual epidemic of acquired immunodeficiency syndrome (AIDS) in Papua New Guinea (PNG) and probably in the rest of Melanesia. From the social and behavioural perspectives, Melanesia is strikingly similar to other areas of the world with serious epidemics of AIDS. High levels of other sexually transmitted infections indicate behaviour patterns that would also facilitate transmission of human immunodeficiency virus (HIV) and presence of cofactors for HIV infection. Low levels of male circumcision parallel the situation in other epidemic areas. Near-parity by sex in cases reported so far in PNG is evidence that primary infection is largely heterosexual. The late start of a major epidemic in PNG can probably be attributed to: (a) the relatively small aggregation of people in urban centres (even Port Moresby has only one-quarter of a million people); (b) a highway system that does not network across the whole country; (c) limited size of the organized commercial sex sector; and (d) possibly low level of chancroid to act as a cofactor. The situation is now changing. Over the last seven years, HIV infection, probably the highest in Port Moresby and mostly measured there, has been rising by about 60% per annum. This rise is genuine and, if sustained, would infect 10% of the adult population of PNG in little more than 12 years. Some countries of sub-Saharan Africa have witnessed such exponential rises.

A highly sensitive, nested polymerase chain reaction based method using simple dna extraction to detect malaria sporozoites in mosquitos.

Dried Anopheles farauti mosquitos caught in Solomon Islands in 1990 were examined for malaria sporozoites by ELISA and nested polymerase chain reaction (PCR). Only heads and thoraces were used. Plasmodium genus-specific nested PCR amplifications were carried out on all samples. Of the 402 pools of mosquitos that were processed, 30 were positive for malaria. Nest 1 products of positive samples were subjected to further PCR amplifications with species-specific primers for P. falciparum and P. vivax. Twenty pools were positive for P. vivax by PCR while only 7 were positive by ELISA. For P. falciparum 2 pools were positive by both ELISA and PCR, and one of these was a pool which was positive for P. vivax by PCR and ELISA. Thus the sensitivity of PCR for P. vivax was 100% while the specificity was 96.7%. For P. falciparum the sensitivity and specificity were 100%. The PCR technique is highly sensitive and can be used on dried mosquitos which makes it a valuable tool for determining sporozoite rates of mosquitos, even in remote areas.

The serological status of Solomon Island blood donors.

The serological status of Solomon Island blood donors in 1995 and in particular the seroprevalence of antibodies to Hepatitis B and C and prevalence of risk factors for these chronic infections was studied. A questionnaire of risk factors for Hepatitis B and C was undertaken. All blood donors had been previously screened for HIV antibody without any positive cases recorded. 598 donors had serum collected of which 36 samples (6.0%) were third generation HCV EIA antibody positive and 3 samples were RIBA positive but none were PCR positive. 25.1% of samples were positive for HBsAg and anti-HBc antibody was found in 84.4%. Elevated ALT levels (>35 U/l) were found in 6.5% of samples but there was no statistically significant association with HCV or HBsAg status. 15.4% were TPHA positive and 5.4% had RPR titers more than or equal to 1. Anti-HTLV-1 antibody was positive in 12.3% randomly selected samples. All 10 positive samples were then found to be antibody indeterminate with Western blot assay. Of the 585 samples with completed questionnaires, analysis of the relationship between anti-HCV status with tattoo status and ear piercing also failed to reach statistical significance. Consistent with other studies from tropical malaria-prone countries, a positive anti-HCV antibody test even by the third generation EIA is probably a false positive test in most cases. In addition, high prevalence rates of HBV, yaws or syphilis infection were demonstrated.

Malaria in Honiara, Solomon Islands: reasons for presentation and human and environmental factors influencing prevalence.

During February and March 1995, out-patients attending health clinics and the Central Hospital in East Honiara, Guadalcanal, Solomon Islands, were surveyed with the aim of determining factors influencing the differing rates of malaria, the proportion of transmission occurring within the town, and the reasons for presentation. Three hundred and nine adult patients, who were sick and had blood smears taken, were asked about their general knowledge of malaria transmission. Of those interviewed, 120 were visited at their home in East Honiara, to determine variables. EpiInfo 5.1 was used in analysis. A history of fever alone was not a good indicator of parasitemia. Most precautions, including bed nets, window screens and personal precautions were of little benefit. Significant protection was afforded individuals and families with indoor kitchens. Patients not completing their antimalarial treatment fared worse in terms of parasitemia and malaria history. Most malaria/parasitemia was indigenous to Honiara. Many patients had a good knowledge of malaria transmission and mosquitos, but this did not translate into a lower rate of parasitemia or malaria.

Malaria in Honiara, Solomon Islands: vector studies.

Adult and larval specimens of anopheline mosquitos were collected throughout eastern Honiara during a study into risk factors for malaria illness in adults. Species identification was by morphology, DNA probes and by PCR. Only Anopheles farauti s.s. were identified from part-night landing catches carried out from 1900 to 2200 hours. Most mosquitos attracted to humans were culicines. The majority of anophelines (85%) were captured between 1900 and 2000 hours. An. farauti s.s. larvae were most common but one An. farauti No. 7, and ten An. punctulatus larvae were also collected.

The economic impact of Plasmodium falciparum malaria on education investment: a Pacific Island case study.

A small but intensive study was carried out adopting a simple method which attempts to quantify the economic consequences Plasmodium falciparum malaria on education investment through school pupil absenteeism in a community in Solomon Islands. In a randomized sample of 4,920 cases of P. falciparum malaria in a community, 2,886 occurred in children of primary school age group of 7 to 13 years. On average a case gave rise to a mean school absenteeism of 5.3 days. In the final analysis a total of 11,028 pupil days schooling were lost due to the sampled cases of malaria caused by the species. This is equivalent to 55.14 school pupil years as a child is expected to attend school for 200 days in a year. A primary school teacher with an average annual salary of US$3,990.00 is expected to teach 6,500 school pupil days a year. When this is adopted as an economic indicator for investment in education the loss is calculated to be US$6,769.57 or equivalent to US$1.38 per case. When this is applied nationally, assuming that rates are similar for 79,203 cases of P. falciparum reported in 1990, the total consequence for investment in education is US$108,966.00, which is equivalent to 27.31 teachers being paid for not teaching, an unacceptable impact for a small nation like the Solomon Islands.

The effect of permethrin impregnated bednets on the incidence of Plasmodium falciparum, in children of north Guadalcanal, Solomon Islands.

The effect of permethrin impregnated bednets was studied for the first time amongst a large community in North Guadalcanal, Solomon Islands. The community was divided into two; one covered 23 villages with 860 people who were given bednets impregnated at 0.5 g/m2, and the other 20 villages with 520 people was used as control. Parasitological data were collected by regular prevalence surveys and examination of records of malaria patients who have sought treatment in clinics. Entomological data by landing catches using human bait. The entomological results showed a 71% reduction of Anopheles farauti. Even though there was no significant reduction observed with An.punctulatus, as the density was already very low, the number biting indoor was much lower than those outdoor of houses with treated bednets. Parasitologically there was a steady decline in the incidence between surveys with Plasmodium falciparum in the under 10 years old. Even though there was no significant reduction in the other variables measured, there was a steady increase in the clearance rate between surveys which might also be due to easy accessibility to chemotherapy. The study showed the significant beneficial effect of permethrin impregnated bednets, which was found to be still effective up to twelve months, against stable P. falciparum malaria in children.

Theoretical considerations in the vector control of filariasis.

In order to assist in assessing progress of vector control of filariasis a theoretical model is constructed, using retrospective data on infected persons removed to a vector-free situation. This shows that the decrease of microfilaraemia is not regular, but is gradual for the first 3 years and then more rapid, reaching zero at about 10 years. An estimate is made of the level to which the vector must be reduced before transmission of filariasis ceases, showing that the degree of efficiency required is considerably less than for malaria.

Vector control of filariasis in the Solomon Islands.

In Solomon Islands, filariasis is caused by the nocturnally perodic form of Wuchereria bancrofti and is transmitted by the same vectors of malaria. This study explores the control of this disease as an additional effect of the Malaria Eradication Programme.