Which of the following are vector hosts?

Options

A. Rabbit, snake, lizard, frog
B. Sand fly, tse fly, house fly, culex
C. Tse tse fly, Trypanosoma, sand fly, leish-mania
D. House fly, frog, sand fly

Answer

To determine which of the following are vector hosts, we need to identify the options that include organisms that act as vectors for pathogens. Vectors are organisms that carry and transmit pathogens from one host to another, leading to disease.

### Step-by-Step Solution:

1. **Understand the Definition of Vectors**:
- Vectors are organisms that carry pathogens (disease-causing agents) from one host to another. Common examples include certain insects and arthropods.

2. **Review the Options Provided**:
- **Option 1**: Rabbit, snake, lizard, frog
- **Option 2**: Sandfly, tsetse fly, housefly, culex
- **Option 3**: Tsetse fly, Trypanosoma, sandfly, Leishmania
- **Option 4**: Housefly, frog, sandfly

3. **Analyze Each Option**:
- **Option 1**: Rabbit, snake, lizard, frog
- None of these are known vectors for pathogens. They do not transmit diseases.
- **Option 2**: Sandfly, tsetse fly, housefly, culex
- All of these are known vectors. Sandflies transmit leishmaniasis, tsetse flies transmit sleeping sickness, houseflies can carry various pathogens, and Culex mosquitoes can transmit diseases like West Nile virus.
- **Option 3**: Tsetse fly, Trypanosoma, sandfly, Leishmania
- Tsetse fly and sandfly are vectors, but Trypanosoma and Leishmania are pathogens, not vectors. This option is incorrect.
- **Option 4**: Housefly, frog, sandfly
- Housefly and sandfly are vectors, but frog does not transmit diseases. This option is partially correct but includes a non-vector.

4. **Conclusion**:
- The correct answer is **Option 2**: Sandfly, tsetse fly, housefly, culex, as all of these are recognized vectors for various pathogens.

### Final Answer:
The vector hosts among the options provided are: **Sandfly, tsetse fly, housefly, culex** (Option 2).