Leptospira Serovars for Diagnosis of Leptospirosis in Humans and Animals in Africa: Common Leptospira Isolates and Reservoir Hosts

The burden of leptospirosis in humans and animals in Africa is higher than that reported from other parts of the world. However, the disease is not routinely diagnosed in the continent. One of major factors limiting diagnosis is the poor availability of live isolates of locally circulating Leptospira serovars for inclusion in the antigen panel of the gold standard microscopic agglutination test (MAT) for detecting antibodies against leptospirosis. To gain insight in Leptospira serovars and their natural hosts occurring in Tanzania, concomitantly enabling the improvement of the MAT by inclusion of fresh local isolates, a total of 52 Leptospira isolates were obtained from fresh urine and kidney homogenates, collected between 1996 and 2006 from small mammals, cattle and pigs. Isolates were identified by serogrouping, cross agglutination absorption test (CAAT), and molecular typing. Common Leptospira serovars with their respective animal hosts were: Sokoine (cattle and rodents); Kenya (rodents and shrews); Mwogolo (rodents); Lora (rodents); Qunjian (rodent); serogroup Grippotyphosa (cattle); and an unknown serogroup from pigs. Inclusion of local serovars particularly serovar Sokoine in MAT revealed a 10-fold increase in leptospirosis prevalence in Tanzania from 1.9 % to 16.9 % in rodents and 0.26% to 10.75 % in humans. This indicates that local serovars are useful for diagnosis of human and animal leptospirosis in Tanzania and neighbouring countries

Mycobacterium tuberculosis volatiles for diagnosis of tuberculosis by Cricetomys rats.

Tuberculosis (TB) diagnosis in regions with limited resources depends on microscopy with insufficient sensitivity. Rapid diagnostic tests of low cost but high sensitivity and specificity are needed for better point-of-care management of TB. Trained African giant pouched rats (Cricetomys sp.) can diagnose pulmonary TB in sputum but the relevant Mycobacterium tuberculosis (Mtb)-specific volatile compounds remain unknown. We investigated the odour volatiles of Mtb detected by rats in reference Mtb, nontuberculous mycobacteria, Nocardia sp., Streptomyces sp., Rhodococcus sp., and other respiratory tract microorganisms spiked into Mtb-negative sputum. Thirteen compounds were specific to Mtb and 13 were shared with other microorganisms. Rats discriminated a blend of Mtb-specific volatiles from individual, and blends of shared, compounds (P = 0.001). The rats' sensitivity for typical TB-positive sputa was 99.15% with 92.23% specificity and 93.14% accuracy. These findings underline the potential of trained Cricetomys rats for rapid TB diagnosis in resource-limited settings, particularly in Africa where Cricetomys rats occur widely and the burden of TB is high

Leptospira infections in freshwater fish in Morogoro Tanzania: a hidden public health threat

Tanzania journal of health research 2014; 16 (2):Leptospirosis caused by spirochete bacterium of genus Leptospira affects humans and animals worldwide. Rodents are major reservoirs of leptospires whereas wetland and aquatic migratory birds also carry and transmit leptospires. Leptospirosis studies in fish are lacking in African countries despite favourable environment and abundant reservoirs, which can spread leptospires into aquatic habitats and infect fish. The objectives of this study were to determine presence of Leptospira in fish; the prevalent Leptospira serovars and whether are related to serovars reported in animals; and to ascertain potential public health risk. Live tilapia, catfish and eel fish (n=48) were caught in Mindu Dam in Morogoro Municipality in eastern Tanzania. Blood sample was collected using syringes and needles to obtain serum for serological detection of leptospirosis using gold standard microagglutination test utilizing local and reference Leptospira serovars Sokoine, Kenya, Pomona and Hebdomadis. Twenty-six fish (54.2%) were positive for serovar Kenya (29.2%) and Sokoine (25%). Leptospira prevalence was high in both catfish (58.3%) and tilapia fish (47.8%). Thus, different fish types are infected with Leptospira found in animals. Fish could be source of Leptospira infection to humans since tilapia and catfish are the common fish type widely consumed in Tanzania. Further study covering lakes, rivers and dams is required to better understand the prevalence of Leptospira in fish and actual public health threats

From pests to tests : training rats to diagnose tuberculosis

Journal of Eur Respir J 2020; 55: 19022432020 is the year of the rat. The rat is the first of the 12 Chinese zodiac signs, and represents spirit, alertness, flexibility and vitality. In respiratory medicine, we may think of rats as vectors for diseases, such as pulmonary forms of hantavirus disease or leptospirosis, and pneumonic plague. Rodent control is thus part of hygiene guidelines and the International Health Regulations. And yet, the rat’s keen sense of smell has led to its incredible career as a living tuberculosis (TB) detector. The TB detection rat journey began with an idea in Tanzania in 2001, roughly 120 years after the TB-causing Mycobacterium tuberculosis was discovered by microscopy and bacterial culture. African giant pouched rats (Cricetomys ansorgei) had already been successfully trained using positive reinforcement to find explosives [1]. So, the question arose if they could do more for humanity by helping to also combat disease. But how would the rats use their noses to find bacteria or otherwise sniff out TB patients? For centuries, olfaction had already informed diagnostics in medical practices, e.g. in detecting metabolic issues such as ketoacidosis or tissue decay such as gangrene [2]. In the Flemish common language, the word tering, which etymologically refers to the smell of tar, is used for TB. The advent of chromatographic techniques allows characterisation of the organic compounds causing odours

Seroprevalence of Leptospira infection in bats roosting in human settlements in Morogoro municipality in Tanzania

Leptospirosis is a neglected emerging infectious disease with high burden in Africa. Major reservoirs of leptospirosis are rodents and other small mammals. Studies of leptospirosis in bats and the extent to which they contribute to its transmission to humans and domestic animals in Tanzania are lacking. The objective of this study was to determine the prevalence of leptospirosis and local Leptospira serovars in bat colonies found around human settlements in Morogoro, Tanzania. In this study, mist nets were used to capture bats at Sokoine University of Agriculture main campus, whereas bats roosting on trees at Nunge A, Nunge B and Mwere primary school were captured manually. Leptospirosis was determined using the gold standard microscopic agglutination test for determination of Leptospira antibodies. Six live Leptospira serovars including local Leptospira serovar Sokoine, Kenya and Lora reported in rodents and domestic animals in Tanzania, and reference serovars Hebdomadis, Canicola and Pomona were used in the study. Leptospirosis prevalence was high in bats (19.4%) and higher within colonies (27.3%). Leptospira serovar Sokoine was more prevalent (19.4%) compared to serovars Kenya (2.8%) and Lora (2.8%). Serovars Pomona, Canicola and Hebdomadis were not detected in bats. In conclusion, bats are potential reservoir and transmitter of Leptospira serovar Sokoine, hence should be prevented to access houses and roosting in human settlements to avoid public health risks. Routine diagnosis of human leptospirosis is needed in Tanzania as evidence show a high prevalence of Leptospira in reservoir hosts interacting with humans

Leptospirosis in sugarcane plantation and fishing communities in Kagera northwestern Tanzania.

BackgroundLeptospirosis is a bacterial zoonotic disease of worldwide importance, though relatively neglected in many African countries including sub Saharan Africa that is among areas with high burden of this disease. The disease is often mistaken for other febrile illnesses such as dengue, malaria, rickettsioses and enteric fever. Leptospirosis is an occupational disease likely to affect people working in environments prone to infestation with rodents which are the primary reservoir hosts of this disease. Some of the populations at risk include: sugarcane plantation workers, wetland farmers, fishermen and abattoir workers. In this study we investigated the prevalence of antibodies against Leptospira among sugarcane plantation and factory workers, fishing communities as well as among rodents and shrews in domestic and peridomestic environments within the study areas.MethodsThe study was conducted in Kagera region, northwestern Tanzania and it involved sugarcane plantation workers (cutters and weeders), sugar factory workers and the fishing community at Kagera Sugar Company in Missenyi district and Musira island in Lake Victoria, Kagera, respectively. Blood was collected from consenting human adults, and from rodents and shrews (insectivores) captured live using Sherman traps. Serological detection of leptospiral antibodies in blood serum was carried out by the microscopic agglutination test (MAT).ResultsA total of 455 participants were recruited from the sugarcane plantation (n = 401) and fishing community (n = 54) while 31 rodents and shrews were captured. The overall prevalence of antibodies against Leptospira in human was 15.8%. Sugarcane cutters had higher seroprevalence than other sugar factory workers. Prevalent antibodies against Leptospira serovars in humans were against serovars Lora (6.8%), Sokoine (5.3%), Pomona (2.4%), Hebdomadis (1.1%) and Kenya (0.2%). Detected leptospiral serovars in reservoir hosts were Sokoine (12.5%) and Grippotyphosa (4.2%). Serovar Sokoine was detected both in humans and small mammals.ConclusionLeptospirosis is a public health threat affecting populations at risk, such as sugarcane plantation workers and fishing communities. Public awareness targeting risk occupational groups is much needed for mitigation of leptospirosis in the study areas and other vulnerable populations in Tanzania and elsewhere

Prevalence of leptospirosis and toxoplasmosis: A study of rodents and shrews in cultivated and fallow land, Morogoro rural district, Tanzania

Leptospirosis and toxoplasmosis are among understudied zoonotic diseases that are also not diagnosed routinely in Tanzania. Humans get leptospirosis and toxoplasmosis through contact with an environment contaminated with Leptospira bacteria and Toxoplasma protozoa from reservoir hosts, which are rodents and cats, respectively. The objective of this study was to determine the prevalence of Leptospira and Toxoplasma infections in rodents and shrews in Mikese area of Morogoro Rural District in eastern Tanzania. A total of 89 rodents and one shrew from cultivated and fallow land were tested for leptospirosis using six Leptospira serovars: Sokoine, Kenya, Canicola, Lora, Hebdomadis and Pomona. Toxoplasmosis was determined in 46 rodents brain smears. The prevalence of leptospirosis was 25.8%, and Leptospira serovar Sokoine was the most prevalent serovar (16.9%). Toxoplasma was detected in one rodent (2.17%) individual while three rodent individuals had Toxoplasma-like parasites hence were considered suspect positive. Findings suggest potential existence of human leptospirosis which needs to be further investigated. Public awareness of leptospirosis and toxoplasmosis should be promoted and their diagnosis considered in patients in health care facilities

Prevalence of leptospirosis and toxoplasmosis: A study of rodents and shrews in cultivated and fallow land, Morogoro rural district, Tanzania

Leptospirosis and toxoplasmosis are among understudied zoonotic diseases that are also not diagnosed routinely in Tanzania. Humans get leptospirosis and toxoplasmosis through contact with an environment contaminated with Leptospira bacteria and Toxoplasma protozoa from reservoir hosts, which are rodents and cats, respectively. The objective of this study was to determine the prevalence of Leptospira and Toxoplasma infections in rodents and shrews in Mikese area of Morogoro Rural District in eastern Tanzania. A total of 89 rodents and one shrew from cultivated and fallow land were tested for leptospirosis using six Leptospira serovars: Sokoine, Kenya, Canicola, Lora, Hebdomadis and Pomona. Toxoplasmosis was determined in 46 rodents brain smears. The prevalence of leptospirosis was 25.8%, and Leptospira serovar Sokoine was the most prevalent serovar (16.9%). Toxoplasma was detected in one rodent (2.17%) individual while three rodent individuals had Toxoplasma-like parasites hence were considered suspect positive. Findings suggest potential existence of human leptospirosis which needs to be further investigated. Public awareness of leptospirosis and toxoplasmosis should be promoted and their diagnosis considered in patients in health care facilities