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AN OUTBREAK OF TETRODOTOXIN POISONING FROM CONSUMING HORSESHOE CRABS IN SABAH

Suleiman M, Muhammad J, Jelip J, William T, Chua TH

Southeast Asian J. Trop. Med. Public Health, 2017 Jan;48(1):197-203.
PMID: 29644840

The horseshoe crab (Carcinoscorpius rotundicauda) is consumed by those
residing near the coastal areas of Kota Marudu District in Malaysia, as it is considered
a delicacy. During June to August, 2011 thirty cases of tetrodotoxin poisoning
were reported from Kota Marudu District following ingestion of horseshoe
crabs caught in Kota Marudu Bay. The purpose of this study is to describe this
case series in order to determine risk factors to prevent further outbreaks. There
were six confirmed and 24 probable cases of tetrodotoxin poisoning identified in
the study area during the study period as diagnosed by clinical presentation and
laboratory findings. Symptoms included dizziness (80%), circumoral and lingual
numbness (80%), hand and feet numbness (63.3%), nausea and vomiting (30%)
and weakness and difficulty in breathing (26.6%). Three cases (10%) died while 27
cases recovered. Forty-seven percent of the cases had onset of symptoms within
30 minutes of ingestion and 14% 31-60 minutes after ingestion of horseshoe crab
meat. Urine samples were collected from the cases, while horseshoe crabs, cockles
and sea water from the epidemic area were also taken for analysis. Tetrodotoxin
was detected in the urine of six cases; the highest concentrations recorded were
among the three cases who died. High tetrodotoxin concentrations were found
in the hepatic cecum and eggs of the tested horseshoe crabs. Dinoflagellates were
not detected in the sea water or cockle samples. Intensive health education was
initiated quickly to stop other members of the Marudu Bay community from
consuming the horseshoe crabs. This is the first documented epidemic of tetrodotoxin
poisoning in Sabah.
High incidence of Plasmodium knowlesi malaria compared to other human malaria species in several hospitals in Malaysia

Lai MY, Rafieqin N, Lee PYL, Amir Rawa MS, Dzul S, Yahaya N, et al.

Trop Biomed, 2021 Sep 01;38(3):248-253.
PMID: 34362867 DOI: 10.47665/tb.38.3.065

Through the regional control programme, Malaysia has been successfully reducing the incidence of Plasmodium falciparum and Plasmodium vivax infections. However, the incidence of zoonotic malaria Plasmodium knowlesi infection is increasing and now has been the major cause of malaria in Malaysia especially Malaysian Borneo. The emergence of knowlesi infection has threatened the malaria elimination programme which the government aims to reduce the overall malaria infections by 2020. Unlike other benign human Plasmodium spp., P. knowlesi can cause fatal infections. The aim of this study was to determine the incidence and distribution of five human malaria parasites including P. knowlesi in Peninsular Malaysia and Malaysian Borneo. A total of 112 blood samples were collected from seven states and district hospitals in Peninsular Malaysia and Malaysian Borneo from year 2015 to 2016. The samples were examined by microscopy and further confirmed by nested PCR assay targeting 18S rRNA gene of Plasmodium spp. Following the nested PCR assays, a total of 54 (48.2%) samples were positive for P. knowlesi infections, 12 (10.7%) cases were positive for P. vivax infections, followed by 7 (6.3%) cases of P. falciparum and 4 (3.5%) cases of P. malariae. There were 3 cases (2.7%) of mixed infections (P. knowlesi/P. vivax). However, no cases were identified as P. ovale. A total of 32 (28.6%) cases were found as negative infections. LoopMediated Isothermal Amplification Assay (LAMP) was performed to confirm inconclusive results produced by microscopy and nested PCR. P. knowlesi showed the highest prevalence in Sarawak (n= 30), Sabah (n=13), Pulau Pinang (n=5) and Pahang (n=6). PCR and LAMP was not able to detect a large number of microscopy positive samples due to DNA degradation during storage and shipping. Among all the states involved in this study, the highest prevalence of P. knowlesi infection was found in Sabah and Sarawak.
Genetic diversity of secreted protein with an altered thrombospondin repeat (SPATR) of Plasmodium knowlesi clinical isolates from Malaysia

Azlan UW, Lau YL, Hamid MHA, Jelip J, Ooi CH, Mudin RN, et al.

Trop Biomed, 2022 Dec 01;39(4):504-510.
PMID: 36602208 DOI: 10.47665/tb.39.4.006

The Plasmodium knowlesi secreted protein with an altered thrombospondin repeat (PkSPATR) is an important protein that helps in the parasite's invasion into the host cell. This protein has been regarded as one of the potential vaccine candidates against P. knowlesi infection. This study investigates the genetic diversity and natural selection of PkSPATR gene of P. knowlesi clinical isolates from Malaysia. PCR amplification of the full length PkSPATR gene was performed on 60 blood samples of infected P. knowlesi patients from Peninsular Malaysia and Malaysian Borneo. The amplified PCR products were cloned and sequenced. Sequence analysis of PkSPATR from Malaysia showed higher nucleotide diversity (CDS p: 0.01462) than previously reported Plasmodium vivax PvSPATR (p = 0.0003). PkSPATR from Peninsular Malaysia was observed to have slightly higher diversity (CDS p: 0.01307) than those from Malaysian Borneo (CDS p: 0.01212). Natural selection analysis on PkSPATR indicated significant purifying selection. Multiple amino acid sequence alignment revealed 69 polymorphic sites. The phylogenetic tree and haplotype network did not show any distinct clustering of PkSPATR. The low genetic diversity level, natural selection and absence of clustering implied functional constrains of the PkSPATR protein.
Risk factors of tuberculosis among health care workers in Sabah, Malaysia

Jelip J, Mathew GG, Yusin T, Dony JF, Singh N, Ashaari M, et al.

Tuberculosis (Edinb), 2004;84(1-2):19-23.
PMID: 14670342

Tuberculosis (TB) is one of the main public health problems in Sabah; 30% of the total number of TB cases reported in Malaysia every year occur in Sabah. The average incidence of TB among health care workers over the past 5 years is 280.4 per 100,000 population (1, Annual Report of Sabah State TB Control Programme, 1998). At present, there are no specific measures for the prevention of TB transmission in health care facilities. A case-control study was conducted among health care workers in Sabah in 2000-2001. Cases were health care workers with TB diagnosed between January 1990 and June 2000. Controls were health care workers without TB and working in the same facility as cases during the disease episode. The study attempted to identify risk factors for TB among the study population. Data were collected through structured interviews and review of patients' records. The notification rate of TB among health care workers was significantly higher than that to the general population (Z=4.893, p<0.01). The average notification rate of TB among health care workers over the last 5 years was two times higher than in the general population (280.4/100,000 compared to 153.9/100,000). Regression results showed that ethnicity, designation, family contact and TB related knowledge did not significantly contribute to the risk of contracting TB in this study. However, after controlling for the above factors, age, gender, history of TB contact outside the workplace (other than family contact), duration of service and failure to use respiratory protection when performing high-risk procedures, were the main risk factors of TB among health care workers. This study succeeded in identifying some of the risk factors of TB among health care workers. We managed to include the large ratio of controls to case (3:1) and those cases spanned over a period of 10 years. However, the findings from the study have to be applied with caution due to the limitations of this study, which include recall bias, dropouts, and small sample size. Based on the study findings, we recommend that health care workers in the first 10 years of service should take extra precautions, such as using respiratory protection when performing procedures that are considered to be of high risk with respect to TB infection. They should also undergo TB screening at least once every 2 years and, if symptomatic, offered prophylactic treatment. The Respiratory Protection Programme should be fully implemented to help reduce the risk of TB among health care workers in Sabah.
Evaluation of new multiplex PCR primers for the identification ofPlasmodium species found in Sabah, Malaysia

Stanis CS, Song BK, Chua TH, Lau YL, Jelip J

Turk J Med Sci, 2016 Jan 05;46(1):207-18.
PMID: 27511356 DOI: 10.3906/sag-1411-114

BACKGROUND/AIM: Malaria is a major public health problem, especially in the Southeast Asia region, caused by 5 species of Plasmodium (P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi). The aim of this study was to compare parasite species identification methods using the new multiplex polymerase chain reaction (PCR) against nested PCR and microscopy.
MATERIALS AND METHODS: Blood samples on filter papers were subject to conventional PCR methods using primers designed by us in multiplex PCR and previously designed primers of nested PCR. Both sets of results were compared with microscopic identification.
RESULTS: Of the 129 samples identified as malaria-positive by microscopy, 15 samples were positive for P. falciparum, 14 for P. vivax, 6 for P. knowlesi, 72 for P. malariae, and 2 for mixed infection of P. falciparum/P. malariae. Both multiplex and nested PCR identified 12 P. falciparum single infections. For P. vivax, 9 were identified by multiplex and 12 by nested PCR. For 72 P. malariae cases, multiplex PCR identified 58 as P. knowlesi and 10 as P. malariae compared to nested PCR, which identified 59 as P. knowlesi and 7 as P. malariae.
CONCLUSION: Multiplex PCR could be used as alternative molecular diagnosis for the identification of all Plasmodium species as it requires a shorter time to screen a large number of samples.
Fulltext Introduction of Aedes aegypti mosquitoes carrying wAlbB Wolbachia sharply decreases dengue incidence in disease hotspots

Hoffmann AA, Ahmad NW, Keong WM, Ling CY, Ahmad NA, Golding N, et al.

iScience, 2024 Feb 16;27(2):108942.
PMID: 38327789 DOI: 10.1016/j.isci.2024.108942

Partial replacement of resident Aedes aegypti mosquitoes with introduced mosquitoes carrying certain strains of inherited Wolbachia symbionts can result in transmission blocking of dengue and other viruses of public health importance. Wolbachia strain wAlbB is an effective transmission blocker and stable at high temperatures, making it particularly suitable for hot tropical climates. Following trial field releases in Malaysia, releases using wAlbB Ae. aegypti have become operationalized by the Malaysian health authorities. We report here on an average reduction in dengue fever of 62.4% (confidence intervals 50-71%) in 20 releases sites when compared to 76 control sites in high-rise residential areas. Importantly the level of dengue reduction increased with Wolbachia frequency, with 75.8% reduction (61-87%) estimated at 100% Wolbachia frequency. These findings indicate large impacts of wAlbB Wolbachia invasions on dengue fever incidence in an operational setting, with incidence expected to further decrease as wider areas are invaded.